Morphologic alterations in the long Q-T syndrome. Light and electron microscopic observations in the conduction system and in sympathetic trunks.

Post-mortem examinations of 2 patients with long Q-T syndrome revealed marked focal fibrosis and lipomatosis of the conduction system as well as focal round cell ganglionitis of both sympathetic trunks. The patients, young women of different nationality displaying syncopal attacks and a long Q-T interval in the ECG died suddenly of ventricular arrhythmias. A family study of one of them revealed Q-T prolongation in 4 generations. The ultrastructure of the conductive tissue and the ventricular myocardium showed no specific alterations indicative of a primary metabolic defect. Ganglionitis of the sympathetic trunks has not yet been reported in the long Q-T syndrome. Although the etiology of the inflammatory changes is uncertain a chronic viral infection, noninfectious toxic alterations or an autoimmunopathy are among the plausible causes discussed.