Late potentials on signal-averaged electrocardiography eliminated by successful catheter ablation of premature ventricular contractions in a nonischemic cardiomyopathy patient

Figures

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  Figure 1. A: An implantable cardioverter-defibrillator interrogation revealing ventricular fibrillation aborted by a 36 J shock therapy. B: A 12-lead electrocardiogram recorded during an atrial paced rhythm showing 2 kinds of premature ventricular contractions (PVC) of which the coupling intervals are similar. C: Ventricular fibrillation (VF) induced by a bigeminal PVC at midnight. The red arrows highlight the triggered PVC, inducing VF.

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  Figure 2. A: The intracardiac electrograms recorded by an HD Grid mapping catheter (Abbott, St. Paul, MN) on both the right and left interventricular septum that exhibited favorable prepotentials preceding the onset of the QRS complex by 46 ms and 71 ms, respectively. Note that a fractionated delayed potential is recorded within the normal sinus QRS complex preceding the premature ventricular contraction (PVC) beat. B: Past cardiac magnetic resonance imaging depicting late gadolinium enhancement in the intramural myocardium of the basal mid wall. C: Left ventricular voltage mapping and ablation sites. Except for the focalized ablation sites, the left ventricle voltage is relatively preserved.

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  Figure 3. A: An initial evaluation of the signal-averaged electrocardiogram (SA-ECG). Late potentials (LPs) are considered positive if at least 2 of the following criteria are met: (1) filtered QRS duration (fQRSd) ≥120 ms, (2) root mean square voltage of the terminal 40 ms in the fQRS complex (RMS40) <20 mV, and (3) low-amplitude signals <40 mV (LAS40) >38 ms. For each component, it met the criteria expressed by the red dots. The positive late potentials are highlighted by a red square. B: The normalized SA-ECG measured a few months after the premature ventricular contraction (PVC) ablation. C: Comparison of the SA-ECG showing the eliminated late potential highlighted by the red arrow. Upper panel: An abnormal SA-ECG before the ablation procedure. Lower panel: A normalized SA-ECG after the PVC ablation evaluated in the same time zone.