Dynamic cardiac resynchronization therapy by tracking intrinsic conduction
Systems and methods for pacing the heart using resynchronization pacing delays that achieve improvement of cardiac function are described. An early activation pacing interval is calculated based on an optimal AV delay and an atrial to early ventricular activation interval between an atrial event and early activation of a ventricular depolarization. The early activation pacing interval for the ventricle is calculated by subtracting the measured AV EA from the calculated optimal AV delay. The early activation pacing interval is initiated responsive to sensing early activation of the ventricle and pacing is delivered relative to expiration of the early activation pacing interval.
1. A method for operating a cardiac pacing device, comprising:
sensing intrinsic atrioventricular intervals between an atrial event and a ventricular depolarization for at least one ventricle;
calculating an optimal AV delay based on the intrinsic atrioventricular intervals;
determining an atrial to early ventricular activation interval (AV EA );
calculating an early activation pacing interval for the ventricle by subtracting the AV EA from the calculated optimal AV delay;
sensing an early activation of the ventricle during a cardiac cycle;
starting the early activation pacing interval for the cardiac cycle responsive to sensing the early activation; and
delivering pacing to the at least one ventricle for the cardiac cycle relative to expiration of the early activation pacing interval.
2. The method of claim 1 , wherein determining the AV EA comprises determining an interval between the atrial event and a start of a ventricular depolarization, Q*.
3. The method of claim 1 , wherein determining the AV EA comprises:
sensing a depolarization of the His Bundle; and
determining the interval between the atrial event and the His Bundle depolarization.
4. The method of claim 1 , wherein the at least one ventricle comprises the right ventricle.
5. The method of claim 1 , wherein the at least one ventricle comprises the left ventricle.
6. The method of claim 1 , wherein the at least one ventricle comprises a right ventricle and a left ventricle.
7. The method of claim 1 , wherein:
starting the early activation pacing interval responsive to sensing early activation of the ventricle comprises starting the early activation pacing interval responsive to sensing early activation of the right or left ventricle; and
pacing the ventricle relative to expiration of the early activation pacing interval comprises pacing the right and left ventricles relative to expiration of the early activation pacing interval.
8. The method of claim 7 , wherein pacing the right and left ventricles comprises delivering right and left ventricular paces substantially simultaneously.
9. The method of claim 7 , wherein pacing the right and left ventricles comprises sequentially delivering right and left ventricular paces separated by an interventricular delay.
10. A cardiac rhythm management device, comprising:
electrodes configured to electrically coupled to multiple chambers of a heart;
sensing circuitry configured to sense cardiac electrical signals via the electrodes and to detect cardiac signal features associated with cardiac events;
measurement circuitry coupled to the sense circuitry and configured to measure one or more cardiac intervals, including an atrioventricular interval (AVI) between an atrial event and a ventricular depolarization for at least one ventricle and an atrial to early ventricular activation interval (AV EA ) between an atrial event and early activation of a ventricular depolarization for the ventricle;
optimization circuitry configured to calculate an optimal AV delay based on the measured atrioventricular intervals and to calculate an early activation pacing interval for the ventricle by subtracting the measured AV EA from the calculated optimal AVD;
a pacing interval controller configured to start the early activation pacing interval responsive to sensing early activation of the ventricle; and
pacing therapy circuitry configured to pace the ventricle relative to expiration of the early activation pacing interval.
11. The device of claim 10 , wherein the early ventricular activation interval comprises an interval between the atrial event and a start of a ventricular depolarization, Q*.
12. The device of claim 10 , wherein the early ventricular activation interval comprises an interval between the atrial event and the His Bundle depolarization.
13. The device of claim 10 , wherein the at least one ventricle comprises the right ventricle.
14. The device of claim 10 , wherein the at least one ventricle comprises the left ventricle.
15. The device of claim 10 , wherein the at least one ventricle comprises a right ventricle and a left ventricle.
16. The device of claim 10 , wherein:
the pacing interval controller is further configured to start the early activation pacing interval responsive to sensing early activation of the right or left ventricle; and
the pacing therapy circuitry is further configured to pace the right and left ventricles relative to expiration of the early activation pacing interval.
17. The device of claim 16 , wherein the pacing therapy circuitry is further configured to deliver right and left ventricular paces substantially simultaneously.
18. The device of claim 16 , wherein the pacing therapy circuitry is further configured to sequentially deliver right and left ventricular paces separated by an interventricular delay.