Atherosclerosis is one of the most common cardiovascular diseases, characterized by thickening and damage to the blood vessel walls due to the formation of various atherosclerotic changes, most commonly plaques. Treatment can be performed through surgical or endovascular approaches. The endovascular approach often involves the implantation of a stent. Stents are divided based on the method of implantation, into those that expand with a balloon (e.g., metal stents) and self-expanding stents (made of shape memory alloys or polymers). Self-expanding stents cause less damage to the vessel wall during implantation, but it is known that polymer stents have inferior mechanical properties compared to metal stents. However, the development of new and improved materials and manufacturing technologies allows for the production of more complex stent geometries, including customized stent shapes for individual patients. For example, to ensure sufficient radial strength of a polymer stent, it is possible to create a stent with a variable diameter instead of the commonly used straight mesh tube. In this thesis, a simplified geometry of the carotid artery with an atherosclerotic plaque was defined to assess the usability of shape memory polymer stents with a variable diameter. A numerical procedure for stent implantation in the carotid artery was developed using hyperelastic models to describe the material behavior of the vessel wall and stent. The usability of stents with a variable diameter was analyzed using stress in the stent as a criterion, and the effectiveness of the proposed stents in reducing stenosis after implantation was evaluated.