In vivo microarterial freezing: experimental study.

In vivo freezing of microarteries with liquid nitrogen is known to relieve spasm without inducing thrombosis. In the present study the patency rates of microanastomoses in pre- and postfrozen vessels were investigated in the rat model. Freezing of the femoral artery was done with ethyl chloride. The artery was frozen before the anastomosis was performed on the left side (prefrozen), and after on the right side (postfrozen); patency rates were recorded at 2, 10, and 30 days. Patency rates were 100% in prefrozen vessels and 100% in postfrozen ones at all three time intervals. Histologic examination showed depopulation of all vessel walls with loss of the intima layer and fragmentation of the inner elastic lamina. Progressive cellular repopulation and regeneration of the endothelium occurred later, with no differences between pre- and postfrozen arteries. It is concluded that freezing of vessels with ethyl chloride reverts arterial spasm without inducing thrombosis and that frozen arteries can be repaired by microsurgical anastomosis with patency rates comparable to those of virgin arteries.