[Danger of sinoatrial block and the use of antiarrhythmic agents in myocardial infarcts].
Nine cases of major ventricular arrhythmia (tachycardia (VT), fibrillation (VF), torsades de pointe) are reported in patients with sequellae of myocardial infarction but without residual angina or cardiac failure. --Six of these disturbances of excitability occurred after a bradycardia due to sino atrial block (SAB) which favoured the breakthrough of abnormal automatic foci. This form of the bradycardia-tachycardia syndrome was demonstrated by endocavitary electrophysiological exploration.. These were the only cases of major ventricular arrhythmia observed in a series of 88 SABs. Reputedly benign, they illustrate the potential gravity of a conduction defect in patients with sequellae of myocardial infarction. --Three other cases of abnormal ventricular excitability complicating the administration of 1 mg/kg of Ajmaline to test for paroxysmal block after myocardial infarction. These were the only cases of VT observed in a series of 800 Ajmaline tests. The three patients have had no further episodes of VT after 1 year's follow-up. On the other hand, in 43 Ajmaline tests without VT in patients with myocardial infarction, 6 cases of VT and 1 lethal VF were later observed. This demonstrates the lack of significance of episodes of VT during Ajmaline tests, the depressant action of the drug on intracardiac conduction favouring the initiation of reentry. In conclusion, a history of myocardial infarction exposes the patient to the risk of major ventricular arrhythmias in SAB, the detection of which should indicate pacemaker therapy from the first symptoms. The use of an intravenous antiarrhythmic agent should be avoided as it may aggravate arrhythmias. However, the arrhythmia is of no prognostic significance.
D000368:Aged; D000404:Ajmaline / Q000009:adverse effects*; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000209:etiology*; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000150:complications*; D011379:Prognosis; D012848:Sinoatrial Block / Q000150:complications / Q000209:etiology* / Q000503:physiopathology
D000404:Ajmaline
Dangers du bloc sino-auriculaire et de l'emploi d'anti-arythmiques en cas d'infarctus du myocarde.