Transcatheter treatment of tricuspid regurgitation by caval valve implantation--experimental evaluation of decellularized tissue valves in central venous position.

BACKGROUND: Caval valve implantation has been suggested for transcatheter treatment of severe tricuspid regurgitation (TR). Combining the interventional technique with the promising surgical experience with decellularized valves, we sought to evaluate the functional and structural outcome of decellularized pericardial tissue valves (dTVs) in the low-pressure venous circulation in a chronic model of TR. METHODS AND RESULTS: Sixteen pericardial tissue valves were heterotopically implanted in the inferior and superior vena cava in a sheep model (54-98 kg; median 74.5 kg, n = 8) of severe TR. The devices were assembled using self-expanding nitinol stents and bovine pericardia decellularized by a detergent-based protocol (group dTV; n = 8). Glutaraldehyde-fixed pericardial tissue valves served as control (GaTV, n = 8). After 6 months, device function and structural maturation were analyzed using echocardiographic, histologic, immunohistologic, and electron microscopic approaches. After implantation, cardiac output increased significantly from 3.7 ± 1.1 l/min to 4.8 ± 1.1 l/min (P < 0.05) and competent valve function was verified by angiography. At 6 months, angiographic and echocardiographic evaluation revealed moderate to severe regurgitation in all GaTV. In contrast, five of the eight dTVs functioned well with only minor regurgitation. In these animals, autopsy revealed preserved valve structure with tender leaflets without signs of thrombosis or calcification. Conversely, GaTV showed severe degeneration with large calcification areas. Microscopic and histologic analysis confirmed endothelial repopulation in both valve types. However, additional interstitial reseeding was observed in decellularized valves. CONCLUSIONS: In the venous circulation in severe TR, decellularized valves show superior functional performance compared to Ga-fixed tissue valves. Macroscopic and microscopic analyses suggest preserved structural integrity and advanced endothelial and interstitial repopulation with evidence of less degradation in dTV. © 2014 Wiley Periodicals, Inc.

Aortic conduit valve model with controlled moderate aortic regurgitation in rats: a technical modification to improve short- and long-term outcome and to increase the functional results.

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.