CA1228647A - Method and apparatus for cardiogoniometry - Google Patents
Method and apparatus for cardiogoniometryInfo
- Publication number
- CA1228647A CA1228647A CA000421431A CA421431A CA1228647A CA 1228647 A CA1228647 A CA 1228647A CA 000421431 A CA000421431 A CA 000421431A CA 421431 A CA421431 A CA 421431A CA 1228647 A CA1228647 A CA 1228647A
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- CA
- Canada
- Prior art keywords
- electrodes
- qrs
- signals
- determining
- vector
- Prior art date
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/316—Modalities, i.e. specific diagnostic methods
- A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
- A61B5/339—Displays specially adapted therefor
- A61B5/341—Vectorcardiography [VCG]
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/316—Modalities, i.e. specific diagnostic methods
- A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
- A61B5/327—Generation of artificial ECG signals based on measured signals, e.g. to compensate for missing leads
Abstract
ABSTRACT OF THE DISCLOSURE
A cardiogoniometry or vector cardiography system wherein signals directly derived from the bioelectrical field are not directly processed as orthogonal data but are instead especially orthogonalized in an analog computing network. Orthogonalization is based on a derivation electrode configuration space with sloping sagittal and frontal planes. The orthogonalized signals are processed in a cardiogoniometer and are also jointly recorded on a commercial electrocardiograph in parallel thereto. All the represented data which can be used for diagnosis purposes are referenced to a biological zero line, which differs from the electrical neutral point.
The cardiogoniometer permits a vectorial real time measurement on the patient.
A cardiogoniometry or vector cardiography system wherein signals directly derived from the bioelectrical field are not directly processed as orthogonal data but are instead especially orthogonalized in an analog computing network. Orthogonalization is based on a derivation electrode configuration space with sloping sagittal and frontal planes. The orthogonalized signals are processed in a cardiogoniometer and are also jointly recorded on a commercial electrocardiograph in parallel thereto. All the represented data which can be used for diagnosis purposes are referenced to a biological zero line, which differs from the electrical neutral point.
The cardiogoniometer permits a vectorial real time measurement on the patient.
Description
1~286~7 This invention relates to the field of cardiogram pry, particularly vector cardiography, and more spoof-gaily relates to a cardiogoniometry process involving the spatial vector representation of electrical quanta-ties of the heart, and a eardiogoniometer for processing these electrical quantities and for representing the parameter.; derived therefrom for the deaconesses of heart diseases.
The evaluation of an eleetroeardiocJram includes the determination of the maximum voter in the electrical QRS quantity in the frontal plane and is described ho such terms as "left position", "steep position", eta.
In addition, the direction of the depolarization vector, i.e., the behavior of -the electrically detectable T-wave, is, considered, particularly with respect to the duration of the QRS-vector (concordallt or diseordallt behavior of the T-wave). An example is the behavior of the R and T components in -the course of a myoeardial infarction and the recovery therefrom. over, these evaluations are only possible in a roughly qualitative manner end, in addition, they are of tell considerably falsified by projection-caused errors because they are based only on the projection of these vectors on a plane
The evaluation of an eleetroeardiocJram includes the determination of the maximum voter in the electrical QRS quantity in the frontal plane and is described ho such terms as "left position", "steep position", eta.
In addition, the direction of the depolarization vector, i.e., the behavior of -the electrically detectable T-wave, is, considered, particularly with respect to the duration of the QRS-vector (concordallt or diseordallt behavior of the T-wave). An example is the behavior of the R and T components in -the course of a myoeardial infarction and the recovery therefrom. over, these evaluations are only possible in a roughly qualitative manner end, in addition, they are of tell considerably falsified by projection-caused errors because they are based only on the projection of these vectors on a plane
- 2 - 12286~7 but fail to take account of the divergence of the vectors or of components thereof perpendicular to the plane.
The following conclusions can be drawn on the basis of the ambiguity of the projections known from the representing geometry. All HOG derivations are project lions of the true angle in space onto a plane. It is standard practice to consider a concordant T as normal and a discordant T as abnormal. Both can be correct, but as a result of the ambiguity of the projections, both can also be incorrect. Experience has shown that it is very difficult to evaluate a T-wave as to whether it is normal or pathological.
Thus, it is not possible to make a conclusive evaluation without knowing the behavior of the two associated vectors in space. It is therefore necessary to use a three-dimensional or orthogonal derivation system to obtain more accurate information and for quantitatively determining changes to the maximum vectors of QRS and T.
The presently recognized method for the construe-lion of orthogonal derivations (Paul I,ichtlen, Clownish Vektor-Ele~ktrokardiographie, published by Springer, Berlin, Heidelberg, New York) consists of measuring individual local electrical voltages on the surface of a thorax model, the voltages being produced by an internally introduced artificial electric dipole.
Accompanied by the upstream connection of a rustiness network, these voltages are combined to form three derivations which corresporld to the projection of the artificial electric dipole on the frontal, sagittal and horizontal planes of the thorax model. This takes place under the idealized assumption that the electrical field is, as a simplification, a dipole with a fixed neutral point.
This constitutes the SVEC III system of Schmitt and Simon son (1955), that of Frank (1956~, and that of ~IcFee r ox c / to and Purring (1961). The reproducabilit~ in all of the systems is good and they are recognized as being equiva-lent to each other. Elowever, even the authors have admitted that all three systems give precise orthogonal derivations of only a model and the orthogonality can not be strictly obtained on humans due to individual variations in body - and individual heterogeneous electrical conductivity characteristics in the tissues surrounding the heart. It is therefore not surprising that measurements on the same test subject with each of the three systems can easily lead to diverging results, with regard to vector direction (azimuth and elevation) as well as to the vector length i.e., the magnitude (Schmitt 1956, Tuna 1980).
A further disadvantage of these three systems is the complicated derivation technology with 14, 7 or 9 electrodes. As a result, the method is complicated for clinical use and is also very fault-prone so that it has not, as yet, become widely used in a routine manner in clinics.
The search for a simpler derivation system has revealed that it should be theoretically possible to construct orthogonal derivations from only four points on the thorax. This idea is not new and, in 1936, Squealing developed a derivation system with four electrodes. using the term "vector diagram", he employed three derivations at right angles to one another, namely a horizontal from two points, the infraclavicular left (point zero) and right (point one), a vertical from point zero downwards to the thorax, approximately to point V of Wilson referred to by Squealing as point three) and a sagittal from point zero to the dorsal (point two). He considered these three derivations as projections of the dipole and, in each case, linked two of these to form a loop which he made visible with a sraun tube. However, this technically simple method proved to be inaccurate and there were distortions of the loop. Duchosal and Solacer (1949) used the same cubic system but, to avoid these distortions, chose the zero point the origin of the system of coordinates of three axes) as far away as possible from the heart, namely in the back of the body to the rear and to the right. However, this system was also not adopted, although the coincidence with the biophysical derivation system SVEC III of Frank and McKee was to all bad of Schmitt, 1956). The lack of precision of all cubic systems is due, inter a _ , to the premise that each bipolar derivation rep-resents the direct projection of the dipole moment of the heart. This cannot be so, because each derivation is merely a potential difference measurement, i.e., a non-directional or sealer quantity, whereas the dipole moment, apart from its magnitude, also has a clearly defined direction, i.e., a Yea-ion character (Irnich, 1976).
The present invention provides a simple and reliable method for obtaining orthogonal projections of vector quantities.
The present invention also provides a process per-milting, on the basis of the derivations in accordance with the invention, a determination of the true angle in space between the maximum vectors of the QRS-loop and the T-loop.
The locations of the two maximum vectors of QRS and T is to be made possible by their projections on two planes.
The present invention again provides an apparatus for performing the method.
According to the present invention there is provided an apparatus for processing electrical signals representative of cardiac activity, the signals being of the type derived from the human body by electrodes arranged in a predetermined pattern on the body, the signals being referenced to a keyword-Nate system, comprising coordinate transformation means for transforming the signals from one coordinate system to another, said coordinate transformation means forming orthogo net projections in the coordinate system based on the space defined by the confirmation of the electrodes, means for same poling the coordinate - transformed signals, and means for evaluating the sampled signals. Preferably, a first one of the electrodes is positioned at point V4 according to Wilson; a second one of the electrodes is positioned at point v8 accord-in to Wilson; a third one of the electrodes lies generally vertically upwardly with respect to the body above the first electrode with respect to the upright body at a distance equal to the distance between the first and second electrodes multi-plied by a factor having a value between 0.6 and 0.8; a fourth one of the electrodes is positioned along a line generally perpendicular to the line between the first and third elect troves and toward the right body side therefrom at a distance equal to the distance between the first and second electrodes multiplied by a factor having a value between about 0.6 and 0.8 such that the first, the second and the fourth electrode together defining a plane (zoo) of a system of orthogonal axes I y and I and said plane corresponding in a statistical range to a plane defined by a spatial vector-loop of the healthy heart. The electrical signals produced by the elect troves are computed to determine parameters of projections of a spatial vector representing the electrical field of the heart on at least one of the planes defined by the axes of said system.
Preferably the coordinate transformation means come proses an analog computer network for forming orthogonal pro-sections in the coordinate system based on the space defined by the configuration of the derivation electrodes. Suitably the apparatus comprises a cardiogoniometer having a switching network, analog circuit means for processing the signals of aye the orthogonal projection and a microprocessor. Desirably the apparatus comprises a cardiogoniometer having a switching net-work, analog circuit means for processing the signals of the orthogonal projection and a microprocessor. In particular the apparatus includes means for parallel recording of x, y and z signals of the orthogonal projections on the coordinates in the space defined by the configuration of the electrodes.
Preferably the apparatus includes means - pa -aye for measuring and indicating time intervals within two heart-beats.
The present invention will be described with reference to the accompanying drawings, wherein:-Fig. 1 is a diagram illustrating the four point elect trove placement and derivation system in accordance with the invention;
Fig. 2 is a diagram illustrating a projection and the formation of a sum vector therefrom;
Fig. 3 is a diagram showing the formation of the iron-tat plane with three derivations;
Fig. 4 is a quadrant diagram of the sloping sagittal plane;
- I -1;~28~L7 Fig. 5 is a tabular presentation of heart parameters in accordance with the invention;
Fig. G is a diagram Chinook talc establishment of a statistical normal range for T and R vector directions in Cartesian coordinates;
Fig. 6' is a diagram showing the fixing of -the range of T and R in polar coordinates;
Fake. PA and 7B, taken together, are a schematic diagram, in block form, of an apparatus in accordance with the invention;
Fly. is a segment of a typical electrocardiogram wave form;
Fig. 9 is a schematic diagram in block form, of an embodiment of a cardiogoniometer in accordance with the invention;
Fig. 10 is a schematic diagram, in block form, of a portion of the vector analyzer of the apparatus of Fig.
9; and Fig. 11 is a diagram illustrating the method in accordance with the invention.
