Pacer with combined defibrillator tailored for bradycardia patients Number:7,386,344 from the United States Patent and Trademark Office (PTO) owispatent A combination pacer/defibrillator is tailored for bradycardia patients. In one example, its shock-delivery specificity exceeds its sensitivity to shockable ventricular tachyarrhythmias. In another example, its specificity exceeds 95%, or 99%, or even 99.5%. Sensitivity is programmed to a high desired sensitivity value, but only if it can be done without decreasing the specificity below the desired specificity threshold value. This can be conceptualized as "avoiding at all costs" delivering false shocks, even at the expense of failing to deliver a shock to a treatable ventricular tachyarrhythmia. Specificity enhancements include, among other things, inhibiting shock delivery when the patient is breathing or not supine, using multiple channels or a high rate VT/VF detection threshold. The present pacer/defibrillator device could potentially save the lives of bradyarrhythmia patients who are not presently clinically indicated for a defibrillator/pacer, but who have an increased risk of sudden cardiac death due to one or more risk factors.<H defibrillator, bradycardia, Pacer, with, comb, 7386344.html, Patent, pto, 7386344

Title: Pacer with combined defibrillator tailored for bradycardia patients

Abstract: A combination pacer/defibrillator is tailored for bradycardia patients. In one example, its shock-delivery specificity exceeds its sensitivity to shockable ventricular tachyarrhythmias. In another example, its specificity exceeds 95%, or 99%, or even 99.5%. Sensitivity is programmed to a high desired sensitivity value, but only if it can be done without decreasing the specificity below the desired specificity threshold value. This can be conceptualized as "avoiding at all costs" delivering false shocks, even at the expense of failing to deliver a shock to a treatable ventricular tachyarrhythmia. Specificity enhancements include, among other things, inhibiting shock delivery when the patient is breathing or not supine, using multiple channels or a high rate VT/VF detection threshold. The present pacer/defibrillator device could potentially save the lives of bradyarrhythmia patients who are not presently clinically indicated for a defibrillator/pacer, but who have an increased risk of sudden cardiac death due to one or more risk factors.

Patent Number: 7,386,344 Issued on 06/10/2008 to Bocek, et al.

Inventors: Bocek; Joseph M. (Seattle, WA), Dujmovic, Jr.; Richard Milon (Coon Rapids, MN), Foshee; Phil (Woodinville, WA), White; Harley (Carnation, WA), Kim; Jaeho (Redmond, WA), Harrington; Anthony (Woodinville, WA), Sanders; Richard S. (Stillwater, MN), Daum; Douglas R. (Oakdale, MN), De Coriolis; Paul (Bellevue, WA), Smith; Joseph (North Oaks, MN), Fogoros; Richard (Pittsburg, PA)
Assignee: Cardiac Pacemakers, Inc. (St. Paul, MN)

Appl. No.: 10/921,777

Filed: August 18, 2004

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
60600614	Aug., 2004

Current U.S. Class: 607/5 ; 607/4

References Cited [Referenced By]

