Estimating RV-timings from left ventricular (LV) sensing times for adaptive cardiac resynchronization therapy using DDD/VDD LV pacing without a right ventricular (RV) lead

A method of using an implantable medical device (IMD) in the patient's heart comprising:

• sensing heart activity from the patient's heart using a plurality of electrodes;
• employing a processor in the IMD to determine whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the sensed heart activity;
• employing the IMD to determine timing of CRT pacing pulses for delivery to cardiac tissue through one or more pacing electrodes from the plurality of electrodes;
• the IMD processor configured to adjust timing of the CRT pacing pulses comprising:
• (1) determining onset of baseline QRS timing from the sensed heart activity;
• (2) measuring As-onset of baseline QRS (Qon) timing;
• (3) measuring baseline As (Ap)-LVs timing;
• (4) subtracting As(Ap)+Qon+t timing from the As(Ap)-LVs timing to obtain a result where t is a constant parameter representing a difference between onset of QRS and RV sense timing from data collected from a group of patients having an implanted RV lead;
• (5) delivering the CRT pacing pulses to the heart using the IMD and based on subtracting the result in from step 4 from a subsequent As (Ap)-LVs timing measurement;
• thereafter sensing subsequent electrical signals from the patient's heart using the IMD;
• and
• determining, by the IMD based on the subsequent electrical signals, whether the CRT pacing by the IMD provided efficacious resynchronization.

Cardiac pacing system comprising:

• a leadless pacing device (LPD);
• and
• a subcutaneous device (SD) comprising:
• a sensing module comprising a sensing circuit for acquiring heart activity including atrial and ventricular events from the patient's heart using the SD and using the LPD to acquire left ventricular events (LVs);
• and
• a control module comprising a therapy circuit configured to:
• (a) determine whether cardiac resynchronization pacing therapy (CRT pacing) is appropriate based upon the heart activity sensed using the SD;
• (b) determine timing of CRT pacing pulses for delivery to cardiac tissue through the LPD, wherein determining the timing of the CRT pacing pulses comprises:
• (1) detecting an atrial event and determining onset of baseline QRS (Qon) from the heart activity sensed using the SD;
• (2) measuring an atrial event to Qon interval;
• (3) measuring an atrial event to LVs interval;
• (4) subtracting the atrial event to Qon interval and a time interval “t” from the atrial event to LVs interval to obtain a correction factor;
• and
• (5) using the correction factor to obtain a new pacing delay;
• the sensing module further configured to sense heart activity from the patient's heart subsequent to delivery of CRT pacing pulses to the heart using the LPD and using the new pacing delay;
• using the SD;
• and
• the control module further configured to determine, by the SD based on the subsequent sensed heart activity, whether the CRT pacing pulses delivered using the LPD using the new pacing delay provided efficacious resynchronization and whether the delivery and timing of subsequent CRT pacing pulses should be modified.