Atrial Fibrillation

AF involves the heart's electrical system not functioning properly. It occurs when the electrical impulse originating in the sinoatrial node is not conducted throughout the rest of the heart in an organized way. This leads to a disorganized contraction of cardiac muscle in the top of the heart (atria) and an irregular heartbeat.

AF is the most common type of cardiac arrhythmia (irregular heartbeat) and increases with age. It can occur spontaneously but is linked with a number of other causes including cardiovascular disease, hypertension, coronary heart disease, infection, hyperthyroidism and a previous family history.

Symptoms of atrial fibrillation

The palpitations caused in AF are due to the irregular contractions of part of the top of the heart known as the atria which then spread into the main part of the heart known as the ventricles in an irregular rhythm. People may notice their heart racing or be aware of it beating more heavily in their chest.

Shortness of breath associated with AF occurs due to the inefficient way in which the heart is functioning. When the atria do not contract in a coordinated function the heart loses some of it’s effectiveness as a pump. This may lead to a degree of heart failure and accumulation of fluid in the lungs.

In a similar way the symptoms of lightheadedness or fainting are also caused by the inefficient functioning of the heart during AF. The heart may sometimes not be able to pump efficiently enough to perfuse the brain with an adequate supply of blood causing lightheadedness or an episode of fainting.

Chest pain is one of the most serious symptoms of AF, as it can be a symptom of angina or even of a heart attack. This is related to the increased demand of blood supply that occurs in the heart whilst it is in AF.

Investigations for atrial fibrillation

Blood tests are also useful in ruling out other causes of AF, as well as an echocardiogram to assess how well the heart is pumping and whether there is any valvular disease present.

Treatment of atrial fibrillation

The next stage of treatment involves attempting to put the heart into a regular rhythm by either electrical cardioversion or with medication.

Electrical cardioversion is usually used in patients with new-onset (acute) AF that have not had previous episodes. It involves attaching electrical paddles to the front of the chest and shocking the heart while the patient is under mild sedation. The heart can often be “rebooted” or shocked back into a regular rhythm using this method.

The second method of treating AF involves the use of different types of medications. Medications can either be used to try and make the heart revert back into a normal rhythm (chemical cardioversion ), or to simply slow the heart rate allowing it to remain in an irregular rhythm but function better at a slower rate. Some of the medications used include:

• Amiodarone- is used to try and revert an irregular heart rhythm back into a regular one. Amiodarone is an anti-arrhythmic medication that may be used long-term in patients with recurrent AF.
• Procainamide and flecainide- are two other types of anti-arrhythmic drugs that are also used to try and revert an irregular heart rhythm in AF.
• Beta Blockers- include metoprolol, carvedilol, atenolol and bisoprolol. These are used to slow the rate of the heart but may not necessarily help to revert the rhythm back into a regular one.
• Digoxin- this will also slow the rate of the heart, but also helps with the heart’s contraction.
• Calcium Channel Blockers- include diltiazem and verapamil. These also slow the rate of the heart and also help to dilate vessels reducing the work the heart has to do.

As you can see above there are a number of different treatment options involved with AF. Anticoagulation is important to reduce the risk of stroke, while cardioversion of the heart back into a regular rhythm can be achieved either by electrical cardioversion or medication. Finally, rate control alone may be used if the AF is long-standing and the patient is not symptomatic.

Prognosis of atrial fibrillation