Rapid elongation of arteries and veins in rats with a tissue expander.

The saphenous arteries and veins of 40 rats were elongated with 20-cc tissue expanders underlying the leg adductor muscles. The mean rate of successful elongation of the vessels was 84 +/- 47 percent SD, with a maximum gain of 140 percent. The fastest mean elongation velocity reached 45 percent per day. Thrombosis occurred only with stretching velocities of more than 10 percent per day, which seemed to be a safe margin. Distribution of the volume into many intervals was safer than infrequent high-volume injections. Histology showed no reduction in vessel wall diameter or loss intimal integrity. Subendothelial cellular proliferation was an indicator of this rapid regeneration. Microvascular anastomoses performed in elongated arteries and veins had the same patency rate (90 percent) as in controls.