- Cardiac catheterization and electrophysiological study - to determine the extent of heart disease and study abnormal heart rhythms. Cardiac catheterization is done under mild sedation. The groin is numbed with an anesthetic and catheters (thin plastic tubes) are inserted and passed through the blood vessels into the chambers of the heart. Pressures inside the heart are measured and pictures may be taken of the heart arteries. During this procedure an electrophysiology test may be done to study abnormal heart rhythms.