Reverse Ventricular Remodeling Reduces Ischemic Mitral Regurgitation

Abstract

Background-In ischemic mitral regurgitation (MR), mitral leaflet closure is restricted by ventricular remodeling with displacement of the papillary muscles (PMs). Therapy is uncertain because ring annuloplasty does not alleviate PM displacement. We tested the hypothesis that echo-guided PM repositioning using an external device can reduce MR without compromising left ventricular (LV) function. Methods and Results-We studied 10 sheep with ischemic MR produced by circumflex ligation with inferior infarction, 6 acutely and 4 eight weeks after myocardial infarction (MI). A Dacron patch containing an inflatable balloon was placed over the PMs and adjusted under echo guidance to reverse LV remodeling and reposition the infarcted PM. 3D echo assessed mitral valve geometric changes. In 7 sheep, sonomicrometry and Millar catheters assessed changes in end-systolic and end-diastolic pressure-volume relationships, and microspheres were injected to assess coronary flow. Moderate MR after MI resolved with patch application alone (nϭ3) or echo-guided balloon inflation, which repositioned the infarcted PM, decreasing the PM tethering distance from 31.1Ϯ2.5 mm after MI to 26.8Ϯ1.8 with patch (PϽ0.01; baselineϭ25.5Ϯ1.5). LV contractility was unchanged (end-systolic slopeϭ3.4Ϯ1.6 mm Hg/mL with patch versus 2.8Ϯ1.6 after MI). Although there was a nonsignificant trend for a mild increase in stiffness constant (0.07Ϯ0.05 mL

Primary Percutaneous Coronary Intervention Lowers the Incidence of Ischemic Mitral Regurgitation in Patients With Acute ST-Elevated Myocardial Infarction

“…Enlarged LVES and LVED volumes are thought to indicate ventricular remodeling, in which the posterior papillary muscle that tethers the mitral valve is displaced, preventing leaflet closure and thus resulting in IMR. [17][18][19][20] Constituents to the development of heart failure after AMI included the loss of functioning myocytes, development of myocardial fibrosis, and subsequent LV remodeling. The ensuing chamber dilatation and neurohormonal activation lead to progressive LV dysfunction.…”

Mitral Regurgitation

“…19 However, currently in patients with marked subvalvular alterations and unrepairable ischemic MR, valve replacement is an acceptable option.…”

Surgical approaches to treatment of ischemic mitral regurgitation (literature review)

“…Hung и соавт. [46] разработали эпикардиальный бал-лон, который размещался в области зоны инфаркта (рубца) задней стенки ЛЖ. Баллон регулировали под эхокардио-графическим контролем до оптимального уменьшения те-нинга и степени МР.…”

“…Hung и соавт. [46] показали, что применение данного метода эффективно уменьшало сте-пень МР у 10 овец с ишемической МР, не оказывая нега-тивного влияния на конечно-диастолическое давление и функцию ЛЖ. Первоначальные наблюдения через 2 мес после имплантации прибора показали: несмотря на про-должающееся ремоделирование ЛЖ, прибор поддерживает заднюю стенку ЛЖ и папиллярные мышцы, предотвращая развитие МР.…”