Reduced intimal injury to canine arteries with controlled application of vessel loops

Arterial intimal damage caused by elastic vessel loops was quantitated to determine (1) if they produce intimal injury, (2) if the injury is proportional to the force applied, and (3) if the injury is less than that produced by vascular clamps. Vessel loops were wrapped around 30 canine artery segments (5 mm in diameter) and a gram scale was connected to each to measure the force applied. The minimal occlusive force (MOF) and 150, 200, and 250 g force were applied for 30 min. For comparison, a Fogarty vascular clamp was applied at MOF for 30 min. Arteries were then reperfused for 30 min. Half was immediately harvested (group I); the remaining half was harvested at 2 weeks (group II). Scanning electron micrographs were made of each artery's intimal surface and graded from 0 (no injury) to 5 (severe intimal fracture). Mean injury grades were calculated. The MOF for vessel loops was 99 g. In group I, arteries subjected to less than 200 g force had a mean injury grade of 1.0 +/- 0.4; while those exposed to 200-250 g force had an injury grade of 3.5 +/- 0.7. The severity of injury was linearly correlated with the force applied (r = 0.72, P less than 0.009). In group II, the injury grade of 0.4 +/- 0.5 in arteries at MOF was significantly less than the injury grade of 2.8 +/- 0.5 in those at 200-250 g force, (P less than 0.0005). Injury grades of 3.7 and 3 were seen in groups I and II, respectively, when Fogarty clamps were applied. We conclude that vessel loops applied at MOF produce minimal injury. At greater occlusive forces, the injury is proportional to the force applied approaching that of a Fogarty clamp. Intimal injuries may be minimized when vessel loops are applied at MOF.