Before going into a detailed description of the invention itself, certain important points will be briefly reviewed. The path -to the development of a new model representative of the dipole moment is opened by temporarily ignoring the individual derivations, i.e., the individual electrical signals derived from the human body by the placemellt of electrodes thereorl, and considering, as a whole, the electrical conditiorls in a plane formed by three derivation points. When using, in the electrocardiocJram, the concept of a closed mesh, e.g., in the fox of Nub derivatiorls D, A wind I, (I.
Nub, Day Brustwarzen - ~lektrokardiogramm, "Ve~rhandluncJ
don Deutschen Gesellschaft fur Kreislaufforschung" vol.
it, p. 177 (1939)) when considering the electrical conditions in a triangle formed by appropriate placement of electrodes (Fig. 1) a relative measure for ~Z2~3647 the size of the dipole moment can be approximately obtained from the magnitude of the deflections of the electrocardiograph.
Naturally, large or small simultaneous deflections will always give the sum zero, corresponding to the rules of Kerchiefs Law. However, when considering the potential differences given by these three derivations as partial vectors, and when they are summed according to the rules of vectorial addition, taking into account the size of the deflections and their polarity on the one hand and the derivation direction on the other, a sum vector is obtained which, in the presently represented model, can be lucid upon as a dipole moment of the hear-t in its en-turret. Thus, V = D + A + I.
On the basis of this, it is possible to obtain three orthogonal projections x, y and z from four near-heart derivation points and without the upstream connection of the previously no-squired resistance network. Derivations D.A. and I are different cues of electrical potential as measured between -two electrodes such as En and En, El and En, and El and En, as shown in Figure 1.
Naturally, i-t is not possible to claim absolute occur-cay for this new vector construction model. This is due to the heterogeneous conductivity characteristics of the tissues sun-rounding the heart, which varies from individual -to individual, but which is of a constant magnitude for an individual patient so that there is no need to correct i-t in -the way which is required in previous empirical or cubic systems (Squealing, Duchosal, etc.). Due to the heterogeneity of the electrical field and, consequently -the lack of knowledge of the electric flux line gradient at the derivation points according to the in-mention, neither the magnitude nor the direction determination of the dipole is completely accurate, but constancy and long-term l~Z8~i47 reproducibility is obtained for the individual patient, as established by hundreds of measurements. This result is greatly assisted by the simple and reliable derivation method in accord dance with the invention.
- - pa -lxxa647 Fig. 1 shows the four-point derivation system in accordance with the invention. The tetrahedral derivation system, which is to be considered in a spatial sense, shows the four electrode attachment points El, En, En and En. These derivation points are connected in the following way: elect troves El and En are connected as a lower pair I, the location of electrode El corresponding to point V4 according to Wilson and is, indeed, 5ICR (intercostal space) and MEL
(medioclavicular line), and point En which is sagittal to En, and which corresponds to point V8 according to Wilson. Derive-lion point En is perpendicularly above point El and with a preferred spacing of 1/ times the distance from El to En, this dimension being vertical and designated V. The horizontal dimension H defined by points En and En is arranged horizontally and extends toward the right hand side of the patient also for a distance 1/ times the distance between El and En. Reference is also made to the dorsal derivation D
defined by points En, En, and the anterior derivation A (El, En), the spacing between which is determined by the previously described relationships. An additional perpendicular form point En to the anterior derivation is designated zoo In this representation, the plane containing A and I represents the sloping sagittal zoo plane, Z and A represents the frontal ye plane, and ZOO and z,x-plane. The pair of derivation points En, En is an unused plane and, as a redundant pair, is not taken into consideration. This does not mean, however, that diagnostically relevant information cannot be gathered from this derivation.
The two derivation points En, En are relatively uncritical with respect to their positions relative to the patient's heart; in other words, manipulation deviations within certain limits during the fitting of these electrodes 122~3647 always lead to the same result. The derivation point with electrode En is located on relatively displaceable tissue per-pendicularly above the heart apex electrode El, whose position must be very accurately determined. This derivation point En is displaced relative to the geometry employed and, cons-quaintly, the heart, particularly during position changes of the patient during the measurement. However, this does not lead to erroneous measurements. The electrode 3 has limited sensitivity to displacement of the tissue or to location errors which can be looked upon as an advantage of the meat surmount technique. The measurement is not significantly influenced by position changes of the patient. It is pointed out that distinctions are always made between x,y,z-projec-lions and the corresponding electrical derivations or their signals.
The electrodes are fitted to the patients in the following way for the derivation:
1. El corresponding to point V4 (Wilson) equals 5 ICY and MEL;
2. En sagittal to El (corresponding to point v8, Wilson);
The following conclusions can be drawn on the basis of the ambiguity of the projections known from the representing geometry. All HOG derivations are project lions of the true angle in space onto a plane. It is standard practice to consider a concordant T as normal and a discordant T as abnormal. Both can be correct, but as a result of the ambiguity of the projections, both can also be incorrect. Experience has shown that it is very difficult to evaluate a T-wave as to whether it is normal or pathological.
Thus, it is not possible to make a conclusive evaluation without knowing the behavior of the two associated vectors in space. It is therefore necessary to use a three-dimensional or orthogonal derivation system to obtain more accurate information and for quantitatively determining changes to the maximum vectors of QRS and T.
The presently recognized method for the construe-lion of orthogonal derivations (Paul I,ichtlen, Clownish Vektor-Ele~ktrokardiographie, published by Springer, Berlin, Heidelberg, New York) consists of measuring individual local electrical voltages on the surface of a thorax model, the voltages being produced by an internally introduced artificial electric dipole.
Accompanied by the upstream connection of a rustiness network, these voltages are combined to form three derivations which corresporld to the projection of the artificial electric dipole on the frontal, sagittal and horizontal planes of the thorax model. This takes place under the idealized assumption that the electrical field is, as a simplification, a dipole with a fixed neutral point.
This constitutes the SVEC III system of Schmitt and Simon son (1955), that of Frank (1956~, and that of ~IcFee r ox c / to and Purring (1961). The reproducabilit~ in all of the systems is good and they are recognized as being equiva-lent to each other. Elowever, even the authors have admitted that all three systems give precise orthogonal derivations of only a model and the orthogonality can not be strictly obtained on humans due to individual variations in body - and individual heterogeneous electrical conductivity characteristics in the tissues surrounding the heart. It is therefore not surprising that measurements on the same test subject with each of the three systems can easily lead to diverging results, with regard to vector direction (azimuth and elevation) as well as to the vector length i.e., the magnitude (Schmitt 1956, Tuna 1980).
A further disadvantage of these three systems is the complicated derivation technology with 14, 7 or 9 electrodes. As a result, the method is complicated for clinical use and is also very fault-prone so that it has not, as yet, become widely used in a routine manner in clinics.
The search for a simpler derivation system has revealed that it should be theoretically possible to construct orthogonal derivations from only four points on the thorax. This idea is not new and, in 1936, Squealing developed a derivation system with four electrodes. using the term "vector diagram", he employed three derivations at right angles to one another, namely a horizontal from two points, the infraclavicular left (point zero) and right (point one), a vertical from point zero downwards to the thorax, approximately to point V of Wilson referred to by Squealing as point three) and a sagittal from point zero to the dorsal (point two). He considered these three derivations as projections of the dipole and, in each case, linked two of these to form a loop which he made visible with a sraun tube. However, this technically simple method proved to be inaccurate and there were distortions of the loop. Duchosal and Solacer (1949) used the same cubic system but, to avoid these distortions, chose the zero point the origin of the system of coordinates of three axes) as far away as possible from the heart, namely in the back of the body to the rear and to the right. However, this system was also not adopted, although the coincidence with the biophysical derivation system SVEC III of Frank and McKee was to all bad of Schmitt, 1956). The lack of precision of all cubic systems is due, inter a _ , to the premise that each bipolar derivation rep-resents the direct projection of the dipole moment of the heart. This cannot be so, because each derivation is merely a potential difference measurement, i.e., a non-directional or sealer quantity, whereas the dipole moment, apart from its magnitude, also has a clearly defined direction, i.e., a Yea-ion character (Irnich, 1976).
The present invention provides a simple and reliable method for obtaining orthogonal projections of vector quantities.
The present invention also provides a process per-milting, on the basis of the derivations in accordance with the invention, a determination of the true angle in space between the maximum vectors of the QRS-loop and the T-loop.
The locations of the two maximum vectors of QRS and T is to be made possible by their projections on two planes.
The present invention again provides an apparatus for performing the method.
According to the present invention there is provided an apparatus for processing electrical signals representative of cardiac activity, the signals being of the type derived from the human body by electrodes arranged in a predetermined pattern on the body, the signals being referenced to a keyword-Nate system, comprising coordinate transformation means for transforming the signals from one coordinate system to another, said coordinate transformation means forming orthogo net projections in the coordinate system based on the space defined by the confirmation of the electrodes, means for same poling the coordinate - transformed signals, and means for evaluating the sampled signals. Preferably, a first one of the electrodes is positioned at point V4 according to Wilson; a second one of the electrodes is positioned at point v8 accord-in to Wilson; a third one of the electrodes lies generally vertically upwardly with respect to the body above the first electrode with respect to the upright body at a distance equal to the distance between the first and second electrodes multi-plied by a factor having a value between 0.6 and 0.8; a fourth one of the electrodes is positioned along a line generally perpendicular to the line between the first and third elect troves and toward the right body side therefrom at a distance equal to the distance between the first and second electrodes multiplied by a factor having a value between about 0.6 and 0.8 such that the first, the second and the fourth electrode together defining a plane (zoo) of a system of orthogonal axes I y and I and said plane corresponding in a statistical range to a plane defined by a spatial vector-loop of the healthy heart. The electrical signals produced by the elect troves are computed to determine parameters of projections of a spatial vector representing the electrical field of the heart on at least one of the planes defined by the axes of said system.
Preferably the coordinate transformation means come proses an analog computer network for forming orthogonal pro-sections in the coordinate system based on the space defined by the configuration of the derivation electrodes. Suitably the apparatus comprises a cardiogoniometer having a switching network, analog circuit means for processing the signals of aye the orthogonal projection and a microprocessor. Desirably the apparatus comprises a cardiogoniometer having a switching net-work, analog circuit means for processing the signals of the orthogonal projection and a microprocessor. In particular the apparatus includes means for parallel recording of x, y and z signals of the orthogonal projections on the coordinates in the space defined by the configuration of the electrodes.
Preferably the apparatus includes means - pa -aye for measuring and indicating time intervals within two heart-beats.
The present invention will be described with reference to the accompanying drawings, wherein:-Fig. 1 is a diagram illustrating the four point elect trove placement and derivation system in accordance with the invention;
Fig. 2 is a diagram illustrating a projection and the formation of a sum vector therefrom;
Fig. 3 is a diagram showing the formation of the iron-tat plane with three derivations;
Fig. 4 is a quadrant diagram of the sloping sagittal plane;
- I -1;~28~L7 Fig. 5 is a tabular presentation of heart parameters in accordance with the invention;
Fig. G is a diagram Chinook talc establishment of a statistical normal range for T and R vector directions in Cartesian coordinates;
Fig. 6' is a diagram showing the fixing of -the range of T and R in polar coordinates;
Fake. PA and 7B, taken together, are a schematic diagram, in block form, of an apparatus in accordance with the invention;
Fly. is a segment of a typical electrocardiogram wave form;
Fig. 9 is a schematic diagram in block form, of an embodiment of a cardiogoniometer in accordance with the invention;
Fig. 10 is a schematic diagram, in block form, of a portion of the vector analyzer of the apparatus of Fig.
