Comparative in vitro evaluations of vascular graft compliance during dynamic loading

A prosthetic vascular graft should be nonthrombogenic, compliant with anastomosed vessels and resist excessive dilatation or aneurysm formation. Mechanical performance of a negatively charged, glutaraldehyde-tanned bovine heterograft was evaluated, in vitro, during dynamic loading conditions. The grafts were 16 cm in length with internal diameters of 6 mm (n = 10), 8 mm (n = 12), and 10 mm (n = 8). The prostheses were pneumatically cycled, using intragraft balloons, at a pulse pressure of 120/70 mmHg and a rate of 80 beats/min in 37 degrees C saline for 2.6 million cycles (22.6 days). At selected intervals, the diastolic and pulse volumes of the grafts were measured and compliance calculated. These studies demonstrated that this vascular prosthesis had a high initial compliance, independent of graft diameter. During dynamic loading, diastolic volume increased whereas pulse volume and compliance decreased 12%, 43%, and 49%, respectively (P less than 0.001). Greater than 75% of the changes occurred within 5 days after the onset of testing. Despite these changes, isocompliance was demonstrated for the BioPolyMeric grafts following 22 days of cycling, yielding values similar to those reported for human saphenous vein.