A study of the heart’s electrical system is known as an electrophysiology test. During this test, wire electrode catheters are advanced through a vein in the groin to various positions in the heart. The electrical activity of the heart is then examined and the conduction properties of the nerves in the heart are measured. The second part of this test involves electrical stimulation of various parts of the heart in an attempt to induce an abnormal heart rhythm. Identification of this abnormal rhythm allows specific treatment to be tailored towards it. Electrophysiology testing is usually performed on patients with symptoms of dizziness or fainting. In some instances, a Holter monitor may pick up an abnormal and potentially dangerous heart rhythm that is further investigated by electrophysiology study.