Atrial flutter – Causes, Types, Treatment and Prevention

Definition

Atrial flutter is a type of heartbeat problem (arrhythmia) that usually causes a fast heart rate. This fast rate is caused by changes in the electrical system of your heart. Normally, the heart beats in a strong, steady rhythm. In atrial flutter, a problem with the heart’s electrical system causes the two upper parts of the heart (the right atrium and the left atrium) to flutter, or beat very fast. Atrial flutter might be diagnosed using an electrocardiogram (EKG). An EKG translates the heart’s electrical activity into line tracings on paper.

This problem can be dangerous. If the heartbeat isn’t strong and steady, blood can collect, or pool, in the atria. And pooled blood is more likely to form clots. Clots can travel to the brain, block blood flow, and cause a stroke. Over time, atrial flutter can also lead to heart failure.

Types of atrial flutter

There are two types of atrial flutter: typical and atypical.

Typical atrial flutter is more common and usually responds better to treatment. The short-circuit is located in the right upper heart chamber around the heart’s tricuspid valve, which separates the atria and ventricle.

Atypical atrial flutter is caused by scarring on the left side of the heart from prior heart surgeries, previous procedures, or heart disease. The scarring can stretch and injure the upper heart chamber, leading to problems such as heart failure or valvular heart disease. During an RVR, the heart can beat 100-200 times a minute.

Both of these conditions can lead to a rapid ventricular response (RVR), causing the heart to beat 100-200 times a minute.

Epidemiology

Overall, the incidence of AFL in the United States is 88 per 100,000 person-years. 15% of supraventricular arrhythmias are AFL and usually coexist with AF. More than 80% of patients who undergo RFA of typical AFL will have AF within the following 5 years. The incidence of AFL in men is more than twice that of women. Paroxysmal AFL can be seen in patients with no structural heart disease (SHD), whereas chronic AFL is frequently associated with underlying SHD, such as valvular disease or heart failure. Acute AFL may happen secondary to acute disease process, such as pericarditis, pulmonary embolism, exacerbation of lung disease, following heart or lung surgery, or myocardial infarction.

ECG Waves

Pathophysiology of atrial flutter

Atrial flutter is a form of supraventricular tachycardia caused by a re-entry circuit within the right atrium. The length of the re-entry circuit corresponds to the size of the right atrium, resulting in a fairly predictable atrial rate of around 300 bpm (range 200-400)

• Ventricular rate is determined by the AV conduction ratio (“degree of AV block”). The most common AV ratio is 2:1, resulting in a ventricular rate of ~150 bpm
• Higher-degree blocks can occur — usually due to medications or underlying heart disease — resulting in lower rates of ventricular conduction, e.g. 3:1 or 4:1 block.
• Atrial flutter with 1:1 conduction can occur due to sympathetic stimulation, or in the presence of an accessory pathway. The administration of AV-nodal blocking agents to a patient with Wolff-Parkinson-White syndrome can precipitate this
• Atrial flutter with 1:1 conduction is associated with severe haemodynamic instability and progression to ventricular fibrillation

1. The term “AV block” in the context of atrial flutter is something of a misnomer. AV block is a physiological response to rapid atrial rates and implies a normally functioning AV node.

Causes of atrial flutter

Doctors don’t always know. In some people, no root cause is ever found. But atrial flutter can result from:

• Diseases or other problems in the heart
• A disease elsewhere in your body that affects the heart
• Substances that change the way your heart transmits electrical impulses

Heart diseases or problems that can cause atrial flutter include:

• Ischemia: Lower blood flow to the heart due to coronary heart disease, hardening of the arteries, or a blood clot
• Hypertension: High blood pressure
• Cardiomyopathy: Disease of the heart muscle
• Abnormal heart valves: Especially the mitral valve
• Hypertrophy: An enlarged chamber of the heart
• Open-heart surgery

Diseases elsewhere in your body that affect the heart include:

• Hyperthyroidism: An overactive thyroid gland
• Pulmonary embolism: A blood clot in a blood vessel in the lungs
• Chronic obstructive pulmonary disease(COPD): A condition that lowers the amount of oxygen in your blood

Substances that may contribute to atrial flutter include:

