Terminating pacemaker mediated tachycardia (PMT) in dual chamber leadless pacemaker systems

1. A method for terminating a pacemaker mediated tachycardia (PMT), the method for use by an implantable system including an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP), the aLP configured to be implanted within or on an atrial cardiac chamber, wherein during a period that the PMT is not detected the aLP is also configured to deliver an atrial pacing pulse to the atrial cardiac chamber in response to a PA interval expiring without an intrinsic atrial event being detected during the PA interval, the vLP configured to be implanted within or on a ventricular cardiac chamber, and the aLP and the vLP capable of performing implant-to-implant (i2i) communication with one another, the method comprising:

the aLP performing atrial sensing to thereby monitor for intrinsic atrial events in the atrial cardiac chamber;

the vLP performing ventricular sensing to thereby monitor for intrinsic ventricular events in the ventricular chamber;

one of the aLP or the vLP detecting the PMT;

the one of the aLP or the vLP that detected the PMT informing the other one of the aLP or the vLP, via an i2i communication, that the PMT was detected;

the aLP, in response to the PMT being detected, initiating a PMT PA interval that is shorter than the PA interval that the aLP would otherwise use for atrial pacing if the PMT was not detected; and

the vLP, in response to the PMT being detected, initiating a PMT PV interval that is longer than the PMT PA interval;

wherein the PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PA interval expiring without another intrinsic atrial event being detected during the PA interval, during a period that the PMT has not been detected;

wherein the PMT PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PA interval expiring without another intrinsic atrial event being detected during the PMT PA interval, during a period that the PMT has been detected; and

wherein the PMT PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PV interval expiring without an intrinsic ventricular event being detected during the PMT PV interval, during a period that the PMT has been detected.

2. The method of claim 1 , further comprising the aLP detecting the PMT PA interval expiring without an intrinsic atrial event being detected during the PMT PA interval, and in response thereto the aLP:

pacing the atrial cardiac chamber; and

informing the vLP, via an i2i communication, of the pacing the atrial cardiac chamber.

3. The method of claim 2 , further comprising the vLP receiving the i2i communication from the aLP that informs the vLP of the pacing the atrial cardiac chamber, and in response thereto the vLP:

terminating the PMT PV interval; and

initiating an atrioventricular (AV) interval;

wherein the AV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following a paced atrial event, in response to the AV interval expiring without an intrinsic ventricular event being detected during the AV interval, during a period that the PMT has not been detected; and

wherein the paced atrial event can be the pacing of the atrial cardiac chamber that the aLP informs the vLP about via the i2i communication.

4. The method of claim 1 , further comprising the aLP detecting an intrinsic atrial event during the PMT PA interval, and in response thereto the aLP:

terminating the PMT PA interval; and

informing the vLP, via an i2i communication, of the detected intrinsic atrial event.

5. The method of claim 4 , further comprising the vLP receiving the i2i communication from the aLP that informs the vLP of the intrinsic atrial event being detected, and in response thereto the vLP:

terminating the PMT PV interval; and

initiating a PV interval;

wherein the PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial event, in response to the PV interval expiring without an intrinsic ventricular event being detected during the PV interval, during a period that the PMT has not been detected; and

wherein the intrinsic atrial event can be the intrinsic atrial event that the aLP informs the vLP about via the i2i communication.

6. The method of claim 1 , further comprising the vLP detecting an intrinsic ventricular event during the PMT PV interval, and in response thereto the vLP:

terminating the PMT PV interval; and

informing the aLP, via an i2i communication, of the detected intrinsic ventricular event.

7. The method of claim 1 , wherein:

the step of one of the aLP or the vLP detecting the PMT comprises the aLP detecting the PMT;

the step of the one of the aLP or the vLP that detected the PMT informing the other one of the aLP or the vLP comprises the aLP informing the vLP, via an i2i communication, that the PMT was detected;

the step of the aLP initiating a PMT PA interval comprises the aLP, in response to the aLP detecting the PMT, initiating the PMT PA interval that is shorter than the PA interval that the aLP would otherwise use for atrial pacing if the PMT was not detected; and

the step of the vLP initiating a PMT PV interval comprises the vLP, in response being informed by the aLP that the PMT was detected, initiating the PMT PV interval that is longer than the PMT PA interval.

8. The method of claim 1 , wherein:

the step of one of the aLP or the vLP detecting the PMT comprises the vLP detecting the PMT;

the step of the one of the aLP or the vLP that detected the PMT informing the other one of the aLP or the vLP comprises the vLP informing the aLP, via an i2i communication, that the PMT was detected;

the step of the aLP initiating a PMT PA interval comprises the aLP, in response to being informed by the vLP that the PMT was detected, initiating the PMT PA interval that is shorter than the PA interval that the aLP would otherwise use for atrial pacing if the PMT was not detected; and

the step of the vLP initiating a PMT PV interval comprises the vLP, in response the vLP detecting the PMT, initiating the PMT PV interval that is longer than the PMT PA interval.

