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Familial sinus node disease.

A family with evidence of severe malfunction of the sinus node in two senior members and with electrocardiographic evidence of sinus node malfunction in four junior members and an additional adult is presented. Acquired heart disease has been clinically excluded in the patients described. None of the patients demonstrates QT interval prolongation, and there is no family history of congenital deafness. Family histories relative to syncopal episodes, serious cardiac arrhythmia, breath holding spells, or palpitations should be obtained from all patients presenting with serious malfunction of the sinus node regardless of age, and family members so affected should be carefully observed for the development of serious cardiac arrhythmias.