Persistent Reduction of Ischemic Mitral Regurgitation by Papillary Muscle Repositioning

Abstract

Background-Recurrent ischemic mitral regurgitation (IMR) is frequent despite initial reduction by annuloplasty becausecontinued LV remodeling increases tethering to the infarcted papillary muscle (PM). We have previously shown that PM repositioning by an external patch device can acutely reduce IMR. In this study, we tested the hypothesis that IMR reduction persists despite possible continued LV remodeling. Methods and Results-In 7 sheep, we used a chronic ischemic posterior infarct model that produces LV dilatation and MR over 10 weeks. An epicardial patch device was adjusted under echo guidance to reduce MR, with follow-up over a further 8 weeks and evaluation by 3D echo and sonomicrometry. In all 7 sheep, moderate IMR resolved with acute patch application and PM repositioning (6.5Ϯ1.8 mm to 0.6Ϯ1.3 mm proximal jet width, PϽ0.001) without decrease in LVEF (43Ϯ3% to 44Ϯ8%). Eight weeks after PM repositioning, MR was not significantly greater (0.6Ϯ1.3 mm versus 1.0Ϯ1.0 mm, PϭNS) despite an increase in LV volumes in 3 animals (2 had increases of 50Ϯ15%). On average, LV volumes did not change significantly (ESV: 46Ϯ8 mL versus 49Ϯ15 mL; PϭNS and EDV: 85Ϯ16 mL versus 89Ϯ30 mL; PϭNS). LVEF was unchanged from acute to chronic patch (44Ϯ8% versus 43Ϯ8%). Contractility as end-systolic elastance did not decrease from the chronic MI to the acute and chronic patch stages, nor were there any significant changes in dP/dt, LV stiffness constant, or time constant of LV relaxation (Tau). Conclusion-PM

Heart rate variability in patients after cardiac valve surgery

“…Referring to measured values of HRV variables in patients with an implanted artificial valve, excellent patient survival rate was found in the followup period on average of almost 3 years (some patients were followed-up with in a period of 6 years). Reading recent texts on cardiac valve surgery operation techniques [13][14][15][16] and speaking with experienced cardiac surgeons about possible reasons for the obtained differences in the results of this study between groups of patients with an implanted artificial aortic vs. mitral valve, we found that in principle, as long as there are no complications, surgical implantation of an artificial aortic valve lasts shorter than surgical implantation of an artificial mitral valve. Referring to that, the heart arrest, or duration of cardioplegia and hypothermia are shorter during aortic valve surgery than during mitral valve surgery, that certainly can partly explained the obtained differences in results of this study [17,18].…”

Mechanistic Features Associated With Improvement in Mitral Regurgitation After Cardiac Resynchronization Therapy and Their Relation to Long-Term Patient Outcome

“…Decreases in MR after CRT have been attributed to a complex interaction of mechanisms, including recoordination of the papillary muscle closing forces, 20,23,24 reductions in LV volumes with decreases in mitral leaflet tenting angles, and augmentation of transmitral pressure gradient attributable to increased contractility. 22,25,26 Breithardt et al showed that reduction in MR immediately after CRT was directly related to the increase in (r=−0.83; P<0.0001).…”

Ischemic mitral regurgitation: Recent advances

“…Attempts to restore a normal anatomic relationship of the papillary muscles may therefore result in less tethering of the leafl ets and a potential for more durable elimination of ischemic regurgitation. Recently, such potential was re-demonstrated experimentally in a sheep model by Hung et al [21]. Using a patch balloon device sewn epicardially at the region of induced infarction, they were able to incrementally reduce the degree of papillary muscle displacement, thereby eliminating tethering, with a reduction in regurgitation that persisted up to 8 weeks after the procedure [21].…”

“…Recently, such potential was re-demonstrated experimentally in a sheep model by Hung et al [21]. Using a patch balloon device sewn epicardially at the region of induced infarction, they were able to incrementally reduce the degree of papillary muscle displacement, thereby eliminating tethering, with a reduction in regurgitation that persisted up to 8 weeks after the procedure [21]. This epicardial approach has yet to be applied in humans.…”