His capture verification using electro-mechanical delay

1. An ambulatory medical device, comprising:

a cardiac stimulation circuit configured to generate a His-bundle stimulation energy to provide stimulation to a His-bundle:

a processor circuit, including:

a data input, configured to receive first cardiac activity information in response to a His-bundle stimulation energy provided by the cardiac stimulation circuit to the His-bundle, the first cardiac activity information from other than an intrinsic electrical heart signal, and the first cardiac activity information received using a first sensor; and

a processor-readable medium, including instructions that, when performed by the processor, configure the medical device to:

determine a first interval using the first cardiac activity information in response to the His-bundle stimulation energy provided by the cardiac stimulation circuit to the His-bundle; and

provide a cardiac stimulation diagnostic indication about His-bundle capture using the first interval.

2. The ambulatory medical device of claim 1 , wherein the data input is configured to receive intrinsic cardiac activity information using the first sensor.

3. The ambulatory medical device of claim 2 , wherein the processor-readable medium includes instructions that, when performed by the processor, configure the medical device to provide the cardiac stimulation diagnostic indication using the first interval and the intrinsic cardiac activity information.

4. The ambulatory medical device of claim 3 , wherein the processor-readable medium includes instructions that, when performed by the processor, configure the medical device to discriminate between Purkinje fiber cardiac capture, cell-to-cell conduction cardiac capture, and intrinsic conduction cardiac capture.

5. The ambulatory medical device of claim 1 , wherein the data input is configured to receive first cardiac activity information from an indication of central venous pressure from a pressure sensor.

6. The ambulatory medical device of claim 1 , wherein the data input is configured to receive first cardiac activity information from an intracardiac or thoracic impedance provided by an electrode configured to measure impedance.

7. The ambulatory medical device of claim 6 , wherein the processor-readable medium includes instructions that, when performed by the processor, configure the medical device to provide the cardiac stimulation diagnostic indication using a stroke volume signal measured using the electrode.

8. The ambulatory medical device of claim 1 , wherein the data input is configured to receive first cardiac activity information from an indication of a heart sound provided by an accelerometer.

9. The ambulatory medical device of claim 1 , wherein the processor circuit includes a second data input, configured to receive second cardiac activity information using a second sensor different than the first sensor, the second cardiac activity information used to augment the first cardiac activity information.

10. An ambulatory medical device, comprising:

a cardiac stimulation circuit configured to generate a His-bundle stimulation energy to provide stimulation to a His-bundle;

a processor circuit, including:

a first data input, configured to receive first cardiac activity information, from an intrinsic electrical heart signal, using a first sensor; and

a second data input, configured to receive second cardiac activity information in response to a His-bundle stimulation energy provided by the cardiac stimulation circuit to the His-bundle, the second cardiac activity information from other than an intrinsic electrical heart signal, and the second cardiac activity information received using the first sensor; and

a processor-readable medium, including instructions that, when performed by the processor, configure the medical device to:

determine a first interval using the first cardiac activity information;

determine a second interval using the second cardiac activity information in response to the His-bundle stimulation energy provided by the cardiac stimulation circuit to the His-bundle;

form a cardiac stimulation diagnostic metric using at least the first interval; and

provide a cardiac stimulation diagnostic indication about His-bundle capture using the cardiac stimulation diagnostic metric and the second interval.

11. A method comprising:

generating, using an ambulatory medical device, a His-bundle stimulation energy to provide stimulation to a His-bundle;

stimulating a His-bundle at a first time using the His-bundle stimulation energy;

receiving first cardiac activity information, from other than an intrinsic electrical heart signal, from a first sensor at a second time, the first cardiac activity information indicative of a cardiac response to the stimulating the His-bundle at the first time using the His-bundle stimulation energy;

computing a first time interval using the first time and the second time; and

providing a cardiac stimulation diagnostic indication about His-bundle capture using the computed first time interval.

12. The method of claim 11 , wherein the providing a cardiac stimulation diagnostic indication includes comparing the first time interval to a threshold interval.

13. The method of claim 12 , including:

observing an intrinsic His-bundle activation at a third time;

receiving intrinsic cardiac activity information from the sensor at a fourth time, the intrinsic cardiac activity information indicative of a cardiac response to the intrinsic His-bundle activation; and

computing the threshold interval using the third time and the fourth time.

14. The method of claim 11 , wherein the providing a cardiac stimulation diagnostic indication includes discriminating between Purkinje fiber cardiac capture, cell-to-cell conduction cardiac capture, and intrinsic conduction cardiac contraction.

15. The method of claim 11 , wherein the receiving first cardiac activity information from a first sensor includes receiving cardiac activity information from an indication of central venous pressure from a pressure sensor.

16. The method of claim 11 , wherein the receiving first cardiac activity information from a first sensor includes receiving cardiac activity information from an intracardiac or thoracic impedance provided by an electrode configured to measure impedance.

17. The method of claim 11 , wherein the receiving first cardiac activity information from a first sensor includes receiving mechanical cardiac activity information using a lead configured to deliver the stimulating energy.

18. The method of claim 11 , wherein the receiving first cardiac activity information from a first sensor includes receiving cardiac activity information from an indication of a heart sound provided by an accelerometer.

19. The method of claim 11 , wherein the receiving first cardiac activity information from a first sensor includes receiving cardiac activity information from an indication of QRS axis deviation provided by an array of electrodes disposed on or in a body.

20. The method of claim 11 , including receiving second cardiac activity information, from other than an intrinsic electrical heart signal, from a second sensor at a third time, the second cardiac activity information used to augment the first cardiac activity information.