Abstract 14676: Insufficient Papillary Muscle Contraction is Involved in Late Systolic Mitral Valve Prolapse: Quantitative Echocardiographic Study with Speckle Tracking Analysis
Background: Mechanism of late systolic mitral valve (MV) prolapse (MVP) is not fully clarified. Papillary muscle (PM) tip height from mitral annulus is kept almost constant due to shortening (contraction) of both PM and LV wall between PM and the annulus (Figure) in normal subjects. In the presence of constant PM tip height, late systolic worsening of MVP demands considerable elongation of chordae/leaflet tissue in systole. We hypothesized that decrease in PM tip height in systole is involved in late systolic MVP.
Methods: 1) In 8 controls, 6 with holo-systolic MVP, and 6 with late-systolic MVP, MV closing depth, PM tip height from mitral annulus, and PM tip to base length were measured in early and late systole using 2D echo and speckle tracking analysis in apical 4 and 2 chamber views.
Results: 1) In 8 controls and 8 with holo-systolic MVP, MV closing depth only minimally increased in systole (controls: -1.7±3.0 to 0.3±2.0 mm, P<0.05) (holo-systolic MVP: 4.7±2.4 to 5.0±2.2 mm, P<0.05) while the closing depth considerably increased in patients with late systolic MVP (0.2±3.1 to 5.0±1.1 mm, P<0.01). 2) In controls and patients with holo-systolic MVP, PM tip height from mitral annulus only minimally shortened in systole (28.1 ±3.9 to 25.6±3.5 and 29.0±4.5 to 26.8±4.3 mm, P<0.01, respectively) while it considerably decreased (30.8±4.6 to 26.8±5.2 mm, P<0.01) in patients with late systolic MVP. Systolic decrease in PM tip height was significantly greater in patients with late systolic MVP (2.5±0.5 vs. 2.2±1.3 vs. 4.0±0.8 mm, P<0.01). 3) PM tip to base systolic shortening was significantly reduced in late-systolic MVP (13.1±3.1 vs. 15.9±3.4 vs. 8.3±2.5 %, P<0.01). 4) Systolic change in MV closing depth was significantly correlated with both systolic decrease in PM tip height and PM shortening (r=0.61, P<0.05, respectively).
Conclusion: These suggest that insufficient PM contraction, shortening PM tip height from mitral annulus in systole, is involved in late systolic MVP.
- © 2012 by American Heart Association, Inc.