Incidence and treatment of reactive infundibular obstruction following balloon dilatation of critical pulmonary stenosis

Seventeen consecutive newborn and premature babies with critical pulmonary stenosis underwent a technically successful balloon valvuloplasty at our in stitution from March 1991 to February 1998. The only major complication was a thrombosis of the femoral vein in one patient, causing no clinical probl ems. Four patients (24 %) showed a reactive infundibular obstruction after balloon valvuloplasty. The outflow tract obstruction became evident immedia tely after successful dilatation of the pulmonary valve with persistently h igh pressures in the right ventricle. Pathognomonic was a typical notch in the ascending part of the right ventricular pressure curve. We were unable to predict this reaction based on echocardiography or angiography. To relie ve the muscular subvalvar obstruction, we treated the first two patients wi th iv Propranolol (0.05 mg/kg over 2 min). The last 2 patients received Esm olol (0.5 mg/kg over 2 min followed by a continuous infusion with 100 mu g/ kg/min), a very short acting beta-blocker. In the medium-term followup, all 17 patients had a very good result with only mild pulmonary valve regurgit ation. All 4 patients with a reactive infundibular obstruction required no repeat intervention. In the medium-term follow-up there were no differences between these 4 patients and the whole group.