US 3266487 A
Description (OCR text may contain errors)
g- 1966 D. H. WATKINS ETAL 3, 7
HEART PUMP AUGMENTATION SYSTEM AND APPARATUS Filed June 4, 1963 '7 Sheets-Sheei 1 sww TRIGGER PULSE POWER PHASE LAMP PUMP CONTROL ASSEMBLY 0-\ sec WITHDRAWAL PHASE 0-1 sEc POWER PHASE Reg.
INVENTORS Dav/d H. Wafk/ns Erwin J. K//' k Aug. 16, 1966 D. H. WATKlNS ETAL 3,
HEART PUMP AUGMENTATION SYSTEM AND APPARATUS 7 snets-sheet 2 Filed June 4, 1965 mm m/ .EEEIIIII OON INVENTORS Dav/'0' H. Wa/k/ns THE/R ATTO-RNEY 1966 D. H. WATKINS ETAL 3,266,487
HEART PUMP AUGMENTATION SYSTEM AND APPARATUS 7 Sheets-Sheet 4 Filed June 4, 1965 FIG. 5
Q R INVENTORS David H. Waf/r/ns THE 1? ATTORNEY Aug. 16, 1966 D. H. WATKINS ETAL 3,266,437
HEART PUMP AUGMENTATION SYSTEM AND APPARATUS 7 Sheets-Sheet 5 Filed June 4,
INVENTORS David H. Wafk/ns Erw/ J. link BY jx L 1 THE/R ATTORNEY Aug. 16, 1966 Filed June 4, 1963 D. H. WATKINS ETAL HEART PUMP AUGMENTATION SYSTEM AND APPARATUS '7 Sheets-SheetG INVENTORS 00 via H. Wqfk/ns Erw'n J. In BY' fi THE/R ATTORNEY Aug- 16,-1966 D. H. WATKINS ETAL 3,266,487
HEART PUMP AUGMENTATION SYSTEM AND APPARATUS Filed June 4, 1965 7 Sheets-Sheet 7 INVENTORS David H. Wafk/ns Erwin J. K/ink BY 93 an THE/ ATTORNEY United States Patent I r 3,266,487 Ice Patented August 16, 1966 3,266,487 HEART PUMP AUGMENTATION SYSTEM AND APPARATUS David H. Watkins, Denver, Colo., and Erwin J. Klink,
Albuquerque, N. Mex., assignors, by mesne assignments,
to Sundstrand Corporation, Rockford, 11L, a corporation of Illinois Filed June 4, 1963, Ser. No. 285,413 11 Claims. (Cl. 128-1) Our invention relates generally to the art of augmenting natural heart action of an ailing cardiac patient. More particularly, it concerns, in the heart patient, both a method and apparatus for assisting his insufficient natural heart function in required varying extents, ranging up to almost complete substitution for natural heart function.
An object of our invention is to provide a method and apparatus for assisting the insufficient natural heart function in the ailing heart patient in relatively simple and direct manner, enabling the heart itself to work against pressures no greater than those encountered in the diastole phase of the natural heart action.
Another object is to produce, as part of apparatus for assisting the insufficient natural heart action of the ailing cardiac patient, pumping apparatus which is inserted internally in the patient in the aorta and which, suitably controlled during the diastole phase, assists or even replaces the heart action in filling the aorta while emptying the related left ventricle of the heart, and which thereafter and during the systolic phase of cycle of heart opera tion, discharges fresh arterial blood from the aorta into the arterial tree, by application of energy applied to said apparatus from a source external of the patient.
A further object is to provide within a heart-assisting system of the type described, a control system external of the patient, for controlling and operating that portion of the assisting apparatus which is introduced within the arterial system of the patient, which control system serves either to phase the action of the assisting apparatus which has been introduced into the patient with his existing natural heart action as a parameter or to replace the same in its entirety, either failure of the system and apparatus itself or unwanted or out-of-phase operation of the same.
Still another object is to provide heart-assistance apparatus involving augmentation apparatus introduced internally of the patient, all as hereinbefore briefly referred to, together with a control system for said internal augmentation apparatus, which control system is disposed externally of the patient.
Other objects and advantages in part will be obvious and in part will be pointed out during the course of the following discussion, taken in the light of the accompanying drawings.
Our invention accordingly may be considered as comprising a method of alleviating the strainon an ailing heart, including a combination of operational steps and the relationship between the same; heart augmentation apparatus introduced into the vascular system of the heart patient, together with the related mechanical-hydraulic auxiliaries of such apparatus, in large part disposed externally of the patient; and an electronic control for said mechanical-hydraulic system, which said electronic control, upon imposition thereon of particular signal, either taken directly or indirectly from the patient, and serving as a parameter for such electronic control or which is imposed empirically upon such electronic control, thereupon initially amplifies and improves the wave form thereof to an extent sufficient to avoid unwanted electrical potentials of the original signal and thereafter determines the rate, related to the number of heart beats, at which assisting action is imparted by the internal augmentation all in manner nearly foolproof against system. As well, our invention comprises the several parts, elements, constructional features, materials of construction, circuitry, both electrical and electronic, together with energizing and controlling fluids employed in and by the internal augmentation system, and the combination of each of the foregoing with one or more of the others, the scope of the application of all of which is more fully recited in the claims at the end of this specification.
In the several views of the drawings, wherein we disclose certain embodiments of our invention which we prefer at present:
FIG. 1 is a somewhat schematic disclosure of the mechanical-hydraulic system and apparatus of our invention for heart-assisting, for service where an internal pump assists the natural heart action;
FIG. 2 is an enlarged vertical section of the pump appearing in the right-hand portion of FIG. 1;
FIG. 3 is a longitudinal section, on enlarged scale of the expandable membrane pump head employed in the system and apparatus of FIG. 1, such pump head being disclosed as inflated and turned on its side, i.e., horizontally, for ease of depiction;
FIG. 4 is a front view of the control panel for the electronic circuitry controlling the pump of FIG. 1;
FIGS. 5, 6, 7 and 8 are electrical circuit diagrams disclosing, respectively, the electrical input to the electronic control system, the manual control of timing rate, the gate delay part of the control system, and the output part of the control system, which latter imposes properly calibrated timing impulses on the control assembly for the pump disclosed in FIG. 1;
FIG. 9 is a timing diagram for the operation of our heart-assisting system and apparatus, having particular reference to imparting proper timing relation of the pump control to the natural heart heat; while FIG. 10 is a partial schematic view of the system of FIG. 1 in which certain alternative features of construction are employed to provide a blood pumping mechanical-hydraulic system for either partial or complete replacement of the natural heart action of the patient, perhaps with an external supply of blood, as where massive hemorrhaging occurs.
Throughout several views of the drawings like reference characters denote like parts.
In order to gain a more ready and thorough understanding of our invention, it may be noted here that situations are frequently encountered in the treatment of heart patients where the patients heart action is simply not sufiicient to supply the patients bodily needs. And this is so, regardless of the reason therefor. Usually, however, this is attributed to a lack of suflicient muscular activity within the heart itself. Frequently the situation is encountered that while the diastolic action of the heart will bring a volume of blood into the left ventricle of the heart sufficient to supply bodily needs, this ventricle will not fully empty into the aorta. Or, should the ventricale fill the aorta with arterial blood, the systolic action of the heart is not thereafter sufficient in itself to completely discharge the blood content of the aorta into the arterial tree. Blood backs up, stagnates, and seriously impairs bodily function. Conveniently, we term this weakness in heart action, heart failure. Heart failure may be so complete that, for all practical purposes, there is no natural action on the part of the patient. In such situations, auxiliary equipment must completely take over the natural heart function.
