title: Physiologic evidence concerning the re-entry hypothesis for ectopic beats.
mesh_terms: D000818:Animals; D016275:Atrial Function; D005117:Cardiac Complexes, Premature / Q000209:etiology*; D004285:Dogs; D004562:Electrocardiography; D006329:Heart Conduction System / Q000502:physiology*; D010138:Pacemaker, Artificial; D010477:Perfusion