Variability of the diameter of the pulmonary outflow tract and its relation to balloon valvoplasty for congenital pulmonary valvar stenosis

Abstract

SummaryThe diameter of the pulmonary outflow tract was measured from the right ventricular cineangiogram at different phases of the cardiac cycle prior to balloon valvoplasty in 54 patients with congenital pulmonary valvar stenosis. Measured at the level of the hinge point of the valvar leaflets, the pulmonary outflow tract was found to be largest at end-diastole and smallest at end-systole. The mean increase in diameter from systole to diastole was 25.3% (range 6–53%) for 47 patients with typical valvar stenosis, and 24.3% (range 14–41%) for seven patients with dysplastic valvar leaflets (p>0.5). Dilatation using balloons less than 1.2 times the size of the maximal end-diastolic diameter produced a mean reduction in the pressure gradient from right ventricle to pulmonary trunk of 71.1%, compared to 76.2% with bigger balloons (p>0.3). Two patients with an initial ratio between balloon and outflow tract of 0.9 required a second dilatation. The timing of measurement of the diameter of the pulmonary outflow tract should be standardized. Oversized balloons probably are not necessary for pulmonary valvoplasty.