9; and Fig. 11 is a diagram illustrating the method in accordance with the invention.
Before going into a detailed description of the invention itself, certain important points will be briefly reviewed. The path -to the development of a new model representative of the dipole moment is opened by temporarily ignoring the individual derivations, i.e., the individual electrical signals derived from the human body by the placemellt of electrodes thereorl, and considering, as a whole, the electrical conditiorls in a plane formed by three derivation points. When using, in the electrocardiocJram, the concept of a closed mesh, e.g., in the fox of Nub derivatiorls D, A wind I, (I.
Nub, Day Brustwarzen - ~lektrokardiogramm, "Ve~rhandluncJ
don Deutschen Gesellschaft fur Kreislaufforschung" vol.
it, p. 177 (1939)) when considering the electrical conditions in a triangle formed by appropriate placement of electrodes (Fig. 1) a relative measure for ~Z2~3647 the size of the dipole moment can be approximately obtained from the magnitude of the deflections of the electrocardiograph.
Naturally, large or small simultaneous deflections will always give the sum zero, corresponding to the rules of Kerchiefs Law. However, when considering the potential differences given by these three derivations as partial vectors, and when they are summed according to the rules of vectorial addition, taking into account the size of the deflections and their polarity on the one hand and the derivation direction on the other, a sum vector is obtained which, in the presently represented model, can be lucid upon as a dipole moment of the hear-t in its en-turret. Thus, V = D + A + I.
On the basis of this, it is possible to obtain three orthogonal projections x, y and z from four near-heart derivation points and without the upstream connection of the previously no-squired resistance network. Derivations D.A. and I are different cues of electrical potential as measured between -two electrodes such as En and En, El and En, and El and En, as shown in Figure 1.
Naturally, i-t is not possible to claim absolute occur-cay for this new vector construction model. This is due to the heterogeneous conductivity characteristics of the tissues sun-rounding the heart, which varies from individual -to individual, but which is of a constant magnitude for an individual patient so that there is no need to correct i-t in -the way which is required in previous empirical or cubic systems (Squealing, Duchosal, etc.). Due to the heterogeneity of the electrical field and, consequently -the lack of knowledge of the electric flux line gradient at the derivation points according to the in-mention, neither the magnitude nor the direction determination of the dipole is completely accurate, but constancy and long-term l~Z8~i47 reproducibility is obtained for the individual patient, as established by hundreds of measurements. This result is greatly assisted by the simple and reliable derivation method in accord dance with the invention.
- - pa -lxxa647 Fig. 1 shows the four-point derivation system in accordance with the invention. The tetrahedral derivation system, which is to be considered in a spatial sense, shows the four electrode attachment points El, En, En and En. These derivation points are connected in the following way: elect troves El and En are connected as a lower pair I, the location of electrode El corresponding to point V4 according to Wilson and is, indeed, 5ICR (intercostal space) and MEL
(medioclavicular line), and point En which is sagittal to En, and which corresponds to point V8 according to Wilson. Derive-lion point En is perpendicularly above point El and with a preferred spacing of 1/ times the distance from El to En, this dimension being vertical and designated V. The horizontal dimension H defined by points En and En is arranged horizontally and extends toward the right hand side of the patient also for a distance 1/ times the distance between El and En. Reference is also made to the dorsal derivation D
defined by points En, En, and the anterior derivation A (El, En), the spacing between which is determined by the previously described relationships. An additional perpendicular form point En to the anterior derivation is designated zoo In this representation, the plane containing A and I represents the sloping sagittal zoo plane, Z and A represents the frontal ye plane, and ZOO and z,x-plane. The pair of derivation points En, En is an unused plane and, as a redundant pair, is not taken into consideration. This does not mean, however, that diagnostically relevant information cannot be gathered from this derivation.
The two derivation points En, En are relatively uncritical with respect to their positions relative to the patient's heart; in other words, manipulation deviations within certain limits during the fitting of these electrodes 122~3647 always lead to the same result. The derivation point with electrode En is located on relatively displaceable tissue per-pendicularly above the heart apex electrode El, whose position must be very accurately determined. This derivation point En is displaced relative to the geometry employed and, cons-quaintly, the heart, particularly during position changes of the patient during the measurement. However, this does not lead to erroneous measurements. The electrode 3 has limited sensitivity to displacement of the tissue or to location errors which can be looked upon as an advantage of the meat surmount technique. The measurement is not significantly influenced by position changes of the patient. It is pointed out that distinctions are always made between x,y,z-projec-lions and the corresponding electrical derivations or their signals.
The electrodes are fitted to the patients in the following way for the derivation:
1. El corresponding to point V4 (Wilson) equals 5 ICY and MEL;
2. En sagittal to El (corresponding to point v8, Wilson);
3. En perpendicularly above En at the distance 0.7 times the distance between El and En;
4. En horizontal to the right side of the patient at a distance of 0.7 times the distance between El and En; and
5. The ground electrode is preferably fitted to the patient's right arm.
This is a preferred procedure for fitting the elect troves to the patient. However, it is pointed out that for the heart diagnosis on animals, only the geometrical electrode configuration appropriate for the particular animal should be used for derivation, while for determining the orthogonal lX~:~3647 derivation it is merely necessary to provide the coordinate transformation stage with adequate parameters. Thus, the invention is - pa -122864~
equally suitable for use in the heart diagnosis of animals and of humans.
When considering subjects with a healthy heart, the vector loop passes from the upper front right to the bottom front left and, after reversal, back again to the upper front right, i.e., the vector loop is to a greater or lesser extent in or parallel to a plane sloping with respect to the sagittal (according to Fly. 1, the area between the three derivation points El, En and En). HOG
derivations in this plane must consequently react in a very sensitive manner to changes of the vector loop and this has been confirmed on well over- 2,000 HOG
measurements. This plane is used for constructing two perpendicularly directed projections, x and y and the frontal plane is used for constructing a projection zoo perpendicular to the Libya plane.
In order to obtain a right triangle as the derivation triangle, which is advantageous for trigonometric reasons, unlike in the case of Nub, point V7 is not chosen as the dorsal derivation point of the triangle inclined with respect to the sagittal.
instead, V8 corresponding to En is chosen which is lay sagittal to point V4, corresponding to El (apex of heart). Thus, a right angle is obtained over the apex derivation A is perpendicular to derivation I
according to conventional HOG terminology. In addition, derivation point V8 corresponding to En can be clearly determined and easily found. By choosing point V8 according to Wilson as a dorsal derivation point, we obtain with points El, En, En a piano? which is hereinafter called the sloping sagittal plane. The derivation designations D, A and I use by Malibu are maintained.
When choosing the y axis of the present orthogonal system parallel to derivation A and the x axis parallel to derivation I, derivation A can not be assumed to be a projection of the vector on axis y and derivation I
1~28647 cannot be considered as a projection of the vector on axis x.
In fact, for vector construction purposes, all three derivations , Jo D, A and I must be victrola added in the form V = D + A + I.
The thus formed summation vector is projected onto the x and y axes, as shown in Fig. 2. The following formulas are obtained after trigonometric calculations:
X = D coy 45 - I = 0.7D - I (1) Y = D sin 45 + A = 0.7D + A (2) An additional vector projection, which is perpendicular to these two axes, is required as the third axes in the ortho-gonad system. This projection zoo is obtained by derivation in the frontal triangle of points El, En and En, points El and En representing the frontal derivation points of -the sloping sag it-tat triangle. Point En is chosen in such a way that it is equip distant from points El and En and a right angle exists between these two lines as shown in Fig. 3. In this way, a right is-cells triangle is obtained. The following derivations apply in this triangle: horizontal derivation H from En to En, Verdi-gal derivation V from En to El, and anterior derivation A from El to En, -this being identical -to derivation A in the sloping sagittal triangle D, A, I. Using -the same procedure, i-t is also possible to construct a vector in this frontal triangle by interlining the simultaneous deflections of the three don-rations in correct sign and axis manner for vector summation.
The interest of this sum vector is its projection on the axis zoo in Fig. 3. This z axis is perpendicular to A from point En and, consequently, is perpendicular to the sloping sagittal plane. As this perpendicular represents the angle bisector of the right angle at point En, this projection zoo of the vector can ode trigonometrically represented as (V - H) sin 45 . When this expression has a positive sign, this vector is below the sloping sagittal 1~28647 plane, whereas with a negative sign it is above the sloping sagittal plane. In other words, the zoo axis is positive when directed downwardly and negative when directed upwardly and is always perpendicular to the sloping sagittal plane, i.e., per-pendicular to axes x and y. In summary, it can be stated the three orthogonal projections x, y and z are:
x = D coy 45 - I = 0.7D - I (1) y = D sin 45 + A = 0.7D + A (2) z = (V-H) sin 45 = 0.7 (V-H) (3) The calculation of the maximum vectors of QRS, P and T and the determination of the solid angle between two of these maximum vectors is performed in accordance with the con-ventional space-trigonometric procedure. The space vectors are designated 1 and 2 and their projections on the x, y and z axes are designated Al, Yule Al' or x2, Yo-yo 2 quantities belonging to an orthogonal, spatial coordinate system.
The formula for the solid angle conventionally used for vector calculation is:
xlx.~ + Yule -t '2.
_ . _ _ _ _ _ _ _ _ _ I 2 -t 2 Jo I 2)(X2 -I Ye 2 The scaler product is represented by the numerator and the product of the absolute values of the two vectors is the denominator. The length of vector 1 is:
Ye Al (Al) while the length of vector 2 is 2 ' Ye -1- ~22 (5") The maximum vector of the depolarization is, consequent-lye that point of the vector loop of QRS whose sum of the quadrants of the three projections x, y and z is greatest, i.e.:
Vmax(QRS)= (xl2 + yo-yo + zl2) Max (6') The same therefore applies for the maximum vector of the T-loop:
VmaX(QRS)= ~(x2 Ye + Z22) Max (6") Apart from the angle , interest is also attached to the position of the maximum vectors in space of QRS
and T, so that it is necessary to determine the project lions of those vectors in the sloping sagittal plane, on the one hand, and in the frontal plane, on the other.
It is pointed out that, for historical reasons in electrocardiography, particularly vector cardiography, the space coordinate axes are designated in a mathemati-gaily non-standard manner, the x, y and z axes being associated with respect to the human body, the origin being located approximately centrally in the torso. The up and down axis along the body length is the y axis, the negative y axis pointing upwardly toward the head and the positive y axis pointing downwardly. The horizontal axis is the x axis, the positive x axis extending to the fight and the negative x axis to the left. The z axis passes transvcrsc1y through the body from front to rear and that portion extending to the front from the center is the positive z axis, the rearward portion being the nugget z axis. This is in accordance with convention the orthogonal system - 14 - ~2Z86~
according to the invention corresponds to the x, y, zoo system shown in ivy 1 and slopes by 45 to thy sagittal.
