A Comprehensive Fluid Dynamic and Geometric Study for an "In-Vitro" Comparison of Four Surgically Implanted...

Many variables may affect the fluid dynamic of an implanted bioprosthesis. In-vitro studies have provided accurate data such that, when different prostheses are implanted in the same true aortic root, it should be possible to make a fair comparison. The study aim was to evaluate the fluid dynamic and geometric characteristics of the four most widely used stented pericardial bioprostheses.

Four types of pericardial prosthesis (Magna Ease 21, Trifecta 21, Soprano-Armonia 20, and Mitroflow 23) that fitted eight aortic roots with a native annulus diameter of 2.1 cm were implanted and tested in a mock loop.

Energy loss and mean gradients were increased with stroke volume (SV) in all valves tested. The effective orifice area values were fairly stable across the SV intervals (p = 0.57). All hemodynamic-related indices displayed mutually consistent behaviors, with Trifecta showing the lowest hindrance to flow. Both geometric orifice area (GOA) and edge geometric orifice area (eGOA) were increased significantly as the SV increased; the Trifecta valve showed the largest eGOA value, while the Trifecta and Mitroflow provided the largest GOAs. For the Trifecta and Soprano-Armonia prostheses (and the Magna to a lesser extent), the most distal cross-section was systematically greater than the inflow area, suggesting a divergent configuration at the systolic peak.

The study results combined the fluid dynamic reproducibility of the in-vitro setting and the specificity of surgery. A quantitative comparison of the fluid dynamic performance of the different bioprostheses was feasible.