U.S. Patent Documents


RE30372	August 1980	Mirowski et al.
RE30387	August 1980	Denniston, III et al.
4375817	March 1983	Engle et al.
4693253	September 1987	Adams
4727877	March 1988	Kallok
4774950	October 1988	Cohen
4799493	January 1989	DuFault
4880005	November 1989	Pless et al.
4960123	October 1990	Maker
4986270	January 1991	Cohen
4989602	February 1991	Sholder et al.
5027816	July 1991	Cohen
5048521	September 1991	Pless et al.
5054485	October 1991	Cohen
5083563	January 1992	Collins
5085213	February 1992	Cohen
5105810	April 1992	Collins et al.
5111816	May 1992	Pless et al.
5119813	June 1992	Cohen
5190034	March 1993	Sholder
5191884	March 1993	Gilli et al.
5251626	October 1993	Nickolls et al.
5257621	November 1993	Bardy et al.
5269300	December 1993	Kelly et al.
5311874	May 1994	Baumann et al.
5312443	May 1994	Adams et al.
5318591	June 1994	Causey, III et al.
5325856	July 1994	Nitzsche et al.
5336253	August 1994	Gordon et al.
5350401	September 1994	Levine
5350406	September 1994	Nitzsche et al.
5354316	October 1994	Keimel
5391188	February 1995	Nelson et al.
5431682	July 1995	Hedberg
5439482	August 1995	Adams et al.
5554174	September 1996	Causey, III
5584868	December 1996	Salo et al.
5607385	March 1997	Fransischelli et al.
5662687	September 1997	Hedberg et al.
5713924	February 1998	Min et al.
5720294	February 1998	Skinner
5722994	March 1998	Noren et al.
5738105	April 1998	Kroll
5749901	May 1998	Bush et al.
5766225	June 1998	Kramm
5782879	July 1998	Rosborough et al.
5792183	August 1998	Esler
5836971	November 1998	Starkweather
5836976	November 1998	Min et al.
5851220	December 1998	Murphy
5857977	January 1999	Caswell et al.
5868793	February 1999	Nitzsche et al.
5873897	February 1999	Armstrong et al.
5876349	March 1999	Wang et al.
5882352	March 1999	Duncan et al.
5885221	March 1999	Hsu et al.
5891170	April 1999	Nitzsche et al.
5916238	June 1999	Hauser et al.
5931857	August 1999	Prieve et al.
5951592	September 1999	Murphy
5954752	September 1999	Mongeon et al.
5978700	November 1999	Nigam
6076014	June 2000	Alt
6115627	September 2000	Street
6128529	October 2000	Elser
6151524	November 2000	Krig et al.
6169923	January 2001	Kroll
6212428	April 2001	Hsu et al.
6223078	April 2001	Marcovecchio
6230055	May 2001	Sun et al.
6259947	July 2001	Olson et al.
6269267	July 2001	Bardy et al.
6275732	August 2001	Hsu et al.
6317632	November 2001	Krig et al.
6324422	November 2001	Williams et al.
6327499	December 2001	Alt
6370427	April 2002	Alt et al.
6393316	May 2002	Gillberg et al.
6415179	July 2002	Pendekanti et al.
6430435	August 2002	Hsu et al.
6442425	August 2002	Alt
6445949	September 2002	Kroll
6449503	September 2002	Hsu
6477406	November 2002	Turcott
6484055	November 2002	Marcovecchio
6487443	November 2002	Olson et al.
6490478	December 2002	Zhang et al.
6493584	December 2002	Lu
6564097	May 2003	Williams et al.
6567691	May 2003	Stadler
6611713	August 2003	Schauerte
6628986	September 2003	Mouchawar et al.
6687540	February 2004	Marcovecchio
6748269	June 2004	Thompson et al.
6754527	June 2004	Stroebel et al.
6754528	June 2004	Bardy et al.
6801806	October 2004	Sun et al.
7206633	April 2007	Saba
2001/0034539	October 2001	Stadler et al.
2002/0002389	January 2002	Bradley et al.
2002/0032469	March 2002	Marcovecchio
2002/0035335	March 2002	Schauerte
2002/0058968	May 2002	Sun et al.
2002/0091333	July 2002	Hsu et al.
2002/0107544	August 2002	Ostroff et al.
2002/0123768	September 2002	Gilkerson
2002/0169483	November 2002	Henry et al.
2002/0188215	December 2002	Ferek-Petric
2003/0032989	February 2003	Herleikson
2003/0045906	March 2003	Stroebel et al.
2003/0060849	March 2003	Hsu
2003/0074026	April 2003	Thompson et al.
2003/0088282	May 2003	Ostroff
2003/0097153	May 2003	Bardy et al.
2003/0105491	June 2003	Gilkerson et al.
2003/0120316	June 2003	Spinelli et al.
2003/0144700	July 2003	Brown et al.
2003/0204209	October 2003	Burnes et al.
2003/0204210	October 2003	Ousdigian et al.
2003/0216654	November 2003	Xu et al.
2004/0111121	June 2004	Brown et al.
2005/0251215	November 2005	Dujmovic, Jr. et al.

