Hemodynamics in congenital mitral stenosis.

The hemodynamic findings in five patients with congenital mitral stenosis, four of whom resided at mild altitude (5,200 to 6,500 feet) are presented. Pulmonary hypertension was present in all patients. Reactivity of tbe pulmonary vascular bpd was noted in the four patients residing at altitude. The administration of tolazoline and/or 100 percent 0 2 to three patients resulted in an average drop in mean pulmonary artery pressure (PAP) of 20 mm Hg (range 13 to 33) and in TPR of 790 dynes/M2 (range 350 to 1,200). In one patient catheterized 36 hours after being transferred to sea level mean PAP declined from 85 to 40 mm Hg and TPR decreased from 1,590 to 730 dynes/M? These studies have shown the presence of markedly elevated TPR in patients with congenital mitral stenosis who reside at 5,200 feet. The pronounced reactivity of the pulmonary vascular bed with drugs and/or increase in oxygen tension suggests that reactive vasoconstriction, due m part to mild hypoxia, is an important factor in maintaining the high TPR in these patients.