From the foregoing, it will be understood that any practical auxiliary which will assist the natural heart action in some simple, reliable and predictable manner may be expeeted deservedly to receive wide recognition and acceptanoe within the medical field and as well, to subsenve a strongly practical function. That the problem is difficult, however, is apparent simply upon considering that, despite 1ong-felt and very prominent need for such external assistance, and despite the substantial thought, study and work which have been devoted over the years to this overlying problem, no really practical solution has as yet been evolved, either as a method of treatment or as a physical embodiment of heart-assisting means.
We attribute the failure of the medical researchers to come fonward with an adequate solution of this generalized problem to a number of factors, these largely centering about the inability to secure a predictable and reliable synchronization of external aux'liary equipment with the natural heart function, not only within the selected particular heart heat, but in the selected particular phase thereof. Also the inability to establish and achieve a particular selected ratio of auxiliary assistance as related to the natural heart function.
For one reason or another, therefore, the many p-roposals heretofore propounded by the medical researchers have fallen short of minimum requirements, thereby failing in recognition and acceptance within the healing arts. Either they have proved too costly and too complicated, too diflicult, delicate and/or uncertain to maintain in reliable operation, or impractical of fulfilling minimum requirements of either proper relationship with natural heart action or volumetric response to minimum standards. Other proposals and/or related equipment have failed to respond to minimum standards of adjustability to meet adequately the requirements of the cardiac specialist.
An object of our invention, therefore, is to minimize in substantial measure or even to avoid the many defects di-vidual patient, his natural required as in hemorrhaging, entirely to replace such natural heart action for short assisting in the treatment of the patient; which method,
the natural action of the heart.
And now, turning to a description of our invention, attention is directed to the several views of the drawings. It will be seen that our invention comprises essentially, a pump head which is inserted internally of the patient through his femoral artery, preferably that of the left thigh, up into the aorta. A mechanical-hydraulic pump serves to actuate this internally positioned pump head. In its entirety, this mechanical-hydraulic assisting system is referred to as a heart-assisting pump system. We also refer to this system as the Myocardial Augmentation Pump System, designating of FIG. 1 through control circuitry, which latter is best disclosed in FIGS. 4 through 8, inclusive. This we refer to as our Myocardial Augmentation Instrumentation Sys- 4 HEART-ASSISTANCE PUMP SYSTEM As heretofore indicated, our heart-assistance pump system is essentially mechanical-hydraulic in nature. Herein, we provide pump apparatus indicated generally at 10 in the right-hand portion of FIG. 1, together with both means for energizing the same and controls therefor.
Pump control 11 receives power from a two-wire power cable 12 which usually is channeled through the MAIS control previously referred to, and later to be described. Additionally, pump control apparatus 11 receives triggering impulses through line 13 from the MAIS control system. The several parts of pump control assembly 11 will be described in detail at a later point herein. Power to the pump system during the particular beat in which the natural heart action is being augmented is controlled from pump control 11. This is channeled through leads 14, 15 to a three-way solenoid valve indicated generally at 16, which we conveniently term an automatic gas valve. Valve 16 serves to apply either pressure, or pressure and vacuum as the case may be, to the pump apparatus 10, in accordance with a timing sequence which is imparted through pump control 11. Valve 16 includes a solenoid winding and related parts, indicated generally at 16A.
During the power phase which maintains during a portion of each cycle of operation of the pump apparatus 10, solenoid 16A throws the valve 16B to connect with a compressed gas line 17 in such manner that a supply of compressed gas is fed from a conventional source such as a compressor, pressure cylinder or the like through line 17, valve element 16B and line 18, to the pump apparatus. Conveniently the line 18, as well as lines 17 and 42, the latter to be described, are formed of heavy duty flexible hose having 4 inch internal diameter. The supply of compressed gas preferably is air, although either carbon dioxide (CO or oxygen is satisfactory. During the power phase of the MAPS system, the regulated supply of compressed gas courses line 17, valve 16B, line 18, to the pump apparatus 10. Typically and for economy, we employ a conventional air compressor 18A which conveniently supplies gas at pressures up to 60 pounds per square inch at a rate of up to say 3 cubic feet per minute. We prefer to direct the gas from compressor 18A through pressure-regulating and reducing valve, conventional in nature, disclosed at 19. And we preferably equip valve 19 with a sight gauge 20, conveniently indicating pressure up to 30 psi. Moreover, we equip line 17 with a conventional overload safety valve 21 venting to the atmosphere at a selected pressure, typically 20 p.s.i.
When compressor 18A is employed as a source of compressed gas, rather than supplying such gas from a gas cylinder, it is quite possible that the gas may surge in the line, giving rise to momentary variations in pressure. We guard against such surges and make pressure relatively uniform, by inserting in line 17 a conventional compressed gas accumulator 22 which subserves as a pressure stabilizer. Accumulator 22 conveniently has capacity of 5 gallons, with a pressure range of 0 to 30 psi.
Pump apparatus 10 may be envisioned as comprising, as related to the particular cardiac patient, an external pump 23, together details of the external pump 23 will be discussed largely with relation to the details of the construction disclosed in FIG. 2, while the internal pump head 24 will be discussed largely in relation to the disclosure of FIG. 3.
Pump 23 (see FIG. 2) comprises a split casing 25, here formed of a suitable material such as acrylic resin with polished finish, which is comprised of two opposed and rather deep, pan-like members, circular in cross-section, complemental in nature and each open at one end with an internal pump head 24. The 5 brane 36, flexible tube to be described) are clamped together at selected points about their circumference by suitable conventional and removable clamping means, here disclosed as threaded bolts 27. One such rim 25C is conveniently threaded at suitable locations about its circumference, as at 27A, for the threaded reception and seating of the bolts 27. Conveniently although not necessarily, the pump chamber which is comprised as a composite of the two split casing portions 25, is about 2 to 3 inches in diameter, has internal length from bottom 25B to bottom 25B of approximately 5 inches, and has useful volumetric capacity of approximately 300 cubic centimeters.
We provide a free-floating piston 28 in the split casing 25, conveniently formed of aluminum and which we sometimes refer to as a diaphragm-retaining cup. Conveniently, it has a diameter of 2 /2 inches with depth in the neighborhood of 3 inches. Diaphragm 26 is deep and perhaps semi-molded of reinforced rubber. The diaphragm operates under energization from gas line 18 under the control of the three-way valve 16. A quick disconnect coupling 29 (FIGS. 1 and 2) serves to connect external pump 23 to the fluid-energizing system.
As disclosed, we mount split casing 25 (FIG. 2) on a suitable supporting base 30, conventionally formed of plastic acrylic, through the intermediary of relatively short support legs A having enlarged load-receiving heads 30B. Support legs 30A are made fast to base 30 in desired convenient manner, here disclosed as countersunk screws 32.