Foreign Patent Documents


WO-0166180	Sep., 2001	WO
WO-2006020791	Feb., 2006	WO

Other References

"International Search Report and Written Opinion for Application No. PCT/US2005/028592, date mailed Jan. 19, 2006", 18 Pages. cited by other .
"3 Abstracts from the Tenth Annual Scientific Congress of the Hong Kong College of Cardiology", Medical Section, 7(8), Jun. 21-23, 2002, 11-13. cited by other .
Albert, C. M., et al., "Prospective Study of Sudden Cardiac Death Among Women in the United States", Circulation, 107, (2003),2096-2101. cited by other .
Boecker, D , et al., "Benefit of an Enhanced Detection Algorithm in Optimizing Treatment of Slow Ventricular Tachycardia", PACE, 23 (Part II), (Apr. 2000), Abstract 95. cited by other .
Buxton, A. E., et al., "Relation of Ejection Fraction and Inducible Ventricular Tachycardia to Mode of Death in Patients With Coronary Artery Disease--An Analysis of Patients Enrolled in the Multicenter Unsustained Tachycardia Trial", Circulation, 106, (2002),2466-2472. cited by other .
Chung-Seung, C. , "Medical Session--Management of Congestive Heart Failure", Medical Section, 7(8), (2002),4-9. cited by other .
Copie, X. , et al., "Predictive Power of Increased Heart Rate Versus Depressed Left Ventricular Ejection Fraction and Heart Rate Variability for Risk Stratification After Myocardial Infarction", Journal of the American College of Cardiology, 27(2), (1996),270-276. cited by other .
Darpo, B. , et al., "Incidence of Sudden Death After Radiofrequency Ablation of the Atrioventricular Junction for Atrial Fibrillation", The American Journal of Cardiology, 80, (1997),1174-1177. cited by other .
Dodinot, B. , et al., "La Mort Subite Chez le Porteur de Stimulateur Cardiaque", Annales de Cardiologie et D'Angeiologie, (1985),161-166. cited by other .
Engdahl, J. , et al., "The Epidemiology of Out-of-Hospital `Sudden` Cardiac Arrest", Resuscitation, 52, (2002),235-245. cited by other .
Ezekowitz, J. A., et al., "Implantable Cardioverter Defibrillators in Primary and Secondary Prevention: A Systematic Review of Randomized, Controlled Trials", Annals of Internal Medicine, 138, (2003),445-452. cited by other .
Fromer, M. , et al., "Experience with a New Implantable Pacer-, Cardioverter-Defibrillator for the Therapy of Recurrent Sustained Ventricular Tachyarrhythmias: A Step Toward a Universal Ventricular Tachyarrhythmia Control Device", Pace, 14, (1991),1288-1297. cited by other .
Furman, S. , "The Future of the Pacemaker", Pace, 25(1), (2002),1-2. cited by other .
Gasparini, M. , et al., "Long-Term Follow-Up After Atrioventricular Nodal Ablation and Pacing: Low Incidence of Sudden Cardiac Death", Pace, 23(11)(Part II), (2000),1925-1929. cited by other .
Geelen, P. , et al., "The Value of DDD Pacing in Patients with an Implantable Carioverter Defibrillator", Pace, 20 (Part II), (1997),177-181. cited by other .
Golino, A. , et al., "Clinical Experience with the Transvenous Medtronic Pacer Cardioverter Defibrillator (PCD(r)) System", Texas Heart Institute Journal, 20(4), (1993),264-270. cited by other .
Gregoratos, G. , et al., "ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: Summary Article--A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines", Journal of Cardiovascular Electrophysiology, 13(11), (ACC/AHA/NASPE Committee to Update the 1988 Pacemaker Guidelines),(2002),1183-1199. cited by other .
Grimm, W. , et al., "Electrocardiographically Documented Unnecessary, Spontaneous Shocks in 241 Patients With Implantable Cardioverter Defibrillators", Pace, 15(11)(Part 1), (1992),1667-1673. cited by other .
Higgins, S. L. et al., "Indications for Implantation of a Dual-Chamber Pacemaker Combined With an Implantable Cardioverter-Defibrillator", American Journal of Cardiology, 81(11), (1998),1360-1362. cited by other .
