PAC therapy
An implantable cardiac device is programmed to detect and classify premature atrial contractions (PACs) and administer responsive pacing therapy. The responsive pacing therapy is in the form of an atrial extrastimulus, which is intended to preempt initiation of a reentrant tachycardia. The atrial extrastimulus is timed to occur late enough after a PAC to ensure atrial capture, but early enough that the resulting atrial depolarization does not conduct through the AV node to the ventricles if the PAC has already done so. If both of these criteria cannot be met, the device may be configured to inhibit the atrial extrastimulus.
1. A method for operating an implantable cardiac device, comprising:
detecting a premature atrial contraction; and
administering an atrial extrastimulus in response to the premature atrial contraction, the atrial extrastimulus being timed to ensure atrial capture while avoiding AV conduction by selecting an administration time for the atrial extrastimulus bound by an adapatable time range, the time range adapted based on one or more previously administered atrial extrastimulus.
2. The method of claim 1 , further comprising foregoing administration of the atrial extrastimulus in an event that the atrial extrastimulus cannot be timed to ensure atrial capture and avoid AV conduction.
3. The method of claim 1 , further comprising administering ventricular pacing pulses at a rate to maintain a constant interval between consecutive ventricular pacing pulses.
4. The method of claim 3 , further comprising:
initiating a test interval when the atrial extrastimulus is administered; and
administering an atrial pacing pulse if the test interval lapses before a next scheduled ventricular pacing pulse.
5. The method of claim 1 , further comprising:
initiating a primary rate VA interval upon detection of an R-wave caused by one of the premature atrial contraction or the atrial extrastimulus; and
administering an atrial pacing pulse upon termination of the primary rate VA interval.
6. An implantable cardiac device comprising:
sensing circuitry to receive signals indicative of atrial contraction;
a premature atrial contraction (PAC) detector operably coupled to the sensing circuitry to classify certain atrial contractions as premature atrial contractions;
a PAC therapy unit to administer an atrial extrastimulus in response to the premature atrial contraction, the atrial extrastimulus being timed to ensure atrial capture while avoiding AV conduction by selecting an administration time for the atrial extrastimulus bound by an adapatable time range, the time range adapted based on one or more previously administered atrial extrastimulus.
7. The device of claim 6 , wherein the PAC therapy unit foregoes administration of the atrial extrastimulus in an event that the atrial extrastimulus cannot be timed to ensure atrial capture and avoid AV conduction.
8. The device of claim 6 , wherein the PAC therapy unit administers ventricular pacing pulses at a rate to maintain a constant interval between consecutive ventricular pacing pulses.
9. The device of claim 8 , wherein the PAC therapy unit:
initiates a test interval when the atrial extrastimulus is administered; and
administers an atrial pacing pulse if the test interval lapses before a next scheduled ventricular pacing pulse.
10. The device of claim 6 , wherein the PAC therapy unit:
initiates a primary rate VA interval upon detection of an R-wave caused by one of the premature atrial contraction or the atrial extrastimulus; and
administers an atrial pacing pulse upon termination of the primary rate VA interval.