Abstract 1104: Polymer Injection Therapy to Reverse Remodel the Papillary Muscles: Efficacy in Reducing Mitral Regurgitation in a Chronic Ischemic Model
Ischemic mitral regurgitation (IMR) relates to displacement of the papillary muscles from ischemic ventricular distortion. Recurrent IMR is frequent after annuloplasty, particularly when left ventricular remodeling continues to progress. Our hypothesis is that repositioning of the papillary muscles can be achieved by injection of polyvinyl-alcohol (PVA) polymer into the myocardium, in chronic MR with great left ventricle remodeling.
Methods: we studied 8 sheep underwent ligation of circumflex branches to produce chronic ischemic MR over eight weeks. Once MR developed, PVA was injected into the myocardium underlying the infarcted PM. 2D and 3D echocardiograms were used pre infarct (baseline), pre PVA (Chronic MR) and post PVA. Hemodynamic data were obtained
Results: One animal died, in the remaining 7 moderate MR developed. With PVA, the MR decreased significantly from moderate to trace-mild (vena contracta: 5.3 ± 0.9 mm vs 2.3 ± 0.9 mm, post MR vs post PVA; p<0.001). This was associated with a decrease in infarcted papillary muscle-to-mitral annulus tethering distance (33.1 ± 4.6 to 27.4±4.1 mm, post MR vs post PVA, P<0.05), tenting volume (2.1±0.3 to 1.6±0.4 mm, post MR vs post PVA, P<0.05) and leaflet area (9.4 ± 0.8 to 8.2 ± 0.7 mm, post MR vs post PVA, P<0.04). PVA was not associated with significant decreases in LVEF (41±2 % vs 39±2 %, p=ns).
Conclusions: PVA polymer injections improve coaptation and reduce remodeling chronic MR without impairing LV systolic function. This new approach offers a potential alternative for relieving ischemic mitral regurgitation by correcting papillary muscle position, thus relieving tethering that causes ischemic mitral regurgitation.