Commentary: In search of the ideal right ventricle-to-pulmonary artery conduit: Is perfect the enemy of good, or will it foster excellence?

Is perfect the enemy of good?

The cryopreserved femoral vein graft as a right ventricle-to-pulmonary artery conduit performs as well as the pulmonary homograft in the short term.

See Article page 58.

Rastelli and colleagues were the first to report the use of a nonvalved pericardial tube in a child with pulmonary atresia. The following year, Ross reported the use of an aortic homograft (AH) as a right ventricle-to-pulmonary artery (RV-PA) conduit. Homografts were harvested within 48 hours of death, treated with antibiotics, and stored at 4°C for up to 4 weeks. Early techniques used to preserve homografts involved irradiation or freeze drying, which resulted in severe collagen damage of the leaflets with subsequent degeneration. Older techniques were abandoned to make way for cryopreservation with controlled freezing to 196°C with liquid nitrogen, which allowed larger-scale harvest and storage ability for longer periods. Despite issues with long-term durability secondary to cell viability, pulmonary homografts (PHs) remain the gold standard against which newer conduits are compared. Antibodies develop against donor human leukocyte antigens and have been linked to calcification, degeneration, and valve failure, which in one study seemed less evident when compared with decellularized homografts.

The bovine jugular vein (BJV) graft was introduced in 1999 and provided a reliable alternative to homografts with the advantage of being easily available at a variety of sizes (12-22 mm). The early results were promising, with durability comparable with PH. Unfortunately, a well-conducted study demonstrated a significant incidence of endocarditis as high as 10% at 7.5 years.

A multicenter prospective study demonstrated that RV-PA conduits had a significant reoperation rate. Although there was no significant difference in durability among different conduit materials (PH, AH, and BJV), the authors found that small conduit size was associated with failure. The dearth of available homografts in Japan stimulated surgeons to develop hand-made expanded polytetrafluoroethylene conduits, which at medium-term follow up have demonstrated excellent durability.

Sinha and colleagues compared cryopreserved femoral vein homograft (FVH) for RV-PA conduit replacement with PH and AH. They found that the FVH conduit performance was similar to PH and superior to AH. Comparable rates of conduit stenosis were observed with FVH with greater rates of insufficiency. FVHs were available in 10- to 15-mm sizes, which are advantageous in neonates and infants. The excess length at either end of the valve allows more versatility. The lower cost with the potential to acquire multiple conduits from a single vein make this an economical option. FVHs are thin walled with favorable handling characteristics in comparison with the BJV graft and expanded polytetrafluoroethylene conduits, which are thicker walled, making the distal anastomosis in neonates more challenging. The weaknesses of the study are the short follow-up and greater incidence of conduit insufficiency, which is concerning for neonates and infants with pulmonary hypertension.

In conclusion, although FVH is an attractive conduit alternative, longer-term follow-up to evaluate valve function and conduit durability is essential. Although the FVH may become an important tool in the surgeon's armamentarium, the search for the ideal conduit will continue to promote excellence.