WO1998046305A1 - Implantable cardiac stimulator with polarity detection for detecting ectopic beats - Google Patents
Implantable cardiac stimulator with polarity detection for detecting ectopic beats Download PDFInfo
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- WO1998046305A1 WO1998046305A1 PCT/US1998/007520 US9807520W WO9846305A1 WO 1998046305 A1 WO1998046305 A1 WO 1998046305A1 US 9807520 W US9807520 W US 9807520W WO 9846305 A1 WO9846305 A1 WO 9846305A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/3621—Heart stimulators for treating or preventing abnormally high heart rate
- A61N1/3622—Heart stimulators for treating or preventing abnormally high heart rate comprising two or more electrodes co-operating with different heart regions
Definitions
- the present invention relates generally to cardiac stimulating devices, such as pacemakers and defibrillators. More particularly, the present invention relates to a cardiac stimulating device that detects electrical activity in the heart. Still more particularly, the present invention relates to a cardiac stimulating device that can distinguish normal heart beats from abnormal ectopic beats.
- the sinus (or sinoatrial (SA)) node generally located near the junction of the superior vena cava and the right atrium constitutes the primary natural pacemaker by which rhythmic electrical excitation is developed.
- the cardiac impulse arising from the sinus node is transmitted to the two atrial chambers (or atria) at the right and left sides of the heart.
- the atria contract, pumping blood from those chambers into the respective ventricular chambers (or ventricles).
- the impulse is transmitted to the ventricles through the atrio ventricular (AV) node, and via a conduction system comprising the bundle of His, or common bundle, the right and left bundle branches, and the Purkinje fibers.
- the transmitted impulse causes the ventricles to contract, the right ventricle pumping unoxygenated blood through the pulmonary artery to the lungs, and the left ventricle pumping oxygenated (arterial) blood through the aorta and the lesser arteries to the body.
- the right atrium receives the unoxygenated (venous) blood.
- the blood oxygenated by the lungs is carried via the pulmonary veins to the left atrium.
- rhythmic cardiac cycle in which the atrial and ventricular chambers alternately contract and pump, then relax and fill.
- Four one-way valves, between the atrial and ventricular chambers in the right and left sides of the heart (the tricuspid valve and the mitral valve, respectively), and at the exits of the right and left ventricles (the pulmonic and aortic valves, respectively, not shown) prevent backflow of the blood as it moves through the heart and the circulatory system.
- the sinus node is spontaneously rhythmic, and the cardiac rhythm it generates is termed normal sinus rhythm ("NSR") or simply sinus rhythm. This capacity to produce spontaneous cardiac impulses is called rhythmicity, or automaticity.
- the secondary pacemakers tend to be inhibited by the more rapid rate at which impulses are generated by the sinus node.
- An artificial pacemaker (or "pacer" as it is commonly labeled) is a medical device which delivers electrical pulses to an electrode that is implanted adjacent to or in the patient's heart in order to stimulate the heart so that it will contract and beat at a desired rate. If the body's natural pacemaker performs correctly, blood is oxygenated in the lungs and efficiently pumped by the heart to the body's oxygen-demanding tissues. However, when the body's natural pacemaker malfunctions, an implantable pacemaker often is required to properly stimulate the heart. An in-depth explanation of certain cardiac physiology and pacemaker theory of operation is provided in U.S. Patent No. 4,830,006.
- Pacers today are typically designed to operate using one of three different response methodologies, namely, asynchronous (fixed rate), inhibited (stimulus generated in the absence of a specified cardiac activity), or triggered (stimulus delivered in response to a specified hemodynamic parameter).
- the inhibited and triggered pacemakers may be grouped as "demand" type pacemakers, in which a pacing pulse is only generated when demanded by the heart.
- demand pacemakers may sense various conditions such as heart rate, physical exertion, temperature, and the like.
- pacemakers range from the simple fixed rate, single chamber device that provides pacing with no sensing function, to highly complex models that provide fully automatic dual chamber pacing and sensing functions. The latter type of pacemaker is the latest in a progression toward physiologic pacing, that is, the mode of artificial pacing that most closely simulates natural pacing.
- the fifth code position describes the antitachycardia functions, if any. Because this position is not applicable to most commonly used pacemaker types, most common codes comprise either three or four letters. For this reason and for simplicity's sake, the fifth code position is omitted from the following table. Each code can be interpreted as follows:
- typical treatment for patients experiencing either atrial bradyarrythmias with or without A-V block, or normal sinus rhythm with A-V block generally includes using a DDD pacer.
