Overcharged final countershock for an implantable cardioverter defibrillator and method

• US 5,449,377 A
• Filed: 09/22/1993
• Issued: 09/12/1995
• Est. Priority Date: 03/24/1992
• Status: Expired due to Term

• Current Assignee: Ela Medical S.A. (LivaNova Plc)
• Original Assignee: Angeion Corporation (Niterra Co., Ltd.)
• Inventors: Kroll, Mark W., Adams, Theodore P.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Getzow, Scott M.
• Application Number:
  US08/125,288
• Time in Patent Office: 720 Days
• Field of Search: 607/5, 607/7, 607/8, 607/12
• US Class Current: 607/7
• CPC Class Codes: A61N 1/3906 characterised by the form of the shockwave
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An implantable cardioverter defibrillator (ICD) device in operated in an overcharged final countershock condition so as to provide greater efficacy and broader treatment modality for the device. Instead of delivering a repeated series of up to five countershocks at the maximum rated charging voltage in response to a persistent ventricular arrhythmia as is done in existing ICD systems, an overcharged final countershock is delivered for which the electrolytic capacitor charge storage system of the ICD system is charged at a voltage that exceeds a maximum voltage specification. By delivering an overcharged final countershock, the present invention increases the chances of reversing a persistent ventricular arrhythmia which has become increasingly resistant to electrical therapy the longer the arrhythmia persists. As there is little to no risk in overcharging electrolytic capacitors for delivering the overcharged final countershock, and in fact the added electrical energy may overcome the increasing resistance to electrical countershock therapy, the present invention can deliver a more efficacious programmed therapy regimen than is available on existing ICD systems.

Claims

1. A method for operating an implantable cardioverter defibrillator device electrically connected to two or more implanted discharge electrodes located in a human patient to treat myocardial fibrillation, the method comprising the device implemented steps of:

a) sensing for a myocardial fibrillation in a human patient;

b) charging a capacitive charge storage system at least once to a voltage value at or below a nominal maximum voltage in response to sensing the myocardial fibrillation;

c) discharging the capacitive charge storage system through the two or more implanted discharge electrodes;

d) recharging the capacitive charge storage system at least once to an overcharged voltage in excess of the nominal maximum voltage in response to a sensing of a persistent myocardial fibrillation which the at least one discharge according to step (c) failed to treat; and

e) discharging the capacitive charge storage system through the two or more implanted discharge electrodes to effect a final treatment for the myocardial fibrillation.

2. The method of claim 1 wherein the maximum nominal voltage is a maximum programmable voltage specified for the device.

3. The method of claim 1 wherein the maximum nominal voltage is a maximum manufacturer'"'"'s rated charging voltage for the capacitive charge storage system.

4. The method of claim 1 wherein the capacitive charge storage system is a pair of electrolytic capacitors in series and the maximum nominal voltage is a maximum charging voltage across the electrolytic capacitors of greater than 375 volts across each capacitor.

5. A method for operating an implantable cardioverter defibrillator device electrically connected to two or more implanted discharge electrodes located in a human patient to treat myocardial fibrillation, the method comprising the device implemented steps of:

a) sensing for myocardial fibrillation in the human patient;

b) charging a capacitive charge storage system at least once to a maximum nominal voltage in response to sensing a myocardial fibrillation;

c) discharging the capacitive charge storage system through the two or more implanted discharge electrodes to effect treatment of the myocardial fibrillation;

d) reverting immediately to sensing for myocardial fibrillation;

e) repeating steps (b)-(d) a first predetermined number of times if step (d) senses a failure to treat the myocardial fibrillation;

f) switching to an overcharged voltage operation if step (d) senses a failure to treat the myocardial fibrillation and the first predetermined number of times have been exceeded;

g) overcharging the capacitive charge storage system beyond the maximum nominal voltage;

h) discharging the overcharged capacitive charge storage system through the two or more implanted discharge electrodes to effect a final treatment of the myocardial fibrillation;

i) reverting immediately to sensing for myocardial fibrillation;

j) repeating steps (f)-(h) a second predetermined number of times if step (i) senses a persistent failure to treat the myocardial fibrillation; and

k) stopping all myocardial fibrillation treatment efforts after the second predetermined number of times have been exceeded without success in treating the myocardial fibrillation.

6. The method of claim 5 in which the first predetermined number of treatment attempts is less than six.

7. The method of claim 5 in which the second predetermined number of treatment attempts using overcharged voltage is less than four.

8. An implantable cardioverter defibrillator apparatus electrically connected to two or more implanted discharge electrodes adapted to be located in a human patient for treating myocardial arrhythmias comprising:

a) sensing means for sensing a myocardial arrhythmia in the human patient;

b) capacitive charge storage means electrically connected to the two or more implanted electrodes for storing an electrical charge;

c) power source means for charging the capacitive charge storage means to a charging voltage;

d) control means for selectively controlling the power source means and the capacitive charge storage means in response to the sensing of the myocardial arrhythmia in order to deliver at least one electrical countershock to the two or more electrodes in accordance with a programmable therapy regimen stored in the apparatus, the control means including;

d0) means for storing the programmable therapy regimen;

d1) means for regulating a charging voltage applied by the power source means to the capacitive charge storage means in response to a charging voltage value indicated in the programmable therapy regimen;

d2) means for selectively discharging the capacitive charge storage means as an electrical countershock in response to a reconfirmed sensing of the myocardial fibrillation by the sensing means;

d3) means for counting a successive number of failed electrical countershocks in the programmable therapy regimen when the sensing means determines that the electrical countershock was not successful in treating the myocardial fibrillation; and

d4) means for resetting the means for counting to zero after a successful treatment of the myocardial fibrillation,

wherein at least one of the voltages in the programmable therapy regimen is a maximum nominal voltage and at least another of the voltages in the programmable therapy regimen is an overcharged voltage greater than the maximum voltage.

