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Cardiac Rhythm Disorders

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What is a cardiac rhythm disorder?

Also known as arrhythmias or irregular heartbeat, a cardiac rhythm disorder refers to a condition where the heart beats too fast, too slow, or irregularly. All these abnormalities affect the amount of blood pumped from the heart to the rest of the body. While some episodes of arrhythmia do not cause symptoms, the disorder may lead to dizziness and chest discomfort. If left untreated, they also increase the risk of stroke, heart attack, and heart failure amongst many other cardiac conditions.

Heart rhythm disorders can be caused by three broad categories, mainly electrical, circulatory or structural.

  • Electrical - This means there is an issue with the heart’s electrical system that regulates a steady heartbeat.
  • Circulatory - This generally refers to a blockage or narrowing that affects the supply of blood to the heart.
  • Structural - This could be a structural problem with the heart, such as damaged heart muscle or valves, that could disrupt the heartbeat’s rhythm.

Before moving on, let’s first discuss how the normal heartbeat is generated. The heart beats in response to electrical signals which start at the sinoatrial (SA) node. It is the heart’s natural pacemaker and is located at the right atria (upper chamber). The electric signal moves across the atria, into the AV (atrioventricular) node, and finally to the ventricles (bottom chamber or the main pumping chamber). The electric signal causes the chambers to contract, pumping blood from the atria into the ventricles, and from the ventricles to the lungs and other body parts. In healthy adults, the heart beats 60-100 times per minute.

What are the symptoms of a cardiac rhythm disorder?

Some episodes of cardiac rhythms disorders may not cause any symptoms. It is more often recognised during a medical evaluation for other conditions. However, some symptoms that suggest arrhythmia include:

When should I go to a doctor?

If you experience any of the symptoms mentioned above, it is best to consult a heart doctor immediately. Some types of arrhythmia can cause a dramatic drop in blood pressure and are life-threatening if not treated promptly. Episodes may come and go, or be persistent. Regardless, do visit a doctor for a proper diagnosis and treatment for your condition.

What are the types of heart rhythm disorders?

As previously mentioned, arrhythmia could mean that the heart beats too fast or too slow:

  • Tachycardia (too fast) resting heart beats >100 beats/minute
  • Bradycardia (too slow) resting heart beats <60 beats/minute

What is the most common heart rhythm disorder?

The most common heart rhythm disorder is Atrial Fibrillation, often called AFib or AF. This refers to rapid or irregular contractions in the atria, which could lead to clots and eventually, stroke or heart failure.

What could my abnormal heart rhythm mean?

Dr Devinder Singh checking pulse on patient's wrist

It is important to note that if you experience arrhythmia that is severe or unexpected, or accompanied by dizziness or tightness in your chest, please call an ambulance immediately.

Heart Palpitations

Heart palpitations are feelings or sensations of your heart pounding or beating very quickly, and can often be felt in the chest, throat and neck. They are quite common and do not always indicate an abnormality in the heart. Heart palpitations can be linked to:

  • Abnormal heart structures
  • Psychological stress
  • Excessive caffeine, alcohol, or drugs
  • Electrolyte imbalances
  • Sympathomimetic drugs

Syncope (Fainting)

Syncope refers to the sudden loss of consciousness, which often happens because of low blood pressure (hypotension) and the heart does not pump enough oxygen-rich blood to the brain.

Although a single fainting spell may not indicate a serious condition, syncope could be a warning sign of serious life-threatening conditions. If you have a recurrent loss of consciousness without warning or provocations you should consult your cardiologist. 

Sudden Cardiac Death

Sudden cardiac death, or cardiac arrest, is a condition where a malfunction in the heart’s electrical system disrupts the heart’s pumping action, which, in turn, stops blood flow to the body. There are warning signs such as:

  • Chest discomfort
  • Shortness of breath
  • Weakness
  • Fast-beating, fluttering or heart palpitations

If you experience these symptoms, call an ambulance immediately. Conversely, if you see someone suffer from cardiac arrest, please call an ambulance and use a portable Automated External Defibrillator (AED), often located around malls and lifts near Singapore.

Types of heart rhythm disorders

Supraventricular arrhythmias (begin in the atria)

  • Atrial fibrillation (A-fib) — disorganised and rapid heart rhythms because many impulses begin and spread through the atria, competing to travel to the AV node.
  • Atrial flutter and atrial tachycardias — caused by one or more rapid impulses in the atria. Similar to A-fib but is more organized and regular
  • Paroxysmal supraventricular tachycardia (PSVT) — rapid but regular rhythm coming from the atria; usually begins and ends abruptly.
  • Wolff-Parkinson-White (WPW) syndrome — fast heart rhythms caused by abnormal electrical pathways between the atria and ventricles. The abnormal pathway causes impulses to reach the ventricles prematurely and be bounced back to the atria causing overly rapid heartbeats.

