Bursting strength with various methods of renal artery ligation and potential mechanisms of failure

Vascular control is crucial during laparoscopic ligation of the renal vessels. Intracorporeal suture ligation has been replaced by easier methods, such as specialized clip appliers and automatic stapling devices; nevertheless, the optimal application and margin of safety of such devices have yet to be determined. We sought to address this question by measuring the bursting strength of arteries ligated with several standard devices.

One end of an adult porcine artery (3-7-mm diameter) was occluded with a titanium clip, self-locking polymer clip, or laparoscopic linear cutting stapler. Comparisons were made with one or two clips and with different distal cuff lengths (i.e., flush or 2 mm). The open end was secured to a pulsatile infusion pump. Leak/failure pressures were measured using a digital barometer.

The mean bursting pressures for the clips were above physiologic arterial pressures (1220-1500 mm Hg). However, the vessels closed with the stapler leaked at a lower mean pressure (262 mm Hg). Failure of titanium or self-locking polymer clips was the result of vessel retraction into and behind the clip, while staple- line leakage occurred between individual staples. Bursting pressures with the titanium and self-locking polymer clips was unaffected by the number of clips or length of vascular cuff.

All tested methods of vascular control performed well at physiologic pressures, suggesting that safety is not increased with traditional maneuvers such as additional clips or longer cuff length.