Methods and apparatuses for cardiac resynchronization therapy mode selection based on intrinsic conduction

1. A method of selecting a cardiac resynchronization therapy (CRT) mode, the method comprising:

sensing electrocardiogram (ECG) data for a patient;

identifying a PR interval from the sensed ECG data;

comparing the PR interval to a predetermined time threshold; and

selecting a CRT mode by selecting between a synchrony optimization mode and a preload optimization mode, the selection based on the comparison of the PR interval to the predetermined time threshold, wherein:

the synchrony optimization mode is selected if the PR interval is less than the predetermined time threshold, optimizes CRT for fusion between a left ventricular pulse and an intrinsic atrial activity wavefront, and comprises either a LV only CRT that stimulates only the left ventricle or a biventricular simultaneous CRT that stimulates the left ventricle and the right ventricle simultaneously; and

the preload optimization mode is selected if the PR interval is greater than the predetermined time threshold, comprises a biventricular sequential CRT that stimulates the left ventricle and the right ventricle where timing between stimulation of the left ventricular and the right ventricle is optimized for fusion between respective wavefronts of the left ventricular pulse and a right ventricular pulse, and timing between atrial activity and the left ventricular pulse is optimized for blood preloading of the left ventricle.

2. The method of claim 1 , wherein the PR predetermined time threshold is about 190 milliseconds.

3. The method of claim 1 , further comprising:

identifying an additional parameter from the ECG data; and

comparing the additional parameter to a parameter threshold, wherein the selection between the synchrony optimization mode and the preload optimization mode is based on whether the additional parameter exceeded the parameter threshold.

4. The method of claim 3 , wherein the additional parameter comprises an RV-LV interval, RA-LV interval, AV interval, P-Wave duration, QRS complex width, presence of ischemic/non-ischemic condition, atrial fibrillation or AV nodal block.

5. A method of selecting a cardiac resynchronization therapy (CRT) mode, the method comprising:

sensing an electrophysiologic signal containing cardiac data from a patient;

identifying a cardiac parameter from the sensed electrophysiologic data;

comparing the parameter to a predetermined time threshold; and

selecting a CRT mode by selecting between a synchrony optimization mode and a preload optimization mode, the selection based on the comparison of the parameter to the predetermined time threshold, wherein

the synchrony optimization mode optimizes CRT for fusion between a left ventricular pulse and an intrinsic atrial activity wavefront; and

the preload optimization mode optimizes CRT for fusion between respective wavefronts of the left ventricular pulse and a right ventricular pulse.

6. The method of claim 5 , wherein:

identifying the cardiac parameter from the sensed electrophysiologic data comprises identifying a PR interval;

selecting the CRT mode based on the comparison of the parameter to the predetermined time threshold comprises comparing the PR interval to a PR predetermined time threshold;

the synchrony optimization mode is selected if the PR interval is below the PR predetermined time threshold; and

the preload optimization mode is selected if the PR interval is above the PR predetermined time threshold.

7. The method of claim 6 , wherein the PR predetermined time threshold is about 190 milliseconds.

8. The method of claim 6 , wherein the PR predetermined time threshold is between 160-220 milliseconds.

9. The method of claim 5 , wherein identifying the cardiac parameter from the sensed electrophysiologic data comprises identifying an interval indicative of relative timing between atrial and ventricular intrinsic activity and selecting the CRT mode based on the comparison of the parameter to the predetermined time threshold comprises comparing the interval to the predetermined time threshold.

10. The method of claim 5 , wherein the parameter comprises an RV-LV interval, RA-LV interval, AV interval, P-Wave duration, QRS complex width, presence of ischemic/non-ischemic condition, atrial fibrillation or AV nodal block.

11. The method of claim 5 , wherein:

the synchrony optimization mode comprises a LV only CRT or a biventricular simultaneous CRT, each of the LV only CRT and simultaneous CRT optimizing for fusion between a ventricular pulse and the intrinsic atrial activity wavefront; and

the preload optimization mode comprises a biventricular simultaneous CRT that sequentially stimulates the left and right ventricles for fusion between wavefronts associated with the left ventricular pulse and the right ventricular pulse.

