Source: http://www.google.com/patents/US5871510?dq=6,373,753
Timestamp: 2014-03-17 00:14:51
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Patent US5871510 - Method and apparatus for temporarily electrically forcing cardiac output as ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA novel backup approach for tachycardia patients is taught. This approach uses the application of electrical cardiac output forcing to maintain a partial cardiac contraction in the event that antitachycardia therapy accelerates the patients' rhythm into a fibrillation. The partial contraction forces...http://www.google.com/patents/US5871510?utm_source=gb-gplus-sharePatent US5871510 - Method and apparatus for temporarily electrically forcing cardiac output as a backup for tachycardia patientsAdvanced Patent SearchPublication numberUS5871510 APublication typeGrantApplication numberUS 08/548,234Publication dateFeb 16, 1999Filing dateOct 25, 1995Priority dateMay 31, 1994Fee statusPaidPublication number08548234, 548234, US 5871510 A, US 5871510A, US-A-5871510, US5871510 A, US5871510AInventorsKai Kroll, Mark W. KrollOriginal AssigneeKroll; Kai, Kroll; Mark W.Export CitationBiBTeX, EndNote, RefManPatent Citations (20), Non-Patent Citations (14), Referenced by (7), Classifications (12), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMethod and apparatus for temporarily electrically forcing cardiac output as a backup for tachycardia patientsUS 5871510 AAbstract A novel backup approach for tachycardia patients is taught. This approach uses the application of electrical cardiac output forcing to maintain a partial cardiac contraction in the event that antitachycardia therapy accelerates the patients' rhythm into a fibrillation. The partial contraction forces cardiac output at a level sufficient to maintain life.
That which is claimed is: 1. An implantable device for treating ventricular tachycardia with electrical pacing therapy consisting of:a. at least one battery; b. a pacing pulse generating circuit connected to said battery; c. at least one small electrode for placement in a patient's heart connected to the pacing pulse generator circuitry; d. a control circuit connected to the pacing pulse generating circuit to generate pulses of appropriate timing to abolish the ventricular tachycardia according to the techniques of antitachycardia pacing; e. a charging circuit connected to at least one battery capable of charging a capacitor to a voltage of 30-350 volts at least once per second; f. a capacitor for storing energy from the charging circuit; g. at least one large electrode for placement in a patient's heart; and h. an output circuit for delivering pulses from the capacitor to said at least one large electrode,so that, in the event that the antitachycardia pacing causes the ventricular tachycardia to transform into a lethal ventricular fibrillation, the large electrode pulses will electrically force cardiac output to maintain life until the patient could be externally defibrillated. 2. The apparatus of claim 1 in which the large electrode has a greatest dimension of greater than one centimeter.
3. The device of claim 1 in which the control circuit cooperates with the output circuit to restrict the rise time of at least one gradual edge to greater than 100 microseconds.
4. The device of claim 1 in which the control circuit cycles the output circuit so that the output waveform has at least 6 narrow pulses in it.
5. The device of claim 1 in which the pacing pulse generating circuit battery is distinct from the charging circuit battery.
6. The device of claim 1 in which the pacing electrode is actually the same as the large electrode.
7. The device of claim 1 in which the control circuit cycles the output circuit so that the high voltage pulses are delivered at a rate of 60-200 pulses per minute.
8. A method for electrically terminating a ventricular tachycardia in a patient, comprising the steps of:a. providing a plurality of electrodes in the patient's chest; b. detecting the presence of a tachycardia in the patient via said electrodes; c. delivering electrical current pulses of a low voltage to the patient's heart via some of said electrodes after detecting the tachycardia; d. monitoring for possible ventricular fibrillation; e. in the event of the detection of ventricular fibrillation delivering higher voltage electrical pulses to the patient's heart via some of said electrodes at a rate between 60 and 200 pulses per minute, to directly force contraction in the patient's heart whereby a minimum level of cardiac output sufficient to maintain life is provided by said electrical current pulses. 9. The method of claim 8 further comprising the step of slowing the rise time of the higher voltage pulse to give the higher voltage pulse a rise time greater than 100 microseconds thereby minimizing patient discomfort and chest twitching.
