Differences in ventricular wall composition may explain inter-patient variability in the ECG response to variations in serum potassium and calcium

Figures

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  FIGURE 1. 3D heart-torso model used for ECG simulations.

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  FIGURE 2. QRS complex (A) and T wave (B) from a particular simulated case corresponding to a 3D torso-heart model, with the computed duration and amplitude-based ECG markers.

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  FIGURE 3. Linear and non-linear time warping for a particular simulated case (C154) corresponding to a 3D torso-heart model. (A) shows the reference (blue) and investigated (red) T waves obtained for the indicated [K+] and [Ca2+] values. (B) shows the warped T waves, which have the same duration while keeping the original amplitude. (C) depicts the warped T waves after normalization by their L2-norms. The area (yellow region) between both T waves in (D) represents dw,Tu , which quantifies the total amount of warping. The green solid line is the linear regression function γl*(tr) best fitted to the optimal warping function, γ*(t r ), with the latter being represented by the red dotted line. The marker dw,TNL quantifies the non-linear warping by computing the area of the dashed magenta region between γ*(t r ) and γl*(tr) .

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  FIGURE 4. (A–F) Changes in T w, T S/A, dw,Tu , d a,T, dw,TNL and da,TNL for varying [K+] at fixed [Ca2+] = 2.0 mM (black), varying [Ca2+] at fixed [K+] = 5.4 mM (red) and the combination of [K+] and [Ca2+] (blue), for ECGs simulated from the population of models. Central lines indicate the median, whereas bottom and top edges show the 25th and 75th percentiles, respectively.

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  FIGURE 5. (A,B) T waves at varying [K+] and [Ca2+], for a simulated case (C514) and for a patient (P10). (C,D) Changes in T wave markers T w, T S/A, dw,Tu , d a,T, dw,TNL and da,TNL for the same simulated case and patient, respectively. Note the different scales between the plots.

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  FIGURE 6. (A,B,D,E,G,H) Changes in dw,TNL at varying [K+] and [Ca2+], in simulated cases and patients. (C) Pearson correlation coefficients, r, of dw,TNL with [K+] and [Ca2+] for the simulated cases shown in (A) and the patients shown in (B). (F) Pearson correlation coefficient r for the simulated cases shown in (D) and the patients shown in (E). (I) correlation coefficient r for all the simulated cases and all the patients. h 0–h 4 are the HD time points corresponding to the onset and end of HD (h 4 with lowest [K+] and highest [Ca2+] and h 0 with highest [K+] and lowest [Ca2+].

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  FIGURE 7. Pearson correlation coefficients, r, between each T wave marker (T w, T S/A, dw,Tu , d a,T, dw,TNL and da,TNL ) and [K+] (black for simulated cases and blue for patients) or [Ca2+] (red for simulated cases and green for patients), for simultaneous variations in [K+] and [Ca2+].