Abstract
A 65-year-old man underwent surgery for implantable cardioverter defibrillator (ICD) placement for idiopathic ventricular fibrillation (VF) in May 2011. In September 2012, he suddenly lost consciousness at rest but recovered spontaneously by himself. This was his first episode of unconsciousness after ICD placement. After admission, VF, which was terminated by ICD shocks, was recorded by a 12-lead Holter electrocardiogram (ECG). The QRS complexes of premature ventricular contraction (PVC) that triggered VF showed a left bundle branch block pattern with a superior axis; thus, the origin of PVC was suspected to be in the inferior wall of the right ventricle. Catheter ablation (ABL) targeting to trigger PVC was performed immediately. After ABL, VF was cured. For the evaluation of the efficacy of ABL, plot analyses of coupling interval (CI) and RR interval preceding PVC were performed before and after ABL. In comparison with the regression line before and after ABL, the gradient after ABL apparently became steeper than before ABL. In addition, by analyzing the ratio of CI to RR interval preceding PVC in temporal axes, many PVCs with small ratios and a long RR interval preceding PVC were observed just before the onset of VF, suggesting that such repeated stimulations led to the onset of VF. In conclusion, 12-lead Holter ECG is helpful for determining the origin of PVC that triggers VF. Plot analyses of CI and RR interval preceding PVC seemed to be useful for estimating the efficacy of ABL treatment and the mechanism of VF onset.
