**Abstract**

Aortic stenosis (AS) is a chronic, progressive disease. The most common cause of aortic stenosis etiology in advanced age is calcific, degenerative aortic stenosis. Once patients become symptomatic, the disease progresses rapidly. Treatment is surgical aortic replacement. Advanced age and the presence of comorbid conditions increase the risk of surgery. Therefore, a significant number of patients cannot be treated. For this purpose, transcatheter aortic valve interventions were developed and started to be used all over the world. In this article, we discussed the technical features of the transcatheter aortic valve replacement (TAVR) procedure, the types of valves used and the complications of the procedure. Clinical results of the procedure and comparisons with other treatment methods will not be included in our article.

**Keywords:** aortic stenosis, balloon expandable, cusp overlap, self-expandable, transcatheter, heart valve

### **1. Introduction**

Aortic stenosis (AS) is the most common type of valvular heart disease in developed countries. Incidence of AS increases due to the prolongation of life expectancy. Until the 2000s, surgical aortic valve replacement (SAVR) was the unique treatment for symptomatic AS. In 2002, Cribier et al. [1] performed a transcatheter aortic valve replacement (TAVR) procedure with a balloon-expandable valve in an inoperable patient and a new era began.

First, TAVR was approved for patients with high surgical risk but currently as more data gleaned, the focus expanded to the intermediate- and low-risk patients as well [2]. All the available transcatheter heart valves belong to one of the following categories: balloon-expandable valves (BEVs) or self-expandable valves (SEVs). BEV expands using the radial strength of the balloon, in contrast, SEV is deployed until it faces the resistance of the annular wall, adapting to anatomy of aortic annulus [3]. Another classification is according to leaflets mounted within the stented frame to native aortic annulus. Based on this grouping, valves can be classified as supraannular and intra-annular. Supra-annular valves are designed to avoid interaction with native annulus. This prevents blood flow obstruction. Also, supra-annular valves lead to lower transvalvular gradients and higher effective orifice area [4]. On the other hand, intra-annular valves lead to less interaction with coronary ostia, thereby minimizing the risk of obstruction [5].
