Aortic root distensibility and cross-sectional areas in stented and subcoronary stentless bioprostheses in pigs.

A flexible aortic root is essential for natural leaflet stress distribution. It is suggested that stentless bioprosthetic valves retain the flexibility of native valves. We investigated aortic root distensibility and cross-sectional area (CSA) in stentless (Solo, n=4; Toronto SPV, n=7), stented (Mitroflow, n=8) and in native valves (n=8) in pigs. Magnetic resonance imaging was performed to assess aortic root areas. At the annular level the Solo valve had a larger CSA (2.83+/-0.26 cm(2)) than both the Mitroflow (2.24+/-0.23 cm(2)) and Toronto SPV (1.87+/-0.59 cm(2)) (P=0.003; P=0.01). At the sino-tubular junction the Mitroflow valve had a significantly larger CSA (2.96+/-0.80 cm(2)) than the Toronto SPV (2.05+/-0.47 cm(2); P=0.02). At the annular level the percentage change in area between end-diastole and end-systole was lower for the Mitroflow than for all the other valves (P=0.006). No difference was found between native and stentless valves. In conclusion, the Solo valve had a larger CSA at the annulus than both the Mitroflow and the Toronto SPV. However, the stentless valves had a smaller CSA at the sino-tubular junction than the Mitroflow. We, furthermore, found that implantation of stentless heart valves preserves aortic root distensibility at the annular level in pigs.