A Novel Approach for Reducing Ischemic Mitral Regurgitation by Injection of a Polymer to Reverse Remodel and Reposition Displaced Papillary Muscles

Abstract

Background-Ischemic mitral regurgitation (MR) relates to displacement of the papillary muscles from ischemic ventricular distortion. We tested the hypothesis that repositioning of the papillary muscles can be achieved by injection of polyvinyl-alcohol (PVA) polymer, a biologically inert biomaterial that has been specially formulated to produce an encapsulated, stable, resilient gel once injected into the myocardium. The purpose is to materially support the infarcted myocardium while at the same time repositioning the papillary muscles that become apically tethered in MR. Methods and Results-Nine sheep underwent ligation of circumflex branches to produce acute ischemic MR. PVA polymer was then injected by echo guidance into the myocardium underlying the infarcted papillary muscle.

Intracoronary Injection of In Situ Forming Alginate Hydrogel Reverses Left Ventricular Remodeling After Myocardial Infarction in Swine

“…Injectable biomaterial could also repair or prevent mechanical complications after MI. A recent preliminary study showed that injection of polyvinyl alcohol polymer into inferior MI in 6 sheep resulted in decreased severity of acute mitral regurgitation (MR) compared with baseline (30). Using injectable alginate solution in a dog model of inferior MI (n ϭ 30) showed that the severity of ischemic MR can be reduced during a 6-month follow-up (31).…”

Mitral valve disease—morphology and mechanisms

“…Such interventions include direct surgical left ventricular reconstruction or using an adjustable external pericardial patch or polymer injected into the subpapillary muscle of the ventricular wall, or surgical papillary muscle approximation. 10,11,226,237,275,277,279–283 Chordal modi‐fication can relieve tethering by cutting the secondary chordae that most restrict leaflet motion or by implanting chords to reduce the papillary muscle‐to‐annulus tethering distance. 276,278,284–289 Saddle‐shaped annuloplasty can also reduce leaflet stress 48,112 and improve coaptation.…”

Exercise Dynamics in Secondary Mitral Regurgitation

“…Mitral leaflet augmentation, surgical papillary muscle relocation and/or approximation, or secondary chordal cutting have been proposed, as well as attempts to locally remodel the left ventricle e.g. by injecting a polymer in the ventricular wall, acting as a tissue-bulking agent reversing the ischemic distortion and limiting the outward displacement of the papillary muscle(s) 116, 117 . Despite promising results in small sample series or animal studies, none of these subvalvular or ventricular techniques have gained widespread clinical use or acceptance.…”