What we term the outlet end of the split casing 25, i.e., that end disposed to the right in FIG. 2, is provided in thebottom 2513 with a suitable outlet 33 (FIG. 1), here disclosed as a nylon connector, about which a flexible tube 34 is removably stretched and clamped in position through a conventional hose clamp 35 (see also FIG. 3).
It is to be noted that the membrane 26 divides split casing 25 into two parts, left and right as seen in the drawings and indicated generally as A & B, respectively. These are effectively sealed from each other. Moreover, it is apparent from inspection that the piston 28 is forced to the right in FIG. 2 under positive pressure from the external system, through valve 16 and line 18, while the piston is withdrawn to the left under vacuum from vacuum line, not yet described, when the latter is connected through line 18 and three-Way switch 16 (FIG. I).
The pump head employed in our system and apparatus is itself best illustrated at the bottom right in FIG. 1 as well as in FIG. 2. Here tube 34 (see also FIG. 3), suitably formed of rubber or the like, conveniently is approximately 2 /z feet long externally of membrane 36, with external diameter of one-quarter inch and internal diameter of A of an inch, i.e., with thickness of of an inch. At its free end, remote from casing 25, the flexible tube 34 is attached to and enters within an elongated inflatable membrane 36 approximately 12 inches in length with expanded diameter of about one and a quarter inches. The junction between flexible tube 34 and elongated inflatable member 36 is indicated at 37 (FIG. 3). Membrane 36 is collapsible to a deflated volume of approximately 8.0 cc. While inflated, it occupies a volume of approximately 150 cc. Just interiorally of mem- 34 is sealed to a semi-flexible gas release tube 38 provided with a number of orifices 38A conveniently spaced along the length of the tube 38 and within the collapsible membrane 36. Typically, we form membrane 36 from butyl rubber, reinforced with nylon monofilament. We find this product compatible to the human system and not conducive to undesired coagula- .tion, a typical resisting mechanism to the introduction of foreign bodies into the blood stream.
For the purpose of inflating membrane 36, we elect to employ carbon dioxide as the gaseous vehicle. Should incident occur, as for example, rupture of membrane 36,
,this gas will be absorbed readily into the blood stream withoutdamage to the patient, permitting corrective measures to be taken. Should oxygen or air be employed, however, an embolism might well be encountered. The inflating carbon dioxide (see FIG. 1), is supplied the lowermost portion 25A of split casing 25, corresponding to that disclosed at the right of FIG. 2, through line 39, three-way valve 40 and line 41.
The pressure changes inside of upper chamber A of pump 10 (see FIG. 1) can be monitored on the oscilloscope of the MAIS control assembly by connecting to chamber A through a detector valve 39A to a pressure detector, not shown, in the MAIS assembly. We provide a vacuum 42 which connects through suitable auxiliaries, shortly to be described, to a suitable and conventional source of vacuum 43. While the vacuum source 43 may be of any suitable and conventional type, we elect to employ a vacuum pump, the capacity of which is approximately 3 cubic feet per minute. This pump conveniently is regulated through valve 44 to desired convenient extent, preferably through a range of from about 0 to about 20 inches of mercury. We provide sight gauge 45, registering up to say, about 30 inches of mercury. To smooth out any pulsations which may occur in the action of vacuum pump 43 during its operation and to provide uniform and sufficient vacuum action, we normally elect to branch off the vacuum line 42, as by branch line 46, to a suitable vacuum-equalizing container 47, here disclosed as of approximately 5 gallons capacity. We may provide a suitable hand valve 48 in vacuum line 42.
It is helpful at this stage of the disclosure to note the purpose and operation of the construction so far disclosed. Typically, the surgeon will enter the femoral artery, preferably in the left leg, and gently force the collapsed membrane 36, perhaps expanded to some slight extent to facilitate introduction, along the arterial tree and thence along the length of the aorta to a region just short of the heart valve controlling the outlet from the left ventricle of the heart.
Inflation, or expansion, then deflation, or collapse, of membrane 36 is bad alternately by way of compressed air and vacuum applied to tube 34 through action of pump 23. Compressed air from line 17, during the power phase 11A of pump control apparatus 11, is introduced by way of line 17 and the three-way valve 16, through the line 18 to the inlet side of the external pump 23 (see the left of FIG. 2 and. the top of FIG. 1). It may be noted as concerns the pump control 11, that the trigger-pump control switch 11D provided on this panel permits the selection of receiving triggering impulses from the MAIS trigger pulse 13 (as when the switch 11D is turned downwardly) or of receiving impulses from an external source (as when almost complete heart failure is encountered and the switch 11D is in its upward position in FIG. 1). Lamp 11C is energized during the power phase of the control 11. Adjustment of the power phase 11A will determine the duration of the power phase of the pump operation during the particular heat beat for which pump action is triggered through the electronic control circuitry. Similarly, dial 11B controls the duration, with a span of 0 to 1 second, of the corresponding withdrawal or vacuum phase. The calibrated knob of the power phase control 11A is connected to a potentiometer, a detailed description of which is not necessary to an understanding of this invention.
Recalling that the inflatable membrane 36 is within the aorta, and assuming the time sequence to be such that the first part of the systolic beat of the heart takes place, then the heart valve will open from left ventricle to the aorta. At the same time, membrane 36 is vacuum-deflated, so that instead of occupying a volume of about 150 cc. within the aorta it suddenly is collapsed to occupy only about 8 cc. This provides a blood displacement volume in the aorta of about cc. or less. And under pressure not exceeding the diastolic phase of the patients existing heart action, say in the neighborhood of not more than 70 mm. of mercury, blood flows under the action of the heart muscle together with moderate vacuum assist of the collapsing membrane, from the left ventricle into the space made available in the aorta, filling the same. Upon completion of such systolic phase and with aorta substantially filled, then with the natural heart action the valve closes between ventricle and aorta, The pressure requirement of the heart is at a minimum because instead of calling on the heart to supply the arterial tree, against the back-pressure there obtaining, it merely is required to supply blood to the space provided in the aorta by collapse of the membrane 36. The pressure necessary to supply the arterial tree comes from inflation of the membrane, as noted hereinafter.
At or about the time of heart valve closure, the threeway valve 16 connects the compressed air supply through the several regulating devices and line 17 and line 18, to the inlet end of the external pump 23. During this power phase the piston 28 is forced to the right in FIG. 2 (downwardly in FIG. 1). Carbon dioxide (CO entering through line 39, is forced downwardly in chamber B (to the right in FIG. 2), through flexible tube 34 and into membrane 36, expanding the latter to a volumetric capacity of about 150 cc. Such expansion forces the fresh arterial blood with which the aorta has just been filled, under positive external pressure, out of the aorta and into the arterial tree. This action takes place at a pressure closely approximating the normal pressure maintaining in the healthy patient during the systolic stroke of the natural heart function. Note that it is pump 23 rather than the heart itself which takes the strain of supplying the arterial tree.
During the next or withdrawal phase under control of element B of pump control 10, three-way valve 16 interrupts connection of compressor line 17 with pump line 18. At the same time it establishes connection between vacuum line 42 and pump line 18, so that a vacuum is imposed on the base 28A of piston 28. As a result, this piston 28 is now drawn to the left in FIG. 2 (to the top in FIG. 1). When this action takes place, membrane 36 of the internal pump head 24 is collapsed by drawing the CO up into the chamber B of external pump 23.