The sloping sagittal plane, determined by axes x and y, is subdivided into 360 degrees, the Lyon being horizontally to the rear, the 90 line being to the left and downwardly, 180 to the front, and minus 90 upwardly and to the right, as generally illustrated in Fig. 4. The conversion of the orthogonal coordinates x and y into polar coordinates takes place in accordance with the following formulas, the polar angle in the sloping sagittal plane being designated TABLE I
Quadrant I x+, y+ = arc tan Ye (7) II x-, y+ a = arc tan MY- (8) III x-, y- = arc tan -x (9) IV x+, y- = arc tan I (10) As an example, assume x to have a value of -10 and y a value of +15. From the polarity, this vector must be in quadrant II. The value of angle alpha is thus arc tan (15/-10) + 180 = 124. This example is illustrated in the second quadrant, Fig. 4.
The same procedure is used when converting the orthogonal coordinates z and y in tile frontal plane while using, as a basis, the y axis of the sloping sagittal plane such that 0 is to the lower left and 180 slopes upwardly to the right. The base in the frontal plane is consequently 45 to the body axis, i.e., the sloping sagittal and not the horizontal as in lZ28G47 the Frank derivations. The polar angle in the frontal plane is designated beta. Angle beta gives the precise projection of the vector on the frontal plane and, if beta is positive, the vector passes below the sloping sagittal plane. If beta is negative, it passes above the sagittal plane.
The determination of the maximum vectors of QRS, P
and T on the basis of the derivations D, A, I and H, A, V, i.e., the use of the electrical derivations signals, is the function of the cardiogoniometer according to the invention.
The five derivation signals D (Duracell A (anterior), I
(Lowry H (horizontal) and V (Vertical) are formed from the four measuring points En, En, En and En (Fig. l) and in accord dance with the above formulas 1, 2 and 3 converted into the three projections x, y and z. The three resulting time-depen-dent electrical signals form three curved paths corresponding to the projections which are measured at time intervals of, for example, three milliseconds. Finally, these values are stored in a memory for subsequent use. Between the T wave and the following P wave of the next beat, the zero line is deter-mined and corresponding corrections are made. If necessarily of these stored values are referenced to the established zero value. The maximum sum quadrant of x1, Ye and Al on the one hand, and x2, Ye and Z2 on the other is determined. On the basis of this data, the cardiogoniome-ter then calculates the value of coy according to formulas 4 and determined therefrom arccos I.
Thus, almost immediately, the angle of the single given heartbeat is made available. The cardiogoniometer then calculates the angles or, cut, R and T on the basis of formulas 7-10 and this data, including the base data Al, Ye Al' x2, Ye, Z2 are stored. Thus, in all, 11 parameters can be provided for the same heartbeat while the beat interval is available as a Thea parameter. Alternatively, the problem of the slowly varying zero line can be solved with a digital or analog high-pass filter.
For the purpose of checking the cardiogoniometer in operation it is possible, for example, to simultaneously jointly record projections x, y and z on a three-channel elect trocardiograph as illustrated in Fig. 9. The signals complex calculated by the cardiogoniometer are marked on the strips containing the curve traces. As a result, a reading is obtained which corresponds or is similar to the conventional representation of the HOG while there is also a graphic rep-presentation of certain calculated data or actual projections of the derivations. According to a practical embodiment of the cardiogoniometer, six measured quantities ~,~ R, R, I T, a T, as well as the beat interval, are continuously printed on a printer (Fig. 5). In this way, measurement takes place roughly every third heartbeat. Thus, in a short time, a series of measurements can be performed on patients, making it possible to determine statistical values such as the mean value and standard deviation.
As an example, the standard values are determined on a group of 100 test subjects with healthy hearts and fulfill-in the following criteria:
1. No clinical criteria indicating an organic heart disease;
2. Normal HOG in the 12 standard derivations according to the prior art;
3. Constant values for all five parameters I, R, IT, I T according to the invention over an interval of 10 heartbeats, the dispersion being less than plus or minus five degrees, which means that for each heartbeat the depolarize-lion and depolarizations take the same "electrical path'.
lZZ8~i47 The thus determined values read as follows:
- aye -- 17 - l~Z8647 TABLE II
R I T B T
+ 15 89.9 9 498 o 3.2 s 7.9 11.6 7.810.5 8.8 When choosing + 2 standard deviations as the standard limits, the following standard values (rounded off) are obtained for subjects with healthy hearts in the supine position:
= ox to 31 a R = 65 to 115 R = +25 to -10 T = 75 to 120 T = ~20 to -15 This group contained 56 men and 44 women, the age of the test subjects ranging between 14 and 89 years, 95.4% of the cases being statistically covered by plus or minus two standard deviations.
In the normal case, the maximum vectors for depolarization and depolarization are very close together, the true angle in space representing 0 to 31 (15 + 16). With an angle smaller than 31, pathological conditions can still exist if both the depolarization and depolarization are disturbed. Thus, reat importance is attached to the location of R and Max Tax with respect to the sagittal and frontal planes.
These are located in a small circle around the central maxillary line (angle alpha = 90) and slightly above or below the sloping sagittal plane (angle beta = 0).
Fig. 6 graphically illustrates these points.
A divergence of the vectors from this electrical center (according to Fig. 6' and indicated by a longer l~Z8~
vector arrow) to the front, rear, top and bottom and, finally also on the rear surface (referring to the representation on the spherical surface according to Fig. 6') means a pathologic eel finding. Thus, there are typical displacements of the R-vector, e.g., in the case of bundle-branch blocks LOB and/or RUB and other blocks, as well as in the case of R-losses after infractions. Moreover, each depolarization disturbance is manifested by a divergence of the T-vector in the opposite direction from the focus of the lesion.
In the left side position, the heart is generally rearwardly displaced by approximately 10. Thus, with respect to the angle alpha, the standard values are displaced 10 rearwardly to: d R = 55 to 105; T = 65 to 110.
The hitherto widely-held idea that, in the left position, perfusion problems to the right coronary artery (RCA) could occur was confirmed when using the invention in comparison with coronarograms of coronary patients, so that in the left side position in the case of ischemia in the region of the right coronary artery, there is a forward displacement of the T-vector (alpha T becomes larger that 110). There is also an opening for increase in the angle which designates the true angle in the space between the maximum vectors QRS
and T. Thus, as a routine measure, a cardiogoniogram in the left position should always be taken as a small functional test of the RCA.
A more or less pronounced fluctuation of the T-vec-ion values was found in series measurements on patients with coronary insufficiencies in the presence of technically perfect projections x, y and z. The standard deviation of 10 measure-mints is consequently above the arbitrarily fixed value of probably indicating myocardial ischemia. The cardiogoniometer and derivation process according to the invention made it posy I
Sibley for the first time, to observe this phenomenon of floating in a patient in status anginosus shortly before the occurrence of a front wall infarction.
Figs PA and 7B show in simplified form the appear-tusk for performing the process. In Fig. PA, information obtained from the human body is processed in four subsequent stages 10, 20, 30 and 40 up to digitalization. The first stage 10 includes circuit means for obtaining signals from the body and shows the derivations as represented generally in Fig. 1. These derivations are obtained by the derivation pro-cuss according to the invention with the aid of four thorax electrodes El-E4 and a ground electrode EM which is preferably fixed to the right arm. Of the six derivations which can, in principle, be obtained from this tetrahedron, three are fin-early independent and, in the present example, five are used.
The derivation not further identified between points En and En is not used because it is considered to belong to the unite-resting projection plane or is omitted as a redundant pair.
The five derivations used are designated H for horizontal, D
for dorsal, V for vertical, I for lower, and A for anterior.
The electrical signals of these five derivations are fed by derivation stage 10 into the coordinate transformation stage 20 wherein the designed projections are carried out in an orthogonal system. This is performed by a network 22, which is preferably an analog network, although it is also possible to directly process three linearly independent derivations in a digitizing coordinated transformation stage 20. The projections x, y and z pass from the coordinate transformation stage 20 into a sampling stage 30 where they are sampled by sample and hold circuits 32. A multiplexing circuit I converts the information from parallel into series and also forms part of the sampling stage 30.
Sue The serially arranged data representing the indivi-dual projections now passes from sampling stage 30 into a dig-itizing stage 40 which, in a simplified - lea -8~i~7 representation, comprises an analog-to-digi-tal converter 42.
The x, y, z projections are, for example, digitized as eight bit words in this stage, this arrangement having proved adequate for practical purposes. However, for more detailed resolution of the measurements or for discovering still unknown effects within the electrical signals, it is clearly possible to provide a 16-bit or larger word arrangement. Symbolically, the digitized projections are designated (x, Ye Z)di Fig. 7B shows in highly simplified form -the main par-t 50 of the cardiogoniometer in accordance with -the invention, wherein the digitized projections (x, Ye Z)di are converted into the corresponding informative quantities. In accordance with the previously described example, these are angles I, where-in is the true angle in space between -the QRS and or maximum vectors, together with the values OR, IT, OR and IT
related -to the coordinate system. The heartbeat interval is derived, for example, between two QRS flanks. The cardigan-meter part 50 as shown includes a memory 52 continuing the actual heartbeat data, this memory or store being of a random access type; a memory 54 containing the processing program; and a microprocessor 56 which can be, for example, a Motorola Type 6800, and which is used for the data management and also is used in the present cardiogon:iometer for control of the various lung-lions; as well as the symbolically represented switching network 58, for example, a bus system for malting available interesting data from a memory, e.g. memory 64 (Fig. 9), which can naturally also be supplied in serial manner from the cardiogoniometer.
Strictly speaking, the data is only obtained after conversion in peripheral devices such as, for example, a display unit, a printer, a screen or the like, but this simplified description is only intended to show how the electrodes attached to the patient lead to very exact diagnostic results by signal and 1~2864~
data processing.
Fig. 8 shows the various stances for processing of a heartbeat-cycle interval as a function of -time. The -typical picture of an HOG survey is shown in partial form in -the period from a completely acquired QRS-complex wave to a completely acquired QRS+l complex wave. The steep QR-flank is particularly suitable for triggering functional sequences. Following OR
triggering at a threshold value 1, a start is made -to the measure-mint of the beat interval as well as the subdivision of =
(QRS+l-QPS) into various data windows tars; to; to; to; tot;
i.e., into intervals which are to be individually stored, vital importance being attached to the time to. At this point, the base line of the curve is measured then averaged and compared with the electrical neutral point at zero volts (OX). This base line voltage BY is used as a correction value for all of the amplitude dependent quantities such as, for example, the indicated QRS magnitude MARS and represents -the actual biologic eel zero line.
