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Published on: April 5, 2011
Value of QT dispersion in evaluating spatial dispersion of ventricular repolarization during acute myocardial
1Department of Biophysics, School of Physics, Nankai University, Tianjin, People's Republic of China, and.
Insights
Epicardial Activation-Recovery Interval (ARI) dispersion is a more sensitive indicator of ventricular repolarization heterogeneity during acute myocardial ischemia than epicardial QT interval dispersion.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
- Myocardial Ischemia Research
Background:
- Ventricular repolarization heterogeneity is a critical factor in cardiac arrhythmogenesis.
- Assessing repolarization heterogeneity is crucial for understanding and predicting cardiac events.
- Epicardial electrocardiography (ECG) offers a direct measure of myocardial electrical activity.
Purpose of the Study:
- To evaluate the efficacy of epicardial QT interval dispersion in predicting ischemia-induced ventricular repolarization heterogeneity.
- To compare the sensitivity of epicardial QT interval dispersion versus Activation-Recovery Interval (ARI) dispersion in detecting acute myocardial ischemia.
Main Methods:
- Acute myocardial ischemia was induced in open-chest sheep by occluding a major coronary artery branch.
- A 64-channel epicardial ECG was recorded before and after ischemia induction.
- Wavelet transformation was employed to analyze QT intervals and ARI, and their respective dispersions.
Main Results:
- Acute myocardial ischemia did not significantly alter average QT interval or ARI.
- Epicardial QT interval dispersion remained unchanged during ischemic events.
- Epicardial Activation-Recovery Interval (ARI) dispersion significantly increased following acute ischemia (P<0.001).
Conclusions:
- Epicardial QT interval dispersion demonstrates limited sensitivity in reflecting ischemia-induced repolarization heterogeneity.
- Epicardial ARI dispersion is a more sensitive marker for quantifying ventricular repolarization abnormalities during acute myocardial ischemia.
Objectives:
To study the value of epicardial QT interval dispersion in predicting ischemia-induced heterogeneity of ventricular repolarization.
Animals And Methods:
Ischemia was produced by total occlusion of the obtuse branch of the circumflex coronary artery in seven open-chest sheep. A 64-channel electrocardiogram (ECG) was acquired from the epicardium before and after coronary artery occlusion. Wavelet transformation was used to determine the characteristic points of the epicardial ECGs, and to measure the QT interval and activation-recovery interval (ARI) and their dispersions.
Results:
The average QT interval and ARI from the epicardial ECG were not changed by acute myocardial ischemia (P=0.07 and P=0.13, respectively). QT dispersion remained unchanged during ischemia (P=0.17), whereas ARI dispersion was significantly increased by acute ischemia (59.9+/-24.0 ms versus 126.3+/-32.1 ms, P<0.001).
Conclusions:
These findings indicate that epicardial QT dispersion is less sensitive than ARI dispersion in estimating repolarization heterogeneity induced by acute myocardial ischemia.
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