Transapical mitral valved stent implantation: computed tomographic evaluation of different prototype designs

AIMS: The evaluation of in vivo shaping of mitral valved stent prototypes using cardiac computed tomography (CT) was the focus of this study. METHODS AND RESULTS: Twelve pigs received a self-expanding mitral valved stent, composed of an atrial element connected to a tubular ventricular body at a modified angle (45°, 90°, 110°) resulting in three designs. Cardiac CT was performed three weeks after implantation, with focus placed on stent design-related parameters: possible left ventricular outflow tract obstruction and stent shaping. CT was successfully conducted in 11/12 animals showing correct stent position within the mitral annulus and no obstruction of the left ventricular outflow tract in 9/11 animals. Minor radial deformations of the stent body were detected. At the atrioventricular junction, deformations of the stent structure were observed in all cases. Stents with a 45° angle exhibited the greatest deflection (≤56.4°±14.5°). CONCLUSIONS: The effectiveness of cardiac computed tomography in the development process of valved stents to provide essential information and quantitative data about the in vivo stent geometry was demonstrated. The in vivo mechanical deformations of the stent were quantified, identifying critical design areas: a larger preset angle leads to less deflection and improved alignment and hence reduces the mechanical load.