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Bioprosthetic valves fail due to torn leaflets as a result of increased forces applied on the commissural posts during the cardiac cycle. To face this problem a novel Support System (stent) with large openings at the Commissural posts made from acetal copolymer (POM-C) or Titanium has been developed. The hydrodynamic performance and durability of bioprosthetic valves constructed using this stent went under evaluation.
This stent was initially designed to accommodate aortic and pulmonary valves derived from marine mammal origin (Phoca Groelandica), showing excellent hydrodynamic performance when tested in a steady flow system. The same stent was used to create three trileaflet composite porcine valves of 23mm (titanium), 27mm and 31mm (POM-C) in diameter and one 25mm (titanium) bovine pericardial valve wrapped around the stent. All valves were tested in a steady flow system. The three porcine valves underwent fatigue accelerating testing to define their long term durability.
For the porcine valves the peak pressure was measured as 12.5mmHg, 9.1 mmHg and 7.3mmHg for the 23mm, 27mm and for the 31mm valve respectively. The 25mm pericardial valve showed a peak pressure of 5.5mmHg. The durability test showed valve deterioration after 225x106cycles for the 23mm, 265x106 cycles for the 27mm and 240x106 cycles for the 31 mm, values far above the passing standards according to ISO/DIS 5840.
This novel stent for bioprosthetic valves offers excellent hydrodynamic performance for a variety of biological issues tested and above the standards long term durability, possibly due to the amelioration of forces applied on the commissural posts during the cardiac cycle.