10. The method of claim 8 further comprising the step of forming each higher voltage pulse of a train of at least 10 narrow pulses thereby minimizing patient discomfort and chest twitching.
11. The method of claim 8 further comprising the step of controlling the output voltage so that the higher voltage pulses have an amplitude of 30-350 volts.
12. The method of claim 8 further comprising the step of providing a high current output circuit so that the higher voltage pulses have a current of greater than 300 milliamperes.
13. The method of claim 8 in which at least one of the electrodes has a dimension greater than 1 cm.
14. The method of claim 8 in which the low voltage pulses of part c are delivered via the same electrodes as used for the higher voltage pulses of part e.
15. The method of claim 8 comprising the additional step of automatically communicating with another party in the event of ventricular fibrillation.
16. A device, for implantation in the human body, for performing antitachycardia pacing, and for maintaining cardiac output of a patient's heart during a possible ventricular fibrillation induced by said antitachycardia pacing using electrical forcing fields comprising:a. means for supplying battery power; b. an arrhythmia detector connected to said means for supplying batter power; c. a communication connection from said means for supplying battery power and said arrhythmia detector to the patient's heart; and d. an output control circuit connected to said arrhythmia detector and to said means for supplying battery power and communicatively adapted to be connected to the heart for delivering multiple electrical current pulses to the heart after detection of a fibrillation, said electrical current pulses having a voltage between 30-350 volts and current greater than 300 mA whereby contraction of the patient's heart is directly forced by said current pulses to generate a minimum level of cardiac output sufficient to maintain life. 17. The device of claim 16 further comprising bradycardia output pacing means.
18. The device of claim 16 in which the output control means includes an inverter powered by said battery and driving a high energy capacitor.
19. The device of claim 16 further comprising means to automatically alert another party in the event of ventricular fibrillation.
20. The device of claim 16 further comprising means for storing programmable parameters for the detection of the arrhythmias, the antitachycardia pacing parameters, and the electrical cardiac output forcing parameters.
21. The device of claim 16 further comprising means to store the patient's internal electrical signals.
22. The device of claim 16 further comprising blood pressure monitoring means connected to said arrhythmia detection means.
23. The device of claim 22, in which said blood pressure monitoring means monitors cardiac output and further comprising the step of adjusting said electrical current pulse amplitude by said output control means to maintain predetermined level of cardiac output based on blood pressure thereby conserving battery means.
This application is a continuation-in-part of Ser. No. 08/251,349, filed on May 31, 1994, entitled, "Method and Apparatus for Temporarily Electrically Forcing Cardiac Output in a Tachyrhythmia Patient" which application is now abandoned and was continued under FWC Ser. No. 08/543,001, filed on Oct. 13, 1995, which application was also abandoned in favor of FWC Ser. No. 08/754,712, filed on Dec. 6, 1996, which is currently pending.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiment of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, applicants provide these embodiments so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art.
FIG. 2 is a diagram showing the connection of the device 130 to the heart 40 in an epicardial patch configuration. In this configuration, current passes through an output lead pair 32 to electrode patches 42 which direct the current through the heart 40. There is an optional pressure sense lead 34 which passes the signal from an optional pressure transducer 46 which lies in the heart 40. The ECG is monitored by sense electrodes 44 and passed to the device 130 by a lead 36. The area of the electrodes 42 is a least 0.5 cm2. The size of the electrode is greater than that of a pacing lead and no more than that of a defibrillation electrode or between approximately 0.5 cm2 and 20 cm2 each.
FIG. 3 shows a non-thoractomy system embodiment of the invention. In this system, the current passes from a coil electrode 52 in the heart 40 to the housing of the device 140. An endocardial lead 50 combines the ECG sensing lead and the pulse output lead. The ECG is monitored by sense electrodes 44 in the heart 40 and passes through the endocardial lead 50. There is an optional pressure transducer 46 in the heart 40 which passes a signal to the device 140 via optional lead 34.
