Insights in Cardiac Electrical Activity: Exploring the Potential of Advanced ECG Techniques

Abstract

The electrocardiogram (ECG) measures signals caused by electrical activation and recovery of the heart through electrodes placed on the chest. Although certain heart diseases can be detected using the ECG, in others the ECG appears normal despite underlying electrical abnormalities. To detect subtle abnormalities, advanced ECG techniques were investigated in this thesis which used new calculation methods, more electrodes and/or visualization of electrical activity on a 3D heart model. Three techniques were investigated: CineECG, body surface potential mapping (BSPM) and ECG imaging (ECGi). These techniques were applied in two cardiac diseases: myocardial infarction and arrhythmogenic cardiomyopathy (ACM). CineECG, which presents the average location of electrical activity on a 3D-heart model, was sensitive for early electrical changes during myocardial ischemia, and was able to differentiate between subjects with and without myocardial infarction in cases where standard ECG interpretation was insufficient. Moreover, using this technique, it was possible to detect abnormal electrical activity in asymptomatic carriers of a genetic variation associated with ACM while their ECG was otherwise considered normal. Using BSPM, a 67-lead ECG, the variability of electrical signals over the entire torso was determined in healthy subjects. Additionally, electrical abnormalities were found outside standard ECG configuration in asymptomatic carriers of an ACM-related genetic variant. ECGi, combining BSPM with patient-specific 3D heart models, showed abnormal patterns of the recovery phase that were associated with ventricular arrhythmias, even in asymptomatic carriers. The results of this thesis show that advanced ECG techniques are promising tools for the early detection of different cardiac diseases.