Synchronization of anti-tachycardia pacing in an extra-cardiovascular implantable system

A method performed by an extra-cardiovascular implantable cardioverter defibrillator (ICD) system, comprising:

• receiving a first cardiac electrical signal by an electrical sensing circuit of the extra-cardiovascular ICD system via a first extra-cardiovascular sensing electrode vector;
• sensing cardiac events from the first cardiac electrical signal;
• detecting tachycardia from the first cardiac electrical signal by a control circuit of the ICD system;
• determining a tachycardia cycle length from the first cardiac electrical signal;
• determining a first ATP interval based on the tachycardia cycle length;
• setting a first extended ATP interval that is longer than the first ATP interval;
• delivering a first plurality of ATP pulses to a patient's heart via an extra-cardiovascular pacing electrode vector different than the first extra-cardiovascular sensing electrode vector, the first plurality of ATP pulses comprising a first leading ATP pulse delivered at the first extended ATP interval after a cardiac event is sensed by the sensing circuit from the first cardiac electrical signal and a second ATP pulse delivered at the first ATP interval following the first leading ATP pulse.

A non-transitory, computer-readable storage medium comprising a set of instructions which, when executed by a control circuit of an extra-cardiovascular implantable cardioverter defibrillator system, cause the system to:

• receive a cardiac electrical signal by an electrical sensing circuit via an extra-cardiovascular sensing electrode vector;
• sense cardiac events from the cardiac electrical signal;
• detect tachycardia from the cardiac electrical signal;
• determine a tachycardia cycle length from the cardiac electrical signal;
• determine an ATP interval based on the tachycardia cycle length;
• set an extended ATP interval that is longer than the ATP interval;
• deliver a plurality of ATP pulses to a patient's heart via an extra-cardiovascular pacing electrode vector different than the extra-cardiovascular sensing electrode vector, the plurality of ATP pulses comprising a leading ATP pulse delivered at the extended ATP interval after a cardiac event is sensed by the sensing circuit from the cardiac electrical signal and a second ATP pulse delivered at the ATP interval following the leading ATP pulse.