12. A cardiac resynchronization therapy (CRT) system, the system comprising:

memory;

an implantable housing configured to be implanted in a patient;

a plurality of electrodes coupled to the housing;

sensing circuitry configured to sense a least one electrocardiac signal using at least some of the plurality of electrodes;

stimulation circuitry configured to deliver a CRT using at least some of the plurality of electrodes in a synchrony optimization mode with pulse timing for fusion between a left ventricular pulse and an intrinsic atrial activity wavefront, and a preload optimization mode with pulse timing for fusion between respective wavefronts of the left ventricular pulse and a right ventricular pulse; and

a controller configured to execute program instructions stored in the memory to cause the system to identify at least one parameter of the at least one electrocardiac signal, compare the parameter to a parameter predetermined time threshold, and select between the synchrony optimization mode and the preload optimization mode for therapy delivery using the stimulation circuitry based on the comparison of the parameter to the parameter predetermined time threshold.

13. The system of claim 12 , wherein:

the at least one parameter identified from the electrocardiac signal comprises a PR interval;

the parameter predetermined time threshold to which the PR interval is compared is a PR predetermined time threshold;

the synchrony optimization mode is selected if the PR interval is less than the PR predetermined time threshold; and

the preload optimization mode is selected if the PR interval is greater than the PR predetermined time threshold.

14. The system of claim 13 , wherein the PR predetermined time threshold is about 190 milliseconds.

15. The system of claim 13 , wherein the PR predetermined time threshold is about 160-220 milliseconds.

16. The system of claim 12 , wherein:

the at least one parameter identified from the electrocardiac signal comprises an interval indicative of relative timing between atrial and ventricular intrinsic activity;

the comparison of the parameter to the parameter predetermined time threshold comprises comparing the interval indicative of relative timing between atrial and ventricular intrinsic activity to an interval predetermined time threshold;

the synchrony optimization mode is selected if the interval exceeds the interval predetermined time threshold; and

the preload optimization mode is selected if the interval is less than the interval predetermined time threshold.

17. The system of claim 12 , wherein the at least one parameter identified from the electrocardiac signal comprises an RV-LV interval, RA-LV interval, AV interval, P-Wave duration, QRS complex width, presence of ischemic/non-ischemic condition, atrial fibrillation or AV nodal block.

18. The system of claim 12 , wherein:

the synchrony optimization mode comprises a LV only CRT or a biventricular simultaneous CRT, each of the LV only CRT and simultaneous CRT optimizing for fusion between a ventricular pulse and the intrinsic atrial activity wavefront; and

the preload optimization mode comprises a biventricular simultaneous CRT that sequentially stimulates the left and right ventricles for fusion between wavefronts associated with the left ventricular pulse and the right ventricular pulse.

19. A system of selecting a cardiac resynchronization therapy (CRT) mode, the system comprising:

means for sensing an electrophysiologic signal containing cardiac information from a patient;

means for identifying a cardiac parameter from the sensed electrophysiologic signal;

means for comparing the parameter to a predetermined time threshold; and

means for selecting a CRT mode by selecting between a synchrony optimization mode and a preload optimization mode, the selection based on the comparison of the parameter to the predetermined time threshold, wherein

the synchrony optimization mode optimizes CRT for fusion between a left ventricular pulse and an intrinsic atrial activity wavefront; and

the preload optimization mode optimizes CRT for fusion between respective wavefronts of the left ventricular pace and a right ventricular pace.

20. The system of claim 19 , wherein:

identifying the cardiac parameter from the sensed electrophysiologic signal comprises identifying a PR interval;

selecting the CRT mode based on the comparison of the parameter to the predetermined time threshold comprises comparing the PR interval to a PR predetermined time threshold of about 190 milliseconds;

the synchrony optimization mode is selected if the PR interval is less than the PR predetermined time threshold; and

the preload optimization mode is selected if the PR interval is greater than the PR predetermined time threshold.

21. The system of claim 19 , wherein:

identifying the cardiac parameter from the sensed electrophysiologic signal comprises identifying an interval indicative of relative timing between atrial and ventricular intrinsic activity;

selecting the CRT mode based on the comparison of the parameter to the predetermined time threshold comprises comparing the interval to the predetermined time threshold;

the synchrony optimization mode is selected if the interval is less than the interval predetermined time threshold; and

the preload optimization mode is selected if the interval is greater than the interval predetermined time threshold.

22. The method of claim 19 , wherein:

the synchrony optimization mode comprises a LV only CRT or a biventricular simultaneous CRT, each of the LV only CRT and simultaneous CRT optimizing for fusion between a ventricular pulse and the intrinsic atrial activity wavefront; and

the preload optimization mode comprises a biventricular sequential CRT that sequentially stimulates the left and right ventricles for fusion between wavefronts associated with the left ventricular pulse and the right ventricular pulse.