The effect of the shape of ischaemic regions in the heart on the resulting extracellular epicardial potential distributions

The majority of recent studies on ischaemia during the ST segment assume that ischaemia progresses from the endocardium to the epicardium and the ischaemic region is rectangular in shape. The presence of sharp edges in these models plays a significant role in the determination of ST segment epicardial potential distributions (EPDs), with current loops forming around these edges. This numerical study looks at ischaemic geometries which remove some or all of the sharp edges and how this affects the resulting EPDs. The two key ischaemic region geometries studied are cylindrical and semi-ellipsoidal in shape. Using a simple anisotropic model for the cardiac geometry and realistic conductivity values, this study shows that cylindrical ischaemic regions give similar results to their rectangular counterparts. However ellispoidal geometries differ, especially at medium levels (30%-70%) of ischaemia, where the EPD splits into 2 depressions instead of the 3 found with the other ischaemic geometries.