title: Quinidine syncope: torsade de pointes with low quinidine plasma concentrations.
abstract: In 2 patients without clinically significant ischemic heart diseases, oral quinidine was used to control supraventricular arrhythmias. In both patients, syncopal attacks occurred, caused by a particular type of ventricular tachyarrhythmia called torsades de pointes. Quinidine plasma concentrations were low (2.6 and 1.2 mg/1, respectively); QRS duration was normal, but the Q-T interval was markedly prolonged.
mesh_terms: D000368:Aged; D001282:Atrial Flutter / Q000150:complications / Q000188:drug therapy; D005117:Cardiac Complexes, Premature / Q000139:chemically induced*; D003692:Delayed-Action Preparations; D004562:Electrocardiography; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008875:Middle Aged; D011802:Quinidine / Q000008:administration & dosage / Q000009:adverse effects* / Q000097:blood; D013575:Syncope / Q000139:chemically induced*; D013610:Tachycardia / Q000139:chemically induced*
chemical_list: D003692:Delayed-Action Preparations; D011802:Quinidine