Summary
Between 1975 and 1982, valve xenograft conduits were used to establish continuity between the right ventricle and the pulmonary arteries in 28 patients between the ages of 3 to 39 years (mean 14.7 years) with 4 hospital deaths (14%). The indications for operation were pulmonary atresia types I and II in 7, extreme tetralogy of Fallot with hypoplastic pulmonary artery and valvular ring in 10, secondary obliteration of the infundibulum following Waterston shunt in 4, pulmonary valve insufficiency after transannular right ventricular out-flow tract patch in 5 and tetralogy of Fallot with anomalous coronary artery in 2.
Twenty-one patients (87%) between 9 and 41 years of age (mean 17.4 years) were available for follow-up 1/2 to 8 years after operation. The late death incidence during the follow-up period was 8% (2/24). Postoperative cardiac catheterization, which included right and left ventriculogram and measurements of gradients, was performed in 14 patients 4 months to 6 years after operation. Four patients were in New York Heart Association (NYHA) class 1, 6 in class II and 4 in class III. The other 7 non-catheterized patients were in class II. There were resting peak systolic gradients of 15 to 35 mmHg in 4, 36 to 55 mmHg and more than 55 mmHg across the xenograft valve and the proximal anastomosis in 4 other patients. The right and left ventricular end-diastolic pressures (RVEDP, LVEDP) averaged 18 and 17.5 mmHg, respectively, in 3 patients. The mean ratio of PRV/PLV quotient in NYHA class I group was 0.3, in class II 0.45 to 0.7 and in class III > 0.7 (including 2 with residual VSD and pulmonary hypertension).
Late densitometric studies for assessing pulmonary valve competence revealed regurgitant fraction of up to 40% of the total stroke volume in the absence of a residual shunt 2 to 4 years after conduit implantation. Three children underwent uneventful surgical replacement of calcified xenograft conduit 1 1/2 to 4 1/2 years after surgery with antibiotic-sterilized valve allograft. Four other patients have residual ventricular septal defects (VSD), 2 of them underwent surgical reclosure while the other 2 patients with pulmonary hypertension still have their residual VSD open.
Conclusion: Xenograft valve conduit in children could prevent immediate postoperative pulmonary insufficiency but will degenerate very early causing obstruction and/or pulmonary insufficiency. Our present policy is to reconstruct the right ventricular outflow tract with antibiotic-sterilized valve allograft preserved at 4 °C in a nutrient medium.
Key words
Porcine valved conduits - Pulmonary atresia - Extreme tetralogy of Fallot - Late results
