Intentional Laceration of the Anterior Mitral Valve Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter MitralValve Replacement: Pre-Clinical Findings.

Abstract

The authors propose a novel transcatheter transection of the anterior mitral leaflet to prevent iatrogenic left ventricular outflow tract (LVOT) obstruction during transcatheter mitral valve replacement (TMVR). LVOT obstruction is a life-threatening complication of TMVR caused by septal displacement of the anterior mitral leaflet. Invivo procedures in swine were guided by biplane x-ray fluoroscopy and intracardiac echocardiography. Retrograde transaortic 6-F guiding catheters straddled the anterior mitral leaflet. A stiff 0.014-inch guidewire with polymer jacket insulation was electrified and advanced from the LVOT, through the A2 leaflet base, into the left atrium. The wire was snared and externalized, forming a loop that was energized and withdrawn to lacerate the anterior mitralleaflet. The anterior mitral leaflet was successfully lacerated in 7 live and 1 post-mortem swine under heparinization. Lacerations extended to 89 ± 19% of leaflet length and were located within 0.5 ± 0.4 mm of leaflet centerline. The chordae were preserved and retracted the leaflet halves away from the LVOT. LVOT narrowing after benchtop TMVR was significantly reduced with intentional laceration of the anterior mitral leaflet to prevent LVOT obstruction than without (65 ± 10% vs. 31 ± 18% of pre-implantation diameter, p< 0.01). The technique caused mean blood pressure to fall (from54 ± 6 mm Hg to 30 ± 4mmHg, p< 0.01), but blood pressure remained steady until planned euthanasia. No collateral tissue injury was identified on necropsy. Using simple catheter techniques, the anterior mitral valve leaflet was transected. Cautiously applied inpatients, this strategy can prevent anterior mitral leaflet displacement and LVOT obstruction caused by TMVR.