Scanning electron microscopic study of disturbances in arterial walls following microsurgical needle perforations.

In the canine femoral artery we studied the extent of endothelial and subendothelial damage caused by the passage of seven different commonly used microsurgical needles. Precautions were taken to prevent collapse and risk of early vascular trauma prior to needle perforations and fixation for SEM. Since surgical anastomosing procedures are done with grafted vascular segments maintained at normal length and Omm Hg pressure, prior to clamp removal and redilation, SEM specimens were prepared under similar conditions. Under normal vessel tension, needles were passed through the vessel thus producing an entry and exit wound. Vascular templates were constructed with sagittally sectioned arteries pinned to cardboard mounts to display the needle puncture sites and prevent vascular shrinkage. Mounted vessels were maintained in oxygenated lactate-ringers at body temperature prior to glutaraldehyde fixation. Intimal folds consisting of normal undislodged endothelial cells were seen in all areas except at needle puncture sites. Needles produced varying degrees of gross damage at entry and exit wounds. Most taper point needles tend to spread apart intimal folds while some cutting edge needles slice through endothelial cells. Cutting edge needles tend to tear off endothelial cells surrounding the wound exposing the internal elastic lamina. We have observed intact cytoplasmic extensions between endothelial cells of adjacent intimal folds remote from the wound. These extensions appear broken in the vicinity of the wound. At certain lesion sites smooth muscle cells are regularly spaced between intact and cut elastic fibers. SEM provides ultrastructural information of mechanical disturbances to the walls of arteries caused by common microsurgical needles.