title: Arrhythmia resulting from sensing malfunction in a P wave triggered pacemaker.
abstract: P wave triggered pacemakers can produce complicated arrhythmias during normal function. A ventricular, R wave inhibited pacemaker and an atrial sensing pacemaker were both present and functioning normally in the patient reported here. A premature paced beat was observed every 12th beat which resulted from discharge of the atrial sensing pacemaker. This arrhythmia appeared because a "P" wave occurred during the noise sampling period of the atrial sensing pacemaker, disabling the demand function and resulting in generator discharge on or near the T wave of a preceding unsensed beat while the pacemaker was in the asynchronous mode.
mesh_terms: D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000628:therapy; D006801:Humans; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000009:adverse effects* / Q000295:instrumentation