Implantable batteries are also limited to a certain power output and energy storage. If an output pulse is 50 V and the electrode impedance is 50Ω, the power during the pulse is P=V.sup.2 /R=50 V*50 V/50Ω=50 W. If the pulse has a duration of 2 ms then the energy per pulse is 0.1 J. If two pulses are delivered every second, the charger must be capable of delivering 0.2 J per second which is 200 mW. This is well within the limits of an implantable battery. An implantable battery can typically deliver 5 W of power. However, 200 V pulses at 3 per second would require 4.8 W which is near the limit of the battery and charging circuitry. A typical implantable battery energy capacity is 10,000 J. Delivering forcing pulses at a rate of 4.8 W would deplete the battery in only 35 minutes. (10,000 J/4.8 W=2083 seconds). Thirty five minutes may not be enough time to transport the patient to a hospital. Therefore 200 V represents the highest practical voltage for continuous operation in an implantable embodiment, although voltages of up to 350 V (maximum voltage for electrolytic capacitors) could be used for short periods and adjusted down when hemodynamic output is verified. A practical lower limit is about 10 V. During normal sinus rhythm, 10 V delivered through the patches would pace. However, during fibrillation the 10 V could not pace and only cells very near the electrodes would be captured. This would be insufficient for forcing cardiac output. A typical range would be 30-200 V with an optional 350 V initial burst.
These calculations also suggest other differences between an implantable ECOF and an ICD. With a battery storing 10,000 J and an ECOF pulse having 0.1 J, this ECOF would be capable of delivering 100,000 pulses. An ICD can only deliver 200-400 shocks of about 30 J. The ECOF is also very different from an implantable pacemaker which typically delivers 150,000,000 pacing pulses (5 years at 60 BPM) each of about 0.00005 J.
FIG. 5 is a flowchart illustrating the method of the invention, which is provided for purposes of illustration only. One skilled in the art will recognize from the discussion that alternative embodiments may be employed without departing from the principles of the invention. The flow diagram shown in FIG. 5 represents a method of automatically treating a heart which is in fibrillation, tachycardia, or asystole and thereby pumping inefficiently or not at all. Electrodes are attached 69. A diagnosis of the presence of an arrhythmia is made 70. A series of cardiac output forcing electric pulses 72 is automatically delivered. It should be understood that the therapy 72 may be delivered for any output compromising cardiac arrhythmia. After delivery of 10 forcing pulses (at a rate of 60-200 BPM) in the first block 72, the status of the heart is determined 74. If an arrhythmia is still present and there exists low pressure within the heart, more forcing pulses are delivered 78. If the heart is pumping at a safe level, the therapy ceases and exits 76. Note that this means that the ECOF successfully defibrillated the patient's heart even though this is not a primary goal of the system. This could be tested in patients who were scheduled to receive an ICD, in a hospital setting. Those patients who are defibrillated by ECOF pulse therapy could then receive the ECOF instead of the larger ICD. After the therapy 78 has been delivered, the pressure and ECG is again monitored 74. If the therapy 78 is successful, it ceases and exits 76. If the therapy 78 is unsuccessful in producing a safe level of pumping efficiency, the method proceeds to a continuous cardiac assist mode 80. The therapy may only be stopped by an external command, for example, a telemetry signal or a magnet which is applied to the chest activating a magnetic reed switch 82 which terminates the therapy and exits 76. To minimize patient discomfort and maximize battery life, the forcing voltage could be adjusted down when sufficient pressure signals or adequate flow measured by other means were detected, for example, the pressure sense transducer could be replaced by an oxygen detector or a doppler flow measuring device. The pulse rate could also be adjusted to maximize output.
