Cardiac resynchronization therapy can reverse abnormal myocardial strain distribution in patients with heart failure and left bundle branch block
Ole-A. Breithardt, MD* ,*,
Christoph Stellbrink, MD, FESC*,
Lieven Herbots, MD,
Piet Claus, PhD,
Anil M. Sinha, MD*,
Bart Bijnens, PhD,
Peter Hanrath, MD, FESC, FACC* and
George R. Sutherland, MD, FESC
* Department of Cardiology, University Hospital Aachen, Aachen, Germany
Department of Cardiology, University Hospital Gasthuisberg, Katholic University Leuven, Leuven, Belgium
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Figure 1 An example of typical velocity, strain rate, and strain curves from the mid-septum in left bundle branch block. Each curve represents an average from three consecutive cardiac cycles. Dotted vertical lines separate the isovolumic intervals from the ejection period, as identified by mitral and aortic valvular opening (AVO) and closure (AVC). In this patient, longitudinal septal shortening (indicated by negative strain rate and negative strain) starts early in the cardiac cycle, and peak negative strain occurs briefly after AVO (open arrow), whereas the peak systolic velocity is identified in late systole (solid arrow). Only a small part of septal shortening contributes effectively to ejection, as indicated by the hatched area in the strain curve. ECG = electrocardiogram; IVCT = isovolumic contraction time; IVRT = isovolumic relaxation time.
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Figure 2 Velocity and strain curves before (LBBB) and after cardiac resynchronization therapy (CRT) from the septal and lateral wall mid-segments in a 73-year-old patient. The derived strain curves from the mid-segments clearly show the regional asynchrony in deformation. Maximal septal contraction occurs before aortic valve opening (top left panel, arrow) and is accompanied by lateral wall lengthening. The septum lengthens after aortic valve opening and does not contribute to ejection. Peak lateral wall contraction is observed very late in systole and persists into the post-systolic period (bottom left panel, arrowhead). During CRT, systolic contraction occurs simultaneously in both walls, contributing equally to ejection (right panels). Note also the shorter isovolumic contraction (IVC) time with CRT. IVRT = isovolumic relaxation time.
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Figure 3 Curved color M-mode echocardiogram acquired by post-processing color Doppler myocardial imaging data displaying regional velocity (left panels) and strain rate (right panels) in the mid-septum (top panels) and mid-lateral wall (bottom panels) of a study patient. The vertical line indicates the onset of the QRS complex. The septal wall shows early systolic shortening (arrow), coded yellow-red in the strain rate image, despite negative velocities in early systole (coded blue in the velocity image). In contrast, the lateral wall moves apical toward the transducer, as indicated by the red color in the velocity image, but shortens significantly later, as compared with the septum (arrowhead). Early systolic lengthening (coded blue in the strain rate image) precedes systolic shortening.
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Figure 4 Same patient as in Figure 3 after cardiac resynchronization therapy (CRT). Compared with left bundle branch block (Fig. 3), CRT had no significant effect on the velocity profiles. In contrast, systolic shortening occurred simultaneously in both walls (arrows).
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