What is atrial flutter?
Atrial flutter refers to an abnormal heart rhythm involving an electrical short circuit occurring in the heart’s upper chambers.
How does atrial flutter occur?
Atrial flutter refers to an electrical short circuit involving the right atrium which cycles at 300 times per minute. The short circuit is triggered by ectopic beats or “electrical sparks” usually arising from the left atrium.
During atrial flutter, both the left and right atria are stimulated too rapidly and cannot pump effectively as a result. The AV node will typically allow only every second or third of the rapid electrical impulses to reach the heart’s lower pumping chambers. This results in a pulse rate of 100 to 150 beats per minute.
Medications including beta blockers, calcium channel blockers, and digoxin help the AV node filter out more of these rapid impulses to bring the heart rate into a normal range, even while the upper chambers remain in short circuit.
Ultimately, the best way to treat atrial flutter is to break the circuit permanently by performing a minimally invasive catheter ablation procedure which is both safe and highly effective.
What are the possible consequences of atrial flutter?
Three main consequences
- Atrial flutter symptoms. The heart becomes inefficient at pumping blood around the body. This produces breathlessness, dizziness, and fatigue, often accompanied by palpitations. These are the key symptoms of atrial flutter, and are not in themselves life threatening.
- Stroke. During atrial flutter, the upper chambers of the heart weaken and pump ineffectively. Blood flow slows down, and can stagnate in the “nooks and crannies” of the left atrium. In some individuals, this may result in blood clot formation. If released into circulation, such blood clots may lodge in the brain causing stroke.
- Heart failure. Atrial flutter causes the heart’s lower chambers to pump too quickly. If left untreated, these muscular chambers can weaken and distend, resulting in heart failure. It is important to prevent this either by slowing down the rapid heart rate with medications, or correcting the short circuit altogether so that normal electrical function resumes.
What tests do I need if I have atrial flutter?
You may require the following initial tests:
- Blood tests – To determine if there is an underlying condition that has provoked your arrhythmia, such as thyroid or electrolyte disturbances and to check the condition of your liver and kidneys.
- ECG – To evaluate your heart rhythm.
- Holter monitor – To evaluate your heart rhythm over a 24 h period. If you are in normal rhythm, this may reveal episodes of AF that correspond with your symptoms, or which you may be unaware of. However, if you are in atrial flutter, this assesses whether your heart rate is too rapid, or is well-controlled with medications.
- Echocardiogram – To evaluate the structure and function of your beating heart. Left atrial size is an important indicator of how established AF has become. Left ventricular size and function provide an idea of whether there is an element of heart failure accompanying your AF. Your “ejection fraction” is a key measure of the strength of your heart.
How is atrial flutter treated?
- Blood thinners. In some individuals, atrial flutter promotes blood clot formation. Depending on a number of factors, you may benefit from a blood thinner to prevent blood clot formation and stroke. This may be warfarin, or one of the new generation of blood thinners: Pradaxa, Xarelto, or Eliquis.
- Direct current reversion (DCR). Atrial flutter can be terminated with an electrical shock to the chest, delivered under a very brief general anaesthesia. This “resets” the heart’s electrical system, allowing normal rhythm to resume. DCR does not prevent atrial flutter from returning: there is a 50% chance of developing atrial flutter again in the next 12 months. Arrhythmia medications may prevent recurrence, but are not as effective as catheter ablation.
- Medications. Atrial flutter is sometimes managed with medications. Anti-arrhythmic medications prevent atrial flutter episodes, and these include sotalol, flecainide, and amiodarone. Rate controlling medications allow atrial flutter to continue, but slow down the heart rate by acting on the AV node. This prevents the lower chambers from being over stimulated. In many individuals, medications are ineffective or cause unwanted side effects which are at times worse than the symptoms of atrial flutter.
- Atrial flutter (AFL) ablation. This is a safe and minimally invasive procedure that cures atrial flutter. It is highly effective with a success rate of 98%. A catheter is used to deliver radiofrequency energy to ablate (destroy) a critical part of the short circuit in the right atrium, which breaks the circuit and prevents it from recurring. The procedure is normally done under a general anaesthetic, because the ablation is performed in a sensitive part of the heart.