Fig. 9 shows in somewhat more detail the cardigan-meter according to the invention. I've electrical measuring values of the five derivations D, A, I, V and H pass through individual input amplifiers 24 to an analog calculating network 25 which represents the essential part of the coordinate transformation circuit 22 in which is determined the projections x, y and z according to -the given formulas and the signals of the projection quantities are made available. These signals are subsequently amplified in output amplifiers 26 to enable them -to be recorded in a parallel operating cardiograph or its recording instrument and, for this purpose connecting lines 29 are provided.
The x, y, z signals are supplied -through individual amplifiers 31 to sample and hold circuits 32 the sample times of which are determined by signals provided from a control pro-:, 122~3647 gram on line 35 from control circuit 53. In synchronism there-with a multiplexer 34 is controlled for sampling the signals which are provided and this is under -the control of the same control network 53 through line 36. This circuit portion in-corporate the analog signal processing, the analog signals being converted to digital data in analog-to-digital converter 42.
As previously indicated, in -the present embodiment an Betty for-mat is used, but this can he expanded without significant add-tonal expenditure to a 16-bit format. The digital data process sing includes an input circuit 51, a data store 52, shown as a random access memory, and a control program store 54, shown as an EPROM, as well as an associated microprocessor 56. The random access s-tore is used for data storage while -the EPROM is preferred for storing the control program. To have control of the calculated value done by the microprocessor, a digital disk play 57 interfaced ho interface network 55 is used. For more flexibility as to peripheral equipment the bus 58 can be used with, as options, a printer Grow a CP~T-display 63, mass memory means 64 like tapes, floppy-drivers, etc. all interfaced by corresponding interface networks 61. All -these black boxes are subsumized under a port-furl evaluation block 110. As shown in Fig. 7B, -the stored data relate to the digitized heart rhythm curves according to Fig. 8 while -the control program is represented in the strikeout-gram of the process illustrated in Fig. ILL.
A detailed description of the analog--to-digital adapt ton module will be given before the structogram is described.
The network in question is shown in Fig. 10 and includes the x, y and z input amplifiers 31, the outputs of which are connect ted to the associated sample and hold circuits 32. As previously indicated, the sample and hold circuits are synchronized from input circuit 51 to the microprocessor by the control network 53 and control line 35. Apart from the x, y and z data signals, which are at the input end in analog form, the multiplexer receives channel selection instruction O and 1 as well as a multiplexer release instruction from digital input circuit 51.
furthermore, input amplifiers 31 and an intermediate amplifier 38 are controlled from the same circuit as to the level of amply-ligation by means of corresponding signals transmit-ted through line 65. The heart signals from multiplexer 34 which are -to be digitized are intermediately amplified in amplifier 38 and delivered to the ADO 42. This converter is additionally con-netted through a separate line for status indication purposes to input circuit 51 in addition to the data bus. The input air-cult 51 starts the ADO conversion by means of a "convert" signal on a separate line. In the conventional manner, the input air-cult 51 is connected to the microcomputer by means of three bus systems, the data bus, the address bus, and the control bus.
Finally, Fig. 11 shows a Jackson Structogram in Sims plified form. Jackson Structograms are read from -top to bottom and from left to right. Examining this structogram from the left in the drawing, there is in a first stage a learning phase which represents the adaptation of the equipment -to the patient and the establishment of parameters for -the amplification, sampling intervals and beat intervals result from this phase.
For this purpose, -three to six cycles of the type shown in Fig.
8 are used. From the beat intervals, the time measurement bet-wren two heartbeats is obtained, as well as -the patient-specific adaptation of the various data windows shown in Fig. 8. This followed by data acquisition from which are obtained trigger points, the heartbeat intervals, and the offset correction.
The heartbeat signals are continuously sampled, for example, in three millisecond intervals. The values of a heartbeat cycle are stored and evaluated only after the trigger point has been detected. This trigger point is determined by exceeding a pro-lZZ864~7 determined steepness of the OR flank. Trigger point searches and heartbeat interval determinations are accomplished on a repetitive basis. Every third heartbeat can easily be deter-mined at the data conversion rate of the present embodiment.
Every heartbeat can be determined if the necessary additional expenditure for faster circuitry is made.
- aye -Sue In the preliminary development stage, the processing of these signals relates to the calculation of the maximum vectors R and T, the calculation of the quantities R, cut, R, T, etc. as well as the data conversion and preparation.
The calculated quantities are then used for evaluation pun-poses in so-called online readings, i.e., readings of meat surged values are presented on a real-time basis for diagnosis during the measurement on the patient, often called the bed-side method. These include the measuring data readout on a digital display, the readout thereof and of further data on a printer for recording and filling purposes, as well as the readout on a screen in the form of a graph. Then, in so-called off line evaluations, i.e., away from the patient, stored signals from memory 52 are made ready for further data processing, such as statistical evaluation and the like which, transferred to large data files, can be further evaluated with somewhat more complicated programs in larger computers.
It is not possible with prior art electrocardio-graph to completely determine the electrical processes of the heart because such devices only involve measurements in one plane. Such analysis is only possible with a three-dimen-signal derivation system, i.e., vector cardiography. Cardiogo-niometry, as a first stage of bedside vector cardiography, now uses a novel and technically simple three-dimensional derive-lion system which permits the three-dimensional determination of the electrical processes at the patient's side. Initially, it only determines the maximum vectors of the QRS loop and the T loop. The information content of these two quantities is still very large.
It was not previously possible to obtain more come pled evaluations of measured values at the bedside. It was conventional practice, for example as described in US. Patent lZ286~
4,106,495, Kennedy, to collect measured data on the body and record these, followed by their time-consuming evaluation on a computer. It was not unusual for the patient to be dead before his data underwent evaluation. Thus, the virtually direct determination, evaluation and representation of complex relationships within one or a few heartbeats meets a practical need. On-line evaluation makes it possible to observe the reaction of the heart, for example, on a screen, in the case of medical use on the ergometer and with manipulation of all types.
The QRS vector corresponds to the so-called electric eel heart axis. Its position in space is now qualitatively characterized by the terms transverse or lateral position, steep position, horizontal position, left type, etc. In place of these qualitative terms, cardiogoniometry (KIM) provides a direction which is clearly defined in space. Even minor changes to this direction can be established in the course of time, e.g., increases or decreased of heart dilatation or hypertrophy, the development of a left anterior fascicular block, and the like, before it is possible to note any change in the standard electrocardiogram such as when measuring according to the prior art. Changes to the QRS vector in the acute test, such as, for example, the position change of the QRS vector in the left side position, or after stressing or administering medications such as, for example, nitroglycer-ire, make it possible to detect local and small circulation problems in the septet branches of the coronary arteries.
Position changes of the T vector give information on the hear depolarization conditions, i.e., on disturbances of the metabolism or perfusion problems in the myocardium. If there is an ischemia of the rear wall (RCA) the T vector is no longer in the standard region and is, instead, positioned fur-lZZ8~4qther forward. In the case of an ischemia of the front wall (LEA) it is outside the standard range and further to the rear. These changes also appear in the case of local metabolism problems of the front or rear wall. If the - aye -zza6~
myocardium at rest is still sufficiently perfused, then the T-vector will probably still have normal values. In this case a relative ischemia, that is a latent coronary insufficiency may be demonstrated by decreasing the coronary throughput, e.g. by means of nitroglycerine. Nitroglycerine decreases reload as well as the systolic volume. This results in a lower lever of blood pressure. But nitroglycerine also increases the frequency of the heart beat. Both effects tend to reduce the flow -through the coronaries which is especially true for slightly contracted ones. As a result of those effects, the T-vector departs from the ischemic myocard position. This effect is sufficiently distinct so that exercising may not be necessary.
The T-vector may drift in a rather limited area if the coronary-stenosis is not -total or not complete. The earlier mentioned effect called floating can be found by cardigan-metric measurements on a series of heart cycles. This effect may be demonstrated e.g. after short heart s-tops.
Cardiogoniometry may prove very useful for supervision of patients suffering from lucks diseases especially after my-cardiac infarcts or patients submitted to heart surgery, be-cause both vectors reacts very sensitively to disturbances of the circulation with the heart.
As cardiogoniome-try is a non-invasive method lacking of unwanted side-effects it is well adapted to be used for periodic tests of the heart functions and to early detect latent coronary insufficiencies in patients liable to suffer from my-cordial infarctions such as, for example, smokers, diabetics, managers and hydrcholoes-terolmics. As the method acts very sensitively and directly to perfusion problems of the coronary arteries, it should also be suitable for checking heart-active medications.
As the cardiogoniometer does not merely store the lz2a6~7 medium vectors, but, rather, stores both vector loops in tot, it is possible to obtain further quantities or magnitudes in off-line processes. Examples are random intervals such as tQRmaX and OR, or tQTmaX and IT, as well as the representation of a vector X and time X, e.g., initial vectors. It is then possible to display these on a screen which applies not only to the maximum vectors but also the entire QRS and T loops, either individually or in series for showing, for example, a possible floating effect. Thus, an accurate and completely computerized heart diagnosis results and, as a result of the very small size of the cariodgoniometer in accordance with the invention, it is particularly suitable for use in outpatient departments.
This is a preferred procedure for fitting the elect troves to the patient. However, it is pointed out that for the heart diagnosis on animals, only the geometrical electrode configuration appropriate for the particular animal should be used for derivation, while for determining the orthogonal lX~:~3647 derivation it is merely necessary to provide the coordinate transformation stage with adequate parameters. Thus, the invention is - pa -122864~
equally suitable for use in the heart diagnosis of animals and of humans.
When considering subjects with a healthy heart, the vector loop passes from the upper front right to the bottom front left and, after reversal, back again to the upper front right, i.e., the vector loop is to a greater or lesser extent in or parallel to a plane sloping with respect to the sagittal (according to Fly. 1, the area between the three derivation points El, En and En). HOG
derivations in this plane must consequently react in a very sensitive manner to changes of the vector loop and this has been confirmed on well over- 2,000 HOG
measurements. This plane is used for constructing two perpendicularly directed projections, x and y and the frontal plane is used for constructing a projection zoo perpendicular to the Libya plane.
In order to obtain a right triangle as the derivation triangle, which is advantageous for trigonometric reasons, unlike in the case of Nub, point V7 is not chosen as the dorsal derivation point of the triangle inclined with respect to the sagittal.
instead, V8 corresponding to En is chosen which is lay sagittal to point V4, corresponding to El (apex of heart). Thus, a right angle is obtained over the apex derivation A is perpendicular to derivation I
according to conventional HOG terminology. In addition, derivation point V8 corresponding to En can be clearly determined and easily found. By choosing point V8 according to Wilson as a dorsal derivation point, we obtain with points El, En, En a piano? which is hereinafter called the sloping sagittal plane. The derivation designations D, A and I use by Malibu are maintained.
When choosing the y axis of the present orthogonal system parallel to derivation A and the x axis parallel to derivation I, derivation A can not be assumed to be a projection of the vector on axis y and derivation I
1~28647 cannot be considered as a projection of the vector on axis x.
