Abnormal Heart Rhythm / Arrhythmia

Arrhythmia, also known as abnormal heart rhythm or irregular heartbeat, refers to any change in the normal sequence of electrical impulses produced by the heart. The abnormal heart rhythms can be slow or fast in rate, having extra beats, or have rhythm irregularity.

Age increases the probability of experiencing an arrhythmia. It can occur in people who do not have structural heart disease. Arrhythmias often occur during and after heart attacks. Some types of arrhythmias, such as ventricular tachycardia and fibrillation, are serious and potentially life-threatening. Arrhythmias can result in poor blood circulation to the vital organs of the body.

Slow heart rates (less than 60 beats per minute) are called bradycardias. Fast heart rates (more than 100 beats per minute) are called tachycardia.

The most common type of heart rhythm problem is atrial fibrillation (AF), which occurs when there is abnormal electrical activity within the upper chambers (atria) of the heart, resulting in the lower chambers (ventricles) to beat in a fast and irregular manner.

While some arrhythmias are harmless, it is important to rule out any serious arrhythmias (abnormal heart rhythms) or pre-existing heart problems.

Complications of cardiac arrhythmias

These arrhythmic heart palpitations can have serious implications:

Supraventricular tachycardia (SVT)
This is a prevalent arrhythmia in young adults This is experienced as a sudden burst of rapid heartbeats that begin and end abruptly, lasting for seconds or hours. SVT is usually not life threatening.

Atrial fibrillation
This fast and irregular palpitation occurs in the atria or upper chambers of the heart and could last a few minutes to an hour. Atrial fibrillation arrhythmias could become chronic and lead to stroke. It is seldom life-threatening, but the heart palpitations could indicate underlying coronary artery disease or heart valve disorders.

Ventricular tachycardia (VT)
Ventricular tachycardia is a very rapid, but regular heartbeat of 100 beats or more a minute occurring in the lower chambers (ventricles) of the heart.

Sustained heart palpitations lasting more than 30 seconds are considered a medical emergency. They could indicate pre-existing heart diseases such as coronary artery disease or heart valve disorders.

Ventricular fibrillation (VF)
If ventricular tachycardia is left untreated, it will lead to a life-threatening condition called ventricular fibrillation, characterised by very fast and very irregular heartbeats. It usually precedes a heart attack. You could lose consciousness within seconds and die within minutes.

The symptoms of an arrhythmia or abnormal heart rhythm include: 

• A fast heartbeat, pounding or fluttering chest sensations
• Skipping a heartbeat
• Dizziness or fainting spells
• Shortness of breath
• Chest pains
  
  

​While arrhythmias may not always be prevented, having regular health screening or checkups with your doctor can help you note on any irregularities in heart rhythms. 

Arrhythmias or abnormal heart rhythm occur when there is a short-circuit in the electrical impulses controlling your heartbeat. These electrical impulses are what will cause your heart to beat too rapidly, too slowly or irregularly.

There are different causes for cardiac arrhythmias, including intrinsic heart problems, endocrinological and metabolic causes. Some common triggers are exercise, stress, caffeine, alcohol, appetite suppressant and decongestants in cough and cold medicines.

Other risk factors of arrhythmias include:

An abnormal heart rhythm or arrhythmia is diagnosed by a physical examination, electrocardiograms and electrophysiologic studies. However, as arrhythmias are not always present, they may not occur during the physical examination.

You may have already received diagnostic tests to confirm if you have an arrhythmia and its likely causes. Otherwise, your doctor may discuss some of these tests with you to see if you have AF:

• Electrocardiogram (ECG)
• Holter (continuous heart rhythm monitoring between 24 to 48 hours)
• Blood tests and ultrasound of the heart may be required
  
  

The treatment of arrhythmias is targeted at its underlying cause if any, rate control and/or rhythm control, with focus to maintain adequate blood circulation to the rest of the body and to prevent complications of the arrhythmias.

In some cases, treating the underlying heart disease remove the arrhythmia. In general, arrhythmias can be treated with drugs, electrical shock (cardioversion), implanting automatic implantable defibrillators, pacemakers, catheter ablation, or surgery.

Other treatments for arrhythmias include:

Medication

Often arrhythmias can be managed by drug therapy alone. Anti-arrthymic drugs are commonly classified using Vaughan Williams cliassification. Response to drugs is usually measured by electrocardiogram (ECG), holter monitor or electrophysiologic study.

Procedures or surgeries

• Pacemakers that send electrical signals to make the heart beat properly can be implanted under the skin during a simple procedure. Pacemakers are used mainly to correct bradycardia.
• Automatic implantable defibrillators correct life-threatening ventricular arrhythmias by recognising them and then restoring a normal heart rhythm by pacing the heart or giving it an electric shock. They are usually implanted under the skin at the chest, without major surgery. They read the cardiac rhythm and store information for future evaluation by physicians. Automatic implantable defibrillators have proven to be more effective in saving lives than drugs alone. They are often used in conjunction with drug therapy.
• Ablation, a procedure to alter the heart tissue causing the arrhythmia in order to prevent a recurrence, can be performed through a catheter or surgery. Supraventricular tachycardia can be treated successfully with ablation. Ablation treatments are used when medications fail.
• Maze surgery treats atrial fibrillation by making multiple incisions in the atrium to direct electrical impulses in a appropriate fashion. This is often recommended for patients who have not responded to drugs or cardioversion.
  
  

Arrhythmia and Pacemaker Clinic at the National Heart Centre Singapore (NHCS)

This clinic evaluates patients with cardiac arrhythmias, providing tertiary service for patients with complex cardiac arrhythmias that require further investigations and evaluations. It also provides follow up monitoring and care for patients with pacemakers or defibrillators.

If you suspect you may have arrhythmia or an abnormal heart rhythm, you may make an appointment with a cardiologist for further investigations and treatment.

To make an appointment at NHCS, please visit here:
Book an Appointment

​Arrhythmia (irregular heartbeat) can also result in other types of heart conditions.

Often, a life-threatening arrhythmia is linked to heart conditions such as:

• Coronary artery disease: The Singapore study found that 81 per cent of all sudden cardiac deaths were caused by coronary artery disease (hardening and narrowing of the arteries supplying the heart).
• Heart attack: Almost 75 per cent of all sudden cardiac arrest patients show signs of a previous heart attack (myocardial infarction).
• Hypertrophic cardiomyopathy: An abnormal thickening of the heart muscle can cause ventricular fibrillation, especially during exertion.
• Electrical disorders of the heart: One of these disorders is Wolff-Parkinson-White (WPW) syndrome, characterised by an extra nerve connecting the heart chambers. This can cause an ‘electrical short-circuit’ in the heart, resulting in a rapid heartbeat. Brugada syndrome and long QT syndrome are also examples of electrical disorders.
  
  

When to seek emergency medical care

Please seek immediate medical help if your abnormal heart rhythm is accompanied by the following symptoms:

• Severe chest pain
• Shortness of breath
• Unusual sweating
• Loss of consciousness
  
  

It is also important to consult a doctor without delay if you have pre-existing heart conditions or a family history of sudden death.