The effect of twist on microvascular anastomotic patency and angiographic luminal dimensions

Microvascular anastomoses must be constructed perfectly in order to be successful. One of the subtle technical errors that can occur during construction is twisting of the anastomosis. In the present study, we examined the effect of twist on the immediate, 2-h postoperative angiographic dimensions and patency of microvascular anastomoses.

Sixty-four Sprague-Dawley rats were assigned randomly to four groups. The femoral arteries were dissected for a distance sufficient to permit the application of an 8.5-mm-long microanastomotic approximator clamp. Microarteriorrhaphies were performed with twists of 0 degrees, 90 degrees, 180 degrees, or 270 degrees. Patency was assessed 2 h after surgery using transabdominal aortic arteriography with run-off. Measurements were recorded for each anastomosis, as well as for the narrowest and widest diameters of the vessels within 10 mm of the anastomosis.

Fifty-nine of the 64 rats had technically satisfactory angiograms which permitted measurement of vascular dimensions. The cross-sectional areas of the narrowest areas and the anastomoses were inversely related to the degree of twist, and were significantly reduced at 270 degrees (P < 0.05). Two-hour patency rates were 86% with 0 degrees twist, 82% with 90 degrees twist, 71% with 180 degrees twist, and 33% with 270 degrees twist. The reduction in patency with 270 degrees twist was statistically significant (P < 0.05).

Twists of 0 degrees, 90 degrees, and 180 degrees did not impair patency at a statistically significant level, but twists of 270 degrees did significantly reduce patency of microvascular anastomoses (P < 0.05).