• Alcohol (wine, beer, or hard liquor)
• Stimulants like cocaine, amphetamines, diet pills, cold medicines, and even caffeine

Symptoms of atrial flutter

The electrical signal that causes Atrial Flutter (AFL) circulates in an organized, predictable pattern. This means that people with AFL usually continue to have a steady heartbeat, even though it is faster than normal. It is possible that people with AFL may feel no symptoms at all. Others do experience symptoms, which may include:

• Feeling tired and not have enough energy
• Heart palpitations (feeling like your heart is racing, pounding, or fluttering)
• Fast, steady pulse
• Shortness of breath
• Trouble with everyday exercises or activities
• Pain, pressure, tightness, or discomfort in your chest
• Dizziness, feeling lightheaded, or fainting

Risk factors

There are many risk factors for this type of flutter. The following is a list of some of the more common risk factors:

• High blood pressure
• Obesity
• Diabetes
• Heart failure
• Ischemic heart disease and/or a previous heart attack
• Serious acute illnesses
• Heavy alcohol intake and/or binge drinking
• Advanced age
• Hyperthyroidism
• Chronic lung disease
• Recent surgery
• Congenital heart disease

Complication

• Heart failure; acute atrial flutter can impair cardiac function, lower blood pressure, and initiate myocardial ischaemia.
• Thromboembolism (transient ischaemic attacks and stroke). Systemic embolism is less commonly associated with atrial flutter than with atrial fibrillation, but is still a significant risk. One study showed the annual incidence of ischaemic stroke to be 1.38%.
• Tachycardia-induced cardiomyopathy.
• Persistent untreated atrial flutter can become chronic atrial fibrillation.

Diagnosis

Doctors start to consider AFL if your heartbeat at rest goes above 120 bpm and if your ECG shows signs of atrial flutter.

Your family history may be important when your doctor is trying to diagnose AFL. A history of heart disease, anxiety, and high blood pressure can all affect your risk.

Your primary care doctor can make a preliminary diagnosis of AFL with an ECG. You may also be referred to a cardiologist for further testing.

Several tests are used to diagnose and confirm AFL:

Echocardiograms use ultrasound to show images of the heart. They can also measure the flow of blood through your heart and blood vessels and see if the heart has shown any signs of getting weak due to beating fast (tachycardia induced cardiomyopathy) or dilation of the atria (chambers of the heart where AFL originates).

Electrocardiograms record the electrical patterns of your heart.

Holter monitors allows a doctor to monitor the heart’s rhythm for at least a 24-hour period.

Electrophysiology (EP) studies are a more invasive way to record heart rhythm. A catheter is threaded from the veins of your groin into your heart. Electrodes are then inserted to monitor heart rhythm in different areas.

Atrial flutter treatment

The goal of treatment is to control the heart rate, prevent stroke, and maintain a normal heart rhythm.

• To control heart rate, you may be given a prescription medicine that can slow down the heart rate.
• To prevent stroke, your doctor may prescribe a blood thinner (anticoagulant) to prevent a blood clot in the heart. This clot can break free and travel to the brain

Rhythm control involves either medicine or a procedure.

• Antiarrhythmics. These medicines can be taken as needed to stop an episode. Or you can take them every day to prevent future atrial flutter.
• Electrical cardioversion. This is an outpatient procedure where large electrode patches are placed on your chest and back. Energy is sent through these patches as a shock that is synchronized with your heartbeat. In many cases, this restores normal rhythm. This is typically done with IV sedation so that the shock is not felt. Sometimes your doctor may start you on an antiarrhythmic medicine around the time of the cardioversion. This helps maintain a normal rhythm for a longer period of time after cardioversion. Or it may help the cardioversion to be a success.
• Cardiac ablation. This is a non-surgical, catheter-based procedure that can often cure atrial flutter. It involves threading wires through a vein in your leg to the heart. Either heat energy or cold energy is used to destroy the abnormal circuit.

The success rate of each treatment varies. Discuss this with your doctor.

Prevention

Prevention of atrial flutter focuses on controlling or preventing the risk factors.

• Stay at a healthy weight.
• Drink alcohol only in moderation, if at all.
• Stop tobacco use.
• Control high blood pressure and diabetes.