Medical devices and methods for making and using medical devices are disclosed. A method of mapping electrical activity of a heart may comprise sensing a plurality of signals with a plurality of electrodes positioned within the heart. The method may further comprise separating the plurality of signals into a first group of signals and a second group of signals, and generating a data set that includes at least one known data point and one or more unknown data points. In some examples, the at least one known data point is generated based on the first group of signals.