New experimental tools, advances in numerical blood flow simulation and in molecular biology of haemostasis and thrombosis have enabled new insights into the mechano-biological factors that affect clot formation in mechanical valves flowing blood10, 17, 18, 26, 27, 28, 29, 30
LTV valve operating mode
compared to current mechanical valves and tissue valves:
Recent studies suggest that the chronic activation of coagulation in current mechanical valves is not due to blood reactions to the artificial materials used, nor to the forward flow phase, but to their inherent design characteristics, which requires reverse flow to initiate closure:
- during the reverse flow phase and rebound, leaflet impact on the valve housing results in very high velocity backflow jets that damage blood during each cardiac cycle.
- non-physiological flow leads to shear gradient-dependent platelet aggregation mechanisms17.
- platelet activation and aggregation drive thrombosis10, particularly in the hinge area of the valve.
Tissue valves do not require warfarin anticoagulation therapy because of their natural design and physiological operating mode. Chemically treated porcine, bovine and equine tissues are “bio-polymers” not living tissues. They are no less reactive in blood contact applications than ceramic carbon, titanium or polymers currently used in mechanical valves. The concept of “bioprosthesis” refers to natural valve design and not to materials with intrinsic thrombo-resistant properties of living tissues.
Numerous experimental, numerical and animal testing demonstrate that the Lapeyre-Triflo valve operates physiologically like native heart valves and current tissue valves:
- leaflets close gently during flow deceleration,
- do not produce high velocity backflow jets,
- do not have low flow area within the pivoting space
- do not elicit haemostatic response at closure.
The Lapeyre-Triflo valve may thus not require permanent warfarin anticoagulation therapy(*).