Repair of 1 cm incisions in small-diameter arteries and veins with VCS clips results in wound healing as good as that achieved with standard suture closure, when assessed for patency, leakage, degree of narrowing, and intimal reaction. The time required for clip closure is considerably shorter than for suture closure.

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Traditional suture reconstruction of tubular organs creates a perforating needle injury, leaves suture material on the endothelial or mucosal surfaces, and is cumbersome when done endoscopically. One alternative method of reconstruction of tubular organs could use the new nonpenetrating clip to create an everted closure. In five pigs, a longitudinal incision of the infrarenal aorta, inferior vena cava, left ureter, gallbladder, and the common bile duct (in two) was closed with Vascular Closure Staples (VCS-clips). Four weeks after surgery, all ten blood vessels remained patent with no thrombosis. There was a well-healed wound with continuous intimal layer. The ureteral, gallbladder, and common bile duct wounds healed without leakage or obstruction in all animals. There was complete mucosal bridging of the wound, although in some specimens one or two clips were exposed to the lumen. The VCS-clips are easily and quickly applied and are safe insofar as can be determined by short-term follow-up.

This study was designed to assess platelet activity in vivo with vascular prostheses seeded with endothelial cells to determine the time course for development of thromboresistance and to test the ability of prostheses to produce prostacyclin. Sixteen dogs were randomly allocated to receive seeded (experimental group) or unseeded (control group) velour Dacron aortic prostheses. Serial measurements of platelet survival were performed to assess platelet interaction with prostheses in vivo, and platelet serotonin was monitored as an index of platelet release in vivo. After placement of prostheses, dogs in the experimental group had rapid normalization of platelet survival, with most having normal platelet survival at 4 to 8 weeks after surgery. In contrast, most control animals had reduced platelet survival throughout the 12 week period of study. Significant differences between groups in mean platelet survival were noted at 8 weeks after surgery (p < .005) and in mean platelet serotonin at 12 weeks after surgery (p < .05). Luminal surface production of 6-keto-PGF1, from seeded prostheses was similar to aortic production and significantly greater (p < .05) than that of control prostheses. Gross thrombus was present on 6.0 ± 3.4% of the prosthetic surface in experimental animals in comparison to 26.6 + 19.2% in controls (p < .005). The results of these studies document accelerated nonreactivity with platelets of seeded prostheses due to rapid coverage with endothelium possessing a normal ability to produce prostacyclin. Circulation 69, No. 3, 632-639, 1984. PLATELET INTERACTION with vascular prosthetic surfaces is an undesirable process that contributes to occlusive thrombosis and distal embolization.1' 2 After placement of arterial prostheses in man and experimental animals, platelets rapidly and continuously accumulate on the surface.3-' The process can be monitored quantitatively by serial measurement of platelet survival time or by imaging radiolabeled platelets on the surface.6 In dogs, measurement of platelet serotonin also reflects platelet interaction with prosthetic surfaces, and changes in platelet serotonin parallel changes in platelet survival.5 Studies in baboons and dogs have documented that platelet survival, which is

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