Method and apparatus for improving cardiac efficiency based on myocardial oxygen consumption

• US 20070150017A1
• Filed: 12/22/2005
• Published: 06/28/2007
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Salo, Rodney
• Granted Patent: US 9,155,896 B2
• Time in Patent Office: Days
• US Class Current: 607/22
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

Devices and methods for improving cardiac efficiency involve measuring, patient-internally, an oxygen saturation parameter indicative of oxygen usage of myocardial tissue of the heart. A cardiac electrical therapy is adjusted to cause a change of the measured oxygen saturation parameter, and the adjusted cardiac electrical therapy is selected for delivery based on a changed oxygen saturation parameter indicative of an increase in cardiac efficiency.

Claims

1. A method of improving cardiac efficiency, comprising:

measuring, patient-internally, an oxygen saturation parameter indicative of oxygen usage of myocardial tissue of the heart;

adjusting a cardiac electrical therapy to cause a change of the measured oxygen saturation parameter; and

selecting the adjusted cardiac electrical therapy for delivery based on a changed oxygen saturation parameter indicative of an increase in cardiac efficiency.

2. The method of claim 1, wherein measuring the oxygen saturation parameter comprises measuring the oxygen saturation parameter in a coronary vein of the patient'"'"'s heart.

3. The method of claim 1, wherein measuring the oxygen saturation parameter comprises measuring the oxygen saturation parameter in the great cardiac vein of the patient'"'"'s heart.

4. The method of claim 1, comprising correcting for changes of the measured oxygen saturation parameter due to external work load.

5. The method of claim 4, wherein correcting for changes of the measured oxygen saturation parameter due to external work load comprises computing a measure proportional to the patient'"'"'s cardiac output based on the patient'"'"'s heart rate and a measure of stroke volume.

6. The method of claim 1, wherein selecting the adjusted cardiac electrical therapy comprises computing the patient'"'"'s cardiac efficiency based on a relationship defined by

$\frac{(\mathrm{SV}·}{}$

PP ) ( 1 - O 2 ) ,

where SV is the associated stroke volume measurement, PP is the associated pulse pressure measurement, and O₂ is the oxygen saturation level measurement.

7. The method of claim 1, wherein selecting the adjusted cardiac electrical therapy comprises computing the patient'"'"'s cardiac efficiency based on a relationship defined by

$\frac{(\mathrm{SV}·}{}$

HR ) ( 1 - O 2 ) ,

where SV is the associated stroke volume measurement, HR is the associated heart rate, and O₂ is the oxygen saturation level measurement.

8. The method of claim 1, comprising monitoring the oxygen saturation parameter to detect a change indicative of a change in the patient'"'"'s cardiac efficiency.

9. The method of claim 1, wherein the cardiac electrical therapy comprises a pacing therapy.

10. The method of claim 1, wherein the cardiac electrical therapy comprises a pacing therapy, and adjusting the cardiac electrical therapy comprises adjusting an atrioventricular (A-V) delay of the pacing therapy.

11. The method of claim 1, wherein the cardiac electrical therapy comprises a pacing therapy, and adjusting the cardiac electrical therapy comprises adjusting a pacing rate of the pacing therapy.

12. The method of claim 1, wherein the cardiac electrical therapy comprises a pacing therapy, and adjusting the cardiac electrical therapy comprises adjusting a pacing site for the pacing therapy.

13. The method of claim 1, wherein the cardiac electrical therapy comprises a resynchronization therapy delivered to the heart.

14. The method of claim 1, wherein the cardiac electrical therapy comprises a bi-ventricular pacing therapy, and adjusting the cardiac electrical therapy comprises adjusting an inter-ventricular delay of the bi-ventricular pacing therapy.

15. An apparatus for delivering a cardiac electrical therapy to a heart, comprising:

a lead comprising at least one electrode and configured to be positionable within vasculature of the heart;

a blood oxygen saturation sensor provided on the lead, the blood oxygen saturation sensor configured to measure an oxygen saturation parameter indicative of oxygen usage of myocardial tissue of the heart;

an implantable housing;

a pulse generator disposed in the housing and coupled to the lead; and

a processor disposed in the implantable housing and coupled to the pulse generator, the processor configured to adjust a cardiac electrical therapy delivered to the heart to cause a change of the measured oxygen saturation parameter and select the adjusted cardiac electrical therapy for delivery based on a changed oxygen saturation parameter indicative of an increase in cardiac efficiency.

16. The apparatus of claim 15, wherein the blood oxygen saturation sensor is configured for placement within a coronary vein of the heart.

17. The apparatus of claim 15, wherein the blood oxygen saturation sensor is configured for placement within the great cardiac vein of the heart.

18. The apparatus of claim 15, wherein the pulse generator is configured to deliver a pacing therapy to the heart.

19. The apparatus of claim 15, wherein the pulse generator is configured to deliver a resynchronization therapy to the heart.

20. The apparatus of claim 15, further comprising a sensor configured to sense one or more parameters indicative of stroke volume, wherein the processor is configured to compute the patient'"'"'s cardiac output using the one or more parameters indicative of stroke volume and a heart rate parameter developed by the pulse generator.

21. The apparatus of claim 20, wherein the processor is configured to correct for changes of the measured oxygen saturation parameter due to external work load using the patient'"'"'s computed cardiac output.

22. The apparatus of claim 20, further comprising a sensor comprises an intracardiac impedance sensor.

23. A system for improving cardiac efficiency, comprising:

means for measuring, patient-internally, an oxygen saturation parameter indicative of oxygen usage of myocardial tissue of the heart;

means for adjusting a cardiac electrical therapy to cause a change of the measured oxygen saturation parameter; and

means for selecting the adjusted cardiac electrical therapy for delivery based on a changed oxygen saturation parameter indicative of an increase in cardiac efficiency.

24. The system of claim 23, comprising means for correcting for changes of the measured oxygen saturation parameter due to external work load.

25. The system of claim 23, comprising means for computing the patient'"'"'s cardiac efficiency.

26. A system for improving regional cardiac efficiency, comprising:

means for measuring, patient-internally, a first oxygen saturation parameter indicative of oxygen usage of myocardial tissue of the entire left ventricle;

means for measuring, patient-internally, a second oxygen saturation parameter indicative of oxygen usage in a region of the left ventricle; and

means for adjusting a cardiac electrical therapy based on a difference between the first and second oxygen saturation measurements.

27. The system of claim 26, wherein:

the means for measuring the first oxygen saturation parameter comprises means for oxygen saturation sensing in the great vein; and

the means for measuring the second oxygen saturation parameter comprises means for oxygen saturation sensing in a cardiac vein draining the region of the left ventricle.