In fact, for vector construction purposes, all three derivations , Jo D, A and I must be victrola added in the form V = D + A + I.
The thus formed summation vector is projected onto the x and y axes, as shown in Fig. 2. The following formulas are obtained after trigonometric calculations:
X = D coy 45 - I = 0.7D - I (1) Y = D sin 45 + A = 0.7D + A (2) An additional vector projection, which is perpendicular to these two axes, is required as the third axes in the ortho-gonad system. This projection zoo is obtained by derivation in the frontal triangle of points El, En and En, points El and En representing the frontal derivation points of -the sloping sag it-tat triangle. Point En is chosen in such a way that it is equip distant from points El and En and a right angle exists between these two lines as shown in Fig. 3. In this way, a right is-cells triangle is obtained. The following derivations apply in this triangle: horizontal derivation H from En to En, Verdi-gal derivation V from En to El, and anterior derivation A from El to En, -this being identical -to derivation A in the sloping sagittal triangle D, A, I. Using -the same procedure, i-t is also possible to construct a vector in this frontal triangle by interlining the simultaneous deflections of the three don-rations in correct sign and axis manner for vector summation.
The interest of this sum vector is its projection on the axis zoo in Fig. 3. This z axis is perpendicular to A from point En and, consequently, is perpendicular to the sloping sagittal plane. As this perpendicular represents the angle bisector of the right angle at point En, this projection zoo of the vector can ode trigonometrically represented as (V - H) sin 45 . When this expression has a positive sign, this vector is below the sloping sagittal 1~28647 plane, whereas with a negative sign it is above the sloping sagittal plane. In other words, the zoo axis is positive when directed downwardly and negative when directed upwardly and is always perpendicular to the sloping sagittal plane, i.e., per-pendicular to axes x and y. In summary, it can be stated the three orthogonal projections x, y and z are:
x = D coy 45 - I = 0.7D - I (1) y = D sin 45 + A = 0.7D + A (2) z = (V-H) sin 45 = 0.7 (V-H) (3) The calculation of the maximum vectors of QRS, P and T and the determination of the solid angle between two of these maximum vectors is performed in accordance with the con-ventional space-trigonometric procedure. The space vectors are designated 1 and 2 and their projections on the x, y and z axes are designated Al, Yule Al' or x2, Yo-yo 2 quantities belonging to an orthogonal, spatial coordinate system.
The formula for the solid angle conventionally used for vector calculation is:
xlx.~ + Yule -t '2.
_ . _ _ _ _ _ _ _ _ _ I 2 -t 2 Jo I 2)(X2 -I Ye 2 The scaler product is represented by the numerator and the product of the absolute values of the two vectors is the denominator. The length of vector 1 is:
Ye Al (Al) while the length of vector 2 is 2 ' Ye -1- ~22 (5") The maximum vector of the depolarization is, consequent-lye that point of the vector loop of QRS whose sum of the quadrants of the three projections x, y and z is greatest, i.e.:
Vmax(QRS)= (xl2 + yo-yo + zl2) Max (6') The same therefore applies for the maximum vector of the T-loop:
VmaX(QRS)= ~(x2 Ye + Z22) Max (6") Apart from the angle , interest is also attached to the position of the maximum vectors in space of QRS
and T, so that it is necessary to determine the project lions of those vectors in the sloping sagittal plane, on the one hand, and in the frontal plane, on the other.
It is pointed out that, for historical reasons in electrocardiography, particularly vector cardiography, the space coordinate axes are designated in a mathemati-gaily non-standard manner, the x, y and z axes being associated with respect to the human body, the origin being located approximately centrally in the torso. The up and down axis along the body length is the y axis, the negative y axis pointing upwardly toward the head and the positive y axis pointing downwardly. The horizontal axis is the x axis, the positive x axis extending to the fight and the negative x axis to the left. The z axis passes transvcrsc1y through the body from front to rear and that portion extending to the front from the center is the positive z axis, the rearward portion being the nugget z axis. This is in accordance with convention the orthogonal system - 14 - ~2Z86~
according to the invention corresponds to the x, y, zoo system shown in ivy 1 and slopes by 45 to thy sagittal.
The sloping sagittal plane, determined by axes x and y, is subdivided into 360 degrees, the Lyon being horizontally to the rear, the 90 line being to the left and downwardly, 180 to the front, and minus 90 upwardly and to the right, as generally illustrated in Fig. 4. The conversion of the orthogonal coordinates x and y into polar coordinates takes place in accordance with the following formulas, the polar angle in the sloping sagittal plane being designated TABLE I
Quadrant I x+, y+ = arc tan Ye (7) II x-, y+ a = arc tan MY- (8) III x-, y- = arc tan -x (9) IV x+, y- = arc tan I (10) As an example, assume x to have a value of -10 and y a value of +15. From the polarity, this vector must be in quadrant II. The value of angle alpha is thus arc tan (15/-10) + 180 = 124. This example is illustrated in the second quadrant, Fig. 4.
The same procedure is used when converting the orthogonal coordinates z and y in tile frontal plane while using, as a basis, the y axis of the sloping sagittal plane such that 0 is to the lower left and 180 slopes upwardly to the right. The base in the frontal plane is consequently 45 to the body axis, i.e., the sloping sagittal and not the horizontal as in lZ28G47 the Frank derivations. The polar angle in the frontal plane is designated beta. Angle beta gives the precise projection of the vector on the frontal plane and, if beta is positive, the vector passes below the sloping sagittal plane. If beta is negative, it passes above the sagittal plane.
The determination of the maximum vectors of QRS, P
and T on the basis of the derivations D, A, I and H, A, V, i.e., the use of the electrical derivations signals, is the function of the cardiogoniometer according to the invention.
The five derivation signals D (Duracell A (anterior), I
(Lowry H (horizontal) and V (Vertical) are formed from the four measuring points En, En, En and En (Fig. l) and in accord dance with the above formulas 1, 2 and 3 converted into the three projections x, y and z. The three resulting time-depen-dent electrical signals form three curved paths corresponding to the projections which are measured at time intervals of, for example, three milliseconds. Finally, these values are stored in a memory for subsequent use. Between the T wave and the following P wave of the next beat, the zero line is deter-mined and corresponding corrections are made. If necessarily of these stored values are referenced to the established zero value. The maximum sum quadrant of x1, Ye and Al on the one hand, and x2, Ye and Z2 on the other is determined. On the basis of this data, the cardiogoniome-ter then calculates the value of coy according to formulas 4 and determined therefrom arccos I.
Thus, almost immediately, the angle of the single given heartbeat is made available. The cardiogoniometer then calculates the angles or, cut, R and T on the basis of formulas 7-10 and this data, including the base data Al, Ye Al' x2, Ye, Z2 are stored. Thus, in all, 11 parameters can be provided for the same heartbeat while the beat interval is available as a Thea parameter. Alternatively, the problem of the slowly varying zero line can be solved with a digital or analog high-pass filter.
For the purpose of checking the cardiogoniometer in operation it is possible, for example, to simultaneously jointly record projections x, y and z on a three-channel elect trocardiograph as illustrated in Fig. 9. The signals complex calculated by the cardiogoniometer are marked on the strips containing the curve traces. As a result, a reading is obtained which corresponds or is similar to the conventional representation of the HOG while there is also a graphic rep-presentation of certain calculated data or actual projections of the derivations. According to a practical embodiment of the cardiogoniometer, six measured quantities ~,~ R, R, I T, a T, as well as the beat interval, are continuously printed on a printer (Fig. 5). In this way, measurement takes place roughly every third heartbeat. Thus, in a short time, a series of measurements can be performed on patients, making it possible to determine statistical values such as the mean value and standard deviation.
As an example, the standard values are determined on a group of 100 test subjects with healthy hearts and fulfill-in the following criteria:
1. No clinical criteria indicating an organic heart disease;
2. Normal HOG in the 12 standard derivations according to the prior art;
3. Constant values for all five parameters I, R, IT, I T according to the invention over an interval of 10 heartbeats, the dispersion being less than plus or minus five degrees, which means that for each heartbeat the depolarize-lion and depolarizations take the same "electrical path'.
lZZ8~i47 The thus determined values read as follows:
- aye -- 17 - l~Z8647 TABLE II
R I T B T
+ 15 89.9 9 498 o 3.2 s 7.9 11.6 7.810.5 8.8 When choosing + 2 standard deviations as the standard limits, the following standard values (rounded off) are obtained for subjects with healthy hearts in the supine position:
= ox to 31 a R = 65 to 115 R = +25 to -10 T = 75 to 120 T = ~20 to -15 This group contained 56 men and 44 women, the age of the test subjects ranging between 14 and 89 years, 95.4% of the cases being statistically covered by plus or minus two standard deviations.
In the normal case, the maximum vectors for depolarization and depolarization are very close together, the true angle in space representing 0 to 31 (15 + 16). With an angle smaller than 31, pathological conditions can still exist if both the depolarization and depolarization are disturbed. Thus, reat importance is attached to the location of R and Max Tax with respect to the sagittal and frontal planes.
These are located in a small circle around the central maxillary line (angle alpha = 90) and slightly above or below the sloping sagittal plane (angle beta = 0).
Fig. 6 graphically illustrates these points.
A divergence of the vectors from this electrical center (according to Fig. 6' and indicated by a longer l~Z8~
vector arrow) to the front, rear, top and bottom and, finally also on the rear surface (referring to the representation on the spherical surface according to Fig. 6') means a pathologic eel finding. Thus, there are typical displacements of the R-vector, e.g., in the case of bundle-branch blocks LOB and/or RUB and other blocks, as well as in the case of R-losses after infractions. Moreover, each depolarization disturbance is manifested by a divergence of the T-vector in the opposite direction from the focus of the lesion.
In the left side position, the heart is generally rearwardly displaced by approximately 10. Thus, with respect to the angle alpha, the standard values are displaced 10 rearwardly to: d R = 55 to 105; T = 65 to 110.
The hitherto widely-held idea that, in the left position, perfusion problems to the right coronary artery (RCA) could occur was confirmed when using the invention in comparison with coronarograms of coronary patients, so that in the left side position in the case of ischemia in the region of the right coronary artery, there is a forward displacement of the T-vector (alpha T becomes larger that 110). There is also an opening for increase in the angle which designates the true angle in the space between the maximum vectors QRS
and T. Thus, as a routine measure, a cardiogoniogram in the left position should always be taken as a small functional test of the RCA.
A more or less pronounced fluctuation of the T-vec-ion values was found in series measurements on patients with coronary insufficiencies in the presence of technically perfect projections x, y and z. The standard deviation of 10 measure-mints is consequently above the arbitrarily fixed value of probably indicating myocardial ischemia. The cardiogoniometer and derivation process according to the invention made it posy I
Sibley for the first time, to observe this phenomenon of floating in a patient in status anginosus shortly before the occurrence of a front wall infarction.
