Echocardiographic differentiation of infundibular from valvular pulmonary stenosis.

Echocardiographic tracings of the pulmonary valve were examined in 24 normal subjects, 16 patients with valvular pulmonary stenosis and 3 patients with infundibular pulmonary stenosis. In normal subjects, atrial contraction produced a slight posterior opening motion of the pulmonary valve leaflet (a wave). This presystolic opening motion (a wave) varied with respiration, and maximal a wave depth recorded during quiet inspiration (Amax) averaged 3.7 plus or minus 1.2 (standard error of the mean) mm (range 2 to 7 mm). In the 10 cases with moderate or severe valvular pulmonary stenosis, increased force of right atrial contraction and elevated right ventricular end-diastolic pressure resulted in an increased posterior or opening motion of the pulmonary valve leaflet, and Amax averaged 9.6 plus or minus 2.0 mm (range 8 to 13 mm, P less than 0.001 versus normal). When both anterior and posterior leaflets were recorded, presystolic opening or doming of the valve was observed. In six cases of mild valvular pulmonary stenosis, Amax averaged 4 plus or minus 2.5 mm (not significant). In patients with infundibular pulmonary stenosis, marked chaotic systolic fluttering of the valve leaflet, which lies in the turbulent stream of blood distal to the obstruction, was recorded. This finding was never seen with valvular pulmonary stenosis. In two cases of mild infundibular pulmonary stenosis, the amplitude of presystolic opening motion was within the normal range of 3 and 7 mm. In one case of severe infundibular pulmonary stenosis, no presystolic opening motion was recorded, thus suggesting that the small pressure changes produced by atrial systole failed to reach the valve leaflets. Echocardiography, therefore, should be of use in differentiating valvular from infundibular pulmonary stenosis.