We have developed a new approach to studying human heart activity using independent component analysis. The electrocardiogram (ECG) is an important tool in diagnosis of heart disease. However, the normal 12-lead ECG can only record limited aspects of heart's electrical signals and mostly their interpretation relies on trained and experienced medical doctors. We have performed experiments in which heart signals were recorded in high spatial resolution. Independent component analysis was applied to the recorded signals to separate distinct temporal components of the recorded signals. The separated components were further analyzed by back-projecting their activities to the surface montage to examine each component's property. Experimental results show this to be a promising approach that can be extended to build more detailed heart activity simulations.