The 'entangled' stent: A preventable cause of paravalvular leak of the Perceval bioprosthesis

Despite the excellent early performance of the Perceval sutureless valve, there have been recent reports of stent infolding, followed by paravalvular leak that was linked to valve oversizing. The purpose of this study was to review published reports by assessing photographic and radiological images. An in vitro study was also conducted with stent twisting that may occur during the collapse of the valve, termed 'stent entanglement', demonstrating consecutive successful valve collapse and implantation. This result has led us to hypothesize that infolding is due to a number of triggers, e.g. distortion of the stent overlooked during the final visual inspection of the implanted valve, rather than to excessive oversizing of the prosthesis as the sole cause, as repeatedly suggested in previous reports.