Aortic Conduit Valve Model With Controlled Moderate Aortic Regurgitation in Rats

BACKGROUND: The objective of this study was to describe a small animal aortic conduit model that could analyze long-term conduit valve (CV) function by echocardiography. METHODS AND RESULTS: Recipient Wistar rats (200-250g, n=20) underwent aortic leaflet injury of their native aortic valve under echocardiographic control. After 2 weeks, U-shaped decellularized CVs obtained from other rats were implanted onto the abdominal aorta. Implanted CVs were analyzed via pulsed-wave echocardiography at day 0, 4 and 12 weeks. CV stenosis was assessed as systolic flow velocity (post-pre CV)/flow velocity in the ascending aorta. CV regurgitation was assessed as the ratio of the amount of reversed diastolic flow to forward systolic flow in post-pre CV. The endpoint was set at 12 weeks. Three rats died immediately after aortic valve injury and all surviving rats received CV implantation (n=17, 85%). The survival rate after conduit implantation was 100% at 4 weeks and 88% (15/17) at 12 weeks. Regarding the CV function at 0, 4 and 12 weeks, the average observed value of CV stenosis was 3.8±7.9%, 3.1±4.1% and 14±10% (P<0.01), respectively. The average value of CV regurgitation was 0%, 12±27% and 52±43%, respectively (P<0.001). CONCLUSIONS: By using this model, the degeneration of implanted CV could be assessed not only qualitatively, but also quantitatively.