9. The apparatus of claim 8 wherein the maximum nominal voltage is a maximum programmable voltage specified for the apparatus.

10. The apparatus of claim 8 wherein the maximum nominal voltage is a maximum manufacturer'"'"'s rated charging voltage for the capacitive charge storage system.

11. The apparatus of claim 8 wherein the capacitive charge storage system is a pair of electrolytic capacitors in series and the maximum voltage is a maximum charging voltage across the electrolytic capacitors of greater than 375 volts across each capacitor.

12. The apparatus of claim 8 wherein the programmable therapy regimen comprises a series of charging voltage values corresponding to at least three electrical countershocks, including:

a first charging voltage value that is less than the maximum voltage;

a second charging voltage value that is equal to the maximum voltage; and

a third charging voltage value that is greater than or equal to the overcharged voltage.

13. The apparatus of claim 12 wherein the programmable therapy regimen includes two or more second charging voltage values, each second charging voltage value further specifying a unique discharge pathway among the two or more electrodes through which the electrical countershock will be discharged.

14. A method for operating an implantable cardioverter defibrillator device electrically connected to two or more implanted discharge electrodes located in a human patient to treat myocardial high rate ventricular tachycardia, the method comprising the device implemented steps of:

a) sensing for a myocardial high rate ventricular tachycardia in a human patient;

b) charging a capacitive charge storage system at least once to a voltage value below a nominal maximum voltage in response to sensing the myocardial high rate ventricular tachycardia;

c) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes;

d) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (c) failed to treat;

e) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes;

f) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (e) failed to treat;

g) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes;

h) recharging the capacitive charge storage system at least once to an overcharged voltage value in excess of the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (g) failed to treat; and

i) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes.

15. The method of claim 14 further comprising after step (e) the steps of:

e1) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (e) failed to treat; and

e2) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes with inverted polarity.

16. The method of claim 14 further comprising after step (g) the steps of:

g1) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (g) failed to treat; and

g2) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes with inverted polarity.

17. The method of claim 14 further comprising after step (i) the steps of:

i1) recharging the capacitive charge storage system at least once to an overcharged voltage value in excess of the nominal maximum voltage in response to a sensing of a persistent myocardial high rate ventricular tachycardia which the at least one discharge according to step (i) failed to treat; and

i2) discharging the capacitive charge storage system through the two or more implanted discharge electrodes with inverted polarity to effect a final treatment for the persistent myocardial high rate ventricular tachycardia.

18. The method of claim 14 wherein the maximum nominal voltage is a maximum programmable voltage specified for the device.

19. The method of claim 14 wherein the below nominal voltage is a programmable voltage at about 600 volts specified for the device.

20. The method of claim 14 wherein the maximum nominal voltage is a maximum manufacturer'"'"'s rated charging voltage for the capacitive charge storage system.

21. The method of claim 14 wherein the capacitive charge storage system is a pair of electrolytic capacitors in series and the maximum nominal voltage is a maximum charging voltage across the electrolytic capacitors of greater than 375 volts across each capacitor.

22. A method for operating an implantable cardioverter defibrillator device electrically connected to two or more implanted discharge electrodes located in a human patient to treat myocardial low rate ventricular tachycardia, the method comprising the device implemented steps of:

a) sensing for a myocardial low rate ventricular tachycardia in a human patient;

b) charging a capacitive charge storage system at least once to a voltage value below a nominal maximum voltage in response to sensing the myocardial low rate ventricular tachycardia;

c) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes;

d) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (c) failed to treat;

e) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes;

f) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (e) failed to treat;

g) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes;

h) recharging the capacitive charge storage system at least once to an overcharged voltage value in excess of the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (g) failed to treat; and

i) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes.

23. The method of claim 22 further comprising after step (c) the steps of:

c1) recharging a capacitive charge storage system at least once to a voltage value below a nominal maximum voltage in response to sensing the myocardial low rate ventricular tachycardia which the at least one discharge according to step (c) failed to treat; and

c2) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes with inverted polarity.

24. The method of claim 22 further comprising after step (e) the steps of:

e1) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (e) failed to treat; and

e2) discharging the capacitive charge storage system in synchrony with an R wave through the two or more implanted discharge electrodes with inverted polarity.

25. The method of claim 22 further comprising after step (g) the steps of:

g1) recharging the capacitive charge storage system at least once to a voltage value at the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (g) failed to treat; and

g2) discharging the capacitive charge storage system asynchronously through the two or more implanted discharge electrodes with inverted polarity.

26. The method of claim 22 further comprising after step (i) the steps of:

i1) recharging the capacitive charge storage system at least once to an overcharged voltage value in excess of the nominal maximum voltage in response to a sensing of a persistent myocardial low rate ventricular tachycardia which the at least one discharge according to step (i) failed to treat; and

i2) discharging the capacitive charge storage system through the two or more implanted discharge electrodes with inverted polarity to effect a final treatment for the persistent myocardial low rate ventricular tachycardia.

27. The method of claim 22 wherein the maximum nominal voltage is a maximum programmable voltage specified for the device.

28. The method of claim 22 wherein the maximum nominal voltage is a maximum manufacturer'"'"'s rated charging voltage for the capacitive charge storage system.

29. The method of claim 22 wherein the below nominal voltage is a programmable voltage at about 450 volts specified for the device.

30. The method of claim 22 wherein the below nominal voltage is a programmable voltage at about 600 volts specified for the device.

31. The method of claim 22 wherein the capacitive charge storage system is a pair of electrolytic capacitors in series and the maximum nominal voltage is a maximum charging voltage across the electrolytic capacitors of greater than 375 volts across each capacitor.