open access

Vol 15, No 5 (2008)
Review articles
Published online: 2008-08-12
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The enigmatic sixth wave of the electrocardiogram: The U wave

Andrés Ricardo Pérez Riera, Celso Ferreira, Celso Ferreira Filho, Marcelo Ferreira, Adriano Meneghini, Augusto Hiroshi Uchida, Edgardo Schapachnik, Sergio Dubner, Li Zhang
Cardiol J 2008;15(5):408-421.

open access

Vol 15, No 5 (2008)
Review articles
Published online: 2008-08-12

Abstract

The U wave is the last, inconstant, smallest, rounded and upward deflection of the electrocardiogram. Controversial in origin, it is sometimes seen following the T wave with the TU junction along the baseline or fused with it and before P of the following cycle on the TP segment. In this review we will study its temporal location related to monophasic action potential, cardiac cycle and heart sounds, polarity, voltage or amplitude, frequency and shapecontour. We will analyze the clinical significance of negative, alternant, prominent U wave, and the difference between T wave with two peaks (T1–T2) and true U wave. Finally we will analyze the four main hypotheses about the source of U wave: repolarization of the intraventricular conducting system or Purkinje fibers system, delayed repolarization of the papillary muscles, afterpotentials caused by mechanoelectrical hypothesis or mechanoelectrical feedback, and the prolonged repolarization in the cells of the mid-myocardium (“M-cells”).

Abstract

The U wave is the last, inconstant, smallest, rounded and upward deflection of the electrocardiogram. Controversial in origin, it is sometimes seen following the T wave with the TU junction along the baseline or fused with it and before P of the following cycle on the TP segment. In this review we will study its temporal location related to monophasic action potential, cardiac cycle and heart sounds, polarity, voltage or amplitude, frequency and shapecontour. We will analyze the clinical significance of negative, alternant, prominent U wave, and the difference between T wave with two peaks (T1–T2) and true U wave. Finally we will analyze the four main hypotheses about the source of U wave: repolarization of the intraventricular conducting system or Purkinje fibers system, delayed repolarization of the papillary muscles, afterpotentials caused by mechanoelectrical hypothesis or mechanoelectrical feedback, and the prolonged repolarization in the cells of the mid-myocardium (“M-cells”).
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Keywords

U wave; sixth wave of electrocardiogram; source hypothesis

About this article
Title

The enigmatic sixth wave of the electrocardiogram: The U wave

Journal

Cardiology Journal

Issue

Vol 15, No 5 (2008)

Pages

408-421

Published online

2008-08-12

Bibliographic record

Cardiol J 2008;15(5):408-421.

Keywords

U wave
sixth wave of electrocardiogram
source hypothesis

Authors

Andrés Ricardo Pérez Riera
Celso Ferreira
Celso Ferreira Filho
Marcelo Ferreira
Adriano Meneghini
Augusto Hiroshi Uchida
Edgardo Schapachnik
Sergio Dubner
Li Zhang

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