Abstract 2265: Injection of a Biomaterial Polymer Results in Reverse Remodeling of Displaced Papillary Muscles and Reduction in Acute Ischemic Mitral Regurgitation
Ischemic mitral regurgitation (IMR) relates to papillary muscle (PM) displacement caused by left ventricular (LV) distortion. We tested the hypothesis that displaced PMs can be repositioned by injection of polyvinyl-alcohol (PVA) polymer, a biologically inert material specially formulated to produce an encapsulated, stable, resilient gel once injected into the myocardium. The aim is to alter the compliance of infarcted myocardium and realign the displaced PMs.
Methods: 9 sheep underwent circumflex branch ligation to produce acute IMR. PVA polymer was then injected by echo guidance into the myocardium underlying the infarcted PM. Hemodynamic data, EF, Elastance (Emax), preload-recruitable stroke work (PRSW), relaxation constant tau, and echo data were measured post IMR and post PVA injection.
Results: One animal died after coronary ligation and 2 had no IMR; MR was moderate in the remaining 6. PVA injection decreased MR vena contracta from 5±0.4mm to 2±0.7mm (p<0.0001), with decreased tethering distance from infarcted PM to mitral annulus (27±4 to 24±4mm, p<0.001). PVA injection did not significantly decrease EF (43±6% vs 37±4%, post IMR vs post PVA, p=ns), Emax (1.5±0.53 vs 1.6±0.42), PRSW (33±12 vs 31±5) or tau (63±49 ms vs 70±25 ms).
Conclusions: PVA polymer injection can acutely reverse LV remodeling to reposition displaced PMs and decrease IMR without adverse effects on LV systolic or diastolic function. This new approach (to alter pathologic anatomy) offers an alternative for relieving IMR by correcting PM position, thus relieving tethering that causes IMR.