Coronary perfusion post valve-in-valve procedure a high-risk aortic root anatomy in-vitro experimental study

Background Transcatheter aortic valve-in-valve replacement (ViV) has been reported as a less-invasive alternative to re-do surgery in patients with bioprosthetic valve failure. Coronary occlusion is a rare but life-threatening complication post-ViV. Meticulous pre-procedural planning is required to define the size and type of prosthesis as well as assess the risk of coronary occlusion (CO) related to a particular patient's aortic root (AR) anatomy. This study aimed at developing an in-vitro experimental setup and protocol for predicting coronary perfusion post-ViV procedure in AR anatomies considered at risk for CO. Methods A female patient undergoing VinV with an associated Chimney technique on the left coronary artery (performed as a precautionary measure) was selected as a case study. The particular geometry of her AR was considered to pose a high risk of CO post-VinV. Starting from the CT image of the patient, a 3D-printed patient-specific AR model was obtained. Subsequently, the same type of prostheses implanted in the patient were used to simulate the ViV procedure. Trifecta 19 (Abbott, St. Paul, MN, USA) was housed inside the AR model, and a TAV CoreValve Evolut 23 (Medtronic, Maastricht, NL) was implanted at five different heights with respect to the surgical prosthesis annulus. For each height, the TAV was implanted in two configurations, i.e., with commissures aligned (0°) and misaligned (60°) with respect to the surgical prosthesis commissures. The AR model was incorporated into a pulsatile flow in-vitro bench setup equipped with a coronary perfusion simulator. Each test was performed pre- and post-ViV procedure under typical rest conditions (heartbeat 60 bpm, stroke volume 80 mL, mean aortic pressure 100 mmHg). The coronary simulator resistance values were adjusted at baseline (pre-ViV) to obtain physiological coronary flow values. Then the resistances were kept constant, allowing for the detection of the potential influence of the ViV procedure on the coronary flow. Each testing condition was repeated three times. The data were assessed for normality and compared using a repeated measures ANOVA. Results The experimental design provided controllable and repeatable flow and pressure conditions. The left and right coronary mean flow did not differ significantly between pre- and post-ViV procedures in any of the tested configurations. The commissural misalignment did not induce any significant alternations in the coronary flow. Conclusion In this proof-of-concept in-vitro experimental study, the AR geometry considered high-risk for CO post-ViV did not provoke any relevant coronary flow alternations for the tested conditions. This study demonstrated how adopting a meticulous method can provide surgeons with support in preoperative planning and prevent unnecessary procedures that would increase the postoperative risk for the patient.