- a DDD pacer paces either chamber (atrium or ventricle) and senses in either chamber.
- a pacer in DDD mode may pace the ventricle in response to electrical activity sensed in the atrium.
- atrial activity presumably resulting from or occurring during atrial contraction
- proper synchronization is maintained between the atria and ventricles, and blood is efficiently pumped through the circulatory system.
- rhythms of the electrical activity in the atrium and ventricle are shown in Figure 2.
- a rhythm representing atrial electrical activity is termed an "atrial electrogram” or "AEGM”.
- An AEGM typically is measured by implanting a pair of electrodes in the left atrium and amplifying the signal received by the pair of electrodes.
- VEGM a ventricular electrogram
- a P-wave an electrical pulse that is generated by the SA node to initiate atrial contraction
- P-wave an electrical pulse that is generated by the SA node to initiate atrial contraction
- a naturally occurring electrical pulse propagates through the ventricles causing the ventricles to contract. This pulse is referred to as an R wave, is detected by the ventricular electrodes.
- DDD pacer operation is exemplified in Figure 2 by event 52 in which a P-wave is detected by the atrial electrodes and is followed by a ventricular pace (VP) pulse produced by the pacer.
- Ventricular pace pulse VP causes the ventricles to contract and pump blood into the pulmonary artery and aorta (not specifically shown in Figure 1).
- the P-wave detected by the atrial electrodes indicates atrial contraction and thus can be used to gauge when the ventricles will be full and ready to be paced.
- the pacer paces the ventricles with a VP pulse at an appropriate time interval after the P-wave, typically 150-200 milliseconds.
- Effective pacing breaks down if atrial activity detected by the atrial electrodes is registered by the pacer as a P-wave from the SA node when, in fact, the origin of the electrical activity was from a site other than the SA node.
- sites of abnormally-originating electrical activity are commonly called “ectopic” sites, and the resulting electrogram rhythm is called an "ectopic beat.”
- ectopic beats There are numerous causes of ectopic beats such as premature atrial beats and premature ventricular contractions (PVC).
- An exemplary PVC is shown in the VEGM of Figure 2 in event 54.
- PVCs normally originate in some part of the specialized ventricular propagating system or in damaged tissue around myocardial infarcts.
- the electrical pulse causing the PVC propagates through the ventricle exciting the ventricles to contract.
- the pulse may further move into the atria and be detected by the atrial electrodes as pulse 54a.
- the polarity of a pulse detected by the atrial electrodes from an ectopic source depends on the location of the ectopic site relative to the atrial electrodes, as described below.
- FIG 3 a schematic view of a heart is shown to include the four chambers of the heart: left atrium (LA), left ventricle (LV), right atrium (RA), and right ventricle (RV).
- Pacer 10 is shown with only a single atrial lead 14 for simplicity.
- the pulse's wave front propagates in the direction of the arrows, generally in the direction from the tip electrode 14a to the ring electrode 14b. If the tip electrode 14a is given a positive polarity with respect to the ring electrode 14b, a positive pulse is detected by the electrodes as the wave front from the SA node passes by the electrodes. Conversely, if a pulse is produced from an ectopic site such as exemplary site 18 and propagates toward the left atrium as indicated, the wave front will impinge on the ring electrode 14b first and then move to the tip electrode 14a resulting in a pulse detected by electrodes 14a, 14b of negative polarity. PVCs originate in the ventricles and, given the electrode orientation shown in Figure 4, thus usually cause the detection of a negative pulse by the atrial electrodes as shown by negative pulse 54a in Figure 2.
- Pacemakers usually include threshold detectors that produce a single detect signal when the magnitude of the electrogram exceeds either positive or negative threshold levels. That is, a detect signal is produced when either the electrogram voltage is more positive than a positive threshold level or more negative than a negative threshold level.
- the detect signal does not encode whether the detected event was a naturally occurring positive P-wave or a negative pulse resulting from an ectopic site, such as caused by a PVC.
- prior pacers were susceptible to incorrectly characterizing negative pulse 54a as a naturally occurring P-wave. In a DDD pacer, this mischaracterization results in the ventricles being unnecessarily and undesirably paced.
- an implantable medical device such as a pacemaker for electrically stimulating the heart to beat.
- the implantable medical device includes an atrial sense circuit for detecting and monitoring electrical activity in the atria of the heart, commonly known as the atrial electrogram.
