Panconductional defect in mixed connective tissue disease: association with Sjogren's syndrome.

A patient in whom mixed connective tissue disease in association of Sjögren's syndrome had previously been diagnosed, experienced a syncopal attack. Electrocardiographic monitoring revealed periods of profound sinus bradycardia, sinus arrest with slow junctional escape rhythm, and first degree atrioventricular block during several episodes of dizziness. Complete right bundle branch block was a constant finding in this patient. Sinoatrial conduction time and sinus node recovery time were prolonged. Coronary heart disease was excluded by normal coronary arteriographic findings. This patient represents a rare case of cardiac involvement in mixed connective tissue disease.