The anatomic substrate for the sick sinus syndrome in adolescence

Abstract

This is a study of the conduction system of two adolescent boys, one 16 and the other 17 years of age, who had prolonged unexplained sinus nodal dysfunction. The first patient had sinus pauses up to 2.5 seconds in duration, absence of persistent sinus bradycardia and prolonged sinus nodal recovery time of 3,451 ms. He died suddenly. Pathologic study of the conduction system revealed degeneration and fibrosis of the approaches to the sinoatrial (S-A) and atrioventricular (A-V) nodes and the atrial preferential pathways. The second patient had a 1 year history of persistent sinus bradycardia (30 to 60 beats/min) and prolonged sinus nodal recovery time of 3,725 ms. He died of acute viral hepatitis. Pathologic study of the conduction system revealed fatty infiltration of the approaches to the S-A and A-V nodes and the atrial preferential pathways. In summary, the approaches to the S-A and A-V nodes and the atrial preferential pathways were altered by fibrosis in Case 1 and by fatty infiltration in Case 2, both of unknown origin. The S-A node itself was not significantly involved in either case.