Atrial Macro-Reentry Arrhythmia
Atrial Flutter
Atrial flutter is a fast, regular rhythm that usually starts in the upper chambers of the heart. It is related to atrial fibrillation but is a different rhythm, and it is often treated differently.
On this page
Understanding the rhythm
What Is Atrial Flutter?
In atrial flutter, electrical activity in the atria, the upper chambers, travels around a fixed loop again and again. This makes the atria beat quickly and regularly.
Not every fast impulse reaches the ventricles, the lower chambers. The ventricles often beat at a fraction of the atrial rate, so the pulse can feel fast, regular, or sometimes irregular.
Atria and ventricles, conceptual
Why it happens
How Atrial Flutter Develops
A flutter circuit needs a loop of tissue that can carry the impulse and a trigger that starts it. Once started, the impulse keeps circling, which is called macro re-entry.
Flutter can occur on its own, after heart surgery or an earlier ablation, with lung disease, or alongside atrial fibrillation. A person can have more than one rhythm at different times.
Re-entry loop, conceptual illustration
The mechanism
Typical Flutter Circuit
The most common form is called typical, or cavotricuspid isthmus-dependent, flutter. The impulse circles around the tricuspid valve in the right atrium and passes through a narrow strip of tissue called the cavotricuspid isthmus.
Loop
The impulse circles the tricuspid valve in the right atrium.
Isthmus
It passes through a narrow strip of tissue between the valve and a large vein.
Direction
The circuit usually runs in one direction, which affects how the ECG looks.
Other forms
Some flutters use different circuits and are called atypical.
Not every flutter uses the same circuit. Identifying the circuit is part of the assessment.
Comparison
Atrial Flutter vs Atrial Fibrillation
The two rhythms are related and can occur in the same person, but they are different.
Atrial flutter
Organised
Electrical activity follows a loop. The atrial rhythm is regular and often looks the same from beat to beat.
The ventricular response is often regular but can vary.
Atrial fibrillation
Disorganised
Electrical activity is chaotic and does not follow one loop. The pulse is usually irregular.
Stroke risk and treatment are assessed individually in both.
What people notice
Symptoms
Some people have no symptoms. Others notice them when the rhythm starts or when it persists.
Palpitations
A fast, pounding or fluttering feeling in the chest.
Breathlessness
Feeling short of breath, especially with activity.
Tiredness
Less energy than usual, or reduced exercise capacity.
Light-headedness
Feeling dizzy or faint in some people.
Chest discomfort
Seek medical advice promptly if this occurs.
Fainting, chest pain or severe breathlessness needs urgent medical care.
What the ECG may show
ECG
On an ECG, typical flutter often shows a regular, repeating pattern of atrial activity, sometimes described as saw-toothed, best seen in some leads. The ventricles may respond to only some of the atrial impulses.
The appearance varies with the circuit and the level of conduction. The ECG is interpreted by a physician together with the history and other tests.
Confirming the rhythm
Diagnosis
Diagnosis relies on recording the rhythm. A resting ECG may be enough if flutter is present at the time. If it comes and goes, longer monitoring may be needed.
Records the rhythm at the time of the test.
Continuous recording over a period of time.
Used when episodes are less frequent.
Further tests
Blood tests and heart imaging may be used to look for related conditions.
Understanding the circuit
EPS and Mapping
An electrophysiology study records electrical signals from inside the heart. It can show whether the flutter uses the typical circuit or another one. Electroanatomical mapping can help show the circuit when it is not typical.
Planning care
Treatment Approach
Treatment depends on symptoms, how often the rhythm occurs and other health conditions. It is chosen together with the treating physician.
Heart rate control
Medicines may be used to slow the response of the ventricles.
Medicines or electrical cardioversion may be used to restore a normal rhythm.
Stroke risk
The need for blood-thinning treatment is assessed, as it is in atrial fibrillation.
May be considered for selected patients, especially in typical flutter.
A procedural option
Catheter Ablation
In typical flutter, ablation usually aims to create a line of treated tissue across the cavotricuspid isthmus. This interrupts the loop so that the impulse can no longer circle.
The team checks whether conduction across the line is blocked. Flutter that uses other circuits may need a different approach. Flutter can also occur together with atrial fibrillation, which may change the plan.
Isthmus line, conceptual illustration
Patient journey
Procedure Pathway
A general outline. The steps depend on the patient and the findings.
Assessment
Review of symptoms, history, ECG and monitoring.
Planning
Discussion of options, stroke risk and preparation.
Catheter placement
Catheters are guided to the heart through a vein, usually in the groin.
Mapping
The circuit is confirmed from the recordings.
Treatment
Energy is delivered along the planned line.
Testing
The team checks whether conduction across the line is blocked.
Recovery
Monitoring while the patient recovers.
Follow-up
A follow-up plan is explained.
After treatment
Follow-up
Follow-up depends on the treatment chosen. It may include rhythm checks, review of symptoms and a decision about continuing blood-thinning treatment. Flutter and atrial fibrillation can occur after treatment, so follow-up matters.
Seek urgent medical care for fainting, chest pain or severe breathlessness.
Questions