Incorporating the anterior mitral leaflet to the annulus impairs left ventricular function in an ovine model

• Published in: JTCVS open 2021-09, Vol.7, p.111-120
• Main Authors: Brunel, Laurencie, Williams, Zoe A., Yata, Mariko, Robinson, Benjamin M., Wise, Innes K., Paterson, Hugh S., Bannon, Paul G.
• Format: Article
• Language: English
• Subjects: Adult: Mitral Valve: Basic Science; left ventricular function; mitral valve; mitral valve replacement; valvular-ventricular interactions
• ISSN: 2666-2736; 2666-2736
• DOI: 10.1016/j.xjon.2021.03.010

Transcatheter mitral valve prostheses are designed to capture the anterior leaflet and surgical techniques designed to fully preserve the subvalvular apparatus at prosthetic valve insertion both serve to shorten the anterior mitral leaflet height, thus effectively incorporating it into the anterior annulus. This study quantifies the acute effects of incorporating the anterior mitral leaflet into the annulus on left ventricular function. Fourteen adult sheep (weight, 48.7 ± 6.2 kg) underwent a mechanical mitral valve insertion on normothermic beating-heart cardiopulmonary bypass, with full retention of the native mitral valve but with placement of exteriorized releasable snares around the anterior mitral leaflet. Continuous measurements of left ventricular mechano-energetics were recorded throughout, alternating incorporating and releasing of the anterior mitral leaflet to the mitral annulus. Echocardiography confirmed the incorporation into the annulus and release. The independent indices of left ventricular contractility (ie, end systolic pressure volume relationship and preload recruitable stroke work) were both significantly impaired when the anterior mitral leaflet was incorporated to the annulus and restored after release, as were the hemodynamic parameters: cardiac output, stroke volume, stroke work, and left ventricular pressure decreased by 15%, 17%, 23%, and 11%, respectively. Echocardiography demonstrated increased sphericity of the left ventricle during anterior mitral leaflet incorporation. Incorporating the anterior mitral leaflet to the anterior annulus adversely affected left ventricular contractility, caused distortion of the left ventricle in the form of increased sphericity, and impaired hemodynamic parameters in normal ovine hearts. Schematic representation of anterior mitral leaflet (AML) incorporation to the anterior annulus and its adverse effects on LV contractility, geometry, and hemodynamic parameters in normal ovine hearts. Compared with AML release, incorporating the AML to the mitral annulus was associated with significant decreases in LV contractility and in cardiac output by 15%, stroke volume by 17%, stroke work by 23% and LVP by 11%. [Display omitted]