Method and apparatus for delivering bundle branch pacing

1. A medical device system, comprising:

a pulse generator configured to generate pacing pulses;

a sensing circuit for sensing a first cardiac electrical signal; and

processing circuitry configured to:

receive at least the first cardiac electrical signal that is sensed by the sensing circuit during bilateral bundle branch pacing delivered from the pulse generator via a bipolar electrode pair comprising an anode positioned along a first bundle branch and a cathode positioned along a second bundle branch opposite the first bundle branch;

determine at least one feature from the first cardiac electrical signal;

determine that the at least one feature meets first bundle branch capture criteria indicating that the bilateral bundle branch pacing has captured the first bundle branch; and

determine anodal bundle branch capture in response to the first bundle branch capture criteria being met; and

determine a pacing pulse output based on determining the anodal bundle branch capture; and

control the pulse generator to generate pacing pulses according to the determined pacing pulse output.

2. The medical device system of claim 1 , wherein the processing circuitry is further configured to:

determine the pacing pulse output for bilateral bundle branch pacing in response to determining the anodal bundle branch capture.

3. The medical device system of claim 1 , wherein the processing circuitry is configured to:

determine the at least one feature from the first cardiac electrical signal by determining at least one of a QRS width, a QRS amplitude, a QRS morphology, a QRS polarity, and an activation time.

4. The medical device system of claim 1 , wherein the sensing circuit is further configured to:

receive the first cardiac electrical signal as a first unipolar signal via a first one of the anode and the cathode as a sensing electrode.

5. The medical device system of claim 4 , wherein:

the sensing circuit is configured to receive a second cardiac electrical signal as a second unipolar signal via a second one of the anode and the cathode; and

the processing circuitry is configured to determine the at least one feature by determining an activation time difference as a time interval between the first feature of the first cardiac electrical signal and a second feature of the second cardiac electrical signal; and

determine that the activation time difference meets the first bundle branch capture criteria.

6. The medical device system of claim 1 , wherein the sensing circuit is further configured to pass at least the first cardiac electrical signal to the processing circuitry by sensing a bipolar signal via the anode and the cathode.

7. The medical device system of claim 6 , further comprising:

the pulse generator configured to generate pacing pulses delivered via the anode and the cathode at each of a plurality of pacing pulse outputs;

wherein the processing circuitry is further configured to:

determine the at least one feature from the first cardiac electrical signal by:

determining, from the bipolar signal, a first QRS morphology corresponding to a first pacing pulse output of the plurality of pacing pulse outputs;

determining, from the bipolar signal, a second QRS morphology corresponding to a second pacing pulse output of the plurality of pacing pulse outputs, wherein the second pacing pulse output is greater than the first pacing pulse output and the second QRS morphology is different than the first QRS morphology; and

detecting in the bipolar signal a change between the first QRS morphology and the second QRS morphology; and

determine that the at least one feature meets the first bundle branch capture criteria in response to detecting the change in the bipolar signal between the first QRS morphology and the second QRS morphology.

8. The medical device system of claim 1 , further comprising:

the pulse generator further configured to:

generate a unipolar pacing pulse delivered via the cathode; and

generate a bipolar pacing pulse delivered via the cathode and the anode;

the sensing circuit further configured to sense at least the first cardiac electrical signal by:

receiving the first cardiac electrical signal as a first unipolar signal via the anode; and

receiving a second cardiac electrical signal as a second unipolar signal via the cathode; and

wherein the processing circuitry is further configured to:

determine, from the first unipolar signal and the second unipolar signal following the unipolar pacing pulse, a first activation time difference from a first fiducial point of the first unipolar signal to a second fiducial point of the second unipolar signal;

determine, from the first unipolar signal and the second unipolar signal following the bipolar pacing pulse, a second activation time difference from the first fiducial point of the first unipolar signal to the second fiducial point of the second unipolar signal;

determine that the second activation time difference is less than the first activation time difference; and

determine that the at least one feature meets the first bundle branch capture criteria in response to the second activation time difference being less than the first activation time difference.

9. The medical device system of claim 8 , wherein:

the pulse generator is configured to deliver a bipolar pacing pulse via the anode and the cathode at each of a plurality of pacing pulse outputs;

the processing circuitry is further configured to:

determine a first lowest pacing pulse output of the plurality of pacing pulse outputs that is associated with anodal bundle branch capture being determined in response to the first bundle branch capture criteria being met;

determine a bipolar bilateral bundle branch pacing capture threshold as the first lowest pacing pulse output of the plurality of pacing pulse outputs;

set the pacing pulse output based on the bipolar bundle branch pacing capture threshold; and

control the pulse generator to deliver bilateral bundle branch pacing by delivering bipolar pacing pulses at the pacing pulse output for capturing the first bundle branch via the anode and the second bundle branch via the cathode.

10. The medical device system of claim 9 , wherein the processing circuitry is further configured to:

determine that the bipolar bilateral bundle branch capture threshold is greater than a maximum pacing output limit;

determine a second lowest pacing pulse output of the plurality of pacing pulse outputs that is associated with the second cardiac electrical signal meeting second bundle branch capture criteria; and

setting the pacing pulse output based on the second lowest pacing pulse output that is associated with the second cardiac electrical signal meeting second bundle branch capture criteria; and

control the pulse generator to deliver single bundle branch pacing by delivering pacing pulses at the pacing pulse output for capturing the second bundle branch via the cathode.

