Simultaneous assessment of bioprosthetic heart valve biomechanical properties and collagen crimp length.

A new morphologic method is described for the simultaneous quantitation of porcine aortic valve collagen crimp length and the assessment of biomechanical properties. This method utilizes the simultaneous real-time video recording of collagen crimp morphology and acquisition of crimp length data through the combination of polarized light microscopy and morphometry. We felt that the development of this method was warranted, due to the fundamental role played by collagen in porcine aortic valve performance. The development of this method involved the design and fabrication of a uniaxial microtensile stage, suitable for mounting on a standard microscope stage. The validation of our test method was accomplished by a comparison of untreated and glutaraldehydetreated porcine aortic valve leaflet tissue, because the biomechanical and morphologic characteristics of the native and fixed aortic valve have been extensively studied. The method described in this communication enables the collection of morphologic and biomechanical data from a single tissue specimen, eliminating the need for independent studies of multiple specimens. Furthermore, this method obviates the need for making assumptions, which may be difficult to verify, concerning the homogeneity of different test specimens with respect to their morphology and corresponding mechanical response to different experimental conditions.