Opening and closing kinematics of fresh and calcified aortic valve prostheses: An in vitro study

Objectives: In vitro testing of biologic valves has been performed using only fresh but treated valves suitable for patient implantation. The present study investigates changes in hemodynamic performance and leaflet kinematics in progressively calcified porcine and pericardial aortic valve prostheses. Methods: Edwards Perimount Magna ( Edwards Lifesciences, Irvine, Calif) ( n = 5) and Medtronic Mosaic Ultra ( Medtronic Inc, Minneapolis, Minn) ( n = 5) heart valves ( 23 mm) were investigated in an artificial circulation system ( 70 beats/min, cardiac output 5 L/min). Leaflet kinematics were visualized with a high-speed camera ( 3000 frames/sec). Valves were then exposed to a calcium-phosphate solution at a constant pulse rate of 300 beats/min for a total of 6 weeks. Repeated testing was performed after 1, 2, 3, 4, and 6 weeks of calcification. The calcification process might not be similar to in vivo performance. Results: Initially, the Perimount Magna valves demonstrated lower pressure gradients compared with the Mosaic Ultra valves ( 9.7 +/- 0.36 mm Hg vs 14.0 +/- 1.16 mm Hg), but they showed higher closing volume and leakage flow. Total energy loss was equivalent after 1 week of calcification. Perimount Magna valves calcified significantly faster and more severely, leading to an increase in gradients and closure volume. Leaflet kinematics showed progressively longer opening and closing times for the pericardial valves ( closing time Perimount Magna 135 +/- 11 msec vs Mosaic Ultra 85 +/- 9 msec after 6 weeks). Conclusions: On the basis of visual inspection, despite the new ThermaFix ( Edwards Lifesciences) tissue treatment, the Perimount Magna pericardial valves calcified in vitro faster and more severely than did the Mosaic Ultra porcine valves, which demonstrated a more constant performance throughout the calcification process. Leaflet kinematics showed a progressive prolongation of opening and closing times for pericardial valves, leading to higher closing volume.