Key result
In a simulated exercise model, pericardial valves demonstrated lower initial pressure gradients (8.5 vs 11.0 mmHg) but higher closing volume (5.3 vs 1.2 ml) compared to porcine valves.
Why the study?
Do pericardial valves demonstrate different hemodynamics and kinematics compared to porcine valves during progressive calcification in a simulated exercise situation?
Do pericardial valves demonstrate different hemodynamics and kinematics compared to porcine valves during progressive calcification in a simulated exercise situation?
In an in vitro simulated exercise model, pericardial valves showed superior systolic function with lower gradients but calcified faster and had higher closing volumes compared to porcine valves.
Answers are grounded in this paper and cite their sources.
Does not support changing valve selection from simulation alone; leaves open need for in vivo exercise comparisons of pericardial versus porcine valves.
OBJECTIVE: Despite continuous development of anticalcification treatment for biological valve prostheses, calcification remains one major cause of structural failure. The following study investigates hemodynamics and changes in opening and closing kinematics in progressively calcified porcine and pericardial valves in a simulated exercise situation. MATERIALS AND METHODS: Five pericardial (Edwards Perimount Magna) and five porcine (Medtronic Mosaic Ultra) aortic valve bioprostheses (23 mm) were investigated in an artificial circulation system (150 beats/min, cardiac output 8l/min). Leaflet kinematics were visualized with a high-speed camera (3000 frames/s). Valves were exposed to a calcifying solution for 6 weeks. Repeated testing was performed every week. All prostheses underwent X-ray and photographic examination including measurement of calcium content for evaluation of progressive calcification. RESULTS: In the exercise situation pericardial valves demonstrated lower pressure gradients initially compared to the porcine valves (8.5+/-1.4 vs 11+/-1.6 mmHg), but significantly higher closing volume (5.3+/-1.2 ml vs 1.2+/-0.2 ml of stroke volume) leading to an equal total energy. Neither valve type demonstrated a significant increase in gradient or closing volume compared to the normal output situation. Opening and closing times were longer for pericardial valves after 6 weeks (opening time 42+/-10 ms vs 28+/-10 ms, closing time 84+/-12 vs 52+/-10 ms after 6 weeks). Pericardial valves calcified faster and more severely leading to an increase in gradients and closure volume. CONCLUSIONS: In the exercise situation pericardial valves demonstrated superior systolic function compared to porcine valves. Therefore pericardial valves have some advantage in active patients due to the lower gradients. Total energy loss remained constant during progressive calcification for both valves. Leaflet opening and closing is faster in porcine valves; clinical impact of these findings is not known. Diastolic performance is also important and should always be tested also in vivo.
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Bakhtiary et al. (2008) studied Valve calcification (in vitro) (n=10). Pericardial aortic valve bioprostheses vs. Porcine aortic valve bioprostheses was evaluated on Initial pressure gradients in simulated exercise situation. In a simulated exercise model, pericardial valves demonstrated lower initial pressure gradients (8.5 vs 11.0 mmHg) but higher closing volume (5.3 vs 1.2 ml) compared to porcine valves.
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