Related Experiment Video

Updated: Jul 11, 2026

High-frequency High-resolution Echocardiography: First Evidence on Non-invasive Repeated Measure of Myocardial Strain, Contractility, and Mitral Regurgitation in the Ischemia-reperfused Murine Heart
11:50

High-frequency High-resolution Echocardiography: First Evidence on Non-invasive Repeated Measure of Myocardial Strain, Contractility, and Mitral Regurgitation in the Ischemia-reperfused Murine Heart

Published on: July 9, 2010

Paradoxic decrease in ischemic mitral regurgitation with papillary muscle dysfunction: insights from

E Messas1, J L Guerrero, M D Handschumacher

  • 1Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Circulation
|October 17, 2001
PubMed
Abstract

Insights

Papillary muscle (PM) dysfunction can paradoxically reduce ischemic mitral regurgitation (MR) by improving leaflet coaptation. This finding highlights geometric factors in MR and suggests new therapeutic approaches.

Area of Science:

  • Cardiovascular Physiology
  • Cardiac Mechanics
  • Medical Imaging

Background:

  • Ischemic mitral regurgitation (MR) has been traditionally attributed to papillary muscle (PM) contractile dysfunction.
  • Current theories focus on left ventricular (LV) distortion causing apical leaflet tethering.
  • However, PM dysfunction is still commonly diagnosed, prompting a re-evaluation of its role.

Purpose of the Study:

  • To investigate the hypothesis that PM contractile dysfunction can paradoxically decrease MR.
  • To explore the role of inferior base ischemia in modulating MR through geometric changes.

Main Methods:

  • Occluded proximal circumflex circulation in 7 sheep, maintaining PM perfusion.
  • Measured leaflet tethering distance and LV ejection volume using 3D echocardiography.
  • Assessed MR by subtracting LV outflow from LV ejection volume.

Main Results:

  • Inferior ischemia alone induced mild-to-moderate MR (25.2+/-2.8% regurgitant fraction) due to PM tip retraction.
  • Adding PM ischemia reduced MR (5.2+/-0.3 to 1.4+/-0.3 mL) and tethering distance.
  • PM strain rate shifted from contraction to elongation, decreasing leaflet tenting.

Conclusions:

  • PM contractile dysfunction can paradoxically decrease MR in inferobasal ischemia.
  • This effect is mediated by reduced leaflet tethering and improved coaptation.
  • Geometric factors are crucial in ischemic MR mechanisms and potential therapeutic strategies.

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