A 90-year-old female had a Holter monitoring recording because of a syncopal episode. She developed a fatal cardiac arrest during the recording. A severe bradycardia was the initiating fatal dysrhythmia. This was followed by ventricular tachycardia and fibrillation and finally cardiac standstill.

The sick sinus syndrome has become the most common indication for permanent pacemaker implantation. 1 In a recent review of 50 patients with the sick sinus syndrome treated with pacemaker insertion, the mean age of the group was 71 years. 2 There are occasional reports of the sick sinus syndrome in young adults. However, many of the reported cases involve postoperative congenital heart disease.3,4 Recently Kay and his group5reported a series of 18 cases of young adults who required pacemakers. Twelve had the sick sinus syndrome and served as the basis of their report. Electrophysiologic studies were performed in only 5 of their 12 cases, and the authors stressed that the corrected sinus node recovery time was normal in their 5 patients. We routinely perform electrophysiologic studies in all patients being considered for pacemaker implantations. We therefore reviewed our experience over 8 years with young adults who required permanent pacemaker insertions.

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Ethacrynic acid is a potent oral diuretic and saluretic agent. It has been used extensively in the treatment of heart failure and its effects on cardiovascular dynamics are well established. The clinical relief of the symptoms of pulmonary congestion frequently precedes any demonstrable diuretic effect suggesting that extra renal factors may also be involved. In spite of ethacrynic acid's wide use in the treatment of heart failure and hypertension, there is no information on the electrophysiologic properties of the drug in man. The present study involving 10 human subjects was undertaken to determine what effect intravenously administered ethacrynic acid has on the human conduction system.