FAILURE OF THE HEMASHIELD EXTENSION IN RIGHT VENTRICLE-TO-PULMONARY ARTERY CONDUITS

Between 1989 and 1991, 17 children underwent 18 right ventricle-to-pul monary artery conduit placement operations using a composite of an aor tic or pulmonary valved homograft and a Hemashield extension to the ve ntricle. Hemashield is a collagen-coated knitted Dacron graft with exc ellent compliance and hemostatic properties. Diagnoses included tetral ogy of Fallot with pulmonary atresia (7), truncus arteriosus (6), and complex transposition of the great arteries (4). Mean age at conduit p lacement was 4.9 +/- 4.2 years, and all patients survived. At a mean f ollow-up of 14 +/- 4 months, postoperative Doppler echocardiographic g radients between the ventricle and pulmonary artery ranged from less t han 20 to 60 mm Hg. At cardiac catheterization 13 +/- 3 months postope ratively (6 patients), the systolic pressure gradient across the condu its ranged from 14 to 90 mm Hg (mean gradient, 59 +/- 29 mm Hg). Condu it obstruction, when present, was demonstrated angiographically to be in the Hemashield portion and led to early conduit replacement six tim es in 5 patients (33% of operations) within 10 to 18 months (mean time , 14 months) after insertion of the original conduit. Pathologic exami nation of the explanted conduits revealed the obstruction to be a thic k neointimal peel that was impossible to separate from the Hemashield graft. Failure of the Hemashield as an extension for ventricle-to-pulm onary artery conduits secondary to accelerated neointimal formation ha s led us to abandon its use in clinical practice.