The Journal of Thoracic and Cardiovascular Surgery, Vol 95, 247-254, Copyright © 1988 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Subaortic stenosis and sudden death
TN James, JD Jordan, L Riddick and LM Bargeron
School of Medicine, University of Alabama at Birmingham.
An obese white boy, 16 years old, collapsed and suddenly died while walking
with friends. Since early childhood he had been known to have mild
subaortic stenosis. At age 6 he exhibited first-degree heart block during
an electrocardiographic exercise test. Neither then nor thereafter was he
known to have any unusual symptoms until his death. Postmortem examination
revealed marked cardiac enlargement without asymmetry or much dilatation.
There was mild subaortic stenosis, but the heart was otherwise grossly
normal. Special studies of his cardiac conduction system demonstrated
fibrotic obliteration of the His bundle and proximal portions of both
bundle branches. The same region had a much thickened central fibrous body
from which the subaortic stenosis ridge protruded. Small arteries in the
vicinity of the atrioventricular node were markedly narrowed. Because those
vessels provide some of the blood supply to the His bundle region, their
narrowing may have contributed to the fibrotic abnormalities observed. The
extent of destruction of the His bundle makes a lethal failure of
atrioventricular conduction the most likely terminal event.