Method and apparatus for providing atrial autocapture in a dynamic atrial overdrive pacing system for use in an implantable cardiac stimulation device

摘要

Techniques for providing capture verification during overdrive pacing are described. If an overdrive pacing pulse fails to evoke capture (i.e. a loss of capture occurs), a high voltage backup pulse is automatically delivered. Once a second loss of capture occurs during a single sequence of overdrive pacing pulses, an overdrive pulse capture threshold detection search, described herein, is performed while overdrive pacing continues. Various techniques for providing rate recovery are also described herein. The rate recovery techniques are designed to avoid problems that might arise from possible fusion of intrinsic beats and overdrive pacing pulses that fail to evoke capture. In a first rate recovery technique, capture detection is suspended during rate recovery due to the possibility of fusion. Instead, an extra safety margin is added to the overdrive pulses. Once two intrinsic beats are detected, automatic capture verification is reactivated for the next two beats to verify capture before the new overdrive rate is finally established. In a second rate recovery technique, capture verification is maintained throughout rate recovery but the pulse magnitude is increased to a high output mode voltage to avoid any risks of fusion. After the output is increased to the high output mode voltage, a subsequent loss of capture is considered to be an intrinsic event for the purposes of terminating rate recovery. In a third rate recovery technique, capture verification is maintained during rate recovery and the output energy is not increased to the high output mode voltage unless loss of capture is first detected. Subsequent loss of capture events are then counted as P-waves.