Mechanism of Vascular Injury in Transcatheter Aortic Valve Replacement

The aim of the study was to determine the potential mechanism of vascular complications due to "catheter-vascular wall" interaction in transcatheter aortic valve replacement using experimental and numerical analysis.

A series of full-scale bench tests and numerical simulations were carried out using the CoreValve commercial transfemoral delivery system for aortic valve bioprosthesis (Medtronic Inc., USA). Full-scale tests were carried out using a phantom of the vascular system (a polymeric silicone model of Transcatheter Aortic Valve; Trandomed 3D Inc., China) with simulation of all stages of delivery system movement along the vascular bed. They involved introduction into the common femoral artery, movement along the abdominal and thoracic parts of the aorta, the aortic arch, and positioning the system to the implantation site. The force arising from the passage of the delivery system was assessed using sensors of a Z50 universal testing machine (Zwick/Roell, Germany). Numerical simulation of transcatheter valve replacement procedure was carried out in a similar way with allowance for the patient-specific anatomy of the recipient's aorta using the finite element method in the Abaqus/CAE environment (Dassault Systèmes, France).

It was found that in the process of the delivery system passing through the vascular system, there occurred force fluctuations associated with catheter bending and its interaction with the aortic wall in the region of its arch. For example, in the initial straight portions, the pushing force was 3.8-7.9 N; the force increased to the maximum (11.1 and 14.4 N with and without the prosthesis) with bending of the distal portion of the catheter. A similar increase was observed when performing numerical simulation with high-quality graphic visualization of stress on the "spots" of contact between the catheter and the vascular wall with an increase in stress to 0.8 MPa.

Numerical and full-scale bench tests prove the significant effect of the properties of delivery system catheter for transcatheter aortic valve replacement on the interaction with the aortic walls.