Patent ID: 6430441
Filing Date: 2002-08-06
Classification: A61N

Abstract:
An implantable cardiac stimulation device for stimulating a patient's heart during a cardiac cycle through at least one electrode adapted for electrical contact with selected cardiac tissue, the stimulation device comprising:a pulse generator electrically coupled to the electrode and configured to generate stimulation pulses at a controlled amplitude and rate to thereby stimulate the patient's heart; a detection circuit electrically coupled to the electrode and configured to receive cardiac signals for determining the presence or absence of an evoked response to each of the stimulation pulses, wherein the detection circuit is further configured to determine the status, for each cardiac cycle, of the presence of an evoked response to each stimulation pulse, the absence of an evoked response to each stimulation pulse, or the presence of an intrinsic cardiac signal without a stimulation pulse; and a controller coupled to the pulse generator for increasing the stimulation pulse amplitude when a first specified criteria has been met, wherein the first specified criteria is the absence of evoked responses from X out of the last Y stimulation pulses where Y is a value greater than 2 and X is a value less than Y, wherein the controller determines the presence of a predetermined sequence of status determinations from M consecutive cardiac cycles, and further determines the presence of N contiguous occurrences of the specified sequence of M status determinations, wherein the controller is configured to increase the controlled rate in response thereto.