Figs PA and 7B show in simplified form the appear-tusk for performing the process. In Fig. PA, information obtained from the human body is processed in four subsequent stages 10, 20, 30 and 40 up to digitalization. The first stage 10 includes circuit means for obtaining signals from the body and shows the derivations as represented generally in Fig. 1. These derivations are obtained by the derivation pro-cuss according to the invention with the aid of four thorax electrodes El-E4 and a ground electrode EM which is preferably fixed to the right arm. Of the six derivations which can, in principle, be obtained from this tetrahedron, three are fin-early independent and, in the present example, five are used.
The derivation not further identified between points En and En is not used because it is considered to belong to the unite-resting projection plane or is omitted as a redundant pair.
The five derivations used are designated H for horizontal, D
for dorsal, V for vertical, I for lower, and A for anterior.
The electrical signals of these five derivations are fed by derivation stage 10 into the coordinate transformation stage 20 wherein the designed projections are carried out in an orthogonal system. This is performed by a network 22, which is preferably an analog network, although it is also possible to directly process three linearly independent derivations in a digitizing coordinated transformation stage 20. The projections x, y and z pass from the coordinate transformation stage 20 into a sampling stage 30 where they are sampled by sample and hold circuits 32. A multiplexing circuit I converts the information from parallel into series and also forms part of the sampling stage 30.
Sue The serially arranged data representing the indivi-dual projections now passes from sampling stage 30 into a dig-itizing stage 40 which, in a simplified - lea -8~i~7 representation, comprises an analog-to-digi-tal converter 42.
The x, y, z projections are, for example, digitized as eight bit words in this stage, this arrangement having proved adequate for practical purposes. However, for more detailed resolution of the measurements or for discovering still unknown effects within the electrical signals, it is clearly possible to provide a 16-bit or larger word arrangement. Symbolically, the digitized projections are designated (x, Ye Z)di Fig. 7B shows in highly simplified form -the main par-t 50 of the cardiogoniometer in accordance with -the invention, wherein the digitized projections (x, Ye Z)di are converted into the corresponding informative quantities. In accordance with the previously described example, these are angles I, where-in is the true angle in space between -the QRS and or maximum vectors, together with the values OR, IT, OR and IT
related -to the coordinate system. The heartbeat interval is derived, for example, between two QRS flanks. The cardigan-meter part 50 as shown includes a memory 52 continuing the actual heartbeat data, this memory or store being of a random access type; a memory 54 containing the processing program; and a microprocessor 56 which can be, for example, a Motorola Type 6800, and which is used for the data management and also is used in the present cardiogon:iometer for control of the various lung-lions; as well as the symbolically represented switching network 58, for example, a bus system for malting available interesting data from a memory, e.g. memory 64 (Fig. 9), which can naturally also be supplied in serial manner from the cardiogoniometer.
Strictly speaking, the data is only obtained after conversion in peripheral devices such as, for example, a display unit, a printer, a screen or the like, but this simplified description is only intended to show how the electrodes attached to the patient lead to very exact diagnostic results by signal and 1~2864~
data processing.
Fig. 8 shows the various stances for processing of a heartbeat-cycle interval as a function of -time. The -typical picture of an HOG survey is shown in partial form in -the period from a completely acquired QRS-complex wave to a completely acquired QRS+l complex wave. The steep QR-flank is particularly suitable for triggering functional sequences. Following OR
triggering at a threshold value 1, a start is made -to the measure-mint of the beat interval as well as the subdivision of =
(QRS+l-QPS) into various data windows tars; to; to; to; tot;
i.e., into intervals which are to be individually stored, vital importance being attached to the time to. At this point, the base line of the curve is measured then averaged and compared with the electrical neutral point at zero volts (OX). This base line voltage BY is used as a correction value for all of the amplitude dependent quantities such as, for example, the indicated QRS magnitude MARS and represents -the actual biologic eel zero line.
Fig. 9 shows in somewhat more detail the cardigan-meter according to the invention. I've electrical measuring values of the five derivations D, A, I, V and H pass through individual input amplifiers 24 to an analog calculating network 25 which represents the essential part of the coordinate transformation circuit 22 in which is determined the projections x, y and z according to -the given formulas and the signals of the projection quantities are made available. These signals are subsequently amplified in output amplifiers 26 to enable them -to be recorded in a parallel operating cardiograph or its recording instrument and, for this purpose connecting lines 29 are provided.
The x, y, z signals are supplied -through individual amplifiers 31 to sample and hold circuits 32 the sample times of which are determined by signals provided from a control pro-:, 122~3647 gram on line 35 from control circuit 53. In synchronism there-with a multiplexer 34 is controlled for sampling the signals which are provided and this is under -the control of the same control network 53 through line 36. This circuit portion in-corporate the analog signal processing, the analog signals being converted to digital data in analog-to-digital converter 42.
As previously indicated, in -the present embodiment an Betty for-mat is used, but this can he expanded without significant add-tonal expenditure to a 16-bit format. The digital data process sing includes an input circuit 51, a data store 52, shown as a random access memory, and a control program store 54, shown as an EPROM, as well as an associated microprocessor 56. The random access s-tore is used for data storage while -the EPROM is preferred for storing the control program. To have control of the calculated value done by the microprocessor, a digital disk play 57 interfaced ho interface network 55 is used. For more flexibility as to peripheral equipment the bus 58 can be used with, as options, a printer Grow a CP~T-display 63, mass memory means 64 like tapes, floppy-drivers, etc. all interfaced by corresponding interface networks 61. All -these black boxes are subsumized under a port-furl evaluation block 110. As shown in Fig. 7B, -the stored data relate to the digitized heart rhythm curves according to Fig. 8 while -the control program is represented in the strikeout-gram of the process illustrated in Fig. ILL.
A detailed description of the analog--to-digital adapt ton module will be given before the structogram is described.
The network in question is shown in Fig. 10 and includes the x, y and z input amplifiers 31, the outputs of which are connect ted to the associated sample and hold circuits 32. As previously indicated, the sample and hold circuits are synchronized from input circuit 51 to the microprocessor by the control network 53 and control line 35. Apart from the x, y and z data signals, which are at the input end in analog form, the multiplexer receives channel selection instruction O and 1 as well as a multiplexer release instruction from digital input circuit 51.
furthermore, input amplifiers 31 and an intermediate amplifier 38 are controlled from the same circuit as to the level of amply-ligation by means of corresponding signals transmit-ted through line 65. The heart signals from multiplexer 34 which are -to be digitized are intermediately amplified in amplifier 38 and delivered to the ADO 42. This converter is additionally con-netted through a separate line for status indication purposes to input circuit 51 in addition to the data bus. The input air-cult 51 starts the ADO conversion by means of a "convert" signal on a separate line. In the conventional manner, the input air-cult 51 is connected to the microcomputer by means of three bus systems, the data bus, the address bus, and the control bus.
Finally, Fig. 11 shows a Jackson Structogram in Sims plified form. Jackson Structograms are read from -top to bottom and from left to right. Examining this structogram from the left in the drawing, there is in a first stage a learning phase which represents the adaptation of the equipment -to the patient and the establishment of parameters for -the amplification, sampling intervals and beat intervals result from this phase.
For this purpose, -three to six cycles of the type shown in Fig.
8 are used. From the beat intervals, the time measurement bet-wren two heartbeats is obtained, as well as -the patient-specific adaptation of the various data windows shown in Fig. 8. This followed by data acquisition from which are obtained trigger points, the heartbeat intervals, and the offset correction.
The heartbeat signals are continuously sampled, for example, in three millisecond intervals. The values of a heartbeat cycle are stored and evaluated only after the trigger point has been detected. This trigger point is determined by exceeding a pro-lZZ864~7 determined steepness of the OR flank. Trigger point searches and heartbeat interval determinations are accomplished on a repetitive basis. Every third heartbeat can easily be deter-mined at the data conversion rate of the present embodiment.
Every heartbeat can be determined if the necessary additional expenditure for faster circuitry is made.
- aye -Sue In the preliminary development stage, the processing of these signals relates to the calculation of the maximum vectors R and T, the calculation of the quantities R, cut, R, T, etc. as well as the data conversion and preparation.
The calculated quantities are then used for evaluation pun-poses in so-called online readings, i.e., readings of meat surged values are presented on a real-time basis for diagnosis during the measurement on the patient, often called the bed-side method. These include the measuring data readout on a digital display, the readout thereof and of further data on a printer for recording and filling purposes, as well as the readout on a screen in the form of a graph. Then, in so-called off line evaluations, i.e., away from the patient, stored signals from memory 52 are made ready for further data processing, such as statistical evaluation and the like which, transferred to large data files, can be further evaluated with somewhat more complicated programs in larger computers.
It is not possible with prior art electrocardio-graph to completely determine the electrical processes of the heart because such devices only involve measurements in one plane. Such analysis is only possible with a three-dimen-signal derivation system, i.e., vector cardiography. Cardiogo-niometry, as a first stage of bedside vector cardiography, now uses a novel and technically simple three-dimensional derive-lion system which permits the three-dimensional determination of the electrical processes at the patient's side. Initially, it only determines the maximum vectors of the QRS loop and the T loop. The information content of these two quantities is still very large.
It was not previously possible to obtain more come pled evaluations of measured values at the bedside. It was conventional practice, for example as described in US. Patent lZ286~
4,106,495, Kennedy, to collect measured data on the body and record these, followed by their time-consuming evaluation on a computer. It was not unusual for the patient to be dead before his data underwent evaluation. Thus, the virtually direct determination, evaluation and representation of complex relationships within one or a few heartbeats meets a practical need. On-line evaluation makes it possible to observe the reaction of the heart, for example, on a screen, in the case of medical use on the ergometer and with manipulation of all types.
The QRS vector corresponds to the so-called electric eel heart axis. Its position in space is now qualitatively characterized by the terms transverse or lateral position, steep position, horizontal position, left type, etc. In place of these qualitative terms, cardiogoniometry (KIM) provides a direction which is clearly defined in space. Even minor changes to this direction can be established in the course of time, e.g., increases or decreased of heart dilatation or hypertrophy, the development of a left anterior fascicular block, and the like, before it is possible to note any change in the standard electrocardiogram such as when measuring according to the prior art. Changes to the QRS vector in the acute test, such as, for example, the position change of the QRS vector in the left side position, or after stressing or administering medications such as, for example, nitroglycer-ire, make it possible to detect local and small circulation problems in the septet branches of the coronary arteries.
Position changes of the T vector give information on the hear depolarization conditions, i.e., on disturbances of the metabolism or perfusion problems in the myocardium. If there is an ischemia of the rear wall (RCA) the T vector is no longer in the standard region and is, instead, positioned fur-lZZ8~4qther forward. In the case of an ischemia of the front wall (LEA) it is outside the standard range and further to the rear. These changes also appear in the case of local metabolism problems of the front or rear wall. If the - aye -zza6~
myocardium at rest is still sufficiently perfused, then the T-vector will probably still have normal values. In this case a relative ischemia, that is a latent coronary insufficiency may be demonstrated by decreasing the coronary throughput, e.g. by means of nitroglycerine. Nitroglycerine decreases reload as well as the systolic volume. This results in a lower lever of blood pressure. But nitroglycerine also increases the frequency of the heart beat. Both effects tend to reduce the flow -through the coronaries which is especially true for slightly contracted ones. As a result of those effects, the T-vector departs from the ischemic myocard position. This effect is sufficiently distinct so that exercising may not be necessary.
