QRS complex and ST segment manifestations of ventricular ischemia: the effect of regional slowing of ventricular
Ljuba Bacharova1, Vavrinec Szathmary, Anton Mateasik
1International Laser Center, Bratislava, Slovak Republic; Institute of Pathophysiology, Medical Faculty, Comenius University, Bratislava, Slovak Republic.
Insights
Computer modeling shows that localized changes in heart electrical activity, mimicking myocardial infarction, alter electrocardiogram (ECG) patterns. These changes, including QRS and ST segments, help understand ischemia effects.
Area of Science:
- Cardiovascular Physiology
- Computational Biology
- Electrocardiography
Background:
- Myocardial ischemia from coronary artery occlusion disrupts cardiac electrogenesis, altering action potentials and conduction velocity.
- These electrophysiological changes manifest as observable patterns in electrocardiogram (ECG) waveforms, specifically the QRS complex and ST segment.
Purpose of the Study:
- To simulate the impact of localized alterations in myocardial depolarization sequence on QRS and ST segment patterns using computer modeling.
- To investigate how changes in impulse propagation velocity within the myocardium affect ECG readings.
Main Methods:
- Developed a computational model of cardiac ventricles using analytical geometry (ellipsoids).
- Incorporated an intramural electrically inactive area surrounded by a transmural zone of slowed impulse propagation.
- Simulated these conditions in anteroseptal and inferior locations to analyze 12-lead ECG effects.
Main Results:
- The electrically inactive area produced QRS changes consistent with myocardial infarction locations.
- Slowed impulse propagation in surrounding areas significantly modified these QRS changes.
- Areas with slowed conduction caused ST segment deviations in reciprocal leads, shifting towards the affected region.
Conclusions:
- Computer modeling demonstrated that localized changes in impulse propagation alter both QRS complex and ST segment.
- The simulated ST segment changes align with those typically interpreted as 'injury current' effects.
- This study validates the use of computational models to understand ECG manifestations of myocardial ischemia.
Objective:
Reduction or interruption of the blood supply to myocardium due to occlusion of coronary artery and consequent ischemia leads to changes of electrogenesis: changes in morphology and duration of action potentials and slowing of conduction velocity in the affected area. In this study we simulated the effects of localized changes in depolarization sequence on the QRS and ST segment patterns, using computer modeling.
Methods:
The model defines the geometry of cardiac ventricles analytically as parts of ellipsoids and allows changing the velocity of impulse propagation in the myocardium. An intramural electrically inactive area encircled by a transmural area with slowed impulse propagation velocity was introduced in anteroseptal and inferior locations. The effects on the QRS complex and the ST segment of the 12-lead electrocardiogram are presented.
Results:
The intramural electrically inactive area caused QRS changes typical for corresponding locations of a myocardial infarction observed in patients, which were further considerably modified by slowed impulse propagation velocity in the surrounding area. Additionally, areas of slowed impulse propagation velocity led to ST segment deviations in the "reciprocal" leads, shifting the ST segment towards the affected areas.
Conclusion:
Using computer modeling we showed that the localized alteration of impulse propagation not only modified the QRS complex, but produced also changes in the ST segment consistent with changes which are usually interpreted as the effect of "injury current".
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