Large gradients in repolarization times (RT) across the ventricles can lead to arrhythmia, or worse sudden cardiac death (SCD). These gradients can give rise to conduction blocks whereby the regular path of the propagating wave of activity is mis-directed. This path can return to itself, forming self-sustaining loops that prevent the ventricles contracting in regular coordination. If these pathological rhythms don't self-terminate and an intervention is not quickly applied, the patient will become another victim of SCD.

The main goal of this project is to assess a patient's vulnerability to arrhythmia. Often the patient has no history of cardiac irregularities. Hence, the screening method must be minimally invasive since invasive procedures cant be justified.

Having access to a patient's RT can give an indication of the patient's risk to such events. One method to approximate repolarization maps is the ECGi vest, whereby the potentials on the epicardium (the outer surface of the ventricles) can be approximated via a numerical tool using the potentials recorded on the torso. This is a non-invasive method, which makes it useful as a screening tool. But the accuracy of the method for computing the potentials has been shown to be poor for some applications, and furthermore, the equipment setup cost is currently quite high for each use.

Another method is by using plunge needle electrodes. These give a clear measurement of the electrical activity, even within the ventricle walls, but the needles can damage the heart and so the procedure is only ever performed on explanted hearts. They can be useful for studying general repolarization maps, but even then, explanted hearts are not generally healthy.

The next best approach is to use electrodes via a catheter that is inserted in the femoral vein, and directed to the ventricles. There it can record unipolar and bipolar signals on the walls.