Cardiac electrophysiology is the study of the heart's electrical system. The heart’s electrical system controls the rhythmic contractions that keep the blood pumping and circulating throughout your body. Arrhythmias are abnormal heart rhythms. Arrhythmias can cause the heart to beat fast or slow and can cause the heart to beat irregularly. Pacemakers are electronic devices surgically implanted into the patient's heart and chest to regulate heartbeat. Clinical research involves investigations into the molecular, genetic and environmental causes of cardiac arrhythmias (irregular heart rhythms) including atrial fibrillation and ventricular tachycardias. Also includes: atrial fibrillation ablation, cardiac re-synchronization therapy for heart failure patients, intra-cardiac defibrillators (ICDs) and pacemakers, sudden cardiac death, and CPR.