Knowledge of basic heart rhythms is important for most nurses regardless of their practice setting but it is an absolute essential for nurses working on telemetry units, in emergency departments, and in intensive care units. Two common atrial rhythms that often get confused are atrial fibrillation and atrial flutter. What’s the difference?
 
To review, the heart pumps most effectively in normal sinus rhythm (NSR). With a regular rhythm, electrical impulses are generated in the sinoatrial (SA) node, the natural pacemaker of the heart. The impulses then travel to the atrioventricular (AV) node, through the Bundle of His, down along the right and left bundle branches to the Purkinje fibers causing the ventricles to contract and pump oxygen-rich blood out to the body. When there is a disruption in the cardiac conduction system, abnormal heart rhythms occur. Atrial fibrillation and atrial flutter are two arrhythmias arising from ectopic foci in the atrial chambers of the heart.
 

Atrial Fibrillation (Kumar, 2023)

Atrial fibrillation (AF) is a common cardiac arrhythmia caused by rapid, disorganized firing of multiple ectopic foci in the atria resulting in an inconsistent, uncoordinated, chaotic atrial rhythm that affects the strength of the atrial contraction and blood flow into the ventricles. It can cause a reduced cardiac output and thrombus formation, increasing a patient’s risk for stroke and peripheral embolization. AF can be categorized as follows:

• Paroxysmal (e.g., self-terminating or intermittent) AF – a rhythm that ends spontaneously or with intervention within seven days of onset.
• Persistent AF – does not self-terminate within seven days. Episodes require pharmacologic or electrical cardioversion to convert back to NSR.
• Long-standing AF – AF that has lasted longer than 12 months.
• Permanent AF – rhythm can’t be converted to NSR; patient and clinician decide together that they will no longer attempt to control the rhythm.

 

Atrial Flutter (Phang, 2024)

Atrial flutter is a macro-reentrant tachycardia in which the atria receive electrical signals at a faster rate than normal. It is characterized by rapid, regular atrial depolarization at a more frequent rate than ventricular depolarization. For example, only every second, third, or fourth atrial beat transmits down to the ventricles resulting in a 2:1, 3:1, or 4:1 ratio of atrial to ventricular beats. Atrial flutter can be associated with valvular heart disease, cardiomyopathy, post-cardiac surgery, pericardial disease, and acute or chronic pulmonary disease. Some patients who have atrial flutter also have atrial fibrillation. Atrial flutter can be categorized as follows:

• Typical atrial flutter – involves a reentry circuit of impulses across the cavo-tricuspid isthmus (CTI) in the right atrium. The impulses travel in a counterclockwise direction creating a “sawtooth” appearance of the P waves on ECG. The signals can also travel in a clockwise direction, called reverse typical atrial flutter, and in rare cases, the signals can travel in both directions.
• Atypical atrial flutter – the CTI is not involved, instead any region of the right or left atria, around areas of scar tissue due to heart disease or surgical/ablation procedures, can cause an abnormal circuit of impulses.

 

Differentiating atrial fibrillation and atrial flutter 

Characteristics of atrial fibrillation and atrial flutter
	Atrial fibrillation	Atrial flutter
Rhythm	Irregularly irregular	Regular/organized or irregular
Rate	Atrial – indiscernible Ventricular – typically rapid, 100 to 175 beats per minute (bpm) if uncontrolled	Atrial – 240 to 340 bpm Ventricular – typically rapid, 150 bpm
P wave	No distinct P waves, instead “fibrillatory” baseline	Appear in a “sawtooth” pattern (also called F or “flutter” waves) in leads II, III, aVF Atrial to ventricular ratio – 2:1, 3:1, 4:1
PR interval	Indeterminate (no P waves)	Indeterminate (no P waves)
QRS complex	Normal (0.6-0.10 seconds)	Normal (0.6-0.10 seconds)
Signs and symptoms	May be asymptomatic in either AF or atrial flutter Symptoms usually mild in atrial flutter Palpitations Fatigue Dyspnea with exertion Chest Pain Syncope Dizziness
Complications	Transient ischemic attack Stroke Heart failure Thromboembolism Bleeding with anticoagulation
Management	Calcium channel blocker or beta blocker for ventricular rate control or an antiarrhythmic for rhythm control Anticoagulant therapy to prevent stroke
Potential procedures	Radiofrequency ablation of AV node with pacemaker implantation Electrical synchronized cardioversion Pharmacologic cardioversion

 
In summary, atrial fibrillation and atrial flutter are two serious arrhythmias that should be evaluated and treated to prevent serious adverse events such as stroke. The main differences between the two rhythms are (Nall, 2024):

• AF is more common than atrial flutter.
• The electrical signals in AF are disorganized and chaotic whereas the signals in atrial flutter are organized.
• In AF, there is no discernable P wave and an irregular ventricular rate is observed on ECG. In atrial flutter, a “sawtooth” pattern will appear on ECG with a regular ventricular rate.
• Symptoms of atrial flutter may be mild compared to AF.
• Individuals with aflutter may develop AF, even after treatment.

References 

Nall, R. (2024, April 5). Atrial flutter vs. atrial fibrillation. Healthline. https://www.healthline.com/health/atrial-flutter-vs-atrial-fibrillation

Kumar, K. (2023, October 31). Atrial fibrillation: Overview and management of new-onset atrial fibrillation. UpToDate. https://www.uptodate.com/contents/atrial-fibrillation-overview-and-management-of-new-onset-atrial-fibrillation 
 
Phang, R. & Prutkin, J.M. (2024, March 7). Overview of atrial flutter. UpToDate.
https://www.uptodate.com/contents/overview-of-atrial-flutter  
 

 

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