title: An analysis of the U-wave and its relation to the T-wave in body surface potential maps for healthy subjects and MI patients.
abstract: BACKGROUND
  The aim of this study was to analyze the U-wave morphology and its relation to the T-wave in one group of healthy subjects and in two groups of myocardial infarction (MI) patients-with and without ventricular tachycardia (VT) episodes. The context of the U-wave origin was also discussed and the U-wave as a potential marker of VT was investigated.
  
  
  METHODS
  The study was carried out on three groups of subjects: 20 healthy subjects, 14 MI patients not at risk of VT, and 22 MI patients at risk of VT. The morphology of the repolarization phase was examined in the high-resolution body surface potential maps recorded from 64 surface ECG leads. The temporal and spatial distributions of several ECG parameters were studied.
  
  
  RESULTS
  The U-wave was present in almost all the studied subjects. The spatial heterogeneity and smooth change in both the T- and U-wave shapes on the entire torso were observed in all the studied groups. The statistical significance of discrimination between the MI patients without VT and MI patients with VT was observed for QRS interval, QT interval, U-wave integral, and normalized U-wave integral.
  
  
  CONCLUSIONS
  High-resolution measurement of body surface potentials and an advanced data analysis allow for a detailed description of U-wave morphology and its relation to the T-wave. This might be of value in discriminating intracardiac repolarization effects, mechano-electrical feedback, and arrhythmia risk stratification.
authors.affiliation: Department of Biophysical Measurements and Imaging, Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Fereniec
authors.forename: Günter
authors.initials: G
authors.lastname: Stix
authors.forename: Michał
authors.initials: M
authors.lastname: Kania
authors.forename: Tomasz
authors.initials: T
authors.lastname: Mroczka
authors.forename: Roman
authors.initials: R
authors.lastname: Maniewski
mesh_terms: D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000150:complications / Q000503:physiopathology
keywords: BSPM, U-wave; T-wave; repolarization; ventricular tachycardia