Abstract 13848: Temporal Changes in Inter Papillary Muscle Distance as an Active Indicator of Ventricular-valvular Interaction in Functional Mitral Regurgitation in Humans
OBJECTIVE: Functional mitral regurgitation(FMR) is common in left ventricles (LV) with impaired systolic function, irrespective of their geometric size. A quantitative measure that relates systolic loss of function to valvular regurgitation is lacking. In this study, we hypothesize that temporal changes in inter-papillary muscle distance(IPMD-Fig1A)is a good indicator of FMR as it is governed by the extent of contraction of the underlying myocardial segments and relates to mitral valve geometry and function.
METHODS: 66 patients with systolic dysfunction (EF<50%)from ischemic heart disease underwent cardiac gated phase contrast MRI. On short axis MRI slices, endocardial and epicardial borders were traced by a single user to assess regional myocardial thickening,endocardial radial motion and velocities in a 4-segment anatomical model (Fig1C). Temporal changes in systolic myocardial thickening and motion were measured in each sector, and plotted against temporal changes in IPMD. A correlation analysis between IPMD and MR fraction was performed (R=-0.27,p=0.02).
RESULTS: End-diastolic and end-systolic volumes did not differ between patients with varied FMR severities (Fig 1B). Systolic myocardial thickening was significantly reduced in segments 2 and 3 that underlie the papillary muscles, but not in segments 1 and 4 in the equatorial region of the heart (Fig 1D). Reduction in systolic thickening in these segments, manifested as reduced motion of the two papillary muscles towards one another during systolic radial contraction of the LV. As shown in Fig 1E, IPMD reduction from diastole to systole was largest in mild MR but impaired in the rest.
CONCLUSION: Temporal changes in the inter-papillary muscle distance may be a better predictor of FMR severity, than passive ventricular volume measurement. IPMD is a good measurable end-point, that relates reduced systolic ventricular function to the severity of FMR.
- © 2013 by American Heart Association, Inc.