Hohnloser, S. H., et al., "Changing Late Prognosis of Acute Myocardial Infarction--Impact on Management of Ventricular Arrhythmias in the Era of Reperfusion and the Implantable Cardioverter-Defibrillator", Circulation, 107, (2003),941-946. cited by other .
Iskos, D. , et al., "Physiological Cardiac Pacing in Patients With Contemporary Implantable Cardioverter-Defibrillators", American Journal of Cardiology, 82(1), (1998),66-71. cited by other .
Jouven, X. , et al., "Predicting Sudden Death in the Population--The Paris Prospective Study I", Circulation, 99, (1999),1978-1983. cited by other .
Kanagaratnam, L. , et al., "Matching Approved "Nondedicated" Hardware to Obtain Biventricular Pacing and Defibrillation: Feasibility and Troubleshooting", Pace, 25(7), (2002),1066-1071. cited by other .
Kay, G. N., et al., "The Abate and Pace Trial: A Prospective Study of Catheter Ablation of the AV Conduction System and Permanent Pacemaker Implantation for Treatment of Atrial Fibrillation", Journal of Interventional Cardiac Electrophysiology, 2(2), (1998),121-135. cited by other .
Lamas, G. A., et al., "The Mode Selection Trial (Most) in Sinus Node Dysfunction: Design, Rationale, and Baseline Characteristics of the First 1000 Patients", American Heart Journal, 140, (2000),541-551. cited by other .
Lavergne, T. , et al., "Preliminary Clinical Experience with the First Dual Chamber Pacemaker Defibrillator", Pace, 20(1) (Part II), (1997),182-188. cited by other .
Liu, B. C., et al., "Inappropriate Shock Delivery and Biventricular Pacing Cardiac Defibrillators", Texas Heart Journal, 30(1), (2003),45-49. cited by other .
Mattioli, A. V., et al., "Causes of Death in Patients with Unipolar Single Chamber Ventricular Pacing: Prevalence and Circumstances in Dependence on Arrhythmias Leading to Pacemaker Implantation", Pace, 18(1)(Part 1), (1995),11-17. cited by other .
Morris, M. M., et al., "A Preview of Implantable Cardioverter Defibrillator Systems in the Next Millennium: An Integrative Cardiac Rhythm Management Approach", American Journal of Cardiology, 83(5B), (1999),48D-54D. cited by other .
Myerburg, R. J., et al., "Opportunities for Sudden Death Prevention: Directions for New Clinical and Basic Research", Cardiovascular Research, 50, (2001),177-185. cited by other .
Pinski, S. L., et al., "Permanent Pacing via Implantable Defibrillators", Pace, 23(11 Part 1), (2000),1667-1682. cited by other .
Saksena, S. , et al., "Long-Term Multicenter Experience With a Second-Generation Implantable Pacemaker-Defibrillator in Patients With Malignant Ventricular Tachyarrhythmias", Journal of American College of Cardiology, 19(3), (1992),490-499. cited by other .
Santini, M. , et al., "Indications for Dual-Chamber (DDD) Pacing in Implantable Cardioverter-Defibrillator Patients", American Journal of Cardiology, 78(Supp. 5A), (1996),116-118. cited by other .
Singer, I. , et al., "The Initial Clinical Experience with an Implantable Cardioverter Defibrillator/Antitachycardia Pacemaker", Pace, 14, (1991),1119-1128. cited by other .
Sweeney, M. O., et al., "Adverse Effect of Ventricular Pacing on Heart Failure and Atrial Fibrillation Among Patients With Normal Baseline QRS Duration in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction", Circulation, 107, (2003),2932-2937. cited by other .
Thackray, S. D., et al., "The Prevalence of Heart Failure and Asymptomatic Left Ventricular Systolic Dysfunction in a Typical Regional Pacemaker Population", European Heart Journal, 24, (2003),1143-1152. cited by other .
Twidale, N. , et al., "Predictors of Outcome After Radiofrequency Catheter Ablation of the Atrioventricular Node for Atrial Fibrillation and Congestive Heart Failure", American Heart Journal, 136(4)(Part 1), (1998),647-657. cited by other .
Zehender, M. , et al., "Prevalence, Circumstances, Mechanisms, and Risk Stratification of Sudden Cardiac Death in Unipolar Single-Chamber Ventricular Pacing", Circulation, 85, (1992),596-605. cited by other.

