J Wave Syndrome-Early Repolarization or Delayed Depolarization?

概要

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J wave syndrome (JWS) characterized by J-point ST elevation includes Brugada syndrome and early repolarization syndrome (ERS). J-point ST elevation is detected in ordinary electrocardiograms at a frequency of 1–5%. Parts of J-point ST elevation in ordinary electrocardiograms are believed to be associated with lethal ventricular tachyarrhythmias especially during acute phase of myocardial infarction. Thus, it is important to better understand the mechanism underlying J-point ST elevation. It is controversial whether J-point ST elevation is caused by early repolarization or delayed depolarization. We generated mice genetically deleted in a transcription factor, which is expressed specifically in His-Purkinje system (HPS) and regulates ion channel gene expression. The knockout (KO) mice have disturbed conduction specifically in HPS, and exhibited phenotype similar to ERS, which include J-point ST elevation, enhancement of J-point ST elevation by hypothermia, and incessant ventricular tachycardia induced by myocardial infarction. Our findings show that delayed depolarization induced by disturbed HPS conduction mimics ERS in mice. It is still unproven whether delayed depolarization underline ERS in human and whether early repolarization also contributes to ERS.