What Is Heart Ablation

Introduction

Heart ablation involves hot (radiofrequency ablation) or cold (cryoablation) techniques that create small scars in the heart to block irregular electrical signals or abnormal rhythms (arrhythmia) and restore the normal heartbeat.^1,2 The procedure is carried out using thin tubes known as catheters, which are inserted into the veins or arteries.

This is able to break abnormal circuits in the heart and destroy the area of the heart which triggers arrhythmia.¹ This can also be called cardiac ablation and is known to be an array of treatments which focus on regulating heartbeat.³ This article will explore the causes, symptoms, and procedure of heart ablation.

Overview of the heart

The heart comprises four chambers, divided into two sections, the right and left.⁴ The chambers are named: right atrium, right ventricle, left atrium and left ventricle. The atria are located at the top of the heart while the ventricles are at the bottom.

Deoxygenated blood, received from the body through the superior and inferior vena cava, flows into the right atrium. The blood then goes through the tricuspid valve (which prevents the backflow of blood) into the right ventricle and goes through the pulmonic valve into the pulmonary artery where it reaches the lungs.

Oxygenated blood returns to the heart, enters the left atrium, and then goes through the mitral valve and fills the left ventricle. This chamber is crucial in pumping blood around the body through the aorta. This cycle repeats again for each heartbeat.

Additionally, the heart contains an electrical system which regulates the pumping of the heart, as well as the contraction of each chamber. The sinus node is the natural pacemaker (rhythm regulator) of the heart and is located between the superior vena cava and the right atrium. It automatically produces an electrical impulse approximately 70 times a minute.

This impulse occurs through the right atrial muscle to the atrioventricular node (AV node), which connects the atria and ventricle to allow synchronised beating at the top of the heart. The AV node passes the electrical signal to the bundle of His (this is a group of heart muscles which are specialised to relay electrical impulses) but there is a delay in this as it allows the atria to empty into the ventricles before the ventricles contract due to an electrical signal. 

Understanding heart arrhythmias

Arrhythmia is due to a problem with the rhythm or rate of the heartbeat.⁵ The heart is at risk of beating too fast or too slow, and frequent irregularity means the heart is not pumping enough blood to the body. Examples of arrhythmia include:⁶

Fast heartbeat, known as tachycardia:

• Atrial fibrillation: causing a fast, uncoordinated heartbeat
• Atrial flutter: like atrial fibrillation, but heartbeats are more organised
• Supraventricular tachycardia: irregular beating in the ventricles
• Ventricular fibrillation: causes the lower chambers to shake instead of squeeze
• Ventricular tachycardia: irregular electrical signals in the lower chambers

Slow heartbeat, known as bradycardia:

• Sick sinus syndrome: this can switch between a slow and fast heartbeat due to the scarring near the sinus node
• Conduction block: this causes the signals that trigger heartbeats to slow or stop

 Symptoms include:

• Pounding in the chest
• Fast heartbeat
• Slow heartbeat
• Chest pain
• Shortness of breath
• Anxiety
• Fatigue
• Dizziness
• Sweating
• Fainting

Some conditions can cause arrhythmias such as:

• A heart attack or previous history of heart attacks
• Coronary artery disease
• Changes in the heart’s structure
• Diabetes
• High blood pressure
• COVID-19
• Over or underactive thyroid gland
• Sleep apnea (sleep disorder)
• Some medicine
• Too much alcohol or caffeine
• Drug misuse
• Genetics
• Smoking
• Anxiety

What leads to heart ablation?

Some people who experience atrial fibrillation suffer from shortness of breath or even palpitations.⁷ As this condition increases the risk of strokes, anticoagulants are used to prevent this. Ablation is used to control symptoms rather than eliminate the total need for blood thinners to reduce the risk of strokes. Many who suffer from atrial fibrillation take medicine to help control their heartbeat and rhythm, but some people react negatively and therefore ablation is a solution for them. 