FIG. 7 is a diagram showing the effect of a 50 V forcing pulse on the heart during electrical systole (cells already stimulated). The current is passed through the heart 40 by the electrodes 42. Approximately 20% of cardiac cells 100 would be captured by a 50 V pulse if the cells were in systole. The captured cells 100 are nearest each electrode 42 where the field strengths are highest. Capture in systolic cells means that their activation potential is extended. This capture requires significantly higher fields (5 V/cm) than those required for diastolic cell capture (0.5 V/cm).
Considering the cardiac cells that are originally in diastole, (rows A&B in the table below), the A row represents the diastolic cells that are not captured by the forcing pulse. If 50% of the heart's cells are in diastole and 40% of those are not captured that is 20% of the total cells. These cells will, however, shortly contract on their own (from previous wavefronts or new ones) providing a positive gain in mechanical action and therefore cardiac output. The B row corresponds to the diastolic cells that are captured. If 60% of the diastolic cells (50% of total) contract due to the forcing field this is 30% of the total heart cells. These cells provide the biggest gain in mechanical action and cardiac output. Next consider the activity of the systolic cells (rows C&D). If 50% of the heart's cells are in systole and 80% of those are not captured (row C), that is 40% of the heart's cells. These cells soon relax and negate a portion of the cardiac output. The systolic cells that are captured (row D) are 10% of the heart's cells (20% of 50%). These cells will hold their contraction and be neutral to cardiac output. The net result (Rows A, B, C, and D) is a gain in contraction which forces cardiac output.
__________________________________________________________________________ Percentage    Percentage                     Percentage  ForcingOriginal of the Status of               of the                     of the      CardiacStatus of Cardiac        the Cardiac               Original                     Total Mechanical                                 Outputthe Cells Cells  Cells  Status                     Cells Action                                 Effect__________________________________________________________________________(A)   50%    Diastolic               40%   20%   will start to                                 positive (+)Diastolic    non-captured               of 50%      contract on                           own(B)          Diastolic               60%   30%   contract                                 positive (++)Diastolic    captured               of 50%(C) Systolic 50%    Systolic               80%   40%   will start to                                 negative (-)        non-captured               of 50%      relax on                           own(D) Systolic Systolic               20%   10%   hold  neutral (0)        captured               of 50%TOTAL 100%          100%  100%  more  positive (+)                           contraction__________________________________________________________________________ The net result over a 200 ms mechanical response is given in the next table. The major contribution is in row (B) from the captured diastolic cells contracting.
______________________________________           Change    Status of the                 in       Description ofRow      Cardiac Cells                 Output   Activity______________________________________A        Diastolic    +5%      Positive. Some cells    non-captured          will begin to                          contract on                          their own.B        Diastolic captured                 +30%     Positive. Cells                          contract due to                          forcing fieldC        Systolic     -5%      Negative. Some    non-captured          cells will begin to                          relax on their own.D        Systolic captured                 0%       Neutral. Cells hold                          contraction due to                          forcing field.Net Gain              +30%     A net gain in                          cardiac output due to                          forcing fields.______________________________________
FIG. 9 depicts an example of a waveform designed to minimize the twitching of the chest muscles which can be very uncomfortable to the patient. A low harmonic pulse waveform 120 has a very gradual "foot" 122 and a gradual peak 124. Such a pulse has less high frequency energy components and thus is less likely to stimulate the skeletal muscle.
FIG. 10 shows a technique of going to the opposite extreme. Here, each compound forcing pulse 126 is actually composed of 50 very short spikes 128 each of which is 20 μs in width with a 20 μs spacing. The heart will tend to average out these thin pulses and "see" a 2 ms wide forcing pulse. The skeletal muscle, however, is not efficiently stimulated by these extremely narrow pulses. The skeletal muscle will not average out this signal either. This approach could help minimize skeletal muscle twitching and discomfort.
An alternative system would be to charge the capacitor to 300 V for the first pulse to capture many cells therefore putting those cells into diastole after a delay of 100-200 ms. At this point the voltage could be lowered to 100 V and pulses delivered every 100 ms. A 3 watt DC-DC converter with a 67% efficiency could provide 100 ms interval forcing pulses assuming a 50Ω resistance and 1 ms pulse (0.2 J). This rate is too fast for forcing cardiac output due to mechanical limitations, but is very effective for electrical capture. After sufficient capture, the rate of forcing pulses could be slowed down to 100-170 beats per minute for optimum cardiac output.
