Right ventricular outflow tract reconstruction: Valved conduit of choice and clinical outcomes

BACKGROUND: The valved conduit of choice in right ventricular outflow tract (RVOT) reconstruction provides a challenge for cardiac surgeons. The present study collected data regarding the clinical outcome of valved conduits for RVOT reconstruction, so as to explore various options of ideal conduits in clinical practice. METHODS: English language articles on valved conduits for RVOT reconstruction were retrieved from the MEDLINE database with respect to the commonly used homograft, stented xenograft and stentless xenograft, and the occasionally used autologous tissue valved conduit as well. Clinical outcomes of each conduit were outlined with respect to their early and late mortalities, conduit failure, conduit reoperation, reoperation-free interval, actuarial freedom from reoperation, and survival rates. Conduit-related complications, risk factors and pathological findings of the valved conduits were summarized. RESULTS: Conduit failure was defined as the need for reoperation for conduit stenosis or extrinsic compression, conduit regurgitation, or anastomotic dehiscence. The conduit failure rates at 2 years were 9-55%, 35% and 25% for homograft, stented xenograft and stentless xenograft conduits, respectively. The 5-year actuarial freedoms from reoperation were 87-98.2% for homograft, 37% for Hancock, 81-92% for Carpentier-Edwards, 78% for Contegra, and 82.95% for LabCor, respectively. The result for Hancock at 5 years appeared to be disappointing, although it did prove promising, and was 79.5% at 10 years and 65.8% at 15 years. Autologous pericardial valved conduits for RVOT reconstruction showed superb properties, and the autologous monocusp pulmonary artery conduit functioned well early postoperatively, but data for long-term follow-up are lacking. CONCLUSION: Conduit failure and explant is inevitable. This phenomenon is worse with a longer follow-up. Mechanisms involved in conduit failure are unknown, even though they were accounted for by calcification and extensive intimal proliferation, and somatic outgrowth. Homografts are commonly used and have experienced a long history. The pulmonary homograft is the most commonly used RVOT conduit, especially in small children, due to its excellent characteristics. The newly-developed Contegra conduit has become popular due to its availability in full sizes and the acceptable results obtained at intermediate follow-up. The Hancock conduit can function sufficiently well for as long as 5-10 years, and early valve failure is relatively rare. It is admissible to use the Hancock conduit as an interim measure for future conduit reoperation due to its adequate function until subsequent operation. The application of an autologeous tissue valved conduit should be considered when other alternatives are not available.