EFFECT OF PULSATILE PRESSURE ON THE BREAKING STRENGTH AND MOVEMENT OFPROLENE SUTURES

Purpose: Most studies of sutures used in vascular surgery have used st eadily applied loads. But in vivo, sutures are subject to pulsatile pr essures. Pulsatile pressures could weaken sutures, or they could be be neficial by helping to slide the suture, thereby equilibrating the ten sion between unevenly tightened loops. This study examined the effect of pulsatile pressures on the strength and movement of polypropylene ( Prolene) sutures. Methods: Segments of pig thoracic aorta were cannula ted and studied in a tissue bath in vitro at 37 degrees C. A longitudi nal arteriotomy was made and then closed with running 6-0 Prolene. Ves sels were subjected to (1) no pressure; (2) 100 mm Hg steady pressure; or (3) 112/65 mm Hg pulsatile pressure. After 48 hours the sutures we re studied for breaking strength. Ln a second, separate set of experim ents, longitudinal arteriotomies were closed using running suture line s. These were constructed with either several loose loops or several o verly tight loops. Fine wires were affixed to the suture loops to perm it photographic recording of suture movement. Results: There was no di fference in breaking force among 68 sutures that had been subjected to (1) no pressure; (2) 100 mm Hg steady pressure; or (3) 112/65 mm Hg p ulsatile pressure. These also were no different than sutures that were not sewn into arteries. These findings indicate that neither steady n or pulsatile pressures weaken Prolene sutures. In the second set of ex periments, it was found that pulsatile pressure did cause movement of suture lines where there were loose loops (p < 0.05). However, neither steady nor pulsatile pressures caused movement of loops in suture lin es that contained normal and overly tight loops. Conclusions: Neither steady nor pulsatile physiologic pressures weaken 6-0 Prolene sutures that have been used to close a longitudinal arteriotomy. These pressur es can cause movement of loose suture lines, but do not equilibrate th e tension between normal and overly tight suture loops. Overly tight l oops may place excessive load on a suture line.