Abstract:

Eighteen experimental animals (9 rabbits and 9 mongrel dogs) were used in a feasibility study of heparin and a polymer belonging to polyoxyalkanoates class - homopolymer of в-oxybutyric acid - polyoxybutyrate (POB) to be applied onto the surface of the nitinole self-expanding stent "Alex" ("Komed", Russia) in order to decrease responsiveness of the vascular wall. During a three-month chronic experiment at various terms following implantation, we examined the degree of biocompatibility of the coat-free stents, heparin-treated stents, and those coated with the above polymer. The studies were carried out by means of arteriography, binocular light microscopy, histological examination, electron microscopy; and the study of the ultrastructure of thestented segmentsof the vessels. The experiments carried out on animals showed that: 1. The coating of the stents may positively influence structural alterations in the vascular wall, which improve the conditions of the blood flow along the vessel; 2. Using POB-coated stents is accompanied by lesser intimal hyperplasia, relatively decreased leukocytic infiltration, and development of vasa vasorum; 3. POB may safely be considered the most favourable coating for stents because of minimal structural alterations in the vascular wall. The obtained findings would make it possible to plan future research on polyoxyalkanoatesas modifiers of the histological responseof the vascular wall tissues while implanting stents.

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Abstract:

A multicentered study based on retrospective data covered 2012 patients and aimed at ascertaining the eficiency of various methods of treating patients with coronary restenosis after stenting. The average percent of complications after restenosis was about 20% during the period of study (1 1+4 months). The metaregression data analysis showed the positive correlation between the stage of residual stenosis of the stentet segment and the probability of complications. As the residual stenosis decreased at 1%, the frequency of complications diminished at 0,9%. Another factors under analysis did not show any evident influence, although we have registered a tendency towards better outcomes of the recurring operations as the diameter of the vessel increased. The recurring balloon angioplasty in cases of short restenosis and intracoronar radiation in cases of diffused restenotic lesions have proved to be the most effective operations. The indications for implanting the additional stents must be given very carefully, especially in cases of diabetes.

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