Characterisation of global and regional mitral annular strains in an acute porcine model.

Abstract

OBJECTIVES This study aimed to explore regional mitral annular strain using a novel computational method. METHODS Eight pigs underwent implantation with piezoelectric transducers around the mitral annulus. Interventions of pre- and afterload were performed by inferior vena cava constriction and endovascular balloon occlusion of the descending aorta. The mitral annulus was reconstructed in a mathematical model and divided into six segments. Global and segmental annular strain were calculated from a discrete mathematical representation. RESULTS Global annular strain gradually decreased after isovolumetric contraction until late systole. Mitral annular end-systolic strain demonstrated shortening in all segments except the anterior segment, which showed the least deformation. The P2 annular segment demonstrated the most end-systolic shortening (-7.6 ± 1.1% at baseline, p < 0.001 compared to anterior segment). Systolic global annular strain showed no significant change in response to load interventions but correlated positively with left ventricular contractility at baseline and after preload reduction. CONCLUSIONS Mitral annular systolic strain demonstrates cyclical variations with considerable regional heterogeneity, with the most pronounced deformation in posterior annular segments. Measurements appear independent of changes to pre- and afterload.