New Stent for Transapical Mitral Valve Replacement in Acute Swine Experiment

Abstract Background: Many patients with mitral regurgitation are denied open-heart surgery due to high risk. Transcatheter mitral valve replacement offers an alternative treatment. This study aimed to test the feasibility of a new self-expanding valved stent for transcatheter mitral valve replacement via apex in an acute animal model.Methods: Eight porcine experiments were performed in the acute study. A left thoracotomy was performed. The new self-expanding transcatheter valved stent was deployed under fluoroscopic guidance within the native mitral annulus via apex. Hemodynamic data, before and after implantation, were recorded. Mitral annulus diameter and valve area were measured using echocardiography. Transvalvular and left ventricular outflow tract pressure gradient were measured invasively. Results: Seven animals underwent successful transapical mitral valve replacement; the implantation was unsuccessful in one animal. The mean procedure time, defined from placing the purse-string to tightening the purse-string, was 17.14 ± 7.86 min. Hemodynamic data before and after transapical mitral valve replacement showed no difference in statistical analysis. The mean diameter and mean functional area of the self-expanding device after implantation were 2.58 ± 1.04 cm and 2.70 ± 0.26 cm2, respectively. Trace to mild central and paravalvular leak was detected in 7 valves. Mean pressure gradient across the self-expanding device was 2.00 ± 0.82 mm Hg; the corresponding gradients across the LVOT were 3.28± 1.11 mm Hg. Postmortem examinations confirmed precise device positioning in 7 animals with no signs of LVOT obstruction.Conclusion: Transcatheter mitral replacement of the new valved stent was confirmed feasible in acute preclinical models. The new stent reveals optimal design parameters.