Nonsurgical ablation is used for many types of arrhythmias in the EP laboratory. During this nonsurgical procedure, a catheter is inserted into a specific area of the heart. A defibrillator is used to direct joules through the catheter to small areas of the heart muscle, identified through mapping, that are causing the dysrhythmia. This energy disconnects the pathway of the abnormal rhythm. It can also be used to disconnect the abnormal electrical pathways between the upper chambers (atria) and the lower chambers (ventricles) of the heart.