Abstract 12795: Chronic Polymer Injection to Reduce Ischemic MR: Stabilizes the Mitral Valve-Ventricular Spatial Relationship
Background: Ischemic mitral regurgitation (IMR) results from ischemia induced displacement of the papillary muscles (PM), disrupting the normal mitral valve-ventricular spatial relationship. Prior sheep studies have demonstrated the efficacy of polyvinyl-alcohol (PVA) hydrogel polymer (biologically inert) injection into infarcted myocardium underlying the PM to relieve IMR acutely by altering mitral valve (MV) geometry. We aimed to examine the long term effects of PVA hydrogel injection on MR reduction, MV geometry, LV volume and function in a chronic IMR ovine model.
Methods: Twelve sheep developed chronic IMR (moderate or greater) 2 months post ligation of circumflex branches. Nine sheep were treated with injection of PVA polymer into the infarcted myocardium (PVA group) and 3 sheep were untreated (sham group). Echocardiographic (vena contracta (VC), end diastolic and systolic volumes (EDV, ESV), tenting volume, leaflet area, PM displacement relative to the mitral annulus, regional longitudinal strain adjacent to PVA injection) and hemodynamic data were obtained at baseline, 2 and 4 months post infarction.
Results: MR reduction persisted over 2 months after PVA injection (Table). EDV, ESV, EF and hemodynamic data remained stable. MR reduction was associated with significant decreases in tenting volume and leaflet closed area. Chronic PVA was associated with reduced PM displacement and improved regional strain surrounding the injection, indicating stabilization of the mitral valve-LV spatial relationship. Compared to sham group, PVA group had significantly lower MR severity, higher EF and smaller PM displacement over 4 months post infarction (VC: 0.20 ± 0.08 vs. 0.49 ± 0.05 cm; EF: 42 ± 5 vs. 31 ± 6%; PM displacement: -3.2 ± 0.28 vs. 4.8 ± 0.17mm, all P<0.01).
Conclusions: Chronic PVA injection stabilizes the mitral-LV complex, restraining infarct expansion in a chronic IMR model, resulting in stable reduction of IMR without LV function deterioration.
- © 2011 by American Heart Association, Inc.