Analysis and Simulation of PTMA Device Deployment into the Coronary Sinus: Impact of Stent Strut Thickness

Surgical repair and replacement of mitral valve for functional mitral regurgitation (MR) are often limited due to high operative mortality. Recently, a new non-surgical intervention, percutaneous transvenous mitral annuloplasty (PTMA), is being investigated as an endovascular alternative to invasive open-heart surgery. Excellent short-term results have been reported in animal and several human clinical trials, proving the device is feasible. However, device fracture was observed. It is postulated that PTMA device failure is associated with its design (e.g., material, structural geometry) and interactive coupling effects between the device and hosting tissues. In this study, we developed a computational model to investigate the impact of PTMA design on its performance and fatigue life by simulating the deployment of a variety of anchor stents into human coronary sinus (CS) vessel. Peak stresses, strains, interaction forces (shear, normal) of CS wall and stent, as well as device fatigue life and safety factor, were examined, offering insights for a better PTMA design. Results showed that a stiffer Nitinol stent induced high stresses on the vessel wall. Consequently, using a stiffer stent should be coupled with an alternation of stent geometry (e.g. strut thickness) in order to reduce vessel stress as well as radial structural stiffness.