Experimental Study On Inhibition Of Vascular Stenosis By Homemade 103Pd Radionuclide Stents

IntroductionWith aging of population and increase of intake of high fat food, diseases of vascular occlusion induced by atherosclerosis are increasing gradually. In particular, occlusion of cardiac and cerebral arteries usually causes myocardial and cerebral infarction, necrosis or amputation of limbs, even leading to death and disability immediately. Six - hundred - thousand people died from coronary heart disease each year in America. In our nation, incidence of the coronary heart disease was the fourth in the nineteen fifties, the second in the nineteen seventies, and the first in the nineteen nineties. Percutaneous transluminal coronary angioplasty ( PTC A) is an effective way to increase blood flow volume of myocardium and reduce gradient of blood pressure by dilation of the narrow coronary artery without chest opening and extra - corporeal circulation. Since the first angioplasty on left anterior descending branch of the coronary artery got success in 1977, a great deal of clinical researches have shown that successful PT-CA can obviously improve perfusion of blood flow into local myocardium, its successful rate may reach 90%. But restenosis rates within 3-6 months after angioplasty were reported to be in the range of 40 ~ 60%. In order to prevent restenosis of PTCA, many researchers have made a lot of studies and improvement of techniques, such as, coronary metallic stent angioplasty, intracoronary oriented rotary ablation, laser coronary angioplasty, trituration of intima of coronary artery, drug and gene therapy etc. All of these can not reduce effectively incidence of restenosis.In recent years, European countries and USA applied nuclide to irradiate transluminally stenosis by (β radiation or γ low - energy radiation to inhibit theintimal proliferation. The distance of radiation is only several millimeters, it will not damage heart, lungs and surrounding normal tissues and prevent the resteno-sis. This therapy is not only inhibit proliferation of the medial SMC, but also prevent the vascular elastic contract and vascular remodeling. Its mechanisms are (1) inhibition of proliferation of the medial SMC and the adventitial fibro-blast and prevention of adventitial fibrosis, (2) induction of injury of cell DNA to inhibit proliferation of VSMC and production of extracellular matrix to form neointima by the direct and indirect ways. The most stents used in our country depend on import, because their higher price, the broad use of this technique in clinical practice is obviously limited, therefore, it is very necessary to research and develop homemade stent adapted to our nation conditions. Recent years, though development of homemade stents increases year by year, the development focused on the non - vascular stents. The aim of this study is to explore the possibility of inhibition of restenosis of PTC A with 103Pd radionuclide stent of stainless steel by the cooperation with Metallic Research Institute of Chinese Academy of Science and Atomic Energy Research Institute of China.Pathologic basis of intimal proliferation is that VSMC in the media migrate to the intima, where they are activated, proliferate and secret extracellular matrix. Therefore, basic study of mechanism about proliferation of the intima and VSMC has become a focus.VSMC proliferation of is a result of cell cycle change and apoptosis. The important function of radiation is regulating the course of VSMC cycle, enable the endothelial cells and VSMC staying in Gl phase ( pre - synthesis phase) , but non - radiated VSMC have entered the S phase ( DNA synthesis phase) , continue to proliferate. Therefore radiation may retard the cell cycle by inhibiting VSMC and further influence the ability of cell division. Radiation for 48 hours after angioplasty may obviously inhibit neointimal formation because cell division and proliferation are active in this period, and the most sensitive to radiation. Radiation may also lead to cell apoptosis, enable the DNA damage in a slight degree and cell degradation, nuclear cleavage and cell death in a ser...