Method and apparatus for controlling the change of an escape interval in an active implantable medical device

An active implantable medical device to be borne by a patient comprising:

• means for detecting an instantaneous cardiac rhythm of the patient,
• means for delivering stimulation pulses having an escape interval (EIn) between successive delivered stimulation pulses,
• means for gradually increasing said escape interval comprising means for memorizing information corresponding to an evolution of said cardiac rhythm detected by said detecting means, wherein the gradually increasing means is operated to increase a given escape interval by a variable amount that is a first function of previously memorized information of the detected cardiac rhythm, and
• means for determining a rate of increase of the escape interval (RATEdec) as a second function of said memorized information, wherein the first function further operates on said determined rate of increase RATEdec.

An active implantable medical device to be borne by a patient comprising:

• means for detecting an instantaneous cardiac rhythm of the patient,
• means for delivering stimulation pulses having an escape interval (EIn) between successive delivered stimulation, pulses, and
• means for gradually increasing said escape interval comprising means for memorizing information corresponding to an evolution of said cardiac rhythm detected by said detecting means, wherein the gradually increasing means is operated to increase a given escape interval as a first function of previously memorized information of the detected cardiac rhythm,
• means for determining a state (Ind) of increase or decrease of the escape interval, and
• means for determining a rate of increase of said gradually increasing means, wherein the gradually increasing means, in response to a detected decrease state, is operated to apply the determined rate of increase to increase said escape interval and, in response to a detected increase state, is maintained at the value previously applied.

A method of controlling the escape interval of a cardiac stimulation device comprising:

• (a) providing a base escape interval for stimulating a heart at a basic cardiac rhythm;
• (b) monitoring cardiac electrical activity including spontaneous and stimulated cardiac events;
• (c) determining an escape interval for a cardiac stimulation in the absence of a spontaneous cardiac event;
• (d) determining whether the determined escape interval corresponds to an increasing cardiac rhythm or a decreasing cardiac rhythm;
• and
• (e) in response to a determined increasing cardiac rhythm:
• (i) recording a history of the increase of the cardiac rhythm, and
• (ii) determining a rate of increase of an escape interval as a function of the recorded history;
• and
• (f) in response to a determined decreasing cardiac rhythm:
• (i) applying the rate of increase determined during a determined increasing cardiac rhythm preceding said determined decreasing cardiac rhythm to increase gradually the determined escape interval to the base escape interval, and
• (ii) using the increased escape interval in said device.