- the atrial sense circuit includes a sense amplifier, band pass filter, and a threshold detector and provides detect signals to a logic and control unit upon detecting electrical activity in the atria.
- the threshold detector includes threshold logic to distinguish electrical activity originating at the heart's natural pacemaker (SA node) from electrical activity originating at ectopic sites, such as PVCs.
- SA node natural pacemaker
- a plurality of latches in the threshold detector are activated by output pulses from a pair of comparators.
- a positive comparator produces an output pulse upon detection of cardiac electrical activity exceeding a positive threshold voltage
- a negative comparator produces an output pulse upon detection of cardiac electrical activity more negative than a negative threshold.
- the threshold logic produces output signals indicative of which comparator first produced an output pulse.
- the logic and control unit monitors the output signals from the threshold logic and thus determines whether the associated cardiac electrical activity represented a normal heart beat or resulted from an ectopic beat so that pacing may be appropriately controlled.
- Figure 1 is a schematic cut-away view of a human heart, in which the various relevant parts are labeled;
- Figure 2 shows exemplary atrial and ventricular electrograms including normal atrioventricular coordination, DDD pacing, and a premature ventricular contraction;
- Figure 3 is a schematic diagram of the heart showing atrial electrodes in relation to the SA node and the site of a premature ventricular contraction;
- FIG. 4 is a schematic diagram of a pacer constructed in accordance with the invention implanted in a human body and coupled to the heart with electrodes;
- Figure 5 is a block diagram of the pacer of Figure 4 having an atrial sense circuit with a band pass filter, threshold comparators, and threshold logic for distinguishing atrial detected events resulting from ectopic beats from atrial events resulting from normal beats;
- Figure 6(a) shows an exemplary electrogram, including a positive P-wave and a negative pulse resulting from an ectopic source
- Figure 6(b) shows the output signal produced by the band pass filter of the atrial sense circuit of Figure 5;
- Figures 6(c) and 6(d) show output pulses produced by the threshold comparators of the atrial sense circuit of Figure 5 in response to the band pass filter's output signal of Figure 6(b); and Figure 7 is a schematic diagram of the threshold logic of the atrial sense circuit of Figure
- an implantable medical device 100 constructed in accordance with the preferred embodiment is shown implanted and coupled to the patient's heart by leads 12, 14.
- the implantable medical device 100 may include a pacemaker or any medical device that performs pacing functions.
- a pacemaker or any medical device that performs pacing functions.
- it will hereafter be described as an implantable pacemaker or simply pacer.
- the invention may likewise be employed in any of a variety of implantable medical devices, such as defibrillators.
- leads 12, 14 are positioned in the right ventricle and right atrium, respectively.
- Each lead 12, 14 includes at least one stimulating electrode for delivery of electrical impulses to excitable myocardial tissue in the appropriate chamber(s) in the right side of the patient's heart.
- each lead 12, 14 includes two electrodes. More specifically, lead 14 includes tip electrode 110 and ring electrode 120, and lead 12 includes tip electrode 150 and ring electrode 140.
- two, three, and four terminal devices all have been used or suggested as possible electrode schemes and may be employed in the present invention.
- pacer 100 includes housing or can 130 that houses a conventional battery (not shown), pulse generator 158, atrial sense circuit 208, ventricular sense circuit 218, and logic and control unit 230.
- Pulse generator 158 delivers the appropriate atrial or ventricular pacing pulses as initiated by logic and control unit 230 to the heart generally through one or more electrodes 110, 120, 140, 150 or can 130 which itself may be employed as an electrode in a conventional manner.
- Pulse generators are well known in the art and typically include voltage multipliers, voltage regulators, rate limiters, and output switches.
- Pulse generator 158 preferably is capable of unipolar or bipolar pacing of either the atrium or ventricle. Pulse generator 158 is controlled by logic and control unit 230 via control lines 231.
- Pulse generator 158 delivers a pacing pulse of certain amplitude and time duration (i.e., pulse width).
- Logic and control unit 230 determines the amplitude and pulse width of the pacing pulse and provides that information to pulse generator 158 over control lines 231.
- Atrial sense circuit 208 provides an indication on line 251 to logic and control unit 230 when the atrium contracts.
- ventricular sense circuit 218 indicates to logic and control unit 230 on line 233 when the ventricles contract.
- Signals on lines 252, 253 indicate whether a P-wave or an ectopic beat have been detected, as explained in detail below.
