Non-Invasive Electrocardiographic Mapping of Arrhythmia and Arrhythmogenic substrate in the Human Ventricle.

PhD Theses.The ablation of ventricular tachycardia often involves mapping when the arrhythmia is ongoing. This is often limited by haemodynamic instability. Non-invasive electrocardiographic mapping (ECGI) may aid in the mapping process by allowing expedient localisation. However, insufficient testing of this technology against ground truth data has been conducted. Furthermore, the system could have utility in detection of arrhythmogenic substrate. Current clinical practice uses echocardiography to risk stratify patients for implantation of intracardiac defibrillators (ICDs). Invasive epicardial electrogram data was collected in 8 patients. Activation and repolarisation times were compared to ECGI derived data showing modest correlation. A detailed analysis of ventricular tachycardia sites of origin in the heart was elucidated using validated electrophysiological techniques. These were compared to ECGI derived data in 18 patients, showing better accuracy than the 12 lead ECG with a resolution of ~2.2cm suggesting it may be a useful adjunctive tool in mapping unstable VT. ECGI derived data collected during sinus rhythm was compared to invasive electrogram maps in 16 patients. The capacity of ECGI to localise scar showed modest accuracy. ECGI and Cardiac MRI scans were performed in 21 patients with cardiac amyloidosis. ECGI showed cardiac amyloidosis to be associated with both ventricular conduction and repolarization abnormalities, supporting the hypothesis that arrhythmic mechanisms may be linked to mortality in this condition