DISCLAIMER: All information contained on these pages is intended for Canadian residents only and is NOT intended as specific medical advice for any individual with a medical condition similar to that described herein.

   

Electrophysiology Study

What it is, how it is performed, and more

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 (EKG) is helpful but often the signals doctors need to see are so small that they cannot be seen on an EKG or are hidden. An electrophysiology (EP) study is a diagnostic test that allows your cardiologist to look at these heart signals in more detail and determine if you have an abnormality of your heart beat (a cardiac arrhythmia), and where the problem lies. An EP study is done to diagnose the source of your problem before a catheter ablation is performed.

The EP laboratory room looks a lot like a cardiac catheterization room in that there is a large X-ray machine present along with computer screens and other medical equipment that is needed to keep you safe. During the procedure, there will be 1 or 2 nurses and/or technologists; along with 1-3 doctors in the room. The nurse or technologist will escort you into the room and help you onto the X-ray table. They will then connect you up to an automatic blood pressure cuff and a machine that continuously monitors your oxygen level. You will already be wearing a hospital gown which the nurses will lower so they can attach electrodes to the skin on your chest and shoulders. They will then apply 3 large sticky pads to your body - one of the front and another on the back or the side of the chest and a third on the back of your thigh. Once these are all connected, the nurses may give you some sedating medication through your intravenous line to help you relax. In many cases, the drugs will make you fall asleep for much of the procedure. In other cases where an anesthesiologist is present, he or she will give you the drugs you need to keep you relaxed. The nurse will cover you with a warm blanket and expose the right groin and left shoulder. If necessary, they will shave the areas a bit more to keep it clean of hair.

The physician will clean the right groin and left shoulder areas and then place a large drape over your chest, abdomen and legs to keep the cleaned areas and equipment sterile. The doctor will then inject some local anesthetic (similar to dental freezing) and allow the areas to become numb. You should not feel any discomfort after the local freezing takes effect. The physician 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 a small amount of X-ray to guide their placement in the proper locations in the heart. These soft wires are used to pace your heart at different speeds and also to record electrical signals from inside your heart. 

Electrophysiology (EP) Lab

Ablation catheters are advanced into the heart through veins in the legs and (sometimes) the shoulder

Ablation catheters are advanced into the heart through veins in the legs and (sometimes) the shoulderRecordings and measurements will help the doctors determine the cause and location of your heart rhythm problem. If necessary, the doctors may give you one or more drugs through the intravenous line to help in the determination of the type of problem you have. Once the measurements are complete, 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 catheter ablation is not to be done, the doctors will remove the wires and put pressure on the areas where the veins were punctured so that a firm blood clot can form and seal the puncture holes. Small bandages will be put on these two areas. The little cuts in the skin where the vein are punctured are very small and do not leave any significant scarring. 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. You will then be transferred to a stretcher and taken to a room to recover. You will be asked not to raise your head off the bed and to refrain from coughing too vigorously for the next two to four hours because bleeding from these vein puncture sites can start up again . Your doctor will likely talk to your family about the test results first. 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 EP study.

Ablation catheters are advanced into the heart through veins in the legs and (sometimes) the shoulder

 

Catheter Ablation

What it is, how it is performed, and more

Catheter ablation is a technique whose purpose is to destroy (ablation means "to eliminate or remove") 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. The catheter is connected to equipment that sends electricity up to the catheter tip, causing it to heat up and burn the heart tissue. It is often necessary to deliver more than one burn. When the physician feels that sufficient burns have been applied, he/she will test to see if the heart arrhythmia is still present or has been successfully destroyed. If it is felt that the problem has been eradicated, the doctors will wait up to 30 minutes more before testing again to make sure that the problem does not return.

Medical research is developing newer ways to try and perform catheter ablation. One of the newest is to use a catheter to freeze the abnormal tissue or "cryoablation". Cryoablation has some advantages and is used for certain kinds of ablation procedures. When people hear about catheter ablation, they automatically think that a "laser" is used but that is not true. At the present time, laser energy is not used for catheter ablation because it is too powerful or strong and could easily burn a hole through the heart.

 

Risks of this Procedure  

No test or procedure, especially one that involves the heart, is ever 100% risk-free, but EP study and catheter ablation is associated with a low rate (usually <1%; but your doctor will clarify this with you) of serious complications. You should expect a small amount of bruising at the site where the veins are punctured. Very mild pain at these sites is normal for several days after the procedure and usually disappears after several days.

There are variations in how catheter ablation is performed and the precise risks depend upon the location of the abnormality causing the heart rhythm problem and the exact method used to ablate it. You should discuss these risks with your doctor before the procedure, but in general, risks may include some or all of the following:

  • Injury to the artery from the needle puncture, resulting in a clot and blockage, that in rare circumstances may require an operation to fix.
  • 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 of this air until the leakage seals off. This can sometimes result in a few days more in hospital before it resolves.
  • Formation of blood clots in the veins, arteries, or heart. If these blood clots dislodge and travel through the blood vessels, it can lead to stroke (if the blood clot travels to the brain). Fortunately, this complication is unusual. Your physician will usually use blood thinners like heparin if he/she feels that there is an increased risk of stroke.
  • The formation of a hole in the heart or blood vessels. Although the thin wires used to record signals from your heart are soft, it is possible for one of these wires to poke through the wall of heart muscle (perforation), especially in an elderly patient. This can cause some chest or right shoulder pain at the time but usually resolves when the wire is pulled back. Rarely, muscle perforation can cause bleeding around the heart wall that impairs the heart's ability to pump effectively and may require a needle drainage, or even possibly a surgical procedure to drain the blood and close the small hole in the heart wall.
  • Injury to the heart's normal electrical system during the movement of the catheters in the heart or after the delivery of the burn. Rarely, the heart's normal electrical system could be damaged by the procedure. This is usually temporary, but occasionally, it may result in the need for a permanent pacemaker to be implanted.
  • Damage to the heart's internal structures, or to adjacent structures in the chest. In selected procedures, the burns being delivered by the catheter are near other structures, like the veins bringing blood from the lungs (pulmonary veins), or like the swallowing tube (esophagus). Damage to the pulmonary veins can cause them to narrow, and, rarely lead to problems like cough and shortness of breath, while damage to the esophagus can, rarely, lead to the creation of a hole from the heart to the esophagus. In rare cases, damage to the heart valves has also been reported.
  • Death. Only a handful of deaths have been reported from EP studies and catheter ablation around the world. Although extraordinarily rare, complications can lead to death.

Your doctor will discuss the specifics of the procedure that is proposed for you, along with the risks that apply to you.

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