Introduction

Catheter ablation is a procedure to correct abnormal heart rhythm, a condition known as arrhythmia. There are different types of arrhythmias, in which the heart may beat too fast (tachycardia), too slow (bradycardia), or with an irregular pattern.

Catheter ablation, also known as cardiac ablation, uses heat or cold energy to create tiny scars in small areas of the heart tissues that are responsible for rhythm problems. As the name suggests, catheter ablation is done by inserting a thin, flexible tube called a catheter through a tiny incision in your groin area into your heart. Your doctor may recommend this treatment when oral medication and lifestyle changes prove to be ineffective in controlling your condition. Catheter ablation is presently the first line of treatment for most heart rhythm problems as medications are not very effective.

Before discussing more on catheter ablation, let’s first talk about electrophysiology (EP) studies.

Electrophysiology Study (EPS)

An EP study is used to study the electrical conduction system of the heart, and to detect abnormal conduction that may be responsible for heart rhythm disturbances. On top of diagnosing arrhythmia, it is also used to identify the source of this problem and to help determine the best treatment.

Once identified, your cardiologist may then proceed with treatment, including catheter ablation, to control the condition. Other reasons why your doctor may recommend an EP study is to:

• Identify the cause of sudden loss of consciousness, fainting, dizziness, or palpitations
• Evaluate risk for cardiac arrest (usually following a diagnosis of other heart conditions)
• Assess treatment options (catheter ablation, pacemaker, etc.)
• Evaluate the effectiveness of certain medications & treatments

What happens during an EP Study?

The procedure involves inserting thin wire electrodes into a vein through an area in the groin or neck. This wire will then be threaded through the vein into the heart, using X-ray images as a guide. It is generally painless and usually takes 1 - 4 hours.

Once the electrode is in your heart, there are several things your doctors can do:

• Take a baseline measurement of the heart’s electrical system (intracardiac electrogram).

• Send electrical signals to different areas of the heart, thus stimulating it to beat faster or slower. This is done to see if you have extra electrical signals that cause abnormal heart rhythms.

• Examine how your heart responds to certain types of medicines.

• Map the heart (cardiac mapping) to determine the best area to do catheter ablation to treat arrhythmias.

If your EP study results and other tests suggest that catheter ablation is necessary, the procedure can be done directly following the EP study. An EP study helps your doctor better diagnose your condition and discern whether you are suitable for catheter ablation, or to prescribe other forms of treatment.

Radiofrequency (RF) Ablation of Arrhythmias

Another name for catheter ablation, RF ablation is a procedure to scar up certain areas of the heart tissue that cause abnormal heart rhythms. This is done to prevent abnormal heartbeats and thus restore the heart to its normal rhythm.

Preparing for RF Ablation

• You will have to stop eating and drinking the night before the procedure for at least 6 hours.
• You may be asked to stop taking certain medications. This differs for each patient so do confirm with your doctor and be sure to let them know if you’re taking any medication or supplements.

Before the procedure

• An IV will be inserted via your forearm to deliver sedatives. It is to note that most patients are fully awake during the procedure. Rest assured, it is painless and you are kept as comfortable as possible.

During the procedure

• Local anaesthesia in the form of injection is given at the venous access site in the groin or neck. Access to the vein is achieved via a small needle. The catheter is inserted through a blood vessel, most commonly in the groin area. At times it could also be inserted through the shoulder or neck.
• In some cases, a dye (fluorescence) will be injected through the catheter so that it shows more clearly on X-ray images. These images are used to guide your doctor in performing the procedure.
• Next is the EP study. The electrodes at the tip of the catheter send electric signals and detect the heart’s electrical activity to identify the area of the problem.
• Following that is the ablation. RF Ablation refers to ablation using heat (radiofrequency energy) to create small scars and destroy the cells in the area of the problem.
• An alternative is a cryoablation, where instead of heat, the cells are subjected to extremely cold temperatures to destroy them.
• The procedure, including the EP study, usually takes 3-6 hours. However, this might differ depending on the type of arrhythmia, so do confirm with your doctor.

After the procedure

• You will be taken to the recovery room for monitoring. You will be asked to lie still to decrease the risk of bleeding.
• Most people may go home after a few hours though this depends on your condition. You will be quite sore and the sedatives might still have some effect so do arrange for someone to bring you home.
• Some patients may be recommended to spend a night in the hospital for further monitoring.
• Common symptoms include a mild achy chest and discomfort, soreness, as well as bruising in the area where the catheter was inserted. In most cases, it will resolve itself and people should be able to return to normal activities within a few days.
• Avoid heavy lifting for at least a week after the procedure.
• Contact your doctor or visit the emergency room immediately if you experience unusual pain, swelling, or excessive bleeding.

Common conditions treated with catheter ablation are:

Upper chambers of the heart

• Supraventricular tachycardia (SVT) — abnormally fast or erratic heartbeats that affect the upper chambers of the heart.

