Abnormal heart rhythms, or cardiac arrhythmias, can result in significant physical impairment and can lead to an increased risk for serious medical problems such as stroke or even sudden death. This team uses mathematics to further the understanding of cardiac arrhythmias and to develop new methods to predict which patients are at risk for arrhythmias and methods for their control. In the past year systems were developed to analyze changes in the electrical properties of heart tissue.