- pacer 100 preferably is a demand-type pacemaker and paces the heart in response to one or more physiological signals or parameters such as heart rate and activity level. Activity level may be determined from an activity sensor (not shown), from thoracic impedance measurements, or other commonly known techniques.
- Sense circuits 208, 218 amplify and filter signals from the electrodes 110, 120, 140, 150 and provide signals to logic and control unit 230 indicative of electrical activity in the heart.
- Ventricular sense circuit 218 includes a ventricular sense amplifier 220, band pass filter 225, and threshold detector 227. Ventricular sense circuit 218 receives a signal from pulse generator 158 on line 160 representing the electrical activity in the ventricle in the vicinity of the ventricular electrodes 140, 150.
- Ventricular sense amplifier 220 preferably is a low power amplifier operating from a power supply of approximately one microampere of current. A suitable sense amplifier is disclosed in U.S. Patent. No. 4,913,145, incorporated herein by reference.
- Band pass filter 225 of ventricular sense circuit 218 preferably is a switched capacitor filter such as that disclosed in U.S. Patent No. 4,913,145, or any other suitable low power, reliable filter suitable for use in implantable pacemakers.
- the transition in the frequency response of band pass filter 225 between the pass band (in which signals of frequencies in the pass band range are passed) and the stop band (in which signals of frequencies outside the pass band are attenuated) may be gradual or sharp, depending on the number of poles included in the filter's design.
- the poles are the roots of the denominator polynomial of the filter's transfer function and are known by those of ordinary skill in the art.
- Band pass filter 225 preferably includes eight poles, although more or fewer poles are permissible.
- Threshold detector 227 of ventricular sense circuit 218 compares the signal provided to it by band pass filter 225 to a reference signal (not specifically shown) and provides an output signal to logic and control unit 230 on line 233.
- the output signal on line 233 generally indicates when the band pass filter's output signal exceeds the reference signal.
- the reference signal may be fixed or programmable by logic and control unit 230.
- the reference signal preferably is indicative of the minimum voltage level necessary to cause ventricular contraction.
- the output signal from threshold detector 227 may be encoded as a binary signal; that is, a logic high signal may indicate when the band pass filter's output exceeds the reference signal, and a logic low signal may indicate when the filter's output signal is below the reference signal.
- ventricular sense amplifier 220, band pass filter 225, and threshold detector 227 are shown as three separate components in the block diagram of Figure 5, one of ordinary skill will recognize that these components may be combined into a single circuit or circuits, and this is typically the case for implantable pacemakers.
- band pass filter 225 may be implemented using known switched capacitor technology that includes amplification for signals in the pass band of the filter.
- ventricular sense amplifier 220, band pass filter 225, and threshold detector 227 may be provided in a different order than that shown. The arrangement of ventricular sense amplifier 220 and band pass filter 227, for example, may be reversed with band pass filter 225 coupled to the ventricular electrodes directly and then followed by ventricular sense amplifier 220.
- Atrial sense circuit 208 detects atrial electrical activity on line 161 and comprises atrial sense amplifier 210, band pass filter 215, comparators 240, 245, and threshold logic 250.
- Atrial sense amplifier 210 and band pass filter 215 preferably are of similar construction to the previously described ventricular sense amplifier 220 and band pass filter 225, respectively.
- Atrial sense amplifier 210 and band pass filter 215 may be combined into a single circuit or circuits, or may be provided in an order other than that shown in Figure 5. It should be recognized, however, that the gain of atrial sense amplifier 210 and the frequency response of band pass filter 215 may be adjusted differently than for ventricular sense amplifier 220 and band pass filter 225. Different settings may be necessary to account for differences in the physiology of the atria as compared to the ventricles, as is understood by those skilled in the art.
- Threshold detection in the atrial sense circuit is accomplished preferably by comparators 240, 245 and threshold logic 250.
- comparators 240, 245 and threshold logic 250 are included in comparator circuitry, and comparators 240,
- Comparators 240, 245 would include such components but are not shown in the interest of clarity. Comparators 240, 245 thus represent exemplary schematics only and not complete circuitry.
- Comparator 240 is configured as a positive threshold comparator and comparator 245 is configured as a negative threshold comparator.
- a positive reference voltage +V TPO s is provided to the inverting (-) terminal of comparator 240 and a negative reference voltage -V TNEG is provided to the non-inverting (+) terminal of comparator 245.
- the output signal on line 216 from band pass filter 215 is provided to both the non-inverting (+) terminal of comparator 240 and the inverting (-) terminal of comparator 245.
