Algorithm for systematic valve-crossing in transcatheter aortic valve implantation.

The retrograde valve-crossing of a stenotic aortic valve is a crucial step in the transcatheter aortic valve implantation procedure. In addition to being time-consuming and associated with an increased stroke risk, inappropriate valve-crossing may cause devastating complications. This tutorial review summarizes systematic and detailed techniques to cross the aortic valve. First, the main challenges in retrograde valve-crossing are depicted. Next, a step-by-step guidance on valve-crossing is provided, along with an in-depth description of the three-dimensional anatomy under a two-dimensional fluoroscopy view. Finally, modified techniques for different anatomies are described.