Collagen vascular grafts: a step towards improved compliance in small-calibre bypass surgery; preliminary report

This study assesses the static compliance of a 4-mm-calibre collagen vascular graft. The graft was prepared by extrusion from a gel of collagen obtained from the skin of grown calves. To allow easy surgical handling, the prosthesis was reinforced by embedding a polyester mesh between two concentric tubes of collagen. Compliance was determined in vitro by filling the graft with increasing volumes of saline while intraluminal pressure and longitudinal stretching were simultaneously recorded. A 4-mm polytetrafluoroethylene prosthesis and a freshly-harvested human saphenous vein served as references. In the range of physiological pressures (100 to 200 mmHg), the collagen graft was only half as stiff as the polytetrafluoroethylene graft (5.6 vs 2.7 mm3/mb/m) and, in spite of its reinforcement, yet slightly more compliant than the vein itself (4.5 mm3/mb/m). Thus, from a mechanical viewpoint, a collagen prosthesis seems to be a valuable alternative for small-vessel bypass grafting, but further studies of its flow-surface characteristics are now warranted to assess its potential usefulness in the clinical setting.