During the predetermined succeeding systolic period, the patients heart valve betwen left ventricle and aorta, of course, reopens and blood fills the space in the aorta made available by the collapse of the membrane 36. Actually, the reduced pressure which results in the aorta through collapse of the membrane serves to aid the natural heart function during the systolic phase, by sucking residual blood from the left ventricle. And as previously noted, the back pressure against which the heart operates during the systolic phase is greatly reduced upon collapse of diaphragm 36. During this suction or aspirating action of membrane 36, not only is the left ventricle aspirated, with its open valve, but also to a slight extent, the arterial tree. The algebraic sum total of this difierential action, however, is to reduce the load on the heart muscle, required to discharge from the left ventricle into the aorta.
With the next succeeding closure of the heart valve itself, and filling of the left ventricle, the membrane 36 is again expanded as previously described. The momentarily existing situation is disclosed in FIG. 1. Solenoid valve 16 is energized, whereby positive pressure through lines 17 and 18 forces piston 28 through its related diaphragm 26 downwardly (to the right in FIG. 4), expelling CO gas into expanding membrane 36. This expansion forces blood out of the aorta and into the arterial tree. The lengths of time that membrane 36 is either expanded, or continued after an initial trigger impulse is received through line 13 in pump control assembly 11, is determined by adjustments of the pump control 11. These determine the duration of energization or de-energization of valve 16.
Where desired, as appears more fully hereinafter, the membrane 36 may be expanded only on the succeeding second, or succeeding third or other succeeding heart ELECTRONIC CONTROL SYSTEM The electronic control system of our invention consists of three parts: an i put circuit; a gate and delay circuit; and an output circuit. We relate these three circuits to a central control panel which is common to the three circuits and which is shown in front view in FIG. 4. As helpful in understanding the three circuits it is worthy of note that we trigger the action of the MAPS disclosed in FIGS. 1 through 3, respectively, through impulses derived through this electronic control system. The control system is premised on the use of a parameter comprising impulses taken in desired selected manner from the natural heart action of the patient. For example, the control of parameter impulses may be taken directly from the heart beat, i.e., the pulses taken from a suitable region of the patients anatomy, illustratively, the wrist, ankle, temple, knee or the like, each such region having a comparatively fixed and determined relation, unique to itself, to the timing sequence of the cyclical functions Within the heart.
Alternatively, advantage may be taken of the fact that dynamic electrical activity in the form of electrical impulses is evidenced within the heart as an incident to the cyclical physical heart activity. It has been determined through experimentation that such electrical impulse precedes the actual particular physical phase of the heart action by a short time interval ranging from about 0.04 second to about 0.10 second. This phenomenon serves as the basis of the conventional and well known electrocardiograph, the tracings of which, termed electrocardiograms, is customarily referred to as the ECG. The ECG is made up of a number of lines or tracings representing the various phases of the heart action. The ECG can be identified and related to some particular portion of the patients anatomy. In practice and in a particular study, the ECG is taken at a number of points about the patients anatomy, typically the ankles, the wrist and at various local areas around the front and rear of the chest and heart region. Because of its somewhat greater sensitivity, we usually prefer to obtain our desired parameter from a select-ed ECG tracing, this as distinguished from taking such parameter directly from the patients pulse.
In the practice of our invention the specialist selects that ECG tracing which provides the most satisfactory parameter, the controlling criteria being that it be of reasonably good wave form (i.e. relatively free from undesirable electrical potentials caused by external interference or patient reactions) and of requisite intensity (i.e. amplitude of the wave as related to a suitable scale). In our MAIS control the ECG signal is impressed on a suitable oscilloscope, permitting the specialist to visualize the synchronized parameter at all times during his treatment of the patient.
Within the Wave so selected, which from experience We small portion for MAIS control purposes, and this of relatively limited duration. This is advantageous since the shorter the duration of the parameter, the greater is the possibility of obtaining relatively smooth wave form. This selected portion, called the QRS segment, may be taken on the up swing or down swing of the parameter wave as related to the ordinate of the ECG tracing, and on either the positive or negative side of such ordinate. It is so selected, as noted above, as to have the most uniform wave characteristics; that is, as free as possible from ute to about 200 impulses per minute.
A. The input circuit The input circuit of our electronic control system employs the QRS segment which has been momentarily selected in manner just described, utilizing the same to develop and transmit an electric signal, i.e., an electrical wave, which while having the same frequency as the parameter wave (which usually, as has been stated, is the R-wave from the selected ECG) but which has been modified in the electronic circuitry to possess wave form of substantially greater regularity and more desired configuration than the selected parameter, and which is substantially freed of the unwanted electric potentials which are present in the original wave. Accordingly, the input cir cuit produces and transmits to a succeeding gate circuit a monitoring wave of such amplification (typically, some five to twenty times the amplitude of the ECG parameter) as to transmit a proper signal to the gate delay circuit. This we achieve by means of a potentiometer within the input circuit which has a range of generated signal of from +6 volts to 6 volts. The amplification is adjusted to that voltage level at which triggering takes place. This permits variation in the new wave generated in the input circuit to an extent sufficient to nicely compensate for and to cancel out the effect of any undesired irregularity in the original wave form, say the R-wave as taken from the ECG. Illust-ratively, if the R-wave be highly irregular then a carefully selected trigger voltage is required which selects the R-wave only, rather than other present but undesirable waves.
Thus within the input circuit we produce a wave form of desired frequency, form and amplitude free of theundesired electrical potentials present in the original wave as taken from the patient. The wave had is effectively smoothed to the extent that any spurious signals or undesired electrical potentials present are incapable of producing undesired triggering within the MAPS.
B. Gate or delay circuit The synthesized wave just noted is generated in the input circuit. We impress it at the input terminal of the gate circuit disclosed in FIG. 7. The gate circuit serves a dual function: one is to determine the frequency with which the MAPS operates with respect to the related natural heart beat; that is, whether this pumping system works with every beat of the heart, or with every second beat, or with every third beat, or the like. While the frequency with which the pumping system functions possibly may be slowed, within reason, to an algebraic series of any selected magnitude, we find that in practice the specialist will in all likelihood select a frequency of repeat not greater than once in every three natural heart beats. This function of the gate circuit is brought about by a potentiometer adjustment of the charging rate of a related electrical condenser, both included in such circuit. The gate circuit also serves the function, through a potentiometer-controlled electrical circuitry, of determining the moment of discharge as a triggering impulse of a particular wave which has been synthesized in accordance with the aforesaid selection of particular ones of a series of natural heart beats. Also, it determines the duration of such discharge by way of the synthesized wave. Typically, the span of cyclical action within the gate circuit (before the cycle repeats itself) varies from about one second to about three seconds. This corresponds to a triggering impulse, for usual heart action, ranging from one impluse for every heart beat up to a triggering impulse for every third heart beat. Finally, the gate circuit blanks out and prevents any unwanted electrical interference from triggering the MAIS during a predetermined period, and reacting on the MAPS.
Thus, having selected a signal from the patients circu-' latory system and having further selected a particular portion of such signal to serve as a parameter, the specialist imposes this signal on the input selector switch 49 in the control panel 49A as disclosed in FIG. 4. This selector switch 49 accepts such signals, either directly or as suitably amplified through the use of available and known amplifiers, which do not in themselves form part of our invention. The specialist thus relates, in compatible cyclic response, the action of the heart pump of FIGS. 1, 2 and 3, with the natural heart beats of the patient as monitored on the oscilloscope forming part of our electronic control circuitry.
