Propagation of Onset and PeakTime of Myocardial Shortening in Time of Myocardial Shortening in Ischemic Versus Nonischemic Cardiomyopathy
Assessment by Magnetic Resonance Imaging Myocardial Tagging
Jaco J.M. Zwanenburg, MSc*,*,
Marco J.W. Götte, MD, PhD , ,
J. Tim Marcus, PhD*,
Joost P.A. Kuijer, PhD*,
Paul Knaapen, MD,
Robert M. Heethaar, PhD* and
Albert C. van Rossum, MD, PhD
* Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, the Netherlands
Department of Cardiology, VU University Medical Center, Amsterdam, the Netherlands
Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
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Figure 1 Example tagging images for a patient (top) and a healthy subject (bottom). Early shortening occurs in the septum of the patient (left), whereas this shortening is not preserved at aortic valve closure (end-systole, right).
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Figure 2 Example circumferential strain curves over time for one septal segment and one lateral segment of a mid ventricular slice, showing the definitions of the several timing parameters. (A) Healthy subject, showing synchronous shortening. (B) Nonischemic patient with multiple shortening waves in the septum, leading to a first peak and a maximum peak of shortening. AL = anterolateral; AS = anteroseptal; ECG = electrocardiogram; IL = inferolateral; IS = inferoseptal; Tonset = onset time of shortening; Tpeak,first = time to first peak of shortening; Tpeak,max = time to maximum peak of shortening.
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Figure 3 Mean maps of the timing of shortening, illustrating the different timing patterns in nonischemic patients, ischemic patients, and healthy subjects. Note the similarity in the patterns between onset time and peak times for the nonischemic patients. These patterns are less similar and less distinct for the ischemic patients. The segments are defined in the bulls-eye top left. Tonset, Tpeak,first, and Tpeak,max all in ms from the ECG R-wave. AN = anterior; IN = inferior; other abbreviations as in Figure 2.
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Figure 4 Individual correlation coefficients between onset time and peak time, plotted versus the individual asynchrony in Tonset. The asynchrony in Tonset is defined as the intra-subject variance in Tonset and is a measure for the range of values that is available for the correlation. Each data point represents one subject. (Top row) Correlation coefficients from nonischemic patients (n = 18), using (A) Tpeak,first and (B) Tpeak,max. For some nonischemic patients, no association between Tpeak,max and Tonset exists, even when there is a large asynchrony in Tonset, indicating an important discrepancy between Tpeak,max and Tonset, which is not observed between Tpeak,first and Tonset. (Bottom row) Correlation coefficients from ischemic patients (n = 11) for (C) Tpeak,first and (D) Tpeak,max. A considerable number of ischemic patients show a poor correlation between peak time and onset time, regardless of whether Tpeak,first or Tpeak,max is used. Abbreviations as in Figure 2.
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Figure 5 Individual maps of the timing of shortening, illustrating the difference in performance between Tpeak,first and Tpeak,max. (Subject A) nonischemic patient for whom both Tpeak,first and the Tpeak,max correlated well with Tonset. (Subject B) nonischemic patient for whom only Tpeak,first correlated well with Tonset. *Missing values. Abbreviations as in Figures 2 and 3.
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