Critical pulmonary stenosis with a diminutive right ventricle in neonates.

Thirteen of 19 neonates seen in the first months of life with critical pulmonary stenosis (PS) and an intact ventricular septum had a diminutive right ventricle (RV) evidenced by electrocardiographic and angiocardiographic criteria. All were critically ill and at catheterization had hypoxemia secondary to right-to-left shunting at the atrial level, and RV hypertension. Right ventricular angiogram was useful to evaluate RV size and differentiate the children with PS from those with pulmonary atresia. Pulmonary valvulotomy was the procedure of choice and in ten children the operation resulted in marked improvement with disappearance of cyanosis and cardiomegaly within one year. All are well six months to eight and one half years later. Two children had an additional unrecognized infundibular stenosis and required a shunt after valvulotomy because of persistant cyanosis. One child had a shunt without valvulotomy and died three years later in congestive failure. The three children who have been recatheterized at two to three years postoperatively have RV pressures less than 60 mm Hg. In two the right ventricles more than doubled in size but remain small. These children are critically ill and a good salvage rate depends on rapid evaluation and valvulotomy.