[Doppler echocardiographic estimates of pressure gradients in various types of stenoses: usefulness and limitations].

UNLABELLED: In the present study, the accuracy of Doppler estimates of pressure gradients in various types of stenoses was clinically and experimentally evaluated. Fifty-seven patients, including 23 with ventricular septal defect, 15 with aortic or pulmonary valvular stenosis, four with infundibular stenosis, and five with supravalvular aortic or pulmonary stenosis were observed. The peak systolic pressure gradient (dP (C] was obtained at the time of catheterization in all patients. Before catheterization, the maximum velocity was measured by pulsed or continuous Doppler echocardiography and the estimated systolic pressure gradient according to Doppler (dP (D] was calculated by the simplified Bernoulli equation. The experimental model was designed to create pulsatile flow through a stenosis model. Nine different stenotic model types were used, including three orifice-like stenoses and six truncated cones with heights of 10 mm and 20 mm distal to the stenosis. The orifices in their stenoses were 3, 4 and 5 mm, respectively. Glycerin solution containing Sephadex with a viscosity similar to that of blood was used as the circulation medium. Its specific gravity was 1.16 g/cm3. In each stenotic model, the maximum velocity and instantaneous systolic peak pressure gradient were measured at various water flow rates.

CLINICAL RESULTS: In patients with ventricular septal defect or valvular stenosis, dP (D) correlated very well to dP (C), with the regression equation, y = 0.87x + 2.79 (r = 0.92) or y = 0.96x + 1.02 (r = 0.99). In the other patients except for three with patent ductus arteriosus, dP (D) overestimated dP (C) by 11 to 71 mmHg, and their post-stenotic areas had gradually widened according to angiographic findings.(ABSTRACT TRUNCATED AT 250 WORDS)