- the magnitude of the electrogram may rise to a positive level greater than +V JPOS .
- This condition forces the output signal on line 242 from comparator 240 to a logic high condition indicating the presence of an atrial event.
- the output signal on line 247 from comparator 245 also is forced to a logic high condition indicating the presence of an atrial event.
- FIG. 6(a) represents an atrial electrogram including a positive pulse 60 and a negative pulse 62.
- the positive pulse 60 may be a P-wave such as shown in event
- the trace in Figure 6(b) represents the output signal from band pass filter 215 for which the trace in Figure 6(a) is provided as an input signal.
- a band pass filter generally only passes signals with frequencies in the frequency range of the filter.
- the filter includes a pass band of 20 to 60 Hz, signals in that frequency range are passed through the filter, while signals at all other frequencies (i.e., less than 20 Hz and greater than 60 Hz) are attenuated.
- the amplitude of positive pulse 60 and negative pulse 62 is substantially constant during times Tl and T2.
- a substantially constant signal has a low frequency approaching or equaling 0 Hz, outside the pass band of pass band filter 215. During times Tl and T2, the output signal from band pass filter 215 thus is 0 volts as shown in Figure 6(b).
- the output of the band pass filter is a spike 60c.
- the high to low transition 60b causes a negative voltage spike 60d to be produced by band pass filter 215 as those of ordinary skill would understand.
- the high to low transition 62a of negative voltage pulse 62 causes a negative spike 62c to be produced by band pass filter 215, and the low to high transition 62b results in a positive filter output spike 62d.
- Figures 6(c) and 6(d) show the resulting output pulses of comparators 240, 245, respectively.
- comparator threshold +V- ITOS set at the level shown in Figure 6(b)
- positive comparator 240 will be forced to a logic high state while the band pass filter's output voltage is greater than +V ⁇ p 0S , generally at positive filter spikes 60c and 62d.
- positive comparator 240 produces pulses 64, 68 shown in the trace of Figure 6(c).
- negative comparator 245 produces pulses 66, 67 ( Figure 6(d)) when the output signal from band pass filter 215 becomes more negative than -V TNEG , generally at negative spikes 60d and 62c.
- threshold logic 250 receives the output pulses from comparators 240, 245 on lines 242, 247, respectively. Threshold logic 250 examines the comparators' output signals and determines whether the associated atrial activity represents a normal P-wave or results from an ectopic beat detected remotely by the atrial electrodes. Threshold logic 250 preferably accomplishes this objective by determining which comparator produced the first pulse associated with the atrial event. With reference to Figures 6(c) and 6(d), if the first pulse from the comparators comes from positive comparator 240 (and is followed by a pulse from negative comparator 245), threshold logic 250 determines that the associated atrial event is a P-wave (event 60 in Figure 6(a)). Conversely, if negative comparator 245 produces a pulse before comparator 240 produces its pulse, threshold logic 250 determines that the associated atrial event was merely the effects of an ectopic beat that was detected by the atrial electrodes.
- threshold logic 250 Although numerous embodiments of threshold logic 250 are possible and the present invention is intended to include all such embodiments, Figure 7 includes a presently preferred circuit. It should also be recognized that the function performed by the threshold logic circuitry shown in Figure 7 could be accomplished in software typically included in most pacers today. Comparators
- Latches 254, 255, 256, 257 may include D-flip flops as shown.
- a latch produces on its output pin Q a logic signal equivalent to the logic level present on its input D pin when a CLK signal is provided, for example, by a logic low to high transition. A latch thus "latches" on its output Q pin, the logic level present on its input D pin.
- Reset pins R are used to clear or reset the latches by reset circuitry not shown.
- Logic high signals are continuously provided to the input D terminals of latches 254, 256.
- latches 254, 256 are clocked, the output Q terminals of the latches will become logic high states.
- the output Q signals from latches 254, 256 are provided to the input D terminals of latches
- the output signals from latches 255, 257 are provided as output signals on lines 252, 253 from threshold logic 250.
- the signal on line 252 is referred to as a positive activity signal and indicates the presence of positive polarity atrial activity (P-wave).
- the signal on line 252 is referred to as a negative activity signal and indicates the presence of negative polarity atrial activity resulting, for example, from a PVC.
- OR-gate 258 is also included to logically OR together the output signals from comparators 240, 245.
- the output signal from OR-gate 258 is also provided as an output signal from threshold logic 250 on line 251.
