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Time course of ECG depolarization and repolarization changes during ischemia in PTCA recordings

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Author

Summary, in English

Objectives: In this work we studied the temporal evolution of changes in the electrocardiogram (ECG) as a consequence of the induced ischemia during prolonged coronary angioplasty, comparing the time course of indexes reflecting depolarization and those reflecting repolarization. Methods: We considered both local (measured at specific points of the ECG) and global (obtained from the Karhunen-Loeve transform) indexes. In particular, the evolution of Q, R and S wave amplitudes during ischemia was analyzed with respect to classical indexes such as ST level. As a measurement of sensitivity we used an Ischemic Changes Sensor (ICS), which reflects the capacity of an index to detect changes in the ECG. Results: The results showed that, in leads with low-amplitude ST-T complexes, the S wave amplitude was more sensitive in detecting ischemia than was the commonly used index ST60. It was found that in such leads the S wave amplitude initially exhibited a delayed response to ischemia when compared to ST60, but its performance was better from the second minute of occlusion. The global indexes describing the ST-T complex were, in terms of the ICS, superior to the S wave amplitude for ischemia detection. Conclusions: Ischemic ECG changes occur both at repolarization and depolarization, with alterations in the depolarization period appearing later in time. Local indexes are less sensitive to ischemia than global ones.

Publishing year

2004

Language

English

Pages

43-46

Publication/Series

Methods of Information in Medicine

Volume

43

Issue

1

Document type

Journal article

Publisher

Schattauer GmbH

Topic

  • Electrical Engineering, Electronic Engineering, Information Engineering

Keywords

  • QRS amplitudes
  • ischemia
  • angioplasty
  • ST value

Status

Published

ISBN/ISSN/Other

  • ISSN: 0026-1270