Augmentation of J Wave Following Ventricular Pause in "Benign" Early Repolarization

Abstract

A 24-year-old man was referred to our hospital 3 years previously for counseling regarding abnormalities of his electrocardiogram (ECG). He had no history of syncope or other manifestation of cardiovascular disorder. The 12-lead ECG at rest showed sinus rhythm and type 1, 2nd degree atrioventricular block with 3 : 2 alternating with 4 : 3 ventricular responses (Picture 1). In the precordial leads, prominent J waves were present with the 2nd and 5th QRS, after the longest ventricular cycles due to AV block, and were less prominent with the 3rd, 4th and 6th QRS of the shorter ventricular cycles. The patient has remained free from symptomatic arrhythmia in the 3 years since that examination. Early repolarization is characterized by the presence of distinct J waves, J point and ST segment elevation, most prominently visible in the precordial leads. The ionic, cellular mechanism responsible for J waves is a prominent transient outward current (Ito)-mediated action potential notch in the ventricular epicardium, which produces a transmural voltage gradient in early diastole, accentuated by bradycardia. Aizawa et al observed a similar phenomenon in a patient with idiopathic ventricular fibrillation (1). This ECG is an example of J waves augmented by pauses in a patient presenting with “benign” early repolarization.