Perm Polytechnic University 26 May 2023 13:12
To dilate blood vessels and maintain sufficient blood flow in the human body, doctors use coronary stents made of metal alloys and biopolymers. The most common problem with the operation of this medical device is its fracture with subsequent damage to the arteries. In order to control the properties of products and be able to set their structure, Perm Polytechnic scientists have developed a two-level mathematical model of the supporting "frame" and at the macroscopic level (at the level of the steel grains from which it is made) the most dangerous types of deformation were revealed when the stent was opened with balloon expansion inside the vessel. The resulting technology will prevent destruction during installation in the organ and will help the devices to remain durable during further operation, thereby solving the most important issue of biomechanics.
The results of the work were published in the highly rated Materials magazine in 2022. The research of scientists is conducted within the framework of the program under the Decree of the Government of the Russian Federation No. 220, the so-called "Megagrants", contract No. 075-15-2021-578 of 31.05.2021, and with the support of the RFBR and the Perm Region. The development was carried out within the framework of the Academic Strategic Leadership Program "Priority-2030".
The installation of a stent — a special frame that fits into the lumen of the hollow organs of a person or animal — provides an expansion of the area narrowed by the pathological process. Stents are often deformed when opened inside the vessel and can be damaged up to complete destruction. In order to eliminate the main directions of fracture of a part of the structure, the polytechnics built a two-level matrix model of a biocompatible stainless steel device and studied the effect of the grain size of which it consists on the nature of deformation.
— The simulation was performed using a program that incorporated the physical mechanisms and processes of deformation at the macro and meso levels. Considering a fragment of a steel stent, we found that it consists of about 350 grains, and the orientation of their crystal lattices in space is set according to a random uniform distribution law," shared Roman Gerasimov, a junior researcher at the Laboratory of multilevel Modeling of Structural and Functional materials at PNRPU.
— The study showed that the lower part of the "frame" for vessels opens more significantly than the middle, and the upper part does not open. It turned out that one of the critical factors for the development of the processes of destruction of the stant is the average grain size in a polycrystal and can vary from 10 to 30 micrometers," said Pavel Volegov, Vice—rector for Priority Projects of PNRPU, Associate Professor of the Faculty of Applied Mathematics and Mechanics.
The data obtained at the macro- and mesoscopic level will allow biotechnologists to control the properties of products, set their structure, thereby preventing destruction during installation in a human vessel.
According to scientists, biomedicine is moving to solutions aimed at the needs of specific patients. The technology will significantly improve the recovery of cardiovascular tissues and is recommended for patients with coronary heart disease, angina pectoris, atherosclerosis of blood vessels, pre- and post-infarction conditions, as well as the risk of heart failure.
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The development of Perm Polytechnic scientists will restore cardiovascular tissues
