A pacemaker is a device used to supplement the electrical activity of the heart in patients whose heart is not conducting correctly, i.e their heart rate is beating too slowly, bradycardia. It generally does not provide benefit when the heart beats too quickly. A Biventricular Pacemaker is a pacemaker that paces on both sides of the heart. In selected cases, resynchronising the heart in this fashion can improve cardiac function. An EP Study is the study of normal and abnormal electrical behaviour of the heart. It is an invasive electrical examination of the heart. The procedure is performed in the Cardiac Catheter Laboratory where X-ray equipment is available.