FIG. 13 shows an alternative embodiment in which the antitachycardia pacing is done through the large electrodes 218 rather than through the small electrodes 222. With this approach the output circuit 216 is controlled to deliver voltages on the order of 5-30 volts for the initial antitachycardia pacing. In the event that this pacing was unsuccessful then higher voltage pulses could be used and delivered through the large electrodes 218. The use of large electrodes for antitachycardia pacing is taught in U.S. Pat. No. 5,330,509 of Kroll entitled "Far Field Antitachycardia Pacing." However, that invention did not anticipate the use of the electrical cardiac output forcing backup. In this embodiment of the instant invention, the small electrodes are still used for sensing the rhythm in order to make the correct diagnosis of VT or VF.
FIG. 15 depicts the basic method of the invention. In step 300 the device senses and analyzes the rhythm. If a normal rhythm is sensed it simply stays in a waiting mode. If VT is sensed then the method proceeds to step 302 which is to perform antitachycardia pacing. After each attempt of antitachycardia pacing step 300 is used to analyze the rhythm. If the rhythm has returned to normal, then the method returns to monitoring. If VT is still sensed then the device again tries to perform ATP. If VF is sensed then the device proceeds to step 306 to force cardiac output electrically.
FIG. 16 depicts some of the pulses that are possible with such a device. Pulse 330 is a high comfort pulse. This pulse uses two milliseconds to climb from zero volts to full voltage. This full voltage is shown as 50 V in this example. The full voltage then is maintained for another 2 ms. This slow ramp 332 in the first 2 ms is less likely to stimulate nerve cells and skeletal muscles thus resulting in significantly less discomfort for the patient. However, this high comfort pulse is relatively inefficient as the output circuitry 216 (FIG. 14) must lose some energy (convert it to heat) by gradual turning on and thus is able to deliver fewer total pulses.
The high efficiency pulse 340 is generated by merely directly connecting the capacitor 214 (FIG. 14) through to the output electrodes 218 (FIG. 14) by means of a direct switch in the circuitry 216 (FIG.14). The voltage then follows the exponential decay of the capacitor which is shown here, as an example, decaying to 50 V over a period of 3 ms. Such a pulse is highly efficient in that essentially no energy is wasted in the output circuitry. However, the high frequency spectral content from the fast rising edge 342 can cause a great deal of patient discomfort.
In one embodiment the external receiver sits in the patient's place of living and is connected to the patient's home telephone. In another embodiment the external receiver is a small, very portable unit which is connected to a cellular phone. In operation, when the device 400 detects a VF, it then sends a signal through oscillator 402, antenna 404, antenna 406, and external receiver 408. The external receiver 408 generates a voice message which is channeled through telephone 410 to call a physician's office or the appropriate emergency authorities alerting them that the patient will need defibrillation within the next approximately 1 hour. The external receiver 408 could be made relatively sophisticated and could, for example, generate a detailed fax of the patient's condition which is then transmitted to the nearest emergency room. This fax could also include the various electrical signals recorded from inside the patient's heart. The use of fax transmission is taught in U.S. Pat. No. 5,336,245 of Adams et al. Alternatively, it could call a large battery of numbers such as the local emergency room, rescue squad, and patient's physician. It could also call relatives and neighbors who could be enlisted to provide transportation to the hospital.
The following table gives some examples of device lifetime and its dependence on the various factors of the output voltage, impedance, pulses per minute, and the battery capacity in joules. The voltage is practically limited to 375 V which the maximum rating for a modem photoflash capacitor.