- OR-gate 258 provides a detect signal which merely indicates detected atrial activity (i.e., when either comparator registers activity).
- threshold logic 250 shown in Figure 7 will now be described to determine whether a positive polarity atrial voltage pulse (P-wave) is present in the atrial electrogram. It is assumed that all four latches initially are cleared and a logic low level is present on the output Q pins of each latch. The logic levels on output lines 252, 253, as well as the output of OR-gate 258 on line
- positive comparator 240 For a positive pulse, positive comparator 240 emits a voltage pulse 64 on the rising edge 60a of P-wave 60 followed by a pulse 66 from negative comparator 245 during the trailing edge 60b, as described above with reference to Figures 6 (a-d). Accordingly, the voltage pulse from comparator 240 clocks latches 254 and 257. With a logic high input on its D pin, the output of latch 254 goes high placing a logic high level on the D pin of latch 255. Because the input to latch 257 was a logic low level, the output of latch 257 remains at a logic low state.
- latches 256 and 255 are clocked. Because a logic high level is present on the D pin of latch 255, the output Q pin of latch 255 goes high producing a logic high state for the positive activity signal on line 252. Although the logic high signal on the D terminal of latch 256 is latched through to its Q pin, the logic level on the output Q pin of latch 257 remains unchanged and thus, the negative activity signal on line 253 remains at the logic low state.
- the positive activity signal is high and the negative activity signal is low.
- logic and control unit 230 can determine that the detected atrial event was a P-wave. Once the presence of a P-wave is detected, the latches are reset and positive activity and negative activity signals go to the logic low state.
- threshold logic 250 to an atrial event of negative polarity, such as negative pulse 62 in Figure 6(a), is similar to that described above for positive P-wave pulses.
- negative comparator 245 generates a voltage pulse 67 on the falling edge 62a of negative pulse 62 before positive comparator 240 generates a pulse 68 on the subsequent rising edge 62b.
- the voltage pulse 67 from comparator 245 clocks latches 256 and 255. With a logic high input on its D pin, the output of latch 256 goes high placing a logic high level on the D pin of latch 257. Because the input to latch 255 was a logic low level, the output signal from latch 255 remains at a logic low state.
- latches 254 and 257 are clocked. Because a logic high level is present on the D pin of latch 257, which was latched in during the preceding clocking of latch 256, the output Q pin of latch 257 goes high producing a logic high state for the negative activity signal on line 253.
- Logic and control unit 230 determines that the atrial event was the result of an ectopic beat such as a
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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CA002285614A CA2285614A1 (en) | 1997-04-14 | 1998-04-13 | Implantable cardiac stimulator with polarity detection for detecting ectopic beats |
JP54422698A JP2001520545A (en) | 1997-04-14 | 1998-04-13 | Implantable cardiac stimulator with polarity detection for detecting ectopic contractions |
EP98915575A EP0975388A1 (en) | 1997-04-14 | 1998-04-13 | Implantable cardiac stimulator with polarity detection for detecting ectopic beats |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US08/843,235 | 1997-04-14 | ||
US08/843,235 US5772691A (en) | 1997-04-14 | 1997-04-14 | Implantable cardiac stimulator with polarity detection for detecting ectopic beats |
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WO1998046305A1 true WO1998046305A1 (en) | 1998-10-22 |
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PCT/US1998/007520 WO1998046305A1 (en) | 1997-04-14 | 1998-04-13 | Implantable cardiac stimulator with polarity detection for detecting ectopic beats |
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US (1) | US5772691A (en) |
EP (1) | EP0975388A1 (en) |
JP (1) | JP2001520545A (en) |
CA (1) | CA2285614A1 (en) |
WO (1) | WO1998046305A1 (en) |
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1997
- 1997-04-14 US US08/843,235 patent/US5772691A/en not_active Expired - Lifetime
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1998
- 1998-04-13 JP JP54422698A patent/JP2001520545A/en active Pending
- 1998-04-13 EP EP98915575A patent/EP0975388A1/en not_active Withdrawn
- 1998-04-13 WO PCT/US1998/007520 patent/WO1998046305A1/en not_active Application Discontinuation
- 1998-04-13 CA CA002285614A patent/CA2285614A1/en not_active Abandoned
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Also Published As
Publication number | Publication date |
---|---|
CA2285614A1 (en) | 1998-10-22 |
EP0975388A1 (en) | 2000-02-02 |
US5772691A (en) | 1998-06-30 |
JP2001520545A (en) | 2001-10-30 |
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