Having reference more particularly to specific disclosure of the input circuit diagrams disclosed in FIGS. 5 and 6, the preamplified impulse from the selected parameter is imposed on selector switch 49 (FIG. 4) at junction 50 (at the extreme left in FIG. 5) where resistor 54 and condenser 52 together form a decoupling network. This decoupling network connects to line 53 through current-limiting resistor 51. The decoupling network blocks feed back into the preamplifier output of undesired high frequency signals imposed on the incoming and preamplified wave.
It is to be noted that with .the input circuit of FIG. 5, resistors 54 and 56 comprise an emitter follower. This emitter follower provides an input of high impedance to the control panel 49A. Collectively, transistors 57 and 58 along with resistors 59, 60, 60A, 61 and 62 form a variable-potentiometer type of differential amplifier.
To best understand the function of the foregoing, assume .that the trigger polarity switch 63 is thrown downwardly in FIG. 5 into its positive position and that as well, the movable contact 64 of the potentiometer is also moved in positive direction. So adjusted, the input circuit operates in response to signal selected from the upward sweep of the natural wave as obtained from the patient, and which serves as a parameter.
Now, with no signal present at the emitter of transistor 55, it follows that the base of transistor 58 will be at ground potential. With, however, the base of transistor 57 biased to some positive level, the emitter of this transistor 57 will tend to rise to the same positive level. It will be noted that since the base of transistor 58 is at ground potential, the positive rise of the emitter of transistor 57 will tend to place transistor 58 in a nonconducting state. Should however, a positive signal be obtained from the input channel which is in excess of the voltage set by movable element 64 of the potentiometer, transistor 58 suddenly becomes conductive. It will thereupon greatly amplify the incoming signal. A sharp drop in voltage is then encountered in the collector of transistor 58. It is this sharp drop in voltage which causes the operation of the Schmitt Trigger, consisting of transistors 65 and 66, together with their associated parts. The sharp drop in voltage at the collector of transistor 66 is differentiated by condenser 67 and resistor 68. Finally, transistor 69 serves as an emitter ifollower output. It is this emitter follower output which triggers the oscilloscope and gate circuits.
As has been indicated in the preliminary and general discussion of the input circuit and its function, a manually operable circuit is provided for operation of the hydraulic pumping system by manual control where desired; for example, where natural heart action of the patient is extremely weak. The manual circuit (see FIG. 6) comprises ohm-ic resistors 70 and 71, condenser 72 and pushbutton switch 73. In the normal position of switch 73,
condenser 72 is allowed to charge to approximately /2 volts. When the manual button 73 is pressed and when switch 49 (FIG. 4) is in the manual position (switch 49 conveniently is an ll-position, double-pole non-shorting rotary switch) then the charge on condenser 72 is placed on the input circuit of FIG. 5. This causes a sharp rise in voltage, and initiates a triggering action. The signail, comprising a new wave reproducing the frequency of the parameter but of improved shape and with requisite amplification (these tWo latter combining to rid the new wave of undesired electrical interference which might inadvertently trigger the MAPS system), has now been conditioned for introduction into the gate circuit.
The signal :from the input circuit disclosed in FIG. 5 or that of FIG. 6, is transmitted to disclosed in FIG. 7, at the left thereof. is operated when the initial signal, taken from the patient, is received into the input circuit and from there applied to the gate circuit. The gate circuit holds up transmitting a new wave to the output circuit as disclosed in FIG. 8, and thence to the auxiliary system, for a calibrated and selected interval of time as determined in terms of units of heart impulses either as observed from the R-wave of the ECG or from any other heart siganl taken either directly or indirectly from the patient and which is thereupon employed as a control or parameter. In the gate circuit, as in the case of the input circuit, we may employ as a parameter any portion of the wave. Usually, we employ a portion Of the QRS complex, generally a selected portion of the R- ave, or from such wave as may be taken directly from the patient.
I low the gate circuit may be viewed as essentially comfourth, fifth, sixth or further beat of the heart, in practice we find that every first, every second or every third beat of the heart gives best results. The second part of the gate circuit, disclosed at the right in FIG. 7, determines the precise position within the new wave corresponding to the selected heart beat at which a triggering impulse is transmitted. In addition it determines the duration of each such triggering impulse.
In operation (see FIG. 7), it is to be noted that the sharp negative spike of the new wave generated in the input circuit and coming into the gate circuit at the left in FIG. 7 from transistor 69 (FIG. 5), is coupled through condensers 76 and 77 into the base of transistor 75. Any positive signals appearing in this circuit are bypassed to ground through half-wave rectifier 78. Transistors 75 and 79 together and along with their associated parts form a flip-flop circuit (i.e. a bi-stable multivibrator). The operation is such that the negative signal received at the base of transistor 75 turns transistor 79 on and transistor 75 oft. As soon as transistor 75 is turned off, its collector rises to approximately +20 volts, and allows condenser 80 to start charging through resistors 81, 82 and 83. When the charge on condenser 80 reaches approximately 10 volts, the uni-junction transistor 84 triggers and discharges its related condenser 80 through resistor 85. This discharge of condenser 80 produces a positive pulse at the junction of resistors 85 and 86. The action of the positive pulse thus produced is to reverse the flip-flop back to its original state, wherein transistor 75 is conductive.
The time required for condenser 80 to reach the trigger level of the uni-junction transistor 84 is determined by the position of adjustable resistor 83. And through such adjustment the time for condenser 80 to reach the trigger level of transistor 84 may be adjusted from approximately 16 milliseconds to 3 seconds. Resistor 82 serves to trim the circuit to provide exactly 3 seconds, while resistor 81 serves to limit the charging current when variable resistor 83 is set to minimum value.
The second part of this gate circuit, disclosed to the right in FIG. 7 and which, as previously noted, determines the position within the selected wave form at which a triggering impulse is to be transmitted, as well as the duration of such triggering impulse, comprises transistors '87, 88 and 89 together with their associated parts. For all practical purposes, this circuit is identical in operation to the first portion of the gate circuit, except that it is triggered by the positive rise of the collector of transistor 75. Proper selection of the values of variable resistor g0, fixed resistor 91 and condenser 92 discharge may be adjusted to a maximum time of 1 second as one extreme, and a minimum time of approximately 12 milliseconds as the other extreme. Variable resistor preferably is a logarithmic potentiometer. This permits maximum resolution. near the shorter delays, thereby giving more sensitive control. The same positive trigger that assists the flip-flop in the first part of the gate circuit is utilized to trigger the heart pump one-shot multivibrator on the Output Board.
C. Output circuit We turn now to the output circuit, best disclosed in FIG. 8. Here the transistors 93, 94 together with their associated parts, form a one-shot multivibrator the duration of the discharge of which is two milliseconds. The output of the multivibrator is connected to the heart pump emitter-follower comprising transistor 95, such coupling being through the relay in the remote control receiver and the trigger ofi-and-on switch 97. Where the remote control switch 98 is in its on position and the trigger off-and-on switch 97 is also in its on position, then the heart pump pulses are controlled by the remote control unit. Where, however, the remote control switch 98 is in its off position (i.e. uppermost in FIG. 8) then only the otf-and-on switch 97 can control the heart pump pulses. Transistor is an emitter-follower. Together with fixed resistor 90 and variable resistor 100,'emitter-follower 95 forms a voltage divider. We provide adjustment within resistor 100 to permit an output varying from zero volts to 5 volts. Uni-junction circuit comprises of transistor 101 and its associated parts, connected to transistor 95, is biased so that condenser 102 is charged to a voltage just below the trigger point of transistor 101.
