Echo-guided papillary muscle repositioning using an external device reduced papillary muscle tethering distance from 31.1 mm to 26.8 mm (P<0.01) and resolved moderate ischemic mitral regurgitation.
Does echo-guided papillary muscle repositioning using an external device reduce ischemic mitral regurgitation without compromising left ventricular function in a sheep model of ischemic MR?
An external device that repositions papillary muscles can reduce ischemic mitral regurgitation without compromising LV function in a preclinical model.
Absolute Event Rate: 26.8% vs 31.1%
p-value: p=<0.01
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 (n=3) or echo-guided balloon inflation, which repositioned the infarcted PM, decreasing the PM tethering distance from 31.1+/-2.5 mm after MI to 26.8+/-1.8 with patch (P<0.01; baseline=25.5+/-1.5). LV contractility was unchanged (end-systolic slope=3.4+/-1.6 mm Hg/mL with patch versus 2.8+/-1.6 after MI). Although there was a nonsignificant trend for a mild increase in stiffness constant (0.07+/-0.05 mL(-1) versus 0.05+/-0.03 after MI, P=0.06), LV end-diastolic pressure was unchanged as MR resolved. Coronary flow to noninfarcted regions was not reduced. CONCLUSIONS: An external device that repositions the PMs can reduce ischemic MR without compromising LV function. This relatively simple technique can be applied under echo guidance in the beating heart.
Hung et al. (Tue,) conducted a other in Ischemic mitral regurgitation (n=10). Echo-guided papillary muscle repositioning using an external device vs. Baseline (after MI) was evaluated on Papillary muscle tethering distance (p=<0.01). Echo-guided papillary muscle repositioning using an external device reduced papillary muscle tethering distance from 31.1 mm to 26.8 mm (P<0.01) and resolved moderate ischemic mitral regurgitation.