Heart conditions - atrial fibrillation

Atrial fibrillation (AF) is a type of arrhythmia, which means that the heart beats in an irregular fashion. This is caused by a distortion of electrical messages that control the steady rhythm of the heart, which we know as the ‘heartbeat’. Symptoms are not always obvious but may include palpitations or a fluttering heartbeat, irregular heartbeat, chest pains, dizziness and fainting spells.

Overall, AF affects around one in every 100 people. However, the risk increases with age, with close to one in ten people aged 75 years or more affected. Treatment is important, even if the AF does not present with any symptoms. Untreated, complications can include stroke and heart attack.

A problem with the heart’s ‘pacemaker’
Normally, the heart’s electrical system causes its chambers to contract and relax, following a steady rhythm. Electrical messages are sent from the heart’s top two chambers (atria), in an area known as the sinus node (the heart’s ‘pacemaker’). This causes the atria to contract. These electrical messages then pass from the sinus node to another area of the heart called the atrioventricular node and cause the bottom two chambers (ventricles) to contract.

In atrial fibrillation, a problem with the sinus node causes the atria to twitch or ‘shiver’ rather than contract. This distorts the electrical messages sent to the atrioventricular node and causes the ventricles to contract in a fast and irregular manner. Atrial fibrillation is one of the most common types of arrhythmia.

Symptoms
Atrial fibrillation often has no obvious symptoms and can remain undetected for long periods of time. If symptoms occur, they may include:

• Sensations of a ‘fluttering’ heartbeat (palpitations)
• Irregular heartbeat (detected by checking the pulse)
• Angina (chest pains)
• General malaise
• Dizziness
• Inability to tolerate exercise
• Fainting spells.

• One-off – the heart has a single episode of irregular beating.
• Occasional – the heart is prone to repeat episodes of irregular beating, for short periods of time. This is known as ‘paroxysmal AF’.
• Persistent – the heart beats irregularly all the time. This is known as ‘permanent AF’, ‘sustained AF’ or ‘chronic AF’.

• Chronic high blood pressure (hypertension)
• Coronary heart disease
• Heart valve diseases that interfere with the direction of blood flow in the heart
• Overactive thyroid gland (hyperthyroidism)
• Chest surgery
• Chest trauma
• Excessive intake of ‘social’ drugs such as caffeine and alcohol
• Certain prescribed drugs
• Certain illnesses such as pneumonia.

• Physical examination
• Medical history
• A holter monitor that records the electrical activity of the heart for a long period of time (for example, 24 hours)
• Electrocardiogram (a graph of the heart’s electrical activity)
• Echocardiogram (a special ultrasound of the heart)
• Blood tests
• Diagnostic scans of the legs or lungs (in the case of suspected blood clot)
• Cardiac catheterisation (in the case of suspected heart attack or coronary heart disease).

• Medications to normalise the heart’s rhythm. This includes digoxin, amiodarone and other ‘anti-arrhythmic’ agents. These may be given as injections or tablets. Since some medications may cause toxicity (poisoning), regular tests to check liver and thyroid function may be required.
• Medications to slow the heart rate. This includes beta-blockers.
• Medications to reduce the risk of stroke. Blood-thinning medications (such as aspirin, clopidogrel and warfarin) are often prescribed to reduce the risk of blood clots developing in the heart in those with persistent forms of atrial fibrillation.
• Electric shock therapy to the heart (electrical cardioversion). Given under general anaesthesia, an electrical shock to the chest helps to ‘reset’ the heart’s electrical system. However, long-term medication may be needed to keep the heart beating normally.

• Catheter ablation/ in this procedure, a cardiologist first makes an incision in the upper thigh or groin. A thin tube (catheter) is inserted into a main blood vessel and pushed along until it reaches the heart. The tip of the catheter is fitted with an electrode. Once in position, the electrode is activated. Radio frequency waves destroy the small area of heart tissue responsible for causing the AF.
• Maze operation – this is a similar procedure to catheter ablation, but produces a ‘maze’ of small scars that ‘traps’ the source of atrial fibrillation and allows the sinus node to take control.
• Artificial pacemaker – in some cases, an artificial pacemaker is implanted. An artificial pacemaker helps to keep the heart in a regular rhythm.

• Quit smoking
• Lose weight
• Cut back on alcohol
• Cut back on drinking coffee
• Switch to a low fat, high fibre diet
• Take measures to control high blood pressure or diabetes, if necessary
• Exercise regularly – but be advised by your doctor. For example, people taking warfarin are at increased risk of bleeding so contact sports should be avoided
• Be aware of special dietary issues. For example, people on warfarin may need to limit the amount of green vegetables in their diet, because vitamin K can interfere with this medication. Other dietary cautions may be necessary. Seek advice from your doctor.

• Your doctor
• Cardiologist
• Heart Foundation Tel. 1300 362 787
• NPS Medicines Line Tel. 1300 888 763 (for information on medicines)

• Atrial fibrillation (AF) is a type of arrhythmia, which means that the heart beats irregularly.
• The risk of atrial fibrillation increases with age.
• Some of the known causes of AF include chronic high blood pressure, coronary heart disease, heart valve diseases and hyperthyroidism.
• Treatment includes medication to slow and stabilise the heart rate and reduce the risk of forming blood clots and surgical procedures to destroy the area of heart tissue responsible for the irregular heart rhythm.

This page has been produced in consultation with and approved by:


(Logo links to further information)