• Wolf-Parkinson-White syndrome — a genetic condition where an additional pathway is present between the atrium and the ventricles, causing very fast heart rates due to electrical signals ricocheting between the upper and lower chambers.

• Atrial tachycardia — when the electrical signals that control the heartbeats come from an unusual location in the atria, causing rapid heart beats.

• Atrial flutter — a very fast, steady heartbeat caused by the rapid contraction of muscles in the atria.

• Atrial fibrillation (A-Fib) — A condition where the upper chambers of the heart emit uncoordinated electrical signals, causing irregular or rapid heartbeats.

Lower chambers of the heart

• Premature Ventricular Contractions (PVCs) — heartbeats that happen too early and originate from the ventricles, disrupting the heart’s normal rhythm.

• Ventricular tachycardia — unusually fast heartbeats that start in the ventricles.

Atrial Fibrillation (AF) Ablation

Atrial fibrillation (AF) refers to irregular and often very rapid heart rhythm, which happens when the atria (heart’s upper chamber) beats out of sync with the ventricles (lower chambers). If left untreated, the condition may cause blood clots and is thus a risk factor for stroke, heart failure, and various other heart conditions. About 15-20% of stroke patients have this condition and A-fib is also associated with a 5-fold increased risk of stroke.

Apart from causing an increased risk of stroke, AF can cause symptoms like palpitations, feeling of irregular heart beat, chest discomfort, shortness of breath and loss of consciousness. Long-standing AF can lead to heart failure in certain cases. In some patients, AF can be asymptomatic and detected on routine screening or examination.

The mainstay of AF treatment is to prevent stroke associated with it and to alleviate symptoms. Catheter ablation is one of the first-line treatment options in patients with symptomatic atrial fibrillation. Trial of medication to alleviate symptoms is also an option. Treatment of AF is individualised for each patient and your doctor will discuss, in detail, the different options available.

The general procedure of a cardiac ablation to treat atrial fibrillation is similar to the one mentioned in the previous section. It may involve using heat (RF) or extreme cold (cryoablation) to create scars in your heart tissues. For the different arrhythmias, the difference mainly lies in the target area. In the case of atrial fibrillation, the type of procedure may be:

• Pulmonary vein isolation/ablation - This targets the connections of the pulmonary veins to the left atrium, an area that is usually the cause of AF.

• Atrioventricular (AV) node ablation - This ablation targets the AV node, thus preventing electrical signals for the atria from reaching the ventricles. Following this, patients would need a permanent pacemaker.

Note: this reduces occurrences of A-fib episodes but oftentimes does not cure the condition. Currently, other options are preferred over this method.

• Maze procedure - This procedure involves creating a pattern of scar tissue in the atria to block stray heart signals that cause the A-fib.

Following cardiac ablation, patients may still be put on lifelong blood thinners to prevent strokes. In other cases, your doctor may also recommend another procedure called the left atrial appendage closure. This procedure reduces your risk of stroke and eliminates the need for blood-thinning medication.

Summary

Catheter ablation is a minimally invasive day procedure with a moderately high success rate in treating various types of arrhythmia. That said, not all cases of arrhythmia call for this procedure. Each condition really differs between patients so it is always best to discuss with your doctor to find the most effective strategy to manage the condition. With individualised treatments and lifestyle changes, arrhythmia is definitely manageable.

References

1. “Atrial Fibrillation (Afib); Causes, Symptoms & Treatment.” Cleveland Clinic, 18 July 2019, https://my.clevelandclinic.org/health/diseases/16765-atrial-fibrillation-afib#management-and-treatment. Accessed 13 December 2021.
2. “Cardiac ablation.” Mayo Clinic, 5 March 2021, https://www.mayoclinic.org/tests-procedures/cardiac-ablation/about/pac-20384993. Accessed 13 December 2021.
3. “Electrophysiology (EP) Study.” Mount Elizabeth Hospitals, https://www.mountelizabeth.com.sg/specialties/medical-specialties/heart-vascular/electrophysiology-study. Accessed 13 December 2021.
4. “Facts About Catheter Ablation.” Johns Hopkins Medicine, https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/catheter-ablation. Accessed 13 December 2021.
5. “Heart arrhythmia - Symptoms and causes.” Mayo Clinic, 1 October 2021, https://www.mayoclinic.org/diseases-conditions/heart-arrhythmia/symptoms-causes/syc-20350668. Accessed 13 December 2021.
6. “EP study.” Mayo Clinic, 26 March 2021, https://www.mayoclinic.org/tests-procedures/ep-study/about/pac-20384999. Accessed 13 December 2021.
7. “What is Atrial Fibrillation (AFib or AF)?” American Heart Association, 31 July 2016, https://www.heart.org/en/health-topics/atrial-fibrillation/what-is-atrial-fibrillation-afib-or-af. Accessed 13 December 2021.