Repair of supravalvar aortic stenosis: cardiovascular morphometric and hemodynamic results. Supravalvar aortic stenosis is associated with normal systolic pressure in the aorta and its branches with the singular exception of the coronary arteries, which are hypertensive. This uncommon lesion has been treated by patch aortoplasty of several types. We examined hemodynamics and morphometrics in 13 patients who underwent operation for supravalvar aortic stenosis from 1979 through 1988. They ranged in age from 2 to 43 years (mean age, 14.5 +/- 3.8 years [+/- standard error of the mean]). There were no operative deaths. Preoperative and postoperative (1 to 5 years) catheterization or echocardiography or a combination of these was done in all but 3 patients (1 died late suddenly without a postmortem examination; 1 was lost to follow-up; and 1 has not yet been restudied). Pressure gradients across the stenosis in patients treated with a single-sinus patch (n = 4) were 65 +/- 18 mm Hg preoperatively and 5 +/- 3 mm Hg postoperatively (p less than 0.05) and in patients with a bisinus patch (n = 6), 83 +/- 15 mm Hg preoperatively and 6 +/- 2 mm Hg postoperatively (p less than 0.05); the two groups were not significantly different. Measurements of the diameters of the coronary arteries, aortic annulus, and descending aorta were made, and calculation of the ratio of the coronary artery and annulus diameters to the descending aortic diameters both preoperatively and postoperatively was possible in 5 patients. The left coronary artery was larger than normal before and after operation. Preoperatively there was a disproportionate increase in left coronary artery and annulus size during systole. Left ventricular wall thickness decreased significantly postoperatively (p less than 0.05). Repair of supravalvar aortic stenosis (localized and diffuse) by both single sinus and bisinus patch repair is safe and hemodynamic results are good. 