Right ventricular outflow tract reconstruction with the Contegra bovine jugular vein conduit: a word of caution

Contegra conduit: current outcomes and concerns

A variety of congenital cardiac anomalies with severe right ventricular outflow tract (RVOT) obstruction or RVOT interruption require surgical reconstruction from the infundibulum up to the pulmonary artery bifurcation or even into the branches of the pulmonary arteries. Ideally, the conduit or valve required for such reconstruction has to be formed of autologous tissue that grows, resists infection, lasts for the life span of the patient and is readily available in all sizes. Such conduits, however, are not available and although several alternatives have been used, none of which are without potential drawbacks. Contegra valved bovine internal jugular vein conduit (Medtronic Inc., MN, USA) has recently emerged as a promising option for pediatric RVOT reconstruction and has been advocated for its 'off-the-shelf' availability in sizes ranging from 12 to 22 mm, surgical pliability and encouraging short- and mid-term success in experimental animal, as well as clinical studies. This review focuses on the current outcomes of Contegra conduit and highlights some of the major concerns related to the use of this conduit and strategies to tackle these concerns.

Early Graft Failure of Small-Sized Porcine-Valved Conduits in Reconstruction of the Right Ventricular Outflow Tract

BACKGROUND

The quest for an alternative to homografts for reconstruction of the right ventricular outflow tract is ongoing. The Shelhigh No-React (NR-4000PA series) treated porcine pulmonic valve conduit (SPVC) was developed as a potential alternative.

METHODS

During a 12-month period from May 2004 to May 2005, the SPVC was implanted in 34 patients, of whom 62% were younger than 1 year. Median age at operation was 7 months (range, 5 days to 12 years). Thirteen SPCV conduits size 10, 11 size 12, 8 size 14, and 2 size 16 were initially implanted. Since May 2005, however, we have temporarily abandoned its implantation as we were concerned about a number of early failures.

RESULTS

Until November 2005, 1 early and 1 late death have occurred. Both were not conduit related. Fifteen conduits were replaced in 13 patients. Of these, 10 were size 10, 3 size 12, 2 size 14, and none size 16. Mean time to replacement of the SPVC was 313 +/- 116 days. A pseudointimal peel formation and chronic inflammation with foreign-body reaction was found in all explanted conduits at all levels. The maximum of the inflammatory reaction occurred at the valvular level around the porcine tissues, with shrinkage of the valve and hemodynamic compromise. At valvular level, small punctuate calcifications were observed in 2 cases. In 6 patients an acute inflammatory component was observed. At late follow-up (mean follow-up 366 +/- 102 days, 34 patient-years), echocardiography showed a mean graft gradient of 39.8 +/- 29.7 mm Hg, with mild to moderate insufficiency in 4 patients.

CONCLUSIONS

Although the No-React treated valve largely resists calcification, pseudointimal peel formation was found in all explanted conduits and led to multilevel conduit stenoses. The small-sized SPVC can not be regarded as an ideal conduit for right ventricular outflow tract reconstruction.

Remodelling of the right ventricle after early pulmonary valve replacement in children with repaired tetralogy of Fallot: assessment by cardiovascular magnetic resonance

AIMS

Correct timing of pulmonary valve replacement (PVR) is crucial for preventing complications of pulmonary regurgitation and right ventricular (RV) dilatation after repair of tetralogy of Fallot. We sought to assess the remodelling of the RV after early PVR in children, using cardiovascular magnetic resonance (CMR).

METHODS AND RESULTS

Twenty children with severe pulmonary regurgitation and RV dilatation and mean age 13.9 +/- 3 years underwent CMR evaluation 5.6 +/- 1.8 months before and 5.9 +/- 0.6 months after PVR. PVR was performed when the RV end-diastolic volume exceeded 150 mL/m(2), as measured by CMR. The time interval between primary repair and PVR was 12 +/- 3 years. Post-operative CMR demonstrated a significant reduction of the RV end-diastolic volume from 189.8 +/- 33.4 to 108.7 +/- 25.8 mL/m(2) (P < 0.0001), of the RV end-systolic volume from 102.4 +/- 27.3 to 58.2 +/- 16.3 mL/m(2) (P < 0.0001), and of the RV mass from 48.7 +/- 12.3 to 35.8 +/- 7.7 g/m(2) (P < 0.0001). The RV ejection fraction did not change significantly.

CONCLUSION

Prompt RV remodelling, with reduction of RV volume and mass, is observed after performing PVR if the RV end-diastolic volume exceeds 150 mL/m(2). Early PVR may prevent the detrimental complications of severe pulmonary regurgitation.

Adverse Mid-Term Outcome Following RVOT Reconstruction Using the Contegra Valved Bovine Jugular Vein

BACKGROUND

Current techniques for repair of the right ventricular outflow tract (RVOT) may require interposition of a valved conduit between the right ventricle and the pulmonary artery bifurcation. Recently, the Contegra conduit (Medtronic, Inc.) was introduced as an alternative xenograft tissue for RVOT reconstruction. Promising early hemodynamic and clinical results have been reported so far, but still less is known about mid-term adverse outcome.

METHODS

A total of 38 Contegra valved conduits (12 to 22 mm) were implanted from October 1999 to June 2004, in 36 children less than 5 years old and in 2 patients 8 and 21 years old. Diagnosis included the following: tetralogy of Fallot (n = 21); pulmonary atresia (n = 4); double outlet right ventricle + pulmonary stenosis (n = 3); d-transposition of the great arteries, ventricular septal defect, and pulmonary stenosis (n = 3); truncus arteriosus (n = 3); and other complex malformations (n = 4).

RESULTS

There was no mortality following initial surgery and no valved-conduit-related early morbidity. Early postoperative echocardiographic assessment after 3 months demonstrated favorable hemodynamics in all patients. However, during further follow-up, 5 conduits had to be replaced because of severe stenosis at the level of the distal anastomosis (2 of them had moderate to severe dilatation of the conduit proximally to the valve). Excessive intimal peel formation and severe perigraft scarring reaction were observed in all cases. One child died before surgery.

CONCLUSIONS

The Contegra valved conduit is an interesting concept for reconstruction of the RVOT. However, because of unpredictable incidence of supravalvar stenosis during mid-term results, we cannot recommend routine use of this material.