Effect of geometric taper on thrombosis in vascular prostheses: an ex vivo study

Infragenicular polytetrafluoroethylene bypass with tapered versus straight vascular grafts: results from a prospective multicenter cohort study

Both straight and tapered arterial grafts are commonly used for infragenicular bypass surgery. Opinions vary considerably regarding the use of each type of graft and depend on individual experience, as no trial yet has assessed clinical outcomes comparing both groups. We conducted a prospective, multicenter, cohort study to analyze results for each graft type. From a total of 81 patients, 50 underwent infragenicular bypass surgery with straight PTFE prostheses and 31 with tapered prostheses in a prospective, multicenter trial. Six different centers for vascular surgery took part in the trial. In clinical follow-up at discharge as well as 3, 6, 12, 18, 24, and 36 months after revascularization, various parameters were evaluated comparing patency rates, limb salvage, and major amputation rates. Significant differences were found in limb salvage rates between the two groups. Patients receiving a straight graft fared better in this regard. Further data suggest that short-term primary patency is also improved in straight prostheses. Sixty-four percent of these remained patent after 1 year, while only 50% of tapered prostheses were still patent. No differences between the groups were found for secondary patency. The advantages of straight prostheses seem to be reduction of thrombus formation and intimal hyperplasia. Furthermore, it appears that the surgeons participating in this study prefer the use of straight prostheses. Even though the group of patients that received tapered grafts had slightly more unfavorable preoperative conditions, the data still support the superiority of straight vascular grafts. However, prospective randomized trials are necessary to evaluate the benefit of different bypass designs definitively.

Cardiovascular applications of biomaterials and implants--an overview

This paper was originally commissioned by the UK Department of Health as a contribution to the work of its Biomaterials and Implants Research Advisory Group. This group was set up under the Chairmanship of Professor Sir Colin Berry with the following terms of reference: (i) to identify recent advances in the field of biomaterials; (ii) to consider the future contribution of biomaterials in improving human health; (iii) to advise the Standing Group on Health Technology in areas where developments and assessment are needed; and (iv) to report to the Director of Research and Development (Professor Sir Michael Peckham) by October 1995. The cardiovascular field was one of several areas in biomaterials/implants considered by the Advisory Group. Amongst other areas considered were orthopaedics, dentistry, urology, wound repair and ophthalmology. Additionally, consideration was also given to such topics as chemical and biochemical sensors, drug release, hydrogels, membranes and artificial organs. The final report of the Advisory Group will be published at the end of this year. However, the Department has agreed that individual working papers such as the present one can be published independently in appropriate scientific journals.