Systems and methods for performing cardiac resynchronization therapy (crt) using leadless pacemakers

An implantable system for performing cardiac resynchronization therapy (CRT), comprising:

• a first leadless pacemaker (LP1) configured to be implanted in or on a right atrial (RA) chamber and selectively pace the RA chamber;
• a second leadless pacemaker (LP2) configured to be implanted in or on a right ventricular (RV) chamber and selectively pace the RV chamber;
• a third leadless pacemaker (LP3) configured to be implanted in or on a left ventricular (LV) chamber and selectively pace the LV chamber;
• one of the LP1, the LP2, or the LP3 designated a master LP;
• the LP1 also configured to sense a signal and measure a P-wave duration based on the signal sensed by the LP1;
• the LPI, or another one of the LPs that is designated the master LP, configured to determine an atrio-ventricular (AV) delay based on the measured P-wave duration;
• the LP2, or another one of the LPs that is designated the master LP, configured to determine a first AR or PR interval indicative of a time between an atrial depolarization and a ventricular depolarization in the RV chamber;
• the LP3, or another one of the LPs that is designated the master LP, configured to determine a second AR or PR interval indicative of a time between an atrial depolarization and a ventricular depolarization in the LV chamber;
• at least one of the LPs configured to determine an RV-LV delay indicative of a time it takes for a ventricular depolarization in the RV chamber to propagate to the LV chamber in response to the LP2 pacing the RV chamber;
• at east one of the LPs configured to determine an LV-RV delay indicative of a time it takes for a ventricular depolarization in the LV chamber to propagate to the RV chamber in response to the LP3 pacing the LV chamber;
• and
• the one of the LPs that is designated the master LP configured to determine a delta indicative of a difference between the first AR or PR interval and the second AR or PR interval, determine a correction factor indicative of a difference between the LV-RV delay and the RV-LV delay, and determine a VV delay based on the determined delta and the determined correction factor;
• wherein the LP1, the LP2, and the LP3 are configured to collectively perform CRT using the determined AV delay and the determined VV delay.

A leadless pacemaker (rvLP) configured to be implanted in or on a right ventricular (RV) chamber and configured to perform cardiac resynchronization therapy (CRT) along with a leadless pacemaker (raLP) configured to be implanted in or on a right atrial (RA) chamber and a leadless pacemaker (lvLP) configured to be implanted in or on a left ventricular (LV) chamber, the rvLP comprising:

• one or more pulse generators configured to selectively produce pacing pulses and implant-to-implant (i2i) communication pulses, the pacing pulses for use in pacing the RV chamber, and the i2i communication pulses for use in sending i2i messages to at least one of the raLP or the lvLP;
• a plurality of electrodes at least two of which can be used to deliver one or more pacing pulses to the RV chamber, at least two of which can be used to transmit and receive one or more i2i communication pulses to and from at least one of the raLP or the lvLP, and at least two of which can be used to sense a far-field signal from which cardiac activity associated with at least one of the RA or LV chambers may be detected;
• and
• a controller configured to determine
• an atrio-ventricular (AV) delay based on a P-wave duration measurement received via one or more i2i communication pulses from the raLP;
• an RV-LV delay indicative of a time it takes for a ventricular depolarization in the RV chamber to propagate to the LV chamber in response to the rvLP pacing the RV chamber;
• an LV-RV delay indicative of a time it takes for a ventricular depolarization in the LV chamber to propagate to the RV chamber in response to the lvLP pacing the LV chamber;
• a delta indicative of a difference between a first AR or PR interval and a second AR or PR interval, the first AR or PR interval indicative of a time between an atrial depolarization and a ventricular depolarization in the RV chamber, and the second AR or PR interval indicative of a time between an atrial depolarization and a ventricular depolarization in the LV chamber;
• a correction factor indicative of a difference between the LV-RV delay and the RV-LV delay;
• and
• a VV delay based on the determined delta and the determined correction factor;
• the controller also configured to coordinate performance of CRT collectively by the rvLP, raLP, and lvLP using the determined AV delay and the determined VV delay.