Primary Examiner: Layno; Carl
Attorney, Agent or Firm: Schwegman, Lundberg & Woessner, P.A.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This patent application claims the benefit of priority, under 35 U.S.C. Section 119(e), to Bocek et al. U.S. Provisional Patent Application Ser. No. 60/600,614, filed Aug. 11, 2004, entitled PACEMAKER WITH COMBINED DEFIBRILLATOR TAILORED FOR BRADYCARDIA PATIENTS.

Claims

What is claimed is:

1. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity of ventricular tachyarrhythmia/fibrillation detection, and wherein the ventricular tachyarrhythmia/fibrillation detector circuit is configured such that the specificity exceeds the sensitivity without regard to an operator skill level, and in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, and wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

2. The apparatus of claim 1, in which the specificity is greater than or equal to 99%.

3. The apparatus of claim 2, in which the sensitivity is less than 99%.

4. The apparatus of claim 2, in which the specificity is greater than or equal to 99.5%.

5. The apparatus of claim 4, in which the sensitivity is less than 99.5%.

6. The apparatus of claim 1, in which the one or more parameters is further programmable by a user.

7. The apparatus of claim 1, in which the cardiac rhythm management device further includes a telemetry circuit that is operatively communicatively coupled to a local or remote external programmer, and wherein the local or remote external programmer includes a user interface configured to permit programming of the one or more parameters of the one or more shock control modules.

8. The apparatus of claim 7, in which the user interface includes a display illustrating projected values of the specificity or the sensitivity corresponding to particular settings of one or more parameters of the implantable cardiac rhythm management device.

9. The apparatus of claim 1, in which the one or more shock control modules includes a respiration detector to determine whether the patient is breathing and to withhold shock delivery when the patient is breathing.

10. The apparatus of claim 1, in which the one or more shock control modules includes a posture detector to determine whether the patient is supine and to withhold shock delivery when the patient is not supine.

11. The apparatus of claim 1, in which the one or more shock control modules includes an evoked-response detector to determine, in response to a detected tachyarrhythmia or fibrillation, whether a delivered pacing pulse evokes a responsive heart contraction and to withhold shock delivery when an evoked responsive heart contraction is detected.

12. The apparatus of claim 1, in which the one or more shock control modules includes a high rate detection threshold to determine whether a detected heart rate exceeds a high rate detection threshold value that is in a range between about 200 beats per minute and 250 beats per minute and to withhold shock delivery unless the detected heart rate exceeds the high rate detection threshold value.

13. The apparatus of claim 1, in which the one or more shock control modules includes a last-shocked timer to measure an elapsed time since a most recent shock was delivered, and to withhold shock delivery unless the elapsed time exceeds an elapsed time threshold value.

14. The apparatus of claim 1, in which the one or more shock control modules is operable to automatically disable shock delivery after the cardiac rhythm management device has treated a tachyarrhythmia or fibrillation episode by delivering at least one shock.

15. The apparatus of claim 1, in which the one or more shock control modules is operable to permit the patient to enable or disable shock delivery.

16. The apparatus of claim 1, in which the one or more shock control modules is operable to permit the patient to disable shock delivery only after the cardiac rhythm management device has treated a tachyarrhythmia or fibrillation episode by delivering at least one shock.

17. The apparatus of claim 1, in which the one or more shock control modules includes a duration timer to measure an elapsed time duration since an onset of the tachyarrhythmia or fibrillation episode, and to withhold shock delivery until the time duration equals or exceeds a duration threshold value that is in a range between about 10 seconds and about 60 seconds.

