A mechanism for immediate reduction in mitral regurgitation after Cardiac resynchronization therapy: Insights from mechanical activation strain mapping

We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping. Heart failure patients w...

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Bibliographic Details
Published in:Journal of the American College of Cardiology 2004-10, Vol.44 (8), p.1619-1625
Main Authors: KANZAKI, Hideaki, BAZAZ, Raveen, SCHWARTZMAN, David, DOHI, Kaoru, SADE, L. Elif, GORCSAN, John III
Format: Article
Language:English
Subjects:
Aged
Biological and medical sciences
Biomechanical Phenomena - instrumentation
Blood pressure
Bundle-Branch Block - diagnostic imaging
Bundle-Branch Block - physiopathology
Bundle-Branch Block - therapy
Cardiology
Cardiology. Vascular system
Cardiovascular disease
Classical genetics, quantitative genetics, hybrids
Echocardiography, Doppler
Echocardiography, Doppler, Color - instrumentation
Electrodes, Implanted
Endocardial and cardiac valvular diseases
Female
Fundamental and applied biological sciences. Psychology
Genetics of eukaryotes. Biological and molecular evolution
Heart
Heart failure
Human
Humans
Image Processing, Computer-Assisted - instrumentation
Male
Medical sciences
Microcomputers
Middle Aged
Mitral Valve Insufficiency - diagnostic imaging
Mitral Valve Insufficiency - physiopathology
Mitral Valve Insufficiency - therapy
Mortality
Myocardial Contraction - physiology
Pacemaker, Artificial
Papillary Muscles - physiopathology
Software
Stroke
Stroke Volume - physiology
Studies
Treatment Outcome
Ventricular Function, Left - physiology
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Summary:We tested the hypothesis that an immediate reduction in mitral regurgitation (MR) after cardiac resynchronization therapy (CRT) results from improved coordinated timing of the papillary muscle insertion sites, using the novel approach of mechanical activation strain mapping. Heart failure patients with left bundle branch block often benefit acutely from CRT; however, the role and mechanism of reduction of MR are unclear. Twenty-six consecutive patients undergoing CRT with at least mild MR were studied (ejection fraction 24 +/- 6%; QRS duration 168 +/- 30 ms). Echocardiographic Doppler and strain imaging was performed immediately before and the day after CRT, as well as in 10 normal control subjects. Mechanical activation sequence maps were constructed using longitudinal strain from 12 basal and mid-LV sites, with color coding of time-to-peak strain. Mitral regurgitation by the volumetric method consistently decreased after CRT: regurgitant volume from 40 +/- 20 ml to 24 +/- 17 ml and regurgitant fraction from 40 +/- 12% to 25 +/- 14% (both: p < 0.001 vs. baseline). Normal controls had uniform segmental time-to-peak strain, with a difference of only 12 +/- 8 ms between all segments. In contrast, CRT patients at baseline had a 106 +/- 74 ms time delay between papillary muscle insertion sites (p < 0.001 vs. normal). This interpapillary muscle time delay shortened after CRT to 39 +/- 43 ms (p < 0.001 vs. baseline) and was significantly correlated with reductions in mitral regurgitant fraction (r = 0.77, p < 0.001). Cardiac resynchronization therapy significantly and immediately reduced MR. Improved coordinated timing of mechanical activation of papillary muscle insertion sites appears to be a mechanistic contributor to immediate MR reduction by CRT.
ISSN:0735-1097
1558-3597
DOI:10.1016/j.jacc.2004.07.036