Method and apparatus for optimizing cardiac resynchronization therapy
A method and apparatus for optimizing cardiac resynchronization therapy are provided. An iterative optimization procedure is performed to test the systolic hemodynamic effects of varying A-V-V timing schemes. The hemodynamic effect is assessed based on a surrogate of stroke volume. The stroke volume surrogate is derived from a sensor signal proportional to the blood pressure in the aorta or a major artery. The A-V-V timing scheme corresponding to the highest magnitude stroke volume, as indicated by the stroke volume surrogate, is identified and automatically programmed to maintain optimal A-V-V settings acutely and chronically.
1. A method for optimizing cardiac resynchronization therapy comprising:
a. sensing a signal proportional to a blood pressure development of a patient;
b. determining a stroke volume surrogate from the sensed signal proportional to blood pressure by deriving a signal characteristic that varies proportionally to stroke volume variations;
c. at least temporarily storing in a readable storage medium at least a one of the following: the signal, the stroke volume surrogate, the signal characteristic
d. applying a plurality of A-V-V timing schemes and repeating steps a., b., and c. for at least a subset of said plurality of A-V-V timing schemes; and
e. identifying an optimal A-V-V timing scheme corresponding to the highest magnitude stroke volume based on the stroke volume surrogate for one of said plurality of A-V-V timing schemes.
2. A method according to claim 1 , wherein in the event of degraded diastolic function, performing at least one of the following steps:
repeating steps a-e and storing a degraded diastolic-function signal.
3. A method according to claim 2 , wherein the degraded diastolic function is derived from one of: a relatively decreased mean diastolic pressure and a minimum diastolic pressure.
4. A method according to claim 1 , wherein the method is performed manually.
5. A method according to claim 1 , wherein the method is performed non-invasively.
6. A method according to claim 1 , wherein the method is performed chronically and automatically by operative structure of an implantable medical device (IMD).
7. A method according to claim 6 , wherein the IMD comprises one of: a pulse generator, an implantable pulse generator, an implantable cardioverter-defibrillator.
8. A method according to claim 1 , wherein the sensed signal proportional to blood pressure comprises a signal provided by one of: a tonometer and a phonocardiogram.
9. A method according to claim 1 , wherein the sensed signal proportional to blood pressure comprises a signal provided by one of: an optical sensor, an acoustical sensor, a piezoelectric sensor, an impedance-based sensor.
10. A method according to claim 9 , wherein the sensed signal proportional to blood pressure comprises a signal relating to one of: an arterial wall distension metric and a blood flow metric.
11. A method according to claim 1 , further comprising conveying at least one of the A-V-V timing scheme and the optimal A-V-V timing scheme to a remote device.
12. A method according to claim 11 , wherein the conveying step is performed wirelessly and further comprising:
performing a mode-switch to a non-rate responsive operational mode during said wireless transmission.
13. A method according to claim 1 , wherein the method is performed when an re-optimization signal is manually triggered or stored in a readable memory structure.
14. An apparatus for optimizing cardiac resynchronization therapy comprising:
a. means for sensing a signal proportional to a blood pressure development of a patient;
b. means for determining a stroke volume surrogate from the sensed signal proportional to blood pressure by deriving a signal characteristic that varies proportionally to stroke volume variations;
c. means for, at least temporarily, storing in a readable storage medium at least a one of the following: the signal, the stroke volume surrogate, the signal characteristic
d. means for applying a plurality of A-V-V timing schemes and repeating steps a., b., and c. for each of said plurality of A-V-V timing schemes; and
e. means for identifying an optimal A-V-V timing scheme corresponding to the highest magnitude stroke volume based on the stroke volume surrogate for at least one of said plurality of A-V-V timing schemes.
15. An apparatus according to claim 14 , further comprising means for repeating steps a-e and storing a degraded diastolic-function signal in the event of a degraded diastolic function.
16. An apparatus according to claim 15 , wherein the degraded diastolic function is derived from one of: a relatively decreased mean diastolic pressure and a minimum diastolic pressure.
17. An apparatus according to claim 14 wherein the apparatus comprises one of: a pulse generator, an implantable pulse generator, an implantable cardioverter-defibrillator.
18. An apparatus according to claim 14 , wherein the sensed signal proportional to blood pressure comprises a signal provided by one of: a tonometer and a phonocardiogram.
19. An apparatus according to claim 14 , wherein the sensed signal proportional to blood pressure comprises a signal provided by one of: an optical sensor, an acoustical sensor, a piezoelectric sensor, an impedance-based sensor.