Extra-cardiovascular cardiac pacing system for delivering composite pacing pulses
An implantable medical device has a therapy module configured to generate a composite pacing pulse including a series of at least two individual pulses. The therapy module is configured to generate the composite pacing pulse by generating a first pulse of the at least two individual pulses by selectively coupling a first portion of a plurality of capacitors to an output signal line and generate a second pulse of the at least two individual pulses by selectively coupling a second portion of the plurality of capacitors to the output signal line.
1. A medical device comprising:
therapy circuitry having a plurality of capacitors and an output signal line, the therapy circuitry configured to generate a composite pacing pulse comprising a series of at least two individual pulses by:
generating a first pulse of the at least two individual pulses by selectively coupling a first portion of the plurality of capacitors to the output signal line, the first pulse having a first peak voltage amplitude, and
generating a second pulse of the at least two individual pulses sequentially with the first pulse by selectively coupling a second portion of the plurality of capacitors to the output signal line, the second pulse of the at least two individual pulses having a second peak voltage amplitude different than the first peak voltage amplitude.
2. The medical device of claim 1 , wherein the therapy circuitry is further configured to generate the composite pacing pulse by:
generating the first pulse having a first pulse width; and
generating the second pulse having a second pulse width different than the first pulse width, the composite pacing pulse having a composite pacing pulse width of at least the sum of the first pulse width and the second pulse width.
3. The medical device of claim 1 , wherein the therapy circuitry is further configured to generate the composite pacing pulse as a biphasic composite pacing pulse.
4. The medical device of claim 1 , wherein the therapy circuitry is further configured to generate the composite pacing pulse by generating the first pulse with a terminating edge that is concurrent with a leading edge of the second pulse.
5. The medical device of claim 1 , wherein the therapy circuitry is further configured to generate the composite pacing pulse by generating the second pulse overlapping with the first pulse.
6. The medical device of claim 1 , wherein the therapy circuitry is further configured to generate the composite pacing pulse by:
selecting the first portion of the plurality of capacitors having a first capacitance, the first pulse having a first decay rate corresponding to the first capacitance; and
selecting the second portion of the plurality of capacitors having a second capacitance different than the first capacitance, the second pulse having a second decay rate corresponding to the second capacitance.
7. The medical device of claim 1 , further comprising:
control circuitry configured to:
receive a composite pulse width setting; and
determine a number of individual pulses of the series of at least two individual pulses that are required to meet the composite pulse width setting;
wherein the therapy circuitry is further configured to generate the composite pacing pulse comprising the determined number of individual pulses.
8. The medical device of claim 1 , further comprising:
control circuitry configured to:
start a pacing escape interval; and
determine that the pacing escape interval is expired; and
wherein the therapy circuitry is further configured to generate the composite pacing pulse in response to the pacing escape interval expiring.
9. The medical device of claim 1 , wherein the therapy circuitry is configured to deliver the composite pacing pulse as one of a bradycardia pacing pulse, an anti-tachycardia pacing pulse, a post-shock pacing pulse, an asystole pacing pulse, an entrainment pulse, or a tachyarrhythmia induction pacing pulse.
10. The medical device of claim 1 , further comprising a housing enclosing the therapy circuitry, the housing comprising a connector bore configured to receive an extra-cardiovascular lead.
11. A method comprising:
generating by therapy circuitry of a medical device a composite pacing pulse comprising a series of at least two individual pulses by:
generating a first pulse of the at least two individual pulses by selectively coupling a first portion of a plurality of capacitors to an output signal line, the first pulse having a first peak voltage amplitude, and
generating a second pulse of the at least two individual pulses sequentially with the first pulse by selectively coupling a second portion of the plurality of capacitors to the output signal line, the second pulse of the at least two individual pulses having a second peak voltage amplitude different than the first peak voltage amplitude.
12. The method of claim 11 , wherein generating the composite pacing pulse further comprises:
generating the first pulse having a first pulse width; and
generating the second pulse having a second pulse width different than the first pulse width, the composite pacing pulse having a composite pacing pulse width of at least the sum of the first pulse width and the second pulse width.
13. The method of claim 11 , further comprising generating the composite pacing pulse as a biphasic composite pacing pulse.
14. The method of claim 11 , further comprising generating the composite pacing pulse by generating the first pulse with a terminating edge that is concurrent with a leading edge of the second pulse.
15. The medical device of claim 11 , further comprising generating the composite pacing pulse by generating the second pulse overlapping with the first pulse.
16. The medical device of claim 11 , further comprising generating the composite pacing pulse by:
selecting the first portion of the plurality of capacitors having a first capacitance, the first pulse having a first decay rate corresponding to the first capacitance; and
selecting the second portion of the plurality of capacitors having a second capacitance different than the first capacitance, the second pulse having a second decay rate corresponding to the second capacitance.
17. The method of claim 11 , further comprising:
receiving a composite pulse width setting;
determining a number of individual pulses of the series of at least two individual pulses that is required to meet the composite pulse width setting; and
generating the composite pacing pulse comprising the determined number of individual pulses.
18. The method of claim 11 , further comprising:
starting a pacing escape interval;
determining that the pacing escape interval is expired; and
generating the composite pacing pulse in response to the pacing escape interval expiring.
19. The method of claim 11 , further comprising delivering the composite pacing pulse as one of a bradycardia pacing pulse, an anti-tachycardia pacing pulse, a post-shock pacing pulse, an asystole pacing pulse, an entrainment pulse, or a tachyarrhythmia induction pacing pulse.
20. A non-transitory, computer-readable storage medium comprising a set of instructions which, when executed by control circuitry of a medical device, cause the medical device to:
generate a composite pacing pulse comprising a series of at least two individual pulses by:
generating a first pulse of the at least two individual pulses by selectively coupling a first portion of a plurality of capacitors to an output signal line, the first pulse having a first peak voltage amplitude, and
generating a second pulse of the at least two individual pulses sequentially with the first pulse by selectively coupling a second portion of the plurality of capacitors to the output signal line, the second pulse of the at least two individual pulses having a second peak voltage amplitude different than the first peak voltage amplitude.