Comparison of hydrodynamic characteristics between bovine pericardial and porcine valve using a mock circulatory system mimicking the pulmonary position

Abstract

Background: The most frequently used bioprosthetic cardiac valves have initially been designed for aortic positions. But, these prosthesis has been used in the pulmonary part due to structural similarities in each great artery’s valve structure. No comprehensive evaluation was reported regarding the functioning of tissue prosthetic valves under pulmonary conditions. Methods: Using a Mock circulatory system, a pulse duplicator, we evaluated the hydrodynamic characteristics of bovine pericardial and porcine valves (21, 23, 25, and 27 mm sized Magna and Hancock valve). Geometric orifice area, regurgitant volume, leakage volume, regurgitant fraction, peak pressure gradient, and forward flow volume were evaluated. This procedure was performed under different pulmonary pressure conditions (from15/5mmHg to 75/35mmHg) and normal aortic pressure (110/80 mm Hg) as a reference. In vitro longevity of each type of bioprosthetic valve in pulmonary system was identified by accelerated wear testing. Results: Under normal and hypotensive pulmonary pressure conditions, bovine pericardial valves showed incomplete closure in contrast to the aortic condition. Bovine pericardial valves were associated with larger opening area (0.67 ± 0.01 vs 1.41 ± 0.01 for 21 mm valve; 0.93 ± 0.01 vs 1.70 ± 0.01 for 23 mm valve; 0.99 ± 0.01 vs 1.75 ± 0.01 for 25 mm valve; 1.58 ± 0.01 vs 2.25 ± 0.02 for 27 mm valve, all p < 0.01) and forward flow volume (35.27 ± 0.05 vs 64.7 ± 0.12 for 21 mm valve; 42.27 ± 0.05 vs 64.79 ±0.14 for 23 mm valve; 46.41 ± 0.06 vs 64.28 ± 0.18 for 25 mm valve; 72.64 ± 0.17 vs 73.25 ± 0.07 for 27 mm valve, all p < 0.01). Porcine valves were associated with incomplete opening and smaller opening area, and lower regurgitant fraction. In terms of transvalvular pressure gradient, bovine pericardial valve demonstrated lower peak pressure gradient (20.78 ± 0.38 vs 18.36 ± 0.34 for 21 mm valve; 15.75 ± 0.14 vs 12.57 ± 0.47 for 23 mm valve; 14.85 ± 0.05 vs 12.87 ± 0.28 for 25 mm valve; 15.72 ± 0.32 vs 7.91 ± 0.03 for 27 mm valve). After accelerated were test, there was no change in hydrodynamic data for both types of valves. Conclusion: Bovine pericardial and porcine bioprosthetic valves has different hydrodynamic characteristics under various pulmonary pressure conditions. Bovine pericardial valve was associated with incomplete closure, larger opening area, and greater forward flow volume. Porcine valve showed incomplete opening, smaller opening area, and lower regurgitatnt fraction. Further research is needed to evaluate whether or not these results are associated with potential increased risk of prosthetic valve degeneration in the pulmonary condition.