Electrophysiology

Your family doctor or another heart specialist such as a cardiologist can make a referral to the electrophysiologist after doing some tests on your heart and talking to you about why you might need an opinion from an electrophysiologist.

The heart produces electrical signals that spread through the heart muscle to make the muscle contract. These signals are small but can be picked up on an electrocardiograph machine. The electrocardiogram (ECG) is helpful but often the signals doctors need to see are so small that they cannot be seen on an ECG or are hidden. An electrophysiologist can perform studies and/or ablation procedures for your heart's electrical system and timing.

The nurse or technologist will help you onto the X-ray table. They will connect you to an automatic blood pressure cuff and a machine that continuously monitors your oxygen level and connect electrodes to your chest and shoulders. A nurse or anesthesiologist may give you some sedating medication. In many cases, the drugs will make you fall asleep for much of the procedure. The nurse will cover you with a blanket and expose the right groin and left shoulder.

The doctor will inject local anesthetic. You should not feel any discomfort after the freezing takes effect. The EP specialist will use a needle to enter the veins that run past the groin and left shoulder and thread thin, soft wires (called catheters) up to the heart using an X-ray to guide their placement in the heart.

If necessary, the doctor may give you one or more drugs through the intravenous line to help in the determination of the type of problem you have. Doctors will decide whether the procedure should continue on to catheter ablation (see below), or whether other treatments, such as drug therapy, should be recommended to manage the condition.

If a catheter ablation procedure is warranted by the EP study findings and prior informed consent was obtained, the physicians would leave most of the catheters in place, insert the ablation catheter and proceed with the catheter ablation procedure. When the sedation has worn off, the physician will talk to you and your family to make sure you are aware of the findings from the procedure.

Catheter ablation is a technique whose purpose is to destroy abnormal heart tissue that is causing an arrhythmia. Catheter ablation is used primarily to treat people who have problems with heart racing or rapid beating of their heart. A catheter is inserted into the vein or artery, guided into the heart and placed in contact with the heart tissue identified by the EP study as causing the problem or needing to be destroyed in order to alleviate symptoms. Most commonly, radiofrequency energy is used to "burn" the heart tissue causing the tachycardia.

No test or procedure, especially one that involves the heart, is ever 100 per cent risk-free, but EP study and catheter ablation are associated with a low rate (usually less than one per cent) of serious complications. You should expect a small amount of bruising at the site where the veins are punctured. Precise risks depend upon the location of the abnormality and the method used to ablate it. You should discuss these risks with your doctor before the procedure, but in general, risks may include:

• Injury to the artery from the needle puncture, resulting in a clot and blockage.
• Injury to the lining of the lung during insertion of the needle into the left upper chest vein. This can cause air to leak out of the lung, and may require drainage until it heals.
• Formation of blood clots in veins, arteries, or heart. If clots dislodge and travel through the blood vessels, it can lead to stroke. This complication is unusual.
• Thin wires used to record signals from your heart are soft, but it is possible for one to poke through the wall of heart muscle, especially in an elderly patient. Rarely, muscle perforation can cause bleeding around the heart wall that may require drainage, or possibly a surgical procedure to close.
• Injury to the heart's normal electrical system during catheter movement in the heart. Rarely, the heart's normal electrical system can be damaged by the procedure. This is usually temporary, but occasionally may result in the need for a permanent pacemaker.
• Damage to the heart's internal structures, or to nearby structures in the chest during burning of tissue. Damage to pulmonary veins can cause them to narrow. Damage to the esophagus can, rarely, lead to a hole from the heart to the esophagus. In rare cases, heart valve damage has been reported.
• Death. Only a handful of deaths have been reported from EP studies and catheter ablation around the world. This is extraordinarily rare.

The following resources provide more information on electrophysiology:

• HealthLink BC: Electrophysiology study
• Cardiac Services BC: Electrophysiology procedures
• Providence Health Care: Heart tests and electrophysiology labs
• HealthLink BC: Heart tests: When do I need them?