DYNAMIC AND COMPARATIVE VASCULAR GRAFT HEALING STUDIES USING MULTIPLESEQUENTIAL BIOPSIES

In order to follow the dynamic healing processes of vascular grafts an d to minimize the possible animal-to-animal variables involved in stud y results, we developed a carotid-femoral bypass model with multiple s equential biopsies. After bilateral implantation of 70 cm x 6 mm gelat in-impregnated carotid-femoral bypass grafts in 5 dogs, we biopsied an d replaced three 10-cm-long segments of each bypass at 2, 4, and 6 wee ks, with final retrieval at 8 weeks after the initial implant. The fir st surgery and later biopsy procedures were well tolerated with no mor tality or morbidity, except for some seroma formation. We observed a d ynamic progression of healing processes related to the time course, in cluding perigraft tissue reaction to the graft material and surgical t rauma, gradual absorption of the impregnated gelatin, tissue ingrowth into the graft wall, and changes in and healing of the graft surface. Because of the sizeable tissue sample generated from each biopsy, this model also allowed various study approaches to be performed on the sa me specimen. This experimental model enables study of the continuous d ynamic healing processes of the same graft in the same animal, providi ng the practical advantage of reduction of the number of animals requi red.