Arterial stenting with self-expandable and balloon-expandable endoprostheses.

Coronary angioplasty is complicated by acute occlusion (within 24 hours) and late restenosis (within 6 months) in 2-5% and 20-40% of the cases, respectively. Vascular endoprostheses (stents) may provide the cardiologist with a solution to some of these complications. Several stent-devices are now available for experimental and clinical evaluation. In this study we describe our experience with two metallic stents in normal arteries of swine. Self-expandable, stainless steel stents (3.5 mm diameter) were implanted in 17 peripheral arteries, eight of which were deendothelialized by prior balloon angioplasty. Following implantation, the animals received antithrombotic therapy with acenocoumarol and aspirin (8 stents), or aspirin alone (9 stents). After 1 week repeat angiography was performed, which showed patency of all stented arteries. Microscopy showed complete covering by neointima, 80 microns in thickness. This self-expandable stent (SES) and a balloon-expandable stent (BES), constructed of tantalum, were implanted in normal coronary arteries. SES (3.0 and 3.5 mm) receiving animals were treated with coumadines (10 stents) or received no antithrombotic treatment (16 stents) after implantation. BES receiving animals were also not treated (10 stents). Three untreated animals with SES died suddenly within 48 hours. Postmortem examination showed partial or complete thrombosis of all six stents in these animals, resulting in a patency rate of 62% after 1 week. All animals with SES, which were treated with coumadines, and all animals with BES (untreated) had patent stents after one week. It is concluded that SES implanted in normal coronary arteries of pigs, which do not receive additional antithrombotic treatment, show a 38% occlusion rate within 48 hours, but show 100% patency after 1 week, when the animals are treated with coumadines. BES implanted in normal coronary arteries of pigs, which do not receive antithrombotic drugs, are 100% patent after 1 week.

Cryoprecipitated plasma perfusion preservation and cold storage preservation of duct-ligated pancreatic allografts.

It has been shown previously that, at least in dogs, a vascularized pancreatic allograft with ligation of the pancreatic duct can maintain normal beta-cell function for at least 5 years. In this study common organ preservation techniques, as used in human cadaveric kidney transplantation, were applied to canine pancreatic allografts to determine the influence of 24-hour preservation on beta-cell function, graft survival and histological appearances. Three groups of dogs were compared: group A consisted of 9 dogs with fresh grafts; group B consisted of 5 dogs who received grafts preserved for 24 hours by pulsatile hypothermic cryoprecipitated plasma perfusion; and group C was composed of 5 animals who received grafts that had been flushed with Collins' solution followed by hypothermic storage for 24 hours. It appeared that both preservation methods were equally effective and that preservation did not alter either the graft's function or its histological appearance. No significant differences after transplantation were observed in the endocrine function tests of the three groups when compared with the preoperative values; neither was there a significant difference in the mean graft survival time between the groups.