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Hypertensive stress increases dispersion of repolarization
Bart Hooft Van Huysduynen1, Cees A Swenne, Henk J Ritsema Van Eck
1Cardiology Department, Leiden University Medical Center, Leiden, the Netherlands.
Pacing and Clinical Electrophysiology : PACE
|December 23, 2004
Summary
Hypertensive stress significantly increases cardiac repolarization heterogeneity more than normotensive stress. This heightened heterogeneity may explain why hypertensive stressors are linked to arrhythmogeneity in susceptible individuals.
Area of Science:
- Cardiology
- Physiology
- Biomedical Engineering
Background:
- Repolarization heterogeneity is a key factor in cardiac arrhythmogenesis.
- Previous studies have explored various electrocardiographic indices to quantify repolarization heterogeneity.
- The differential impact of various stressors on these indices remains an area of active investigation.
Purpose of the Study:
- To compare the effects of hypertensive isometric stress versus normotensive gravitational stress on electrocardiographic indices of repolarization heterogeneity.
- To investigate the relationship between hypertensive stressors and cardiac arrhythmogeneity through the lens of repolarization heterogeneity.
Main Methods:
- 56 healthy men underwent ECG and blood pressure monitoring at rest, during hypertensive stress (handgrip), and normotensive stress (leg lowering).
- Analysis focused on subjects with <10% heart rate variation between stressors.
- Key indices measured included QT interval, QT dispersion, Tapex-Tend, and the singular value decomposition T wave index.
Main Results:
- Both stressors increased heart rate, but only hypertensive stress significantly elevated systolic blood pressure.
- The QT interval and Tapex-Tend were significantly longer during hypertensive stress compared to normotensive stress.
- The singular value decomposition T wave index was also significantly higher during hypertensive stress, indicating increased repolarization heterogeneity.
Conclusions:
- Hypertensive stressors induce greater cardiac repolarization heterogeneity than normotensive stressors.
- This increase in repolarization heterogeneity may contribute to the association between hypertensive stress and arrhythmogeneity in vulnerable individuals.
- Electrocardiographic indices effectively capture stress-induced changes in repolarization heterogeneity.