Heart Rhythm Disorders (Arrhythmias)

An arrhythmia is the medical term for an abnormal heart rhythm.

The heart has its own electrical system which provides the impulses for the heart chambers to contract & work in a co-ordinated manner. An arrhythmia is the medical term for an abnormal heart rhythm. Symptoms may include:

  • Palpitations – an increased awareness of the heart beating. This may take the form of extra, irregular or missed beats, or fast heart rates.
  • Dizzy spells or light-headedness
  • Fainting (blackouts) or almost fainting
  • Shortness of breath or fatigue
  • Chest pain

Investigations / Procedures to help make the diagnosis include:

  • Resting ECG
  • Extended ECG or patient-activated monitoring
  • Implantable loop recorder – this is a small device inserted just underneath the skin in the chest, under local anaesthetic. It automatically records fast or slow heart rhythms and can also be activated by the patient to record events. This can last up to 3 years and is suitable for patients with infrequent symptoms.
  • Electrophysiological study – this is an invasive procedure performed by placing special wires inside the heart via the leg vein and can give more detailed information regarding the heart’s conduction system. Abnormal heart rhythms can be treated during the same procedure (ablation)


This is dependent on the cause of the arrhythmia but can include:

  • Medications
  • DC cardioversion – giving an electrical shock to the heart under a light general anaesthetic
  • Ablation – cauterisation of heart tissue
  • Permanent pacemaker (PPM)
  • Implantable defibrillator (ICD)

Common Arrhythmias

Atrial fibrillation (AF) – this is the most common arrhythmia and leads to an irregularly irregular heartbeat. Apart from causing symptoms, AF can increase the risk of stroke, which is managed by thinning of the blood (anticoagulation). Depending on symptoms, AF can be managed with tablets, DC Cardioversion or ablation.

Atrial flutter – the heartbeat tends to be more regular, but this can cause similar symptoms to AF, with the same treatment options.

Supraventricular tachycardia (SVT) – this is a fast regular rhythm that originates in the upper chambers of the heart (atria) and includes conditions such as AVNRT (Atrioventricular nodal re-entry tachycardia), AVRT (Atrioventricular re-entry tachycardia) and Wolff-Parkinson-White syndrome. These can be treated by tablets or by ablation.

Ventricular tachycardia (VT) – this is a fast rhythm originating from the lower chambers of the heart (ventricles) which can be dangerous.

Ventricular fibrillation (VF) – a life-threatening condition when the heart beats extremely fast and irregularly, leading to death unless treated immediately.

VT & VF can be treated with tablets and/or an ICD which will detect the arrhythmia and shock the heart back into a normal rhythm.

VT & VF invariably has an underlying cardiac structural abnormality (eg heart failure) and can also be associated with inherited conditions such as:

  • Long QT syndrome
  • Brugada syndrome
  • Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D)
  • Hypertrophic Cardiomyopathy (HCM)

In these conditions, close family members are also advised to undergo cardiac evaluation.

Sinus node disease (Sick sinus or tachy-brady syndrome) – this is due to disease in the heart’s own pacemaker tissue and can lead to slow heart rhythms (bradycardias) and/or fast heartbeats (tachycardias). The bradycardia may need treatment with a PPM, which detects the slow heart rate and artificially paces the heart. The tachycardia is normally treated with tablets.

Second degree or Complete heart block – this occurs when the heart conduction tissue becomes damaged and can lead to bradycardia or pauses in the heart beat. This can lead to dizzy spells or blackouts and is treated by a PPM.

PPM implantation involves placing one or two leads into the heart and connecting them to an pacemaker placed underneath the skin in the chest. This is usually performed under local anaesthetic.

ICD implantation is a similar procedure with 1-3 leads being placed, depending on the underlying cause.