Acute and early experimental tricuspid valvular stenosis in dogs

Acute and early (two months) experimental tricuspid valve stenosis was produced in 20 dogs. Clinical and hemodynamic alterations that resulted from severe anatomic tricuspid valve narrowing were surprisingly mild. In the acute stenosis studies, the normal tricuspid valve area of 8.2 +/- 0.3 sq cm was narrowed to less than 1.0 +/- 0.1 sq cm with a resulting right auricle-right ventricle diastolic gradient of 3.7 +/- 0.7 mm Hg. In early studies, a decrease in tricuspid valve area from 7.3 sq cm to 1.6 +/- 0.3 sq cm produced a diastolic gradient of 1.8 +/- o.2 mm Hg. After 60 days, overt signs of right-sided failure (pleural effusions and ascites) were absent, and histological evidence of passive congestion (liver and spleen) was unpredictable. The systemic and portal venous vascular beds appear to act as excellent buffers against increases in right-sided cardiac pressures. We conclude that isolated narrowing of the tricuspid valve must be very severe to cause notable clinical and hemodynamic changes.