Reduction of AV delay for treatment of cardiac disease
An implantable pacing device for delivering ventricular pacing may be configured to intermittently reduce the AVD interval for beneficial effect in patients with compromised ventricular function (e.g., HF patients and post-MI patients). The AVD interval may be reduced in an AVD reduction mode, by shortening the AVD in an atrial triggered ventricular pacing mode or by switching to a non-atrial triggered ventricular pacing mode (e.g., VVI) and delivering paces at a rate above the intrinsic rate. The physiological effects of AVD reduction may be either positive or negative on cardiac output, depending upon the individual patient.
1. A cardiac device, comprising:
sensing circuitry for receiving electrogram signals representing atrial and ventricular activity;
pacing circuitry for delivering atrial and ventricular pacing pulses;
a controller programmed to operate the device in either a normal operating mode or AV delay reduction (AVDR) mode, wherein the normal mode and the AVDR modes are atrial-triggered or AV sequential pacing modes in which paces are delivered to one or more ventricular sites after an AV delay interval with respect to an atrial sense or pace;
wherein, in the AVDR mode, the controller is programmed to deliver paces to the one or more ventricular sites using an AV delay interval that is shorter than the AV delay interval used in the normal mode;
wherein the controller is programmed to measure a patient's intrinsic atrio-ventricular interval and compute the AV delay interval used in the AVDR mode as a specified percentage thereof in order to reduce atrial preloading of the ventricles during diastole;
wherein the controller is programmed to intermittently switch from the normal operating mode to the AVDR mode according to a one or more specified entry conditions and switch from the AVDR mode to the normal operating mode according to one or more specified exit conditions;
a posture sensor interfaced to the controller;
wherein the controller is programmed to determine a patient's posture and use a determination that the patient is supine as an exit condition for exiting the AVDR mode.
2. The device of claim 1 wherein one or more of the specified entry or exit conditions is a lapsed time interval to cause periodic switching to the AVDR mode.
3. The device of claim 1 further comprising a sensor for measuring a patient's exertion level and wherein the controller is programmed to operate in the AVDR mode only if the measured exertion level is within a specified range.
4. The device of claim 1 further comprising an impedance sensor for detecting pulmonary edema and wherein the controller is programmed to operate in the AVDR mode only if pulmonary edema is not detected.
5. The device of claim 1 wherein the controller is programmed to eliminate the AV delay interval in the AVDR mode.
6. The device of claim 1 further comprising a sensor for measuring pulmonary arterial pressure and wherein the controller is programmed to operate in the AVDR mode only if pulmonary arterial pressure is within a specified range.
7. The device of claim 1 wherein one or more of the specified entry or exit conditions is a command to enter or exit the AVDR mode received via telemetry or a patient-operated switch.
8. The device of claim 1 wherein the controller is programmed to use different pacing channels in the AVDR mode than in the normal operating mode.
9. The device of claim 1 wherein the controller is programmed to deliver pacing through multiple ventricular pacing channels for each paced cycle, either simultaneously or with one or more specified offsets, during the AVDR mode.
10. The device of claim 1 wherein the controller is programmed to deliver pacing through multiple ventricular pacing channels during the AVDR mode, where the multiple ventricular pacing channels are rotated according to a defined schedule.
11. A method, comprising:
delivering pacing pulses to one or more ventricular sites in either a normal operating mode or AV delay reduction (AVDR) mode;
wherein the normal mode and the AVDR modes are atrial-triggered or AV sequential pacing modes in which paces are delivered to one or more ventricular sites after an AV delay interval with respect to an atrial sense or pace;
wherein, in the AVDR mode, paces are delivered to the one or more ventricular sites using an AV delay interval that is shorter than the AV delay interval used in the normal mode and also shorter than a patient's measured intrinsic AV interval;
measuring a patient's intrinsic atrio-ventricular interval and computing the AV delay interval used in the AVDR mode as a specified percentage thereof in order to reduce atrial preloading of the ventricles during diastole;
intermittently switching from the normal operating mode to the AVDR mode according to a one or more specified entry conditions and switching from the AVDR mode to the normal operating mode according to one or more specified exit conditions; and,
determining a patient's posture and using a determination that the patient is supine as an exit condition for exiting the AVDR mode.
12. The method of claim 11 wherein one or more of the specified entry or exit conditions is a lapsed time interval to cause periodic switching to the AVDR mode.
13. The method of claim 11 further comprising measuring a patient's exertion level and operating in the AVDR mode only if the measured exertion level is within a specified range.
14. The method of claim 11 further comprising using different pacing channels in the AVDR mode than in the normal operating mode.
15. The method of claim 11 further comprising delivering pacing through multiple ventricular pacing channels for each paced cycle, either simultaneously or with one or more specified offsets, during the AVDR mode.
16. The method of claim 11 further comprising delivering pacing through multiple ventricular pacing channels during the AVDR mode, where the multiple ventricular pacing channels are rotated according to a defined schedule.
17. The method of claim 11 further comprising detecting pulmonary edema and operating in the AVDR mode only if pulmonary edema is not detected.
18. The method of claim 11 further comprising eliminating the AV delay interval in the AVDR mode.
19. The method of claim 11 further comprising measuring pulmonary arterial pressure and operating in the AVDR mode only if pulmonary arterial pressure is within a specified range.