Evaluation of the influence of leaflet stiffening on leaflet stresses of porcine bioprosthetic valves using a finite element model

Abstract The magnitude and distribution of mechanical stresses acting on the closed cusps of porcine bioprosthetic valves were estimated using a finite element model. Leaflet stresses were calculated using reported stress-strain properties of glutaraldehyde processed normal porcine valves and stress-strain properties of porcine valve leaflets stiffened by fatigue cycling (658 x 10 cycles). In the normal leaflet, at a pressure of 80 mm Hg, stresses were highest near the commissures (140 kPa), decreased near the center of the leaflet (110 kPa) and were lowest near the base of the leaflet (30 kPa). With increased leaflet stiffening, stresses near the commissures remained relatively unchanged (140 kPa). Stresses near the center of the leaflet, however, increased markedly (170 kPa). With increased leaflet stiffening, stresses near the base of the leaflet remained the lowest (60 kPa). The development of a site of stress concentration near the center of the leaflet following leaflet stiffening, may offer a clue to the etiology of leaflet perforations reported to occur in the central region of leaflets of degenerated porcine bioprosthetic valves.