Ventricular arrhythmias (begins in the ventricles)

  • Ventricular tachycardia (V-tach) — rapid heartbeat originating from the ventricles, preventing the heart from filling up enough blood before pumping it to other parts of the body.
  • Ventricular fibrillation (V-fib) — Disorganised, rapid firing of impulses from the ventricles which prevents effective contraction. This leads to a lack of blood supply to the rest of the body. V-fib is the most dangerous type of arrhythmia and requires immediate medical attention (CPR and defibrillation).
  • Premature ventricular contractions or PVCs: Premature ventricular contractions (PVCs) are extra heartbeats that begin in one of your heart's two lower pumping chambers (ventricles). These extra beats disrupt your regular heart rhythm, sometimes causing you to feel a fluttering or a skipped beat in your chest. Premature ventricular contractions are common — they occur in many people. They're also called: ventricular premature beats or ventricular extrasystole. It can lead to symptoms such as fluttering, palpitations, pounding or feeling of skipped heart beats

Bradyarrhythmias (affects the heart’s conduction system)

  • SA node dysfunction (sick sinus syndrome) — slow heart rhythms caused by scarring near the SA node.
  • Heart block/conduction block — a block or delay in the AV node causing irregular and slow heartbeats.

Are there any complications that arise from untreated heart rhythm disorder?

While some episodes may come without symptoms or are one-off occurrences, heart rhythm disorders are not to be brushed off.  Some arrhythmias are linked to an increased risk of blood clotting. As such, it also increases the risks of stroke, heart failure, and sudden death.

How are cardiac rhythm disorders treated?

Doctor with a patient

There are different types of treatment methods, which depend on the type of arrhythmia and its cause. This could include:

  • Oral medication that:
    • Slow the heartbeat (beta-blockers, calcium channel blockers)
    • Return heartbeat to normal (antiarrhythmic drugs)
    • Prevent blood clots (blood thinners)
  • Lifestyle changes, including:
    • Quitting smoking
    • Avoiding excessive alcohol and caffeine
    • Avoiding drugs that contain stimulants
    • Maintaining adequate physical activity
    • Maintaining healthy body weight
    • Keeping blood pressure and cholesterol levels under control
    • Reducing stress (yoga, mindfulness exercises, using relaxation techniques)
  • Catheter ablation uses heat or extreme cold to scar up small areas of the heart tissues that are causing the arrhythmias
  • Implantable devices:
    • Pacemakers usually treat bradycardia (heart beats that are too slow), the pacemaker monitors the electrical activity of your heart and may generate electrical impulses whenever the heart beats too slowly
    • Implantable cardioverter-defibrillators (ICD) deliver an electrical shock to restore the normal heart rhythm. Usually necessary for life-threatening arrhythmias such as ventricular fibrillation (V-fib).
  • Surgical treatments
    • The maze procedure makes a series of incisions in the atria to create a maze of scar tissue. This maze will block stray electrical impulses, preventing certain types of arrhythmia from reoccurring.
    • Coronary bypass surgery if your arrhythmia is caused by coronary artery disease. This is aimed to improve blood flow to your heart.

What to expect during consultation

If you experience symptoms of arrhythmia, you should book an appointment with a cardiologist. However, if you experience persistent arrhythmia, fainting, shortness of breath, or chest pain, you should visit the emergency room immediately.

To prepare for your consultation, you should:

  • Take note of your symptoms (how often and when it usually happens)
  • Note family history of heart conditions, stroke, high blood pressure, or diabetes
  • Make a list of all medications, vitamins, and supplements you are taking
  • Ask if you need to fast or stop any medication before diagnostic tests

Above discussing your symptoms and medical history, your doctor may also recommend you to take certain tests, such as:

What to expect post-treatment

Arrhythmias may reoccur and it is important to continue managing your condition. This includes:

  • Making lifestyle changes
  • Getting the appropriate treatment
  • Taking prescribed medication regularly
  • Attending your regular follow-ups with your cardiologist

This is important as arrhythmias are linked to various other heart conditions that may be life-threatening. Take note of your follow-up schedule and visit the hospital immediately if you experience persistent symptoms.


Elder couple

While most cases of arrhythmia in itself do not come with any symptoms, the condition is linked to various other conditions and thus should not be brushed off or taken lightly. If you experience any symptoms, book a consultation for a proper diagnosis of your condition and figure out the treatment method that will be most effective for your case. With early diagnosis and proper management, you can keep your condition under control and avoid complications.

Dr Devinder Singh

Senior Consultant Cardiologist &
Cardiac Electrophysiologist

Dr Devinder Singh is the Medical Director of Cadence Heart Centre. He is an experienced Senior Consultant Cardiologist & Cardiac Electrophysiologist with over 20 years of clinical experience.

His expertise lies in clinical cardiology, cardiac rhythm disorders (arrhythmia), cardiac pacing (including cardiac resynchronisation therapy) and cardiac magnetic resonance imaging. He performs electrophysiology studies and radiofrequency ablation of cardiac arrhythmias, and is well versed in pacemaker and defibrillator insertions.

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    Mt Elizabeth Hospital, 3 Mount Elizabeth #14-13
    Mt Elizabeth Medical Centre, Singapore 228510

    Monday - Friday: 9:00AM – 5:00PM
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    No health concern is too small. Contact us to book a consultation or comprehensive diagnosis and treatment plan.

    For urgent enquiries after office hours, please call us at

    (65) 8082 1366


    Farrer Park Hospital, 1 Farrer Park Station
    Road #15-06/07 Connexion, Singapore 217562

    Monday - Friday: 9:00AM – 1:00PM | 2:00PM - 5:00PM
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