Autologous rectus sheath grafts. V. Growth in aortic grafts

Experiments were designed to test autologous rectus sheath as a replacement for the thoracic aorta in the growing dog. Adequacy of graft function was determined by angiography at 4 month intervals; stress-strain measurements and microscopic examination were made at the time of autopsy. A 3 cm tubular graft of rectus sheath tissue was employed as an aortic graft in 13 mongrel puppies. Nine puppies (70%) were long-term survivors and were put to death between 6 and 22 months postoperatively. No deaths were due to graft failure. Angiographic studies demonstrated patency of the graft without development of pressure gradients. An increase in diameter of the aorta (21.25%) and the rectus sheath graft (22.87%) were demonstrated in all cases. During the time of observation, the compliance of the growing aorta (93,120 dynes/cm²) decreased to one fourth that of the control aortic tissue (24,800 dynes/cm²), whereas the compliance of the rectus sheath graft (547,1000 dynes/cm²) decreased to only one eighth that of the control sheath (47,000 dynes/cm²). Tensile strength is maintained in both the growing aorta (4.5 x 10⁷ dynes/cm²) and the rectus sheath graft (4.7 x 10⁷ dynes/cm², p < 0.05). Microscopic examination showed no calcification, thinning, or weakness. Vascularization of the graft had occurred, with cellular proliferation and development of more than 30 lamellar-like units in the media and an adventitia-like surface.