Computer simulations have become an important tool for modeling the electrical behaviour of ischaemia in the heart, in order to better understand the processes involved and increase accuracy in patient diagnosis. Unfortunately, there is still not a complete understanding of the relationship between the electrical and physical properties of a heart which contains ischaemia. The work presented here focuses on obtaining a better understanding of the electrical behaviour at the epicardium due to localised ischaemia during the ST segment. This is achieved by solving the bidomain equations using both steady state and transient methods. Three separate models of increasing complexity are used to represent the cardiac geometry: a rectangular slab of ventricular tissue resting on a large volume of blood; a half-ellipsoid shape, which represents the left ventricle (filled with blood) and a final model (which contains both the left and right ventricles) that is based on experimental measurements of a dog heart.