When a heart pump pulse appears on the emitter of transistor 95, its pulse is diiferentiate-d by condenser 103. The positive spike developed at the emitter of transistor 101 is sufiicient to trigger this transistor into heavy conduction. Condenser 102 is then discharged through the panel lamp 104 (FIG. 4), causing a flash. When condenser 102 discharges and its voltage thereupon drops to momentary low value, related transistor 10 1 ceases to conduct. Condenser 102 is thereupon recharged to a voltage which is determine-d by the voltage divider consisting of fixed resistors 105, 106.
The display output to the gating amplifier is obtained by utilizing a circuit comprised of resistor 107, halfwave rectifier 108, resistor 109 and half-wave rectifier 110. Now, the gate level signal from the gate delay board is normally at a positive level, and this positive level is usually approximately +20 volts. It is to be noted, however, that the heart pump signal from the collector of transistor 94 is normally grounded. By the diode action of half-wave rectifier 108, resistor 1-11 is biased to approximately +5 volts. When an input trigger starts the gate in its delay action, the gate level drops. Transistor 112 is biased off. This is brought about by reason of the positive bias on the emitter of transistor 11 2, which positive bias is obtained through resistor 1'13.
OPERATION Once the heart specialist has determined the exact cardiac problem involved and the nature of the assistance which the patient requires, this ranging from a relatively slight degree of assistance, on say every second or third beat, on up to complete replacement of the natural heart function for the duration of treatment, the specialist inserts the expanding or inflatable membrane 36 through the femoral artery, up through the arterial tree and into the aorta.- The required CO is supplied through line 39 into the external pump assembly 23 and thence through outlet 33 and flexible tube 34 to the membrane 36 as described above.
From the condition and behavior of his patient, the specialist determines whether to use, as the basic impulse on which his electronic system function, the direct pulse action of the patient or some portion of the patients ECG, perhaps as the latter is observed through the oscilloscope. Usually it is a selected wave of the ECG that is employed, the specialist then determining whether it is the positive or negative portion of such wave, and whether it be on the ascending or descending swing that provides a configuration best combining optimum regularity of wave form with requisite amplitude.
Now in the operation of the system and method of our invention, the selected wavefrom the patient is impressed on the input circuit of FIG. 6. And the input circuit amplifies this wave to a value of from live to twenty times that of the original wave. The amplification is to such trigger-voltage level, however, as to insure that no triggering impulse will result from undesired electrical interference within the original wave form. With a highly irregular incoming wave from the patient, as is often the case when the patient is seriously ill, the trigger voltage -level precludes untoward action. The synthesized wave of requisite amplitude and wave form is then impressed upon the gate circuit (FIG. 7). Here triggering frequency is imposed on the wave with relation to-the heart beats, as well as the location and duration of the triggering impulse within the particular heart beat. The output circuit (FIG. 8) imparts this triggering impulse on the pump itself (FIG. 1) in manner illustratively disclosed in FIG. 9.
Having reference to the disclosure of FIG. 9, all described action conveniently is referred to a zero time datum, indicated in a at the left of the figure. Where, for example, the specialist uses the patients R-wave, a portionof this initiates the MAIS oscilloscope sweeps. Of course, as has already been disclosed, the oscilloscope synchronization channel can also be initiated from either the patients arterial blood pressure or from an MAIS internal timer. The zero point also serves as an initiation of the blanking gate interference in the gate circuit of FIG. 7, enduring from zero to as much as 3 seconds. At the same time a pre-set delay in the action of the in- 'flatable membrane 36 (FIGS. 1 and 3) is imparted through adjustment of the dial 115 on the control panel disclosed in FIG. 4. As disclosed in FIG. 9, this delay has been set for 0.1 second. Moreover, it is assumed in FIG. 9 that the blanking gate adjustment at 114 in the control panel of FIG. 4 has been set for 0.8 second, extending from a to d in FIG. 9, and during which time the pump control cannot be recycled.
Position b in the chart of FIG. 9 corresponds to the instant of MAIS output trigger pulse from the output the all adjustment of circuit of FIG. 8. This constitutes the beginning of the power phase of the MAPS system and apparatus of FIG. 1. In the disclosure of FIG. 9 it is assumed that the time interval b-c represents an 0.3 second duration of the power phase as pre-set at 11A in the pump control 11 in FIG. 1. Thus, the time c in FIG. 9 represents the duality of the termination of the power phase b-c and the beginning of-the withdrawal or vacuum phase c-d, the latter enduring for a pre-set time interval of 0.4 second as determines through adjustment of control 1113 in the pump control 11.
From the foregoing it becomes evident that moment d in FIG. 9 represents the termination of the pre-set 0.8 second timing of the blanking gate and the end of the programmed withdrawal phase. For the settings employed, the time interval d-e in FIG. 9 represents a continuation of the withdrawal phase, differing from the first portion of this latter in that during this last 0.2 second, a rest period, the pump control can be triggered or recycled. In FIG. 9 the time interval e-f constitutes a repeat and duplication of the initial delay time interval a-b, having a duration of 0.1 second. The amplitude of the heart pump pulse, as obtained through the electronic control circuitry, is set at a maximum value of from 0 to 5 volts by way of the pump trigger amplitude panel control 116 of FIG. 4.
More generally, it will be seen that FIG. 9 simply discloses a typical application of the operation according to our invention in which, at the end of the 0 to 1 second delay determined by the dial in FIG. 4, an electric impulse is originated for triggering the heart pump of FIG. 1. The electrical or electronic means, as the case may be, provided in the control circuitry is such that a second triggering pulse to the heart pump cannot be supplied until termination of the gate delay, the duration of which within its 0 to 3 second range is fixed through the dial at 114 of the MAIS control panel in FIG. 4, at which time the input signal will again exceed the trigger level. It follows from the foregoing that any unwanted interference which may be encountered in the patient-derived parameter is blocked through proper adjustment of the 0-3 second gate, while the heart pump is triggered at the desired time through proper adjustment of the 01 second delay, proper triggering being noted by a flashing of monitor lamp 104 (FIG. 4). Of course, the heart pump triggering pulse may be halted either temporarily or permanently through control from either the front panel or by remote control, indication of the lack of heart pump triggering being noted through the absence of flashing of the lamp 104.
Referring again to the disclosure of FIG. 4, the particular one of the five modes of operation is determined through adjustment of the dial of the trigger-source selector 39. Thus, the control assembly can be operated from either of two pressure monitors P1, P2, a conventional ECG, a manual control, or from an internal timer. And has been pointed out at earlier points during the course of this description, proper triggering may be obtained on either the positive or the negative slopes of the input signal; and as well, over a wide range of input signal levels. When, however, either the internal timer or manual operation is desired, it becomes necessary to select the positive trigger polarity as obtained through setting the switch 117, and to advance the trigger level control 118 in a positive direction by turning the dial in a clockwise direction. The control panel of FIG. 4 is powered through a main power line (not shown) which, under control of on-off switch 119, is properly protected through a rotatable fuse box 120 on the control panel to the delay switch 115, as in event of short circuit or severe equipment failure. Whether or not power is on is indicated to the remotely-located operator by way of panel lamp 121.
