Hydrodynamic performance of stented bioprostheses is far below that of the native valve. One of the reasons is that the internal diameter of the prosthesis is usually smaller than that of the native valve. However, other valve characteristics are also important in generating the pressure drop. We aimed to assess, in an ex vivo pulsatile mock loop, the hydrodynamic behavior of two bioprostheses, Trifecta and Mitroflow, to ascertain which geometric terms are limiting factors in hydrodynamic performance. At stroke volumes between 30 and 60 ml, Trifecta showed lower pressure drop, energy dissipation and valve resistance, and greater effective orifice area. This trend was overturned at higher stroke volumes, with Mitroflow slightly outperforming Trifecta. The geometric determinants were consistent with these results. Trifecta achieved its maximum opening area already at the lowest stroke volumes, featuring a divergent shape at the systolic peak. Mitroflow showed a complex opening pattern, featuring a convergent shape at the systolic peak for lower stroke volumes, while reaching its maximum opening area at higher stroke volumes, with a divergent shape. The two bioprostheses, although similar in design, displayed different biomechanical behaviors. The internal diameter of each bioprosthesis did not show to be strictly correlated with its hydrodynamic characteristics.
From the *Cardiovascular Department, Cardiac Surgery Unit, Ospedale “A. Manzoni” ASST di Lecco, Italy; †Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy; ‡ForCardiolab, Fondazione per la Ricerca in Cardiochirurgia ONLUS, Milan, Italy; §Cardiovascular Surgery Department, Ospedale “L. Sacco”, Milan, Italy; and ¶Università degli Studi di Milano, Milan, Italy.
Submitted for consideration February 2017; accepted for publication in revised form April 2017.
Disclosures: Giordano Tasca received lecture fees from St-Jude Medical SpA, Italy. All other authors have nothing to disclose.
Correspondence: Giordano Tasca, Operative Unit of Cardiac Surgery, Ospedale “A. Manzoni” ASST di Lecco, Via Dell’Eremo 9/11, 23900 Lecco, Italy. E-mail: email@example.com.