Transverse or longitudinal arteriotomies in end-to-side microvascular anastomoses for small vessels (1-2 mm).

This investigation quantitatively compared lumenal dimensions of 1 mm end-to-side anastomoses with longitudinal or transverse arteriotomies into host arteries 1.5-2 mm in diameter. In 27 rats, 6-7 mm sections of iliac arteries (1 mm in diameter) were sutured as small bypasses onto abdominal aortae (1.5-2 mm in diameter). Half the anastomoses were performed on transverse. and half on longitudinal arteriotomies. Between 1 and 20 weeks following surgery intravascular methacrylate casts were made of the aortae and bypasses, and detailed measurements taken from the casts. The success rate (patency) of the bypasses was 78%; 18 successful casts (36 anastomotic sites) were analysed; 6 failed due to stenosis (3 other successful bypasses were used to develop the techniques). From these, five sites developed small dilations ("aneurysms"), which did not occur preferentially on either longitudinal or transverse arteriotomy sites. Despite a trend towards a greater diameter in the transverse compared with the longitudinal arteriotomies, they were not statistically different. Therefore, the authors recommend for technical reasons that for small end-to-side vascular anastomoses the transverse arteriotomy is preferable: it produces a simple incision which opens the artery and facilitates suturing. With a longitudinal arteriotomy in such small vessels it is often necessary to remove an elliptical area of tissue, which may produce an excessive defect.