Qingsheng Zhu

Future of bradyarrhythmia therapy systems: automaticity.

Since the first fixed-rate ventricular pacemaker was introduced in the late 1950s, pacing systems have evolved rapidly. Current developments focus on making devices more sophisticated and less complex--a challenging combination. Automaticity features such as beat-by-beat capture verification, sensitivity threshold adaptation, and algorithms to govern dynamically the maximum sensor rate have either recently been introduced or are likely to be introduced in the near future. Technologic advances are likely to allow meaningful improvements in current drain, battery performance, memory capacity, signal processing, telemetry, and programmer interface. Bradyarrhythmia therapy devices of the future promise to go beyond the pacemaker. Ultimately, pacing systems will become part of integrated cardiac rhythm management systems.

Effect of pacemaker output coupling capacitor on intracardiac evoked response sensing

Intracardiac evoked response has been used in implantable pacemakers for the application of automatic capture verification. However, reliable detection of evoked response has always been hampered by large residual after potentials associated with pacing stimuli. This article analyzes the cause of the after potential and proposes a solution for evoked response detection through reducing the coupling capacitor in the pacemaker output circuitry. The proposal was tested clinically to evaluate the impact of the capacitance reduction on evoked response sensing as well as on the associated pacing threshold changes.