9. The method of claim 1 , wherein the PMT PV interval equals the PMT PA interval plus a delay, and wherein the delay comprises either a fixed value or a rate dependent value.

10. The method of claim 1 , wherein the PMT PA interval comprises a fixed value or a rate dependent value.

11. An implantable system configured to terminate a pacemaker mediated tachycardia (PMT), the implantable system comprising:

an atrial leadless pacemaker (aLP) configured to be implanted in or on an atrial cardiac chamber, the aLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic atrial event and pacing the atrial cardiac chamber;

a ventricular leadless pacemaker (vLP) configured to be implanted in or on a ventricular cardiac chamber, the vLP including at least one processor and including at least two electrodes that can be used for sensing an intrinsic ventricular event, pacing the ventricular cardiac chamber, and performing i2i communication;

wherein during a period that the PMT is not detected the aLP is configured to deliver an atrial pacing pulse to the atrial cardiac chamber in response to a PA interval expiring without an intrinsic atrial event being detected during the PA interval;

at least one of the aLP or the vLP configured to detect a PMT, and in response thereto, inform the other one of the aLP or the vLP, via an i2i communication, that the PMT was detected;

the aLP configured to initiate a PMT PA interval, in response to the PMT being detected, wherein the PMT PA interval is shorter than a PA interval that the aLP would otherwise use for atrial pacing if the PMT was not detected; and

the vLP configured to initiate a PMT PV interval, in response to the PMT being detected, wherein the PMT PV interval is longer than the PMT PA interval;

wherein the PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PA interval expiring without another intrinsic atrial event being detected during the PA interval, during a period that the PMT has not been detected;

wherein the PMT PA interval specifies when an atrial pacing pulse should be delivered by the aLP to the atrial cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PA interval expiring without another intrinsic atrial event being detected during the PMT PA interval, during a period that the PMT has been detected; and

wherein the PMT PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial sensed event, in response to the PMT PV interval expiring without an intrinsic ventricular event being detected during the PMT PV interval, during a period that the PMT has been detected.

12. The implantable system of claim 11 , wherein the aLP is configured to perform the following, in response to the PMT PA interval expiring without an intrinsic atrial event being detected during the PMT PA interval:

pace the atrial cardiac chamber; and

inform the vLP, via an i2i communication, of the pacing the atrial cardiac chamber.

13. The implantable system of claim 12 , wherein the vLP is configured to perform the following, in response to receiving the i2i communication from the aLP that informs the vLP of the pacing the atrial cardiac chamber:

terminate the PMT PV interval; and

initiate an atrioventricular (AV) interval;

wherein the AV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following a paced atrial event, in response to the AV interval expiring without an intrinsic ventricular event being detected during the AV interval, during a period that the PMT has not been detected; and

wherein the paced atrial event can be the pacing of the atrial cardiac chamber that the aLP informs the vLP about via the i2i communication.

14. The implantable system of claim 11 , wherein the aLP is configured to perform the following, in response to an intrinsic atrial event being detected during the PMT PA interval:

terminate the PMT PA interval; and

inform the vLP, via an i2i communication, of the detected intrinsic atrial event.

15. The implantable system of claim 14 , wherein the vLP is configured to perform the following, in response to receiving the i2i communication from the aLP that informs the vLP of the intrinsic atrial event being detected:

terminate the PMT PV interval; and

initiate a PV interval;

wherein the PV interval specifies when a ventricular pacing pulse should be delivered by the vLP to the ventricular cardiac chamber following an intrinsic atrial event, in response to the PV interval expiring without an intrinsic ventricular event being detected during the PV interval, during a period that the PMT has not been detected; and

wherein the intrinsic atrial event can be the intrinsic atrial event that the aLP informs the vLP about via the i2i communication.

16. The implantable system of claim 11 , wherein the vLP is configured to perform the following, in response to an intrinsic ventricular event being detected during the PMT PV interval:

terminate the PMT PV interval; and

inform the aLP, via an i2i communication, of the detected intrinsic ventricular event.

17. The implantable system of claim 11 , wherein the aLP is configured to detect a PMT and configured to inform the vLP, via an i2i communication, that the PMT was detected.

18. The implantable system of claim 11 , wherein the vLP is configured to detect a PMT and configured to inform the aLP, via an i2i communication, that the PMT was detected.

19. The implantable system of claim 11 , wherein the PMT PV interval equals the PMT PA interval plus a delay, and wherein the delay comprises either a fixed value or a rate dependent value.

20. The implantable system of claim 11 , wherein the PMT PA interval comprises a fixed value or a rate dependent value.