Fig 4. Cyclic dependent strain is dependent on tissue source and fixation.

Longitudinal cycle dependent strain did not occur in unfixed bovine pericardium (A). Conversely, glutaraldehyde-fixed bovine pericardium exhibited negative longitudinal strain with increased cycle number (A). Porcine pericardium exhibited positive cycle dependent longitudinal strain which plateaued by 10 million cycles (A). Both bovine and porcine pericardium underwent negative cycle dependent perpendicular strain with increased cycle number (B). Glutaraldehyde-fixed bovine pericardium underwent positive cycle dependent perpendicular strain at 20 million cycles (B). Samples were assessed using a two-way analysis of variance, comparing means between tissue types and cycle number. n = 6 per group, per cycle number. Groups not connected by the same lower case letter (porcine pericardium), lower case double apostrophe (bovine pericardium), or lower case single apostrophe (glutaraldehyde-fixed bovine pericardium) are statistically significantly different. Data represent the mean ± s.d.