__________________________________________________________________________Pulse       Energy/                  Pulses                        Watts                             Battery Cap                                    MinutesVoltagewidth (ms)      Impedance            Pulse Per Min                        Ave  joules Backup__________________________________________________________________________50   3     100   0.075 120   0.15 5000   556100  3     100   0.3   120   0.6  5000   139200  3     100   1.2   120   2.4  10000  6930   3     100   0.027 150   0.0675                             2000   49470   3     100   0.147 150   0.3675                             5000   227100  3     100   0.3   120   0.6  5000   13970   3     50    0.294 120   0.588                             2000   5770   3     50    0.294 60    0.294                             2000   113__________________________________________________________________________
The calculations ignore converter inefficiencies, which will reduce backup time, yet do use conservative battery ratings, which will increase backup time. In all cases we assume a fixed pulse width of 3 milliseconds. In the first case ECOF pulses of 50 volts are used and the large electrode impedance is 100 ohms using an ECOF pulse rate of 120 pulses per minute and a battery capacity of 5,000 joules. The current would be 500 mA. There are 556 minutes of backup available, or in other words, nearly 10 hours. This is clearly excessive as the patient would find 10 hours of backup very uncomfortable and there are very few places in industrialized society in which the patient could not receive defibrillation within one hour. In the second case, we have a patient requiring a voltage of 100 volts to maintain adequate output. With everything else being the same, this reduces the minutes of backup to 139. It is conceivable that a patient could have a need for a relatively large voltage to maintain minimum cardiac output. An example given here is 200 volts. The current would increase to 2,000 mA. The battery capacity would have to be increased to 10,000 joules in order to maintain a 1 hour backup which is shown here as approximately 69 minutes.
Many patients should have sufficient cardiac output with 30 volt pulses. This would require a current of only 300 mA. If the rate of the ECOF pulses is increased to 150 pulses per minute to maximize output, then the battery capacity could be reduced down to 2,000 joules and the patient would still have 494 minutes of backup. If a patient needed a 70 volt pulse and a rate of 150 pulses per minute to maintain output and the earlier discussed battery capacity of 5,000 joules was used then there would be nearly 4 hours of backup available (actually 227 minutes). If this patient required 100 volt pulses and the pulsing rate was reduced to 120 pulses per minute, then the minutes of backup from the same battery would be reduced to 139, or a little over 2 hours.
A 2,000 joule titanium carbon monofluoride battery should be on the order of 1 cubic centimeter in volume. If this battery were of the SVO type then its volume would be at least 2 cubic centimeters.
The capacitor could also be made very small. Assuming a 60 microfarad capacitance, even with the 200 volt maximum output shown in the table, the total stored energy would only be 1.2 joules. Modem electrolytic capacitors have an energy density of about 1 joules per cubic centimeter and thus this capacitor would have a volume of approximately 1 cm.sup.3. Thus the total volume of the components for the energy (namely the battery and capacitor) would have volumes on the order of 2 or 3 cm.sup.3 compared to volumes of 20-30 cm.sup.3 or more in the present ICDs.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a system constructed in accordance with the principles of the present invention.
FIG. 9 shows a high comfort rounded pulse.
FIG. 10 shows a pulse comprised of many smaller pulses.
FIG. 15 shows the method of the invention.
FIELD OF THE INVENTION The invention generally relates to a method and device for therapies in the treatment of cardiac arrythmias. Specifically, the present invention provides method and apparatus for temporarily forcing cardiac output in the event of fibrillation resulting from an unsuccessful antitachycardia pacing therapy.
BACKGROUND OF THE INVENTION Many patients suffer from an occasional condition of ventricular tachycardia (VT). This is particularly prevalent in patients who survive heart attacks. Generally, VT is an on-set of a condition in which the bottom chambers of the heart (ventricles) beat at a high rate. In sharp contrast to Ventricular fibrillation (VF), VT is not usually life-threatening. However, there are situation in which VT could be fatal. Generally, VT may cause fainting, loss of consciousness, anxiety and may occasionally degenerate into a fatal VF. Accordingly, while VT is not as serious as VF, it is nonetheless a condition that calls for prompt therapy and treatment.
