Spontaneous and induced variations in the threshold of excitability in the in vivo dog heart.
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology; D004285:Dogs; D004562:Electrocardiography; D004594:Electrophysiology; D006329:Heart Conduction System / Q000502:physiology*; D010138:Pacemaker, Artificial