Mitral annular dynamics are influenced by left ventricular load and contractility in an acute animal model

Abstract

The purpose of this study was to investigate the effects of loading conditions and left ventricular (LV) contractility on mitral annular dynamics. In 10 anesthetized pigs, eight piezoelectric transducers were implanted equidistantly around the mitral annulus. High-fidelity catheters measured left ventricular pressures and the slope of the end-systolic pressure-volume relationship (E_es ) determined LV contractility. Adjustments of pre- and afterload were done by constriction of the inferior caval vein and occlusion of the descending aorta. Mitral annulus area indexed to body surface area (MAA_i ), annular circularity index (ACI), and non-planarity angle (NPA) were calculated by computational analysis. MAA_i was more dynamic in response to loading interventions than ACI and NPA. However, MAA_i maximal cyclical reduction (-Δr) and average deformational velocity (- $\overline{v}$ ) did not change accordingly (p = 0.31 and p = 0.22). Reduced E_es was associated to attenuation in MAA_i -Δr and MAA_i - $\overline{v}$ (r² = 0.744; p = 0.001 and r² = 0.467; p = 0.029). In conclusion, increased cardiac load and reduced LV contractility may cause deterioration of mitral annular dynamics, likely impairing coaptation and increasing susceptibility to valvular incompetence.

Keywords: mitral annular dynamics; mitral regurgitation; mitral valve annulus; mitral valve physiology; sonomicrometry.