Development of infundibular obstruction after percutaneous pulmonary balloon valvuloplasty.

A 14 month old boy with suprasystemic right ventricular pressure secondary to pulmonary valvular stenosis and anular size of 10 mm underwent percutaneous balloon valvuloplasty with a 12 mm balloon. Right ventricular pressure almost doubled after valvuloplasty and the electrocardiogram revealed development of severe right ventricular strain. Both findings persisted on the following day. A postvalvuloplasty right ventriculogram demonstrated a severe systolic infundibular obstruction not present before. The patient underwent surgical relief of infundibular obstruction; successful opening of the pulmonary valve by the balloon valvuloplasty was observed. It is concluded that a balloon size 20% larger than anular size can be safe in human subjects and that infundibular obstruction may appear or even worsen after balloon valvuloplasty. Such an obstruction may be related to the severity of pulmonary valvular obstruction and a hypercontractile infundibulum.