Abstract

The T wave in a surface electrocardiogram (ECG) indicates the diastolic phase in the cardiac cycle. Even though the cellular basis of T-wave morphology in surface ECG remains unclear in clinical cardiology, the morphology may be determined by the transmural voltage gradient during the repolarization period that underlies the changes in the T wave and QT interval. The heterogeneous distribution of electrophysiological activity across the heart is essential for normal cardiac function. However, excessive heterogeneity may contribute to arrhythmogenesis and sudden cardiac death. This paper will provide an overview of T wave genesis and the contribution to action potential duration (APD), in which ion channels are involved in the repolarization period, with special emphasis on K+ channels involved in phase 3 repolarization. These channels are primarily Kv11.1 (hERG1), Kv7.1 (KCNQ1), and Kir2.1 (KCNJ2), which are the α-subunits responsible for conducting IKr, IKs, and IK1. Changes in the T wave and QT interval that are affected by both functional loss and gain of these currents are associated with various arrhythmogenic diseases. This review also briefly discusses arrhythmogenesis in diseases that are manifested by changes in the T wave and QT interval. Key words: T wave; Transmural Voltage Gradient; Repolarization; K+ Channel; Arrhythmogenesis

Highlights

  • The T wave in a surface electrocardiogram (ECG) indicates the diastolic phase in the cardiac cycle

  • Even though the cellular basis of T-wave morphology in surface ECG remains unclear in clinical cardiology, the morphology may be determined by the transmural voltage gradient during the repolarization period that underlies the changes in the T wave and QT interval

  • Excessive heterogeneity may contribute to arrhythmogenesis and sudden cardiac death

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Summary

Introduction

The T wave in a surface electrocardiogram (ECG) indicates the diastolic phase in the cardiac cycle. 심실 벽을 구성하는 심근세포는 형태적으로 매우 단일한 형태를 보이나, 전기생리학적인 면에서는 불균질성(heterogeneity)을 지니는 것으로 알려져 있으며, 이러한 전기적 특성은 정상적인 심기능의 유지에 필요하고, 또한 심전도에서 관찰되는 QRS 파와 T파 형성의 기전이 되기도 한다.[1]

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