As has been indicated, the trigger source selector 49 selects the signal which is transmitted to the trigger oscilto the 0.3 second gate in the gate circuit, and to the 0.1 second delay in the output circuit. The pushbutton 122 provides a single operation control of all control panel functions When the trigger source selector 49 is placed in its manual position. The function of the trigger polarity switch 117 is to select the slope of the input signal from which a triggering signal is derived. When placed in the positive position (uppermost in FIG. 4) the trigger will be obtained on a portion of the signal rising from a lower level to a higher level. However, when the switch is thrown to its down position in FIG. 4, corresponding to its negative position, then the trigger impulse will be obtained on a portion of the new signal generated in the input circuit of FIG. 5, falling from a higher level to a lower level. The trigger level 118 of course selects the level at which triggering occurs, either plus or minus with respect to the base or reference line, on the oscilloscope trace.
An internal rate dial 123 (FIG. 4) serves to operate the triggering circuits when the trigger source selector 49 has been placed in the internal position. This, as has been stated, corresponds to the situation where there has been massive failure of the heart.
The pump trigger amplitude adjustment 116 permits adjustment of the heart pump rate to a level for satisfactory action of the pump. The remote control oif-on switch 124 permits the remote control of the several circuits within the panel to be deactivated, to prevent interference from causing a loss of heart pump pulses. The flashing lamp 104 indicates that triggering impulses are being transmitted to the heart pump assembly of FIG. 1. Trigger ofl-on switch 125 permits the transmission of trigger impulses to the heart pump assembly of FIG. 1 while adjustments are being made in such assembly.
When the dial 115 of the control panel of FIG. 4 is set to a preselected value, this controls an electric potentiometer Which inserts an electronic signal into the computer amplifier in such manner as to actuate the amplifier. Actuation of the amplifier energizes and closes the power relay at 16A in FIG. 1, for the time for which the dial thereof has been set. When the power relay 16A is closed, it energizes the automatic three-Way valve 16. During the time for which the control 11A has been set, valve 16 permits the passage of air into the pump assembly 23, causing inflation of the expandable membrane 36.
Thus, when the specialist determines precisely when he desires to initiate inflation of the expandable membrane 36, he sets the delay time into the MAIS. The patients R-wave, where this is the wave employed, triggers the MAIS. And following passage of the pre-set time delay as determined at 123 in FIG. 4, the control sends out a trigger impulse to the MAPS of FIG. 1. This MAIS trigger impulse initiates the action of the MAPS, while the power relay 16A closes for the time interval for which it has been pre-set.
Energization of the MAPS of FIG. 1 actuates valve 16 which permits air presure from source 18 to force piston 28 downwardly in pump assembly 23, so that membrane 36 is inflated by C from the pump chamber B. Since membrane 36 is located inside the patients descending aorta, inflation of this membrane causes the aorta to be emptied of blood, forcing the same into the arterial tree above the heart. This action serves to relieve the strain otherwise suffered by the heart. We time this pulsing action to follow the closure of the aortic heart valve.
This power phase period endures usually about /3 of the time of the heart beat, following which the power phase control de-energizes the power relay. This deenergizes valve 16, so that the three-way valve connects the vacuum line to remove air from the chamber A of the gas pump assembly 23. This causes deflation of membrane 36. Blood from the left ventricle passes through the aortic heart valve and refills the void left by the collapsed membrane within the aorta, collapse of loscope sweep,
the membrane actually serving to aspirate the ventricle as noted above.
As an alternate embodiment of our invention, as where it is desired to supply added blood to a patient suffering from massive hemorrhaging, or where it is desired to Withdraw some blood, we provide an external pumping apparatus. This comprises a motor section and an actuator section, these being separated by a flexible diaphragm, together with an air hose connecting to the motor section of the pump and a cannula with flexible connector and visible hose connecting with the actuator section. We construct the motor and actuator sections of plexiglass and nylon for reasons of visibility, and an ease and certainty in cleaning.
The motor section is fitted with two syringe connector outlets, controlled by a suitable 3-Way hand valve, leading to pressure-indicating and measuring devices. The actuator section connects with the arterial cannula by way of flexible connector and visible hose.
In this embodiment of our inventionthe arterial cannula is inserted in the descending aorta of the patient by way of the femoral arteries which are approached from the groin of the patient. Blood is pumped out of and back into the patient by means of the pump connecting with the cannula, the pumping action being had by controlled air pressure and vacuum applied to the motor section of the pump under control of an appropriate solenoid valve. We synchronize action of the pump with the natu-ral action of the heart so that with the systolic action of the heart blood is [taken into the pump. With the diastolic action the blood from the pump is forced into the arterial tree; closure of the heart valve, of course, precludes any feeding of the blood back into the heart itself. Since, as pointed out above, it is the heart-synchronized pumping action of the electro-mechanical pump which takes the strain of forcing blood into and through the arterial tree the Work of the heart is greatly lessened. And, moreover, the action of the pump during systolic heart action aids in clearing the left ventricle.
More particularly, and perhaps preferably, we employ a pair of external pump heads. In FIGQIO we disclose a pair of pumping apparatuses 10 and 10" which are introduced in the system of FIG. 1 in substitution for the single pumping apparatus 10' there disclosed. The cannulae 124' and 1124" are introduced in the left and right femoral arteries, the cannulae themselves, conveniently being fashioned of nylon and appropriately secured to pumps 23 and 23" by couplings '33 and 33", from the system and fresh blood introduced by way of syringes (not shown) connected to valves 125 and 125".
The pumps themselves are powered with gas under pressure, and then put on vacuum, as in the operation of the system of FIG. 1, by way of line 18'. The pumping sections A and A" of the two pumps are, of course, separated from the two actuator sections B and B" by flexible membranes 26 and 26". With the rhythmic action of the pumps the blood of the patient is withdrawn during the stystolic action of the heart and then, with closure of the heart valve itself, re-introduced during the diastolic action to supply the arterial tree, as more fully described above. Fresh blood is added where desired during this re-introducti-on. Or, where desired, metered quantities of blood may be removed from the patient by Way of one or both pumps 5;
Thus it will 'be seen that we provide a system, method and apparatus in which the various objects hereinbefore set forth are successfully achieved. Our system provides an effective degree of blood handling in the quantities necessary for definitive results, with minimal trauma to the blood produced by hemolysis, denaturation of plasma processes, and other accidents incident to hydro-dynamic stress in flowing blood. Our pumping system and apparatus, either internal or external, connected into the ments disclosed, will readily suggest themselve to proved waveform,
descending aorta contributes to lowering the intra-ventricular pressure, and consequently is especially useful in the treatment of congestive heart failure, heart muscle damage attending coronary arterial thrombosis and several degrees of ischemic shock. Our external pumping system, utilizing intra-arterial catheters, is particularly important in the treatment of both hemorrhagic and ischemic shock under conditions where the periods of ischemia have not been overly prolonged. With increased clinical experience, other uses for our system and apparatus will undoubtedly present themselves.
