A scanning electron microscopy study of micro-arterial damage and repair.

The effects of microvascular clamps on the femoral vessels of rats were studied, using the SEM. The early changes observed were (1) local fusiform dilatation of the area secondary to necrosis of the muscular wall, (2) flattening of the longitudinal ridges in the endothelial (3) loss of laminar flow, (4) endothelial sloughing, (5) platelet aggregation, and (6) leukocyte adherence and diapedesis. The repair of the endothelium occurred by an early replication of the adjacent undamaged endothelial cells -- with their subsequent migration across a platelet bed. The coverage was complete in one week, although reorientation of the neo-endothelial cells took longer. On the basis of this study and our clinical experience, we think the ideal microvascular clamp would possess the following characteristics: small size, light weight, mechanical simplicity, flat jaws (one to two mm in diameter) coated with a non-slip surface, and calibrated to produce a pressure less than 30 gm per mm2. In addition the clamp should be unaffected by blood, autoclaving, or repeated use. No such clamp is commercially available now, but we hope that one will be available in the near future.