Morbimortality of Contegra Duct Replacements Versus Homografts in Pulmonary Position

Overview

Congenital heart diseases are nowadays frequently treated in newborns. These congenital heart defects can directly affect the right ventricular ejection tract (RVOT), or sometimes indirectly, when the left ventricular ejection tract (LVOT) is replaced by the ROVT in a Ross operation. Originally introduced by Ross and Somerville in 1966, the reconstruction of ROVT by valved homografts is since then widely used.Pulmonary and aortic homografts then constituted the gold standard in conduit replacement between the right ventricle and the pulmonary artery (VD-AP). The increasing demand for homografts currently induces a shortage and unmet demands. This lack of availability, and the durability of homografts in young patients, has encouraged the search for alternative conducts.For example, in 1999, Medtronic® put a bovine jugular vein xenograft (VJB) on the market, the Contegra® conduct, as alternative for the homograft for RVOT reconstruction. This duct naturally has a central valve with three valvules, and there is on both sides of the valve a generous duct length allowing unique adaptation options. This conduit, however, is not perfect. Whether using Contegra® ducts or homografts, replacement is inevitable. The aim of this study is to compare operative morbidity and mortality when replacing Contegra® or homograft.

Congenital heart diseases are nowadays frequently treated in newborns. These congenital heart defects can directly affect the right ventricular ejection tract (RVOT), or sometimes indirectly, when the left ventricular ejection tract (LVOT) is replaced by the ROVT in a Ross operation. Originally introduced by Ross and Somerville in 1966, the reconstruction of ROVT by valved homografts is since then widely used. The technique became particularly popular from the mid-1980s, through the routine use of cryopreservation. Pulmonary and aortic homografts then constituted the gold standard in conduit replacement between the right ventricle and the pulmonary artery (VD-AP). Early failure of homografts is mainly due to early calcifications. Lung homografts are, however, less prone to obstructions and calcifications than aortic homografts but are not readily available, particularly in small sizes (10-18mm). The increasing demand for homografts currently induces a shortage and unmet demands. This lack of availability, and the durability of homografts in young patients, has encouraged the search for alternative conducts. For example, in 1999, Medtronic® put a bovine jugular vein xenograft (VJB) on the market, the Contegra® conduct, as alternative for the homograft for RVOT reconstruction. This duct naturally has a central valve with three valvules, and there is on both sides of the valve a generous duct length allowing unique adaptation options. It is stored in a glutaraldehyde solution in concentrations sufficient enough to make it non-antigenic, yet low enough to maintain the flexibility of the tissue.This conduit has many advantages: 1) Immediate availability 2) Available size range from 12 to 22mm internal diameter 3) Possibility of adaptation to morphology and easily suturable 4) Good hemodynamics 5) No need for proximal or distal extension 6) lower cost than homograft and 7) non-antigenicity. This conduit, however, is not perfect. On the one hand, it has no growth potential and therefore risks becoming too small and no longer suitable as the child develops. This problem is particularly encountered in small patients, in whom ducts less than 16mm in diameter have been implanted, and is not specific to the duct in VJB. On the other hand, there is a source of failure specific to the Contegra® prosthesis. These are the stenoses at the level of the distal anastomosis between the duct and the pulmonary artery. Several mechanisms explain this distal stenosis: 1) hypoplasia or distal stenosis of the branches of the pulmonary artery, 2) difference in size between the duct and the pulmonary artery being too important, 3) the surgical technique , 4) immunological and inflammatory reactions, 5) neointimal proliferation, 6) thrombi formation. The most likely cause is multifactorial, with a combination of factors cited above. Prior et al proposed an operative protocol for reducing the distal stenosis rate. With this protocol distal stenosis has become a rare complication but there are still situations in which the VJB conduit needs to be replaced. Therefore, whether using Contegra® ducts or homografts, replacement is inevitable. The aim of this study is to compare operative morbidity and mortality when replacing Contegra® or homograft.