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Principal component analysis of the T-wave in patients with chest pain and conduction disturbances.
Uppsala University, Medicinska vetenskapsområdet, Faculty of Medicine, Department of Medical Sciences.
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2004 In: Pacing Clin Electrophysiol, Vol. 27, 1378-1387 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2004. Vol. 27, 1378-1387 p.
URN: urn:nbn:se:uu:diva-92915OAI: oai:DiVA.org:uu-92915DiVA: diva2:166233
Available from: 2005-04-19 Created: 2005-04-19Bibliographically approved
In thesis
1. Traces of Repolarization Inhomogeneity in the ECG
Open this publication in new window or tab >>Traces of Repolarization Inhomogeneity in the ECG
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Repolarization inhomogeneity is arrhythmogenic. QT dispersion (QTd) is an easily accessible ECG-variable, related to the repolarization and shown to carry prognostic information. It was originally thought to reflect repolarization inhomogeneity. Lately, arguments have been risen against this hypothesis. Other measures of inhomogeneity are being investigated, such as nondipolar components from principal component analysis (PCA) of the T-wave. In all here described populations, continuous 12-lead ECG was collected during the initial hours of observation and secondary parameters used for description of a large number of ECG-recordings.

Paper I studied QTd in 548 patients with chest pain with a median number of 985 ECG-recordings per patient. Paper II explored a spatial aspect of QTd in 276 patients with unstable coronary artery disease. QTd and a derived localized ECG-parameter were compared to angiographical measures. QTd, expressed as the mean value during the observation was a powerful marker of risk. It was however not effective in identifying high-risk patients. Variations in QTd contained no additional prognostic information. In unstable coronary artery disease, QTd was increased by a mechanism unrelated to localization of the disease.

Two relevant conditions for observing repolarization inhomogeneity might occur with conduction disturbances and during initial course of ST-elevation myocardial infarction (STEMI). Paper III compared the PCA-parameters of the T-wave in 135 patients with chest pain and conduction disturbance to 665 patients with normal conduction. Nondipolar components were quantified by medians of the nondipolar residue (TWRabsMedian) and ratio of this residue to the total power of the T-wave (TWRrelMedian). Paper IV described the changes in the nondipolar components of the T-wave in 211 patients with thrombolyzed STEMI. TWRabsMedian increased with increasing conduction disturbance and contained a moderate amount of prognostic information. In thrombolyzed STEMI, TWRabsMedian was elevated and has an increased variability. A greater decrease in absolute TWR during initial observation was seen in patients with early ST-resolution. Nondipolar components do however not reflect identical ECG-properties as the ST-elevation and their change does not occur at the same time.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. 90 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 28
Internal medicine, cardiology, repolarization, ECG, QT dispersion, nondipolar components, T-wave, principal component analysis, repolarization inhomogeneity, Invärtesmedicin
National Category
Clinical Medicine
urn:nbn:se:uu:diva-5747 (URN)91-554-6216-2 (ISBN)
Public defence
2005-05-30, Robergsalen, Akademiska sjukhuset, entrance 40, Akademiska sjukhuset, Uppsala, 09:15
Available from: 2005-04-19 Created: 2005-04-19Bibliographically approved

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