18. The apparatus of claim 1, in which the one or more shock control modules is coupled to an impedance sensor to detect intracardiac impedance and to withhold shock delivery if the intracardiac impedance indicates that a heart wall motion level exceeds a heart wall motion threshold value or that a cardiac output is more than a cardiac output threshold value.

19. The apparatus of claim 1, in which the one or more shock control modules is coupled to an accelerometer to detect patient activity and to withhold shock delivery if the detected patient activity exceeds a patient activity threshold value.

20. The apparatus of claim 1, in which the heart signal sensing circuit includes first and second heart rate signal sensing channels, wherein the first heart rate signal sensing channel is operatively coupled to at least one different electrode than the second heart rate sensing channel, and wherein the one or more shock control modules includes a high rate detection threshold to determine whether a detected heart rate exceeds a high rate detection threshold value as determined from the first and second heart rate sensing channels.

21. The apparatus of claim 1, in which the heart signal sensing circuit includes a ventricular depolarization sensing threshold that is greater than or equal to a threshold value, wherein the threshold value is between about 0.6 millivolts and 2.5 millivolts.

22. The apparatus of claim 1, in which the implantable cardiac rhythm management device includes a flag to disable or enable shock delivery in response to a patient input.

23. The apparatus of claim 1, further comprising means for notifying the patient that a shock will be or has been delivered.

24. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, and in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, and wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population, and in which the one or more parameters is further programmable by a user; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

25. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules includes a respiration detector to determine whether the patient is breathing and to withhold shock delivery when the patient is breathing; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

26. The apparatus of claim 25, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

27. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules includes a posture detector to determine whether the patient is supine and to withhold shock delivery when the patient is not supine; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

28. The apparatus of claim 27, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

29. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules includes an evoked-response detector to determine, in response to a detected tachyarrhythmia or fibrillation, whether a delivered pacing pulse evokes a responsive heart contraction and to withhold shock delivery when an evoked responsive heart contraction is detected; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

30. The apparatus of claim 29, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

31. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules includes a last-shocked timer to measure an elapsed time since a most recent shock was delivered, and to withhold shock delivery unless the elapsed time exceeds an elapsed time threshold value; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

32. The apparatus of claim 31, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

33. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules is operable to automatically disable shock delivery after the cardiac rhythm management device has treated a tachyarrhythmia or fibrillation episode by delivering at least one shock; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

34. The apparatus of claim 33, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

35. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules is operable to permit the patient to enable or disable shock delivery; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulation circuit, coupled to the heart signal sensing circuit, the stimulation circuit configured to deliver to the heart a stimulation at an energy level appropriate to evoke or assist in evoking a responsive heart contraction.

36. The apparatus of claim 35, wherein the one or more parameters are factory programmed to one or more corresponding default values such that the specificity exceeds the sensitivity in a target patient population.

37. An apparatus comprising: an implantable cardiac rhythm management device, the cardiac rhythm management device comprising: a heart signal sensing circuit to sense intrinsic electrical heart signals from a heart of a patient; a ventricular tachyarrhythmia/fibrillation detector circuit, operatively coupled to the heart signal sensing circuit, the ventricular tachyarrhythmia/fibrillation detector circuit operable to detect a ventricular tachyarrhythmia/fibrillation, wherein the ventricular tachyarrhythmia/fibrillation detector circuit has a sensitivity and a specificity, in which the ventricular tachyarrhythmia/fibrillation detector circuit includes one or more shock control modules to determine whether a patient should be shocked, wherein the one or more shock control modules are individually or collectively programmable by one or more parameters, in which the one or more shock control modules is operable to permit the patient to disable shock delivery only after the cardiac rhythm management device has treated a tachyarrhythmia or fibrillation episode by delivering at least one shock; a defibrillation shock circuit, coupled to the ventricular tachyarrhythmia/fibrillation detector circuit, the defibrillation shock circuit configured to deliver a defibrillation shock in response to the detected ventricular tachyarrhythmia/fibrillation; and a stimulati