Reversed Apico-Basal Myocardial Relaxation Sequence During Exercise in Long QT Syndrome Mutations Carriers With History of Previous Cardiac Events

Figures

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  FIGURE 1. Speckle-tracking 2D-strain rate imaging (from an apical 4-chamber view) with interposed ECG trace. On the end-diastolic frame, we manually traced the left ventricular (LV) endocardial border (left upper figure). The epicardial contour is automatically drawn by the software. Then it is adjusted manually so that the LV wall thickness fits the region of interest (ROI). ROIs are subsequently divided into the standard segments (left upper figure) and regional longitudinal strain rate (SR) curves are produced (right figure). Subsequently, LV basal, middle and apical strain rate parameters were derived. Time to V longitudinal early diastolic SR (tESR), a measure of contraction duration and delay in relaxation, was defined as the time interval from the QRS onset to the peak positive early diastolic SR (ESR) early diastolic strain rate.

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  FIGURE 2. Left ventricular (LV) myocardial strain rate (lower left and right) curves in a control (A) and a LQTS patient (B) patient. Longitudinal apico-basal myocardial relaxation sequence (ΔtESR base–apex) was defined as the time difference between basal and apical tESR. In the LQTS patient there is delayed early relaxation phase at the base (longer tESR-red arrow) in relation to the apex (purple arrow) with Δt ESRbase–apex > 0.

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  FIGURE 3. Exercise response of longitudinal apico-basal relaxation sequence (Δ t ESR base-apex) in LQTS mutation carriers and controls. There is reversed relaxation sequence in LQTS with base relaxing later than in apex.

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  FIGURE 4. Electromechanical correlations. (A) Correlation between Δt ESRbase–apex and QTc. (B) Correlation between Δt ESRbase–apex and ESR. (C) Correlation between Δt ESRbase–apex and SV.

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  FIGURE 5. Exercise response of longitudinal apico-basal relaxation sequence in symptomatic and asymptomatic LQTS mutation carriers. The reversed relaxation pattern is more prominent in symptomatic patients at peak exercise.