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Atrial Fibrillation

Updated: Jan 25, 2021

The heart is comprised of 4 chambers; 2 atria, which sit on 2 ventricles. An electrical “timekeeper”, called the sino-atrial node, is located at the top of the right atrium. This is the heart’s natural pacemaker, sending out regular electrical impulses that travel through pathways which run down the atria, through the ‘junction box’ of the heart (known as the AV node) and into the ventricles, allowing the heart to contract and relax regularly and pump blood around the body.

In Atrial Fibrillation, the Pulmonary Veins in the Left Atrial chamber is where the abnormal fast firing occurs leading to the irregular rhythm. The Image below reveals a 3D map of the left atrial chamber with four pulmonary veins ; 2 on the right and 2 on the left. The smaller "smarties" like dots are the ablation lesions delivered to reduce these fast firing areas and allow the normal conduction system to maintain the regular heart rhythm.

Symptoms of AF commonly include palpitations, shortness of breath, and fatigue. Some patients experience dizziness, chest pain and can occasionally lose consciousness. An ECG (electrocardiogram) and Echo (echocardiogram), both non-invasive tests, are usually sufficient to make the diagnosis. It is also important to investigate AF to determine if there are any underlying causes as some of these can be reversible.

Treatment of AF is aimed at two main things:

1) the reduction of stroke risk that is associated with AF, and

2) the treatment of symptoms or other complications such as heart failure.

Stroke prevention treatment involves assessing each individual and then working out whether they need to take medication to thin their blood. This may be warfarin, or one of the relatively recent blood thinners that do not need regular blood checks.

Treatment of symptoms can be either with medication, by cardioversion, where an electrical shock is given to try to stimulate the heart’s normal rhythm. Catheter ablation in the last 20 years has been increasingly performed. The HRS/EHRA/ESC guidelines recommend AF catheter ablation with Pulmonary Vein Isolation as a class 1 indication for symptomatic paroxysmal Atrial Fibrillation refractory to anti-arrhythmic medication. In some cases, more than 1 ablation procedure maybe needed. Catheter ablation is targeted to improve symptoms and reduce the need for incremental anti-arrhythmic medication need. Occasionally a pacemaker with anti-arrhythmic medication  or AV node ablation is performed.

The above image is a 3-D geometry of the Left Atrium with 4 pulmonary veins, 2 on the left and 2 on the corresponding right. The left image is the back of the Left Atrium whilst the image on the right corresponds with the front. The "smarties" - like small round red and salmon pink dots just outside the pulmonary veins are the radiofreqenucy lesions delivered to encircle the veins systematically. This forms a barrier to prevent triggers arising from the pulmonary vein to escape into the left atrium and promote Atrial Fibrillation.

Aside radio frequency, a balloon like catheter with cooling cryo properties can be used to perform pulmonary vein isolation.

Increasingly, lifestyle modification, weight loss, diet and exercise has been shown to improve outcomes and quality of life in patients with Atrial Fibrillation. Treating snoring that culminates in obstructive sleep apnoea has been effective in improving the quality of life and reducing the AF recurrences and maintaining remission. Smoking cessation and alcohol / caffeine intake reduction is strongly advocated.

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