Caveats of balloon dilation of conduits and conduit valves.

The results and complications of percutaneous balloon dilation involving 10 patients with a stenotic right ventricle to pulmonary artery prosthetic conduit and 1 patient with an obstructed right atrium to left pulmonary artery Dacron graft (modified Fontan) are reported. For the 10 patients (14.5 +/- 5 years) with a right ventricle to pulmonary artery conduit, the mean (+/- SD) predilation conduit valve gradient was 57 +/- 22 mm Hg, right ventricular pressure 104 +/- 21 mm Hg and right ventricle to pulmonary artery gradient 75 +/- 23 mm Hg; 2 of the patients had additional pulmonary artery stenosis requiring dilation. In one patient, the balloon could not be advanced across the conduit valve. In 9 of 10 patients in whom dilation was successfully performed, the conduit valve gradient decreased by 59 +/- 13%, right ventricle to pulmonary artery gradient by 43 +/- 22% and right ventricular pressure by 31 +/- 11%. After dilation, right ventricular pressure was less than 65% of systemic pressure in seven patients, although no pressure was less than 40%. In 8 of the 11 patients, surgery was avoided or postponed. Complications included loss of a balloon fragment after rupture during the unsuccessful dilation of the right atrium to left pulmonary artery graft and circumferential balloon rupture requiring catheter retrieval of the distal portion of the balloon from the femoral vein after successful dilation of the right ventricle to pulmonary artery conduit. Conduit valve dilation by balloon can reduce but rarely eliminate conduit obstruction, and balloon rupture may occur and can result in fragment loss or embolization.