Heart wall refinement of arrhythmia source locations

One or more computing systems for refining a source location of an arrhythmia, the one or more computing systems comprising:

• one or more computer-readable storage mediums that store computer-executable instructions for controlling the one or more computing systems to:
• receive an electrocardiogram representing electrical activity of the heart of a patient, the heart wall of the heart having an endocardium, a myocardium, and an epicardium;
• identify an initial source location that is an endocardial source location or an epicardial source location;
• calculate a normal vector that is normal to the heart wall at initial source location;
• access an activation time that is a time within an initial portion of a QRS complex of the electrocardiogram;
• identify an activation vector based on a vector of a vectorcardiogram at the activation time, the vectorcardiogram being derived from the electrocardiogram;
• calculate a depth angle representing the angle between the normal vector and the activation vector;
• and
• generate a refined source location based on the initial source location and the depth angle;
• and
• one or more processors for controlling the one or more computing systems to execute one or more of the computer-executable instructions.