The T-vector may drift in a rather limited area if the coronary-stenosis is not -total or not complete. The earlier mentioned effect called floating can be found by cardigan-metric measurements on a series of heart cycles. This effect may be demonstrated e.g. after short heart s-tops.
Cardiogoniometry may prove very useful for supervision of patients suffering from lucks diseases especially after my-cardiac infarcts or patients submitted to heart surgery, be-cause both vectors reacts very sensitively to disturbances of the circulation with the heart.
As cardiogoniome-try is a non-invasive method lacking of unwanted side-effects it is well adapted to be used for periodic tests of the heart functions and to early detect latent coronary insufficiencies in patients liable to suffer from my-cordial infarctions such as, for example, smokers, diabetics, managers and hydrcholoes-terolmics. As the method acts very sensitively and directly to perfusion problems of the coronary arteries, it should also be suitable for checking heart-active medications.
As the cardiogoniometer does not merely store the lz2a6~7 medium vectors, but, rather, stores both vector loops in tot, it is possible to obtain further quantities or magnitudes in off-line processes. Examples are random intervals such as tQRmaX and OR, or tQTmaX and IT, as well as the representation of a vector X and time X, e.g., initial vectors. It is then possible to display these on a screen which applies not only to the maximum vectors but also the entire QRS and T loops, either individually or in series for showing, for example, a possible floating effect. Thus, an accurate and completely computerized heart diagnosis results and, as a result of the very small size of the cariodgoniometer in accordance with the invention, it is particularly suitable for use in outpatient departments.
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for processing electrical signals representative of cardiac activity, the signals being of the type derived from the human body by electrodes arranged in a predetermined pattern on the body, the signals being refer-enced to a coordinate system, comprising coordinate transfor-mation means for transforming the signals from one coordinate system to another, said coordinate transformation means form-ing orthogonal projections in the coordinate system based on the space defined by the configuration of the electrodes, means for sampling the coordinate - transformed signals, and means for evaluating the sampled signals.
2. An apparatus according to claim 1 wherein said coordinate transformation means comprises an analog computer.
3. An apparatus according to claim 1 comprising means for digitizing said sampled signals.
4. An apparatus according to claim 2 further com-prising a cardiogoniometer having a switching network, analog circuit means for processing the signals of the orthogonal projection and a microprocessor.
5. An apparatus according to claim 1 further com-prising a cardiogoniometer having a switching network, analog circuit means for processing the signals of the orthogonal projection and a microprocessor.
6. An apparatus according to claim 5 including means for parallel recording of x, y and z signals of the orthogonal projections on the coordinates in the space defined by the configuration of electrodes.
7. An apparatus according to claim 6 including means for measuring and indicating time intervals within two heartbeats.
8. An apparatus according to claim 1 comprising the following electrodes laid out on a human body: a first elec-trode located at point V4 according to Wilson; a second elec-trode located at point V8 according to Wilson; a third elec-trode lying generally vertically upwardly with respect to the body above the first electrode with respect to the upright body at a distance equal to the distance between the first and second electrodes multiplied by a factor having a value between 0.6 and 0.8; a fourth electrode lying along a line generally perpendicular to the line between the first and third electrodes and toward the right body side therefrom at a distance equal to the distance between the first and second electrodes multiplied by a factor having a value between about 0.6 and 0.8 such that the first, the second and the fourth electrode together defining a plane (x,y) of a system of orthogonal axes (x, y and z), and said plane corresponding in a statistical range to a plane defined by a spatial vector-loop of a healthy heart.
9. An apparatus according to claim 8 wherein the distances between the first and third electrodes and the dis-tance between the third and fourth electrodes are both equal to the distance between the first and second electrodes multi-plied by 1/?2.
10. An apparatus according to claim 1 comprising the following electrodes laid out on a human body: a first electrode located at point V4 according to Wilson, a second electrode located at point V8 according to Wilson, a third electrode lying substantially vertically above the first elec-trode with respect to the upright body at a distance equal to the distance between the first and second electrode multiplied by a factor having a value between 0.6 and 0.8, a fourth elec-trode lying along a line substantially perpendicular to the line between the first and third electrode and toward the right body side therefrom at a distance equal to the distance between the first and second electrodes multiplied by a factor having a value between about 0.6 and 0.8 such that the first, the second and fourth electrodes together define a plane of location of the axes of said system of orthogonal axes, and said plane substantially corresponding to a plane defined by a spatial vector-loop of a healthy heart.
11. An apparatus according to claim 1 comprising electrodes laid out on a human body such that three said elec-trodes form a plane containing an area defined by the projec-tion of the spatial vector while the spatial vector is execut-ing a heart cycle and whereby this area is maximum, and another said electrode is located outside of said plane.
12. An apparatus according to claim 8 comprising means for computing differences of the values of the electri-cal signal measured between each pair of said electrodes, means for computing a projection of the spatial vector of the electric activity of the heart on planes of a system of axes defined by the locations of the electrodes out of said differ-ences of said values, and means for transforming said computed projections of the spatial vector into projections of the spa-tial vector within the system of orthogonal axes, said ortho-gonal axes defining a plane corresponding to a plane defined by the first, the second and the fourth electrode.
13. An apparatus according to claim 8 comprising means for representing the spatial vector during QRS-portions of the heart cycle.
14. An apparatus according to claim 8 comprising means for representing the spatial vector during T-portions of the heart cycle.
15. An apparatus according to claim 8 comprising means for representing the spatial vector during P-portions of the heart cycle.
16. An apparatus according to claim 8 comprising means for measuring the duration QRS-, T- and P-portions of the heart cycle.
17. An apparatus according to claim 8 comprising means for determining maximum values of the spatial vector, means determining timing relations of such maximum values with respect to the beginning of the QRS-wave of the heart cycle, and means determining both for the QRS-, P- and T-wave of the same heart cycle.
18. An apparatus according to claim 8 comprising means for determining maximum values of the spatial vector, means for determining timing relations of such maximum values with respect to the beginning of the QRS-wave of the heart cycle, and means for determining the angle between two of said maximum values of the spatial vector.
19. An apparatus according to claim 8 comprising means for determining the maximum values of the spatial vec-tor, means of determining timing relations of such maximum values with respect to the beginning of the QRS-wave of the heart cycle, means for determining both said maximum values and said timing relations for the QRS-, P- and T-wave of the same heart cycle and means for computing reference values of the maximum vector according to the principles of statistics.
20. An apparatus according to claim 1 comprising means for determining the maximum values of the spatial vec-tor, means for determining timing relations of such maximum values with respect to the beginning of the QRS-wave of the heart cycle, means for determining both said maximum values and said timing relations for the QRS-, P- and T-wave of the same heart cycle, and means for computing means values and standard deviation values.
21. An apparatus according to claim 8 comprising means for determining the maximum values of the spatial vec-tor, means for determining timing relations of such maximum values with respect to the beginning of the QRS-wave of the heart cycle, means for determining both said maximum values and said timing relations for the QRS-, P- and T-wave of the same heart cycle, and means for establishing a range for nor-met values of the maximum vectors in healthy subjects.
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|---|---|---|---|
| CH89882 | 1982-02-12 | ||
| CH898/82-6 | 1982-02-12 |
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| CA1228647A true CA1228647A (en) | 1987-10-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000421431A Expired CA1228647A (en) | 1982-02-12 | 1983-02-11 | Method and apparatus for cardiogoniometry |
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| EP (1) | EP0086429B1 (en) |
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| DE (1) | DE3380343D1 (en) |
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| ATE35375T1 (en) * | 1984-01-25 | 1988-07-15 | Studer Willi Ag | PROCEDURE FOR DETERMINING THE START AND END POINTS OF CLOSED PHYSIOLOGICAL MEASUREMENT SIGNALS. |
| KR940002772B1 (en) * | 1984-08-31 | 1994-04-02 | 가부시기가이샤 히다찌세이사꾸쇼 | Semiconductor integrated circuit and its manufacturing method |
| DE3536658A1 (en) * | 1985-10-15 | 1987-04-16 | Kessler Manfred | METHOD FOR REPRESENTING ELECTROCARDIOGRAPHIC VALUES |
| EP0278215A1 (en) * | 1987-01-22 | 1988-08-17 | Studer Revox Ag | Method and device for processing signals from a physiologically generated electric field |
| CN1009330B (en) * | 1987-03-30 | 1990-08-29 | 创建基立有限公司 | A kind of computer electrical signal detection blood processor |
| US4850370A (en) * | 1987-07-22 | 1989-07-25 | Dower Gordon E | Method and apparatus for sensing and analyzing electrical activity of the human heart |
| US5010889A (en) * | 1988-02-04 | 1991-04-30 | Bloodline Technology | Intelligent stethoscope |
| US5218969A (en) * | 1988-02-04 | 1993-06-15 | Blood Line Technology, Inc. | Intelligent stethoscope |
| US4961428A (en) * | 1988-05-02 | 1990-10-09 | Northeastern University | Non-invasive method and apparatus for describing the electrical activity of the surface of an interior organ |
| US4949725A (en) * | 1988-07-01 | 1990-08-21 | Bio-Logic Systems Corporation | Apparatus and method for displaying electrical activity generated within a living body |
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1983
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- 1983-02-02 AU AU10927/83A patent/AU570402B2/en not_active Ceased
- 1983-02-07 DE DE8383101139T patent/DE3380343D1/en not_active Expired
- 1983-02-07 ZA ZA83791A patent/ZA83791B/en unknown
- 1983-02-07 US US06/464,765 patent/US4569357A/en not_active Expired - Fee Related
- 1983-02-07 AT AT83101139T patent/ATE45279T1/en active
- 1983-02-07 EP EP83101139A patent/EP0086429B1/en not_active Expired
- 1983-02-11 CA CA000421431A patent/CA1228647A/en not_active Expired
- 1983-02-12 JP JP58020569A patent/JPS58212431A/en active Granted
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1985
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| AU570402B2 (en) | 1988-03-17 |
| ATE45279T1 (en) | 1989-08-15 |
| AU1092783A (en) | 1983-08-18 |
| EP0086429B1 (en) | 1989-08-09 |
| US4569357A (en) | 1986-02-11 |
| EP0086429A2 (en) | 1983-08-24 |
| JPH0347092B2 (en) | 1991-07-18 |
| ZA83791B (en) | 1983-10-26 |
| US4697597A (en) | 1987-10-06 |
| JPS58212431A (en) | 1983-12-10 |
| IL67815A (en) | 1988-01-31 |
| IL67815A0 (en) | 1983-06-15 |
| EP0086429A3 (en) | 1984-10-17 |
| DE3380343D1 (en) | 1989-09-14 |
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