A new domestic self-expanding nitinol stent: in vivo preclinical study

Abstract

Objective. To evaluate the results of implantation of a new domestic self-expanding nitinol stent in experimental animals. Materials and methods. Experimental implantations of a self-expanding nitinol stent were performed in the common iliac artery of three Vietnamese Pot-bellied pigs. In the postoperative period, all animals received dual antiplatelet therapy for 3 months. Vital signs were also assessed throughout the observation period. After 3 months, the animals underwent control angiography and ultrasound examination of the iliofemoral segment, followed by withdrawal from the experiment by euthanasia. The next step was a macroscopic and histological analysis of the stented areas of the vessels. Results. The observation period of the animals was 3 months. Throughout the entire observation period, vital signs in all animals remained within normal values. The results of control angiography and ultrasound examination after 3 months demonstrated patency, as well as the absence of significant in-stent stenoses in two pigs. One animal showed signs of in-stent restenosis. The results of macroscopic and histological analysis showed signs of damage to the subendothelial layer, as well as myointimal hyperplasia. These changes were especially pronounced in the animal with restenosis. Our analysis showed that the presented results were due to excessive oversizing of the implanted stents (20–30 %). Conclusion. Our proposed self-expanding nitinol stent, in general, showed satisfactory results in the in vivo experiment. Nevertheless, it should be borne in mind that severe stent oversizing can cause excessive neointimal proliferation, which, in turn, will lead to the development of restenosis in the long-term postoperative period. In this regard, it is necessary to carry out an additional series of implantation of the presented stent to the experimental animals with less oversizing in order to determine its optimal values for this particular stent model.