Patent ID: 6636766
Filing Date: 2003-10-21
Classification: A61N

Abstract:
In an implantable cardiac pacing device, a method for preventing a sudden rate drop in the heart rate of a patient comprising:sensing an intrinsic heart rate of the patient; and selectively pacing the heart while applying rate smoothing to the heart rate, with the rate smoothing being applied regardless of the magnitude of the ventricular heart rate; wherein the step of selectively pacing the heart is performed while applying downward rate smoothing so as to prevent a sharp heart rate decrease which is hemodynamically compromising and to permit a sharp heart rate increase; wherein the step of selectively pacing the heart comprises the steps of: generating an escape rate based in part on the intrinsic heart rate with the escape rate set to be greater than the intrinsic rate during any sharp drop in the intrinsic rate which is hemodynamically compromising and less than the intrinsic rate during any sharp rate increase; and applying pacing pulses to the heart only while the escape rate is greater than the intrinsic rate; and wherein the step of generating an escape rate includes the steps of: determining a filtered rate interval (FRI), a measured rate interval (MRI), and a sensor indicated rate (SIR); if the FRI is greater than the MRI, resetting the FRI to a maximum of the MRI and the FRI minus a predetermined FRI decrement; and if the FRI is not greater than the MRI, resetting the FRI to a minimum of the MRI and the FRI plus a predetermined FRI increment; and setting an escape interval equal (EI) to a lesser of the reset FRI plus a predetermined EI increment, the SIR, and a predetermined base rate interval.