Vermeidung von Koronarobstruktionen durch die Verwendung kleinerer Transkatheterklappen: In-vitro-Studie aus dem Bereich der Valve-in-valve-Implantationen

Background: The transcatheter aortic valve-in-valve implantation (TAViVI) technique is an evolving treatment strategy for patients with degenerated surgical aortic valve bioprostheses (SAVB) and with high operative risk. Although the hemodynamic results are excellent, there is some concern regarding coronary obstructions, especially in SAVB with externally mounted leaflets, such as the Trifecta (St. Jude Medical, St. Paul, MN). Objective: In vitro coronary flow and hydrodynamics were investigated before and after TAViVI in SAVB with externally mounted leaflets (Trifecta) using an undersized transcatheter heart valve (Sapien XT, Edwards Lifesciences, Irvine, CA). Material and methods: An aortic root model was constructed incorporating geometric dimensions known as risk factors for coronary obstruction. The validation of this model TAViVI was carried out according to the current recommendations with the Sapien XT (size 26 mm) in a Trifecta (size 25 mm) in a mock circulation. Thereafter, implantation of an undersized Sapien XT (size 23 mm) was performed. Hydrodynamic performance and left (lCF) and right coronary flow (rCF) were determined before and after TAViVI at two different coronary ostia heights (COH, 8 and 10 mm) in a pulse duplicator. Results: Validation of the model showed a coronary obstruction (p < 0.001). Using an undersized transcatheter heart valve showed no significant reduction of coronary flow (lCF: COH 8 mm, 0.90–0.87 ml/stroke; COH 10 mm, 0.89–0.82 ml/stroke and rCF: COH 8 mm, 0.64–0.60 ml/stroke; COH 10 mm, 0.62–0.58 ml/stroke). The mean transvalvular pressure gradients (4–5 mm Hg, p < 0.001) increased significantly after TAViVI. Conclusion: In this in vitro model a coronary obstruction after TAViVI could be successfully avoided using an undersized transcatheter heart valve with a modern SAVB.