Balloon dilation angioplasty of peripheral pulmonary stenosis associated with Williams syndrome

Background-Experience of balloon dilation of peripheral pulmonary stenosis (PPS) in Williams syndrome (WS) is limited. Methods and Results-Catheterizations in all patients with WS undergoing the rapy for PPS from 1984 to 1999 were reviewed. Criteria for successful dilat ion included an increase > 50% in predilation diameter and a decrease > 20% in ratio of right ventricular (RV) to aortic (Ao) systolic pressure. Media n age and weight were 1.5 years and 9.5 kg, There were 134 dilations during 39 procedures in 25 patients. The success rate for initial dilations was 5 1%. In multivariate analysis, successful dilation was more likely (I) in di stal than in central pulmonary arteries (P=0.02), (2) if the balloon waist resolved with inflation (P=0.001), and (3) with larger balloon/stenosis rat io (P <0.001). RV pressure was unchanged after dilation (96 +/- 30 versus 9 7 +/- 31 mm Hg), primarily because of failure to enlarge central pulmonary arteries. The Ao pressure increased (102 +/- 14 versus 109 +/- 19 mm Hg, P= 0.03), and the RV/Ao pressure ratio decreased (0.97 +/-0.34 versus 0.91 +/- 0.30, P=0.05). Aneurysms developed after 24 dilations (18%) and were not re lated to balloon/stenosis ratio. Balloon rupture in 12 dilations produced a n aneurysm in all 7 cases when rupture was in a hypoplastic segment. Three patients died, none from pulmonary artery trauma, and all before 1994. Conclusions-Mortality occurred early in our experience. Despite successful dilation of distal pulmonary arteries, there was modest initial hemodynamic improvement, mainly because of persistent central pulmonary artery obstruc tion. A serial approach of distal dilations followed by surgical repair of proximal obstruction may be a rational and successful therapy.