OPTIMAL BOVINE PERICARDIAL TISSUE SELECTION SITES - II - CARTOGRAPHICANALYSIS

In Part I of this work we used small-angle Light scattering (SALS) to quantify the fiber architecture of 20 bovine pericardial sacs, along w ith corresponding tissue-thickness measurements, to determine optimal material selection sites. In order to determine the anatomic consisten cy of these sites, the fiber architecture and thickness data from all 20 sacs were averaged together using a cartographic analysis method th at took advantage of the geometry of the prolate spheroid mold used to process the sacs. Optimal selection sites were determined based on a local criteria where all fiber preferred directions within a 2.54-cm c ircular area were within +/-10 degrees. The largest contiguous area (L CA) for the entire BP sac was 20.54 cm,(2) located in the vicinity of the left ventricle of the heart. The LCA tissue thicknesses were also relatively uniform, further supporting the use of these areas. However , even within these optimal areas there was a +/-20 degrees standard d eviation in local fiber preferred directions, resulting in at best a 4 0 degrees spread in local preferred directions. The observed structura l variability may be due to regionally heterogeneous physiologic loadi ngs induced by the ligamentous attachments. These attachments may alte r the regional fiber preferred orientation to support local mechanical loadings. Overall, given the inherent structural variability of the B P sac, we conclude that use of anatomic location alone will not consis tently guarantee the selection of tissue specimens with a highly homog eneous and predictable fibrous structure. It is thus suggested that a direct fiber measurement presorting method be employed when selecting BP specimens for bioprosthetic applications where tissue structural ho mogeneity and uniformity is critical. (C) 1998 John Wiley & Sons, Inc.