Heart ablation is not necessary for everyone with heart arrhythmia; it is recommended only for those who are unable to control their heart rate through medication and only certain types of arrhythmias can be treated in this way.⁸ These conditions include:⁹

• Atrial fibrillation
• Atrial flutter
• Atrial tachycardia
• Atrioventricular nodal reentrant tachycardia
• Paroxysmal supraventricular tachycardia
• Wolff-Parkinson-White syndrome
• Ventricular fibrillation
• Ventricular tachycardia
• Amyloid cardiomyopathy
• Arrhythmogenic right ventricular dysplasia/ cardiomyopathy
• Familial dilated cardiomyopathy
• Hypertrophic cardiomyopathy

The heart ablation procedure

The following are three types of heart ablation procedures:³

• Catheter ablation: this is the most common type where a thin tube called a catheter is inserted through the vein to the heart. This provides heat or coldness to the heart tissue, leaving scars that block the irregular electrical impulses
• Surgical ablation: this can occur while doing another heart surgery. If you need to do a bypass surgery or valve replacement along with an ablation the doctor may decide to do a maze procedure (an open-heart ablation), which is carried out the same way as a catheter ablation
• Hybrid surgical/ catheter ablation: if you do not need open heart surgery you can undergo a procedure called a mini maze, this is where a small incision is made in the chest to insert a catheter

Before performing any heart ablation treatment, your doctor will evaluate your individual heart condition and needs, considering your overall health before deciding on the procedure. You may be asked to:

• Stop taking thinning medications like aspirin or warfarin, but only stop these when directed
• No eating or drinking the night before
• Arrange transportation from the hospital as it is not safe to drive after the treatment

The process depends on the type of ablation procedure you receive.

During a catheter ablation, an intravenous line is inserted into the arm to pass on anaesthesia. Then a small tube called a sheath is inserted into the vein, in the groin, and thin tubes with wires (these are electrode catheters) are threaded through the sheath, going towards the heart. This process is guided through X-rays and this releases hot or cold energy to regulate heartbeat.

This treatment takes 2 to 4 hours to complete, and after the catheter and sheath will be removed. While recovering, you will stay in the hospital overnight for observation and you will be closely monitored. You may then be discharged and may be prescribed aspirin or blood thinners for several months to avoid blood clots.

On the other hand, during surgical ablation, you will also receive anaesthetic, while the surgeon carries out open heart surgery. They will make a small incision in your chest to access your heart. After the procedure, you will stay in the ICU for a few days, depending on the severity of the surgery. You will then remain in the hospital after you leave the ICU and will also be prescribed aspirin or blood thinners for several months to avoid blood clots.

Risks and benefits

The success rate for this procedure is quite high, however, there are some risks involved which depend on the type of arrhythmia and the area of ablation such as:^3,10

• Death, heart attack or stroke (there is a higher risk of stroke with atrial fibrillation ablation)
• Heart block: this requires a permanent pacemaker
• Cardiac trauma
• Blood clots
• Damage to the vein from the sheath and catheter
• Punctured heart 
• Damaged valves
• Narrowing of the veins between the heart and lungs
• Exposure to radiation (during catheter ablation due to X-rays)
• Infection

If persistent pain, swelling, bleeding, or heat irregularities continue after the treatment, please consult your doctor immediately.

Summary

In conclusion, heart ablation is used to treat irregular or abnormal heartbeat also known as arrhythmia. The electrical system in the heart is important as it regulates the contraction and electrical signals of the heart, naturally done by the sinus node. However, if this is damaged and unable to act as a natural pacemaker, heart ablation may be a viable solution.

There are a range of heart arrhythmias but only a few such as atrial fibrillation can be treated using ablation. A few conditions can lead to irregular heartbeat, but it can mainly be caused by the consumption of medication which does not react appropriately with the body. There are three types of ablations, but catheter and surgical are the main procedures. Following this, there are a range of risks but overall, it is known to have a high success rate.