Method and device for delivering anti-tachycardia pacing therapy

1. A method for delivering a therapy to terminate a tachycardia event, comprising:

sensing cardiac signals and detecting the tachycardia event in response to the sensed cardiac signals;

delivering a first plurality of pacing pulses in response to the detected tachycardia event;

determining a return cycle length generated subsequent to the delivery of the first plurality of pacing pulses;

determining whether the return cycle length is greater than a cycle length associated with the tachycardia event and less than a sum of the cycle length associated with the tachycardia event and a total prematurity associated with the first plurality of pacing pulses; and

adjusting delivery of a second plurality of pacing pulses in response to the return cycle length being greater than the cycle length associated with the tachycardia event and less than the sum of the cycle length associated with the tachycardia event and the total prematurity associated with the first plurality of pacing pulses.

2. The method of claim 1 , further comprising determining a transit time corresponding to a distance between the electrode and a reentrant circuit associated with the tachycardia event.

3. The method of claim 2 , wherein the transit time is determined as one half of a difference between the return cycle length and the cycle length associated with the tachycardia event.

4. The method of claim 2 , further comprising determining a minimum number of pacing pulses to enable delivery of the second plurality of pacing pulses to reach the reentrant circuit in response to the determined transit time.

5. The method of claim 4 , wherein the second plurality of pacing pulses is equal to one more than the determined minimum number of pacing pulses.

6. The method of claim 4 , further comprising determining prematurities corresponding to each pacing pulse of the second plurality of pacing pulses, wherein the total prematurity corresponds to a sum of the determined prematurities, and the minimum number of pacing pulses is determined as a ratio of the transit time and the prematurities.

7. The method of claim 6 , wherein the ratio corresponds to twice the transit time relative to the prematurities.

8. The method of claim 6 , wherein determining prematurities comprises:

determining a cycle length of each pacing pulse of the second plurality of pacing pulses; and

determining a difference between the cycle length of each pacing pulse of the second plurality of pacing pulses and the cycle length associated with the tachycardia event.

9. The method of claim 8 , further comprising increasing the determined prematurity of at least one pacing pulse of the second plurality of pacing pulses.

10. The method of claim 8 , further comprising increasing the determined prematurity of a last pacing pulse of the second plurality of pacing pulses.

11. A medical device for delivering a therapy to terminate a tachycardia event, comprising:

an electrode to sense cardiac signals and to deliver the therapy, the therapy including a first plurality of pacing pulses;

sensing circuitry, electrically coupled to the electrode, to detect the tachycardia event in response to the sensed cardiac signals; and

a processor to control delivery of the therapy, wherein the processor determines whether a return cycle length generated subsequent to the delivery of the first plurality of pacing pulses is greater than a cycle length associated with the tachycardia event and less than a sum of the cycle length associated with the tachycardia event and a total prematurity associated with the first plurality of pacing pulses, and adjusts delivery of a second plurality of pacing pulses in response to the return cycle length being greater than the cycle length associated with the tachycardia event and less than the sum of the cycle length associated with the tachycardia event and the total prematurity associated with the first plurality of pacing pulses.

12. The device of claim 11 , wherein the processor determines a transit time corresponding to a distance between the electrode and a reentrant circuit associated with the tachycardia event.

13. The device of claim 12 , wherein the transit time is determined as one half of a difference between the return cycle length and the cycle length associated with the tachycardia event.

14. The device of claim 12 , wherein the processor determines a minimum number of pacing pulses to enable delivery of the second plurality of pacing pulses to reach the reentrant circuit in response to the determined transit time.

15. The device of claim 14 , wherein the second plurality of pacing pulses is equal to one more than the determined minimum number of pacing pulses.

16. The device of claim 14 , wherein the processor determines prematurities corresponding to each pacing pulse of the second plurality of pacing pulses, wherein the total prematurity corresponds to a sum of the determined prematurities, and the minimum number of pacing pulses is determined as a ratio of the transit time and the prematurities.

17. The device of claim 16 , wherein the ratio corresponds to twice the transit time relative to the prematurities.

18. The device of claim 16 , wherein the processor determines a cycle length of each pacing pulse of the second plurality of pacing pulses, and determines a difference between the cycle length of each pacing pulse of the second plurality of pacing pulses and the cycle length associated with the tachycardia event as the prematurities.

19. The device of claim 18 , wherein the processor increases the determined prematurity of at least one pacing pulse of the second plurality of pacing pulses.

20. The device of claim 18 , wherein the processor increases the determined prematurity of a last pacing pulse of the second plurality of pacing pulses.