Right ventricular outflow tract reconstruction using Contegra valved conduit: natural history and conduit performance under pressure.

OBJECTIVE

To assess the performance of the bovine Contegra valved conduit used for right ventricular (RV) outflow tract reconstruction, particularly in relation to post-operative RV pressure.

METHODS

Follow-up study of 64 consecutive right ventricular to pulmonary artery-conduit implants in 62 patients between January 2000 and April 2003. The majority of cases were forms of pulmonary atresia/VSD (n=24, 39%) or Fallot's tetralogy (n=13, 21%). Thirteen cases (21%) had aortic atresia, truncus arteriosus or discordant connections with pulmonary atresia/VSD. Twelve cases (19%) were conduit replacements. Echocardiography was performed for a median follow-up of 14 months (range 0-38 months).

RESULTS

Median age at implantation was 13.8 months (range 0.1-244 months) and median weight was 8.9 kg (range 2.1-84.1 kg). Thirty-eight patients (59.4%) were <10 kg at the time of surgery. Early mortality was 6.4% (n=4). During follow-up there were four explantations (one for endocarditis and three for conduit dilatation) and 16 (28.6%) catheter interventions. Overall freedom from intervention at 1 and 3 years was 71+/-6% and 53+/-11%, respectively. Freedom from conduit-specific reintervention was 66+/-11% at the end of the study period. Reintervention was associated with small conduits (p=0.04), age <1 year (p=0.04) and with high RV/LV pressure ratio in the immediate post-operative period (p=0.0003). On multivariate analysis, the RV/LV pressure ratio was the strongest single factor predicting the overall reintervention (OR 5.45). Acquired distal conduit stenosis at suture line was the commonest indication for conduit-specific reintervention and was associated with the smaller conduits. The conduits explanted for dilatation showed neointimal proliferation, thrombosis, calcification and chronic inflammation.

CONCLUSIONS

The Contegra conduit is widely applicable to RVOT reconstruction with satisfactory mid-term results. However, there is a significant incidence of conduit-related complications, particularly with the smaller conduits. Adverse performance was strongly associated with high RV/LV pressure ratio at completion of surgery. We would recommend cautious use of the conduits in patients with predicted high RV/LV pressure ratios, where careful monitoring of conduit performance is crucial. There is some element of unpredictability, which adds to the importance of close follow-up. Further studies are needed to explore the issues of thrombogenicity, degeneration, possible 'rejection', and the potential role of anti-platelet and anti-inflammatory modulation.