Heparin and small caliber polytetrafluoroethylene grafts in the carotid arteries of rats.

Polytetrafluoroethylene (PTFE) grafts having an internal diameter of 1 mm were implanted in the common carotid arteries of rats with or without the simultaneous application of various heparin regiments. Graft patency was determined from postoperative angiograms, and grafts were patent 40 days after surgery were harvested for light microscopic examination. The level of anticoagulation produced by the various heparin regimens was measured in separate groups of rats and found to be clinically therapeutic. All of the grafts from rats that did not receive heparin were occluded at 24 hours. In the two groups of rats that received high doses of heparin, 5 of 10 and 4 of 11 grafts were patent 40 days postoperatively. There were no patent grafts three days postoperatively in the group receiving low doses of heparin. The grafts that were patent 40 days postoperatively had lumens that were completely lined with presumptive endothelial cells. Further laboratory experimentation is needed before PTFE small caliber grafts can be recommended for use in humans.