All the foregoing, as well as many other advantages, highly practical in nature, attend the practice of our invention.
It is apparent from the foregoing that once the broad application of our invention is disclosed many embodiments, as well as many modifications of those embodithose we intend the foregoing simply illustrative, and
skilled in the art. Accordingly, disclosure to be considered as not as comprising limitations.
We claim as our invention:
1. A myocardial augmentation system employing as an input a selected portion of one of the patients physiological parameters, comprising: inserted into the patients circulatory system, a pump for delivering fluid to and withdrawing fluid from said cannula means in timed relation to the patients natural heart action, said pump having a pumping chamber, means connecting said cannula means to said pumping chamber; an input circuit for receiving a signal representing the selected parameter of the patient, means for blocking out undesired high frequency signals imposed on the received signal, means for selecting either the upward or downward sweep of the received signal as a control signal, means for selecting the level of the received signal which will initiate a control signal, and means for deriving a control triggering pulse responsive to said selecting means; an intermediate circuit for receiving the control triggering pulse and forming a second control signal in response thereto including means for delaying the second control signal from the triggering pulse, means for blanking any control triggering pulses occurring within a predetermined time period, and means for varying the duration of the second control signal to vary the length of stroke of the pump; and an output circuit for receiving said second control signal and for actuating the pump in response thereto.
2. In a system for assisting the natural action of the human heart, comprising: cannula means capable of being inserted into the patients circulatory system, a reciprocating pumping apparatus for pumping and withdrawing fluid, said pump including a freely floating piston reciprocable within the pump and defining therein an actuating first chamber and a pumping second chamber, flexible seal means separating said chambers, said cannula means being connected in fluid communication to said second chamber, means for supplying fluid under a positive pressure to said first chamber, means for positively selectively withdrawing fluid from said first chamber to control movement of the floating piston; electrical control means for said pumping apparatus including an input circuit having means for producing a new wave of a frequency corresponding to one of the patients physiological parameters and of ima delay circuit for receiving signals from the input circuit including electronic means for transmitting a triggering pulse, an output circuit for transmitting the modulated triggering pulse to said pumping apparatus controls, said pumping controls having means for determining the timing of the pumping and withdrawing of fluid and the duration of the pumping and withdrawing of fluid.
3. A myocardial augmentation system as defined in claim 2 wherein said means for supplying fluid under pressure to said first chamber includes a source of fluid under pressure and said means for withdrawing fluid from said cannula means adapted to be H first chamber includes a vacuum source, and valve means selectively communicating either the pressure source or the vacuum source to said first chamber to effect reciprocating movement of the pump, said seal means including a flexible diaphragm connected to said piston for separating the first and second chambers.
4. In a system for assisting the natural action of the human heart, comprising: cannula means capable of being inserted into the descending aorta of a patient, a reciprocating pumping apparatus for pumping and withdrawing fluid through said cannula means, said pump including a freely floating piston reciprocable within the pump and defining therein an actuating first chamber and a pumping second chamber, flexible seal means separating said chambers, said cannula means being connected in fluid communication to said second chamber; means for sup plying fluid under a positive pressure to said first chamber; means for positively selectively withdrawing fluid from said first chamber to control movement of the floating piston; electrical control means for said pumping apparatus including an input circuit with electronic means for producing a new wave of a frequency corresponding to one of the patients physiological parameters, and of improved waveform and amplitude sufficient to minimize the hazard undesirable triggering of the pumping apparatus, a gate delay circuit for receiving signals from the input circuit including electronic means for transmitting a triggering pulse of predetermined duration to said pump ing apparatus on a predetermined beat of the heart, an output circuit for transmitting the modulated triggering pulse to said pumping apparatus controls, said pump control having means for determining within a selected operating cycle of the pump both the timing of blood out-flow and blood in-flow by way of said cannula means and the duration of each of said out-flow and in-flow phases thereof.
5. A myocardial augmentation system employing as an input a selected portion of one of the patients physiological parameters comprising: cannula means adapted to be inserted into the patients circulatory system, a pump for delivering fluid through said cannula defining a delivery phase and for withdrawing fluid from said cannula means defining a withdrawal phase, both in timed relation to the patients natural heart action, said pump having a pumping chamber, said cannula means being connected in fluid communication to said pumping chamber, means for receiving a signal representing one of the patients physiological parameters, means connected to said receiving means for synthesizing a signal having the same frequency as the patients physiological signal but of improved waveform, a delay circuit for receiving said synthesized signal and for producing a delayed signal in response thereto, means for deriving a pump triggering signal from said delaying means for actuating the pump in timed relation to the patients natural heart action, and selectively operable manually controlled means for activating said means for deriving a pump triggering signal to manually initiate the pumping cycles when the patients physiological parameter is too weak to initiate the pumping operation or when single cycle manual initiation is desired.
6. A myocardial augmentation system as defined in claim 5 wherein said manual control includes a manually operable switch, charging condenser means connected in circuit with said switch for developing a manual trigger signal, and connecting means for connecting said charging condenser means to said delaying means.
7. A myocardial augmentation system employ-ing as an input a selected portion of the patients ECG waveform and particularly the QRS segment thereof, comprising: cannula means adapted to be inserted into the patients circulatory system, a pump for delivering fluid to and withdrawing fluid from said cannula means in timed relation to the patients natural heart action, said pump having a pumping chamber, said cannula means being connected in fluid communication to said pumping chamber, an electronic control circuit for said pump including an input circuit for receiving the ECG Waveform, said input circuit including a differential amplifier responsive to the QRS segment -of the patients ECG waveform, means for varying the threshold level of the differential amplifier so that it responds only to signals above a predetermined level to reduce spurious triggering of the system, means responsive to said difierential amplifier for producing a signal having the same frequency as the patients ECG Wave but of improved Waveform, a delay circuit responsive to said input ducing a triggering pump.
.ing'an input circuit having means for receiving the pa tients ECG waveform, said input circuit including means for select-ing either the upward or the downward sweep of the QRS segment to trigger a control signal, adjustable ment of the pump.
9. A myocardial augmentation system as defined in claim 8 wherein said input circuit includes a differential amplifier, switch means connected to said dilferential am- 10. A myocardial augmentation system employing as an input a selected portion of the patients ECG waveform comprising: cannula means adapted to be inserted into patients natural heart action, said pump having a pumping chamber, said cannula means being connected in fiuid communication to said pumping chamber; and control means for controlling movement of the input circuit, said input circuit having timed relation with the patients QRS segment, for varying the duration of the output signal to vary the Withdrawal phases of the mg multivibrator, said said improved signals, selective means for varying the time constant of the blanking multivibrator so that said multivi'brator remains triggered for a longer period than the period of 1, 2, or 3 of the improved signals so that the blanking multivibrator functions to both triggering during a cardiac cycle and to efiect pumping only on selected QRS Waves as desired.
References Cited by the Examiner UNITED STATES PATENTS 6/1930 Horne 8/ 1946 Desmet.
10/1958 Daughaday 1/1960 Di Vette 5/1960 Donaldson 9/ 1962 Smith 4/1963 Streimer 128-205 7/ 1963 Birtwell 128214 X 8/1963 Steen et a1. 1282.05
OTHER REFERENCES relied on.
RICHARD A. GAUDET, Primary Examiner. D. L. TRULUCK, Assistant Examiner.