The effect of increasing clamping forces on endothelial and arterial wall damage: an experimental study in the sheep

Purpose: This study aimed to relate the level of physical force applied to the arterial wall by atraumatic clamps to the degree of endothelial and wal l damage. Methods: Sixteen sheep carotid and femoral arteries were each dem arcated into four segments 1 cm apart (total 64 segments). Each segment was clamped for 15 min with a standard angled DeBakey Vascular clamp. Four lev els of force were generated by closing the clamp at three, four, five and s ix notches of closure. The extent of endothelial injury was assessed by usi ng a dedicated computer assisted image acquisition program to measure the a rea stained by Evan's blue dye. The extent of damage to the layers of the a rterial wall was analyzed and compared by scanning electron microscopy and light microscopy. Results: For femoral arteries. the area of endothelial in jury was considerably less for three notch (3.76 +/- 0.28 newtons) and four notch (5.68 +/- 0.29 newtons) closure compared with that for five notch (6 .19 +/- 0.31 newtons) and six notch (6.61 +/- 0.16 Newtons) closure (p = 0. 01). For carotid arteries, three notch (5.68 +/- 0.28 newtons) closure caus ed less damage than did four notch (7.98 +/- 0.29 newtons), five notch (9.1 7 +/- 0.40 newtons) and six notch (9.57 +/- 0.64 newtons) closure (P = 0.02 ). Scanning electron microscopy confirmed the extent and depth of arterial injury corresponded directly to the forces generated by the vascular clamps . Conclusions: The closing forces generated by arterial clamps correlated p ositively with the extent of artery wall injury. Vascular clamps should be applied at the minimum level of force that will arrest blood flow. (C) 1999 The International Society for Cardiovascular Surgery. Published by Elsevie r Science Ltd. All rights reserved.