The study is carried out in a cardiac special procedures laboratory by a trained staff including cardiologists, technicians, and nurses.

The cardiologist inserts a catheter through a small incision in a vein in your arm, neck, or groin after cleansing the site and numbing it with a local anesthetic. This catheter is equipped with an electrode connected to electrocardiographic monitors

The catheter is then carefully threaded into the heart using an X-ray imaging technique called fluoroscopy to guide the insertion. The electrode is placed near the electrical conductive tissue within the heart.

Impulses from the conductive tissue are then mapped and any abnormalities in the conduction system can be identified.

Test preparations are similar to those for a cardiac catheterization. Food and fluid are restricted 6 to 8 hours before the test. The procedure takes place in a hospital and you will wear hospital clothing. You must sign a consent form for the procedure.

Your health care provider will give you instructions regarding any changes to medications. Do not modify or stop taking any medications without consulting your health care provider.

A mild sedative is usually given 30 minutes before the procedure. You may not be able to drive home yourself if you are discharged the same day.

During the test, you are awake and able to follow instructions. An incision is made into a vein in your arm, neck, or groin for threading the catheter into the heart. Local anesthesia is given to insert the catheter, so the only sensation is one of pressure at the site.

You may feel some discomfort due to having to remain still for a prolonged period of time.

You may feel your heart beating fast and strong. If arrhythmia is induced as part of the test, the doctor may use medication or electrical energy to terminate it.

The procedure may last from one to several hours.

• To diagnose the source of symptoms
• To evaluate the effectiveness of medication in controlling an arrhythmia
• To evaluate the risk of future cardiac events
• To evaluate the need for a permanent pacemaker, an implantable cardioverter-defibrillator (ICD) or radiofrequency catheter ablation as a treatment for arrhythmia

This is a very specialized procedure, and people referred for this test will almost always have arrhythmias, not normal results.

The exact location of the arrhythmia may be determined so that specific therapy can be instituted. The arrhythmia may originate from any area of the electrical conduction system.

Additional conditions under which the test may be performed:

• Sick sinus syndrome
• Wolff-Parkinson-White syndrome

The procedure is generally very safe. Possible risks include the following:

• Arrhythmias
• Cardiac arrest
• Trauma to the vein
• Low blood pressure
• Infection
• Cardiac tamponade
• Embolism caused by blood clots developing at the tip of the catheter