Prior art therapy methods and devices utilize low voltage timed pulses to control VT. Some of the prior art references which teach antitachycardia pacing using low voltage shock therapy systems include U.S. Pat. No. 4,408,606, U.S. Pat. No. 4,398,536, U.S. Pat. No. 4,488,553, U.S. Pat. No. 4, 488,554, and U.S. Pat. No. 4,390,021, all assigned to Telectronics. Other patents dealing with antitachycardia pacing (ATP) include U.S. Pat. No. 4,181,133 and U.S. Pat. No. 4,280,502, assigned to Intermedics.
Generally, a limitation of the prior art is the fact that low voltage shock therapy for use in antitachycardia pacing may accelerate the VT and may transform it into a lethal VF. In an attempt to reduce this risk, it was necessary to equip patients with a separate implantable defibrillator in the event an antitachycardia pacing therapy for VT induces a VF. However, this arrangement was not only expensive but also rather bulky and inconvenient for the patient. An alternate solution has been to equip an implantable cardioverter defibrillator (ICD) with an antitachycardia pacing device. Such a configuration is disclosed in U.S. Pat. No. 4,830,006.
In spite of the many advances made by the prior art, most of the configurations and devices are cumbersome, expensive and inconvenient for the patient. Specifically, most of the devices incorporated with an ICD require a space-volume of between 60 to 100 Cubic centimeters in volume partly because of the need for large batteries and capacitors.
Accordingly, there is need for a compact antitachycardia pacemaker which is both practicable and space-volume efficient to be implanted in patients to provide specific therapy for VT.
SUMMARY OF THE INVENTION The present invention provides a method and device for antitachycardia pacing therapy. Specifically, the method includes stimulating fibrillating cardiac cells using a predetermined level of voltage pulses at a specified rate and duration to induce a partial contraction of the heart. This approach is advantageously implemented as a backup for antitachycardia pacing in the event that an ATP transforms a VT into a VF.
Specifically, the present invention utilizes a unique method and device to implement electrical cardiac output forcing (ECOF) at a level sufficient to maintain the life and consciousness of the patient until emergency care and external defibrillation could be performed. To this end, the present invention provides a compact and energy efficient system which can be used as a backup for antitachycardia pacing.
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Cardiovasc Res. 1970; 4: 497 501.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS6556865Jan 29, 2001Apr 29, 2003Uab Research FoundationMethod for improving cardiac function following delivery of a defibrillation shockUS6760621Nov 13, 2001Jul 6, 2004Uab Research FoundationMethod for improving cardiac function following delivery of a defibrillation shockUS7043301Oct 11, 2002May 9, 2006Pacesetter, Inc.Implantable cardiac stimulation system providing high output far-field pacing and methodUS7515960 *Mar 31, 2005Apr 7, 2009Medtronic, Inc.Method and apparatus to terminate ventricular tachycardia via pacingUS7706864May 5, 2003Apr 27, 2010Galvani, Ltd.Method and apparatus for electrically forcing cardiac output in an arrhythmia patientUS8401637Nov 22, 2005Mar 19, 2013Galvani, Ltd.Medium voltage therapy applications in treating cardiac arrestUS8483822Jul 2, 2010Jul 9, 2013Galvani, Ltd.Adaptive medium voltage therapy for cardiac arrhythmias* Cited by examinerClassifications U.S. Classification607/14International ClassificationA61N1/39, A61N1/362Cooperative ClassificationA61N1/3625, A61N1/3622, A61N1/395, A61N1/3962, A61N1/3918European ClassificationA61N1/362A2, A61N1/362B, A61N1/39B, A61N1/39M2Legal EventsDateCodeEventDescriptionAug 16, 2010FPAYFee paymentYear of fee payment: 12Dec 12, 2006ASAssignmentOwner name: GALVANI LTD., MINNESOTAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KROLL, KAI;KROLL, MARK;REEL/FRAME:018616/0358Effective date: 19951025Aug 11, 2006FPAYFee paymentYear of fee payment: 8Aug 16, 2002FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google