11. A method, comprising:

receiving at least a first cardiac electrical signal that is sensed during bilateral bundle branch pacing delivered from a bipolar electrode pair comprising an anode positioned along a first bundle branch and a cathode positioned along a second bundle branch opposite the first bundle branch;

determining at least one feature from the first cardiac electrical signal;

determining that the at least one feature meets first bundle branch capture criteria indicating that the bilateral bundle branch pacing has captured the first bundle branch;

determining anodal bundle branch capture in response to the first bundle branch capture criteria being met;

determining a pacing pulse output based on determining the anodal bundle branch capture; and

generating pacing pulses according to the determined pacing pulse output.

12. The method of claim 11 , further comprising:

determining the pacing pulse output for bilateral bundle branch pacing in response to determining the anodal bundle branch capture.

13. The method of claim 11 , further comprising:

determining the at least one feature from the first cardiac electrical signal by determining at least one of a QRS width, a QRS amplitude, a QRS morphology, a QRS polarity, and an activation time.

14. The method of claim 11 , further comprising receiving the first cardiac electrical signal as a first unipolar signal via a first one of the anode and the cathode as a sensing electrode.

15. The method of claim 14 , further comprising:

receiving a second cardiac electrical signal as a second unipolar signal via a second one of the anode and the cathode; and

determining the at least one feature by determining an activation time difference as a time interval between the first feature of the first cardiac electrical signal and a second feature of the second cardiac electrical signal; and

determine that the activation time difference meets the first bundle branch capture criteria.

16. The method of claim 11 , further comprising receiving at least the first cardiac electrical signal by sensing a bipolar signal via the anode and the cathode.

17. The method of claim 16 , further comprising:

delivering pacing pulses via the anode and the cathode at each of a plurality of pacing pulse outputs;

determining the at least one feature from the first cardiac electrical signal by:

determining, from the bipolar signal, a first QRS morphology corresponding to a first pacing pulse output of the plurality of pacing pulse outputs;

determining, from the bipolar signal, a second QRS morphology; and corresponding to a second pacing pulse output of the plurality of pacing pulse outputs, wherein the second pacing pulse output is greater than the first pacing pulse output and the second QRS morphology is different than the first QRS morphology;

detecting a change in the bipolar signal between the first QRS morphology and the second QRS morphology; and

determining that the at least one feature meets the first bundle branch capture criteria in response to detecting in the bipolar signal the change between the first QRS morphology and the second QRS morphology.

18. The method of claim 11 , further comprising:

generating a unipolar pacing pulse delivered via the cathode;

generating a bipolar pacing pulse delivered via the cathode and the anode;

receiving at least the first cardiac electrical signal by:

receiving a first unipolar signal via the anode; and

receiving a second cardiac electrical signal as a second unipolar signal via the cathode;

determining, from the first unipolar signal and the second unipolar signal following the unipolar pacing pulse, a first activation time difference from a first fiducial point of the first unipolar signal to a second fiducial point of the second unipolar signal;

determining, from the first unipolar signal and the second unipolar signal following the bipolar pacing pulse, a second activation time difference from the first fiducial point of the first unipolar signal to the second fiducial point of the second unipolar signal;

determining that the second activation time difference is less than the first activation time difference; and

determining that the at least one feature meets the first bundle branch capture criteria in response to the second activation time difference being less than the first activation time difference.

19. The method of claim 18 , further comprising:

delivering a bipolar pacing pulse via the anode and the cathode at each of a plurality of pacing pulse outputs;

determining a first lowest pacing pulse output of the plurality of pacing pulse outputs that is associated with anodal bundle branch capture being determined in response to the first bundle branch capture criteria being met;

determining a bipolar bilateral bundle branch pacing capture threshold as the first lowest pacing pulse output of the plurality of pacing pulse outputs;

setting the pacing pulse output based on the bipolar bundle branch pacing capture threshold; and

delivering bipolar bilateral bundle branch pacing by delivering bipolar pacing pulses at the pacing pulse output for capturing the first bundle branch via the anode and the second bundle branch via the cathode.

20. The method of claim 19 , further comprising:

determining that the bipolar bilateral bundle branch capture threshold is greater than a maximum pacing output limit;

determining a second lowest pacing pulse output of the plurality of pacing pulse outputs that is associated with the second cardiac electrical signal meeting second bundle branch capture criteria;

setting the pacing pulse output based on the second lowest pacing pulse output that is associated with the second cardiac electrical signal meeting second bundle branch capture criteria; and

delivering single bundle branch pacing by delivering pacing pulses at the pacing pulse output for capturing the second bundle branch via the cathode.

21. A non-transitory computer readable medium storing instructions which, when executed by processing circuitry of a medical device system, cause the device system to:

receive at least a first cardiac electrical signal that is sensed during bilateral bundle branch pacing delivered from a bipolar electrode pair comprising an anode positioned along a first bundle branch and a cathode positioned along a second bundle branch opposite the first bundle branch;

determine at least one feature from the first cardiac electrical signal;

determine that the at least one feature meets first bundle branch capture criteria indicating that the bilateral bundle branch pacing has captured the first bundle branch;

determine anodal bundle branch capture in response to the first bundle branch capture criteria being met;

determine a pacing pulse output based on determining the anodal bundle branch capture; and

generate pacing pulses according to the determined pacing pulse output.