Improved LV septal function and RV remodeling:
Chronic MR is frequently associated with impaired ventricular septal motion. The contribution of septal contraction to RV systolic function ranges from 24% in a normal RV to 35% in RV dysfunction [22, 23]. Interventricular septal contraction is able to maintain RV function and cardiac output despite RV free-wall impairment [3, 22-24]. In this study, LV radial and circumferential strain remained steady at 3-months despite an overall decline in other measurements of LV contractile performance including EF and GLS (Table 5). This observation might suggest a redistribution of LV contractile load from the apex to the base of the heart, possibly related to the mechanical effect of the tether and its fixation to an apical pad. Similarly, more modest changes in RV longitudinal and annular function relative to RVFAC are observed in our study. This suggests that in addition to improvement in intrinsic myocardial contractility of the RV free wall, it is the exaggerated movement of the septum, possibly induced by the tether and apical pad, that contributes to an immediate improvement in overall RV function and warrants future evaluation.