Automatic rate adjustment pacer with natural rate searching means and method of operation

摘要

A demand pacer adapted to normally produce stimulus pulses at a given rate in the absence of detected natural heartbeats, and also having means for searching for the occurrence of natural heartbeats at lower rates in the absence of natural heartbeats. The pacer searching is initiated by detection of a natural heartbeat or by a signal generated independently of any natural heartbeat. During searching the pacer escape interval is lengthened by relatively small steps until a predetermined rate range below the given rate has been searched, and upon detecting a natural heartbeat within said range the pacer escape interval is set to permit continued demand operation within the range.