Two-dimensional mechanical and ultrastructural correlates of bovine pericardium for prosthetic valves.

Scanning electron microscopy of bovine pericardium (BP) shows anisotropic collagen fiber orientation (CFO). We studied the effect of CFO on the breaking strength of longitudinal (L) and transverse (T) strips cut from six pieces of fresh (Fr), glutaraldehyde (Glu)-, or formaldehyde (For)-fixed BP loaded at constant rate until rupture. Maximum tensile stress (Stmax) and strain (Snmax) were measured. The Stmax of L strips were larger than T ones in all groups, and Snmax was the same. Similar results were also observed in 10 pieces of Glu fixed normal canine mitral valves (MV). Maximum tensile stress is obtained when the load is parallel to CFO in both canine MV and BP.