Atrial flutter overview

# Overview
Atrial flutter is an abnormal heart rhythm that occurs in the atria of the heart.  When it first occurs, it is usually associated with a fast heart rate or tachycardia, and falls into the category of supra-ventricular tachycardias.  While this rhythm occurs most often in individuals with cardiovascular disease (eg: hypertension, coronary artery disease, and cardiomyopathy), it may occur spontaneously in people with otherwise normal hearts.  It is typically not a stable rhythm, and frequently degenerates into atrial fibrillation.  However, it does rarely persist for months to years.

# Classification
There are two types of atrial flutter, the common type I and rarer type II. Most individuals with atrial flutter will manifest only one of these.  Rarely someone may manifest both types; however, they can only manifest one type at a time.

# Pathophysiology
Atrial flutter is a form of cardiac arrhythmia characterized by an atrial rate ranging from 240 to 400 beats per minute.  It is the most common atrial tachycardia after atrial fibrillation, with a uniform and regular continuous wave-form.  It is caused by a reentrant rhythm in either the right or left atrium.  Some degree of atrio-ventricular block is usually associated with atrial flutter.  Similar to atrial fibrillation the rate of ventricular beating depends on the degree of conduction through the atrio-ventricular node.  Usual scenario is 2:1 or 4:1 conduction but occasionally there can exist a 1:1 conduction.

# Causes
Atrial flutter is caused by a re-entrant rhythm in either the right or left atrium.  Causes of atrial flutter can be grouped into two categories, intrinsic diseases and abnormalities of the heart and diseases elsewhere in the body that can affect the heart.  Most common causes of atrial flutter are coronary artery disease, hypertensive heart disease and valve abnormalities of the heart.

# Differentiating Atrial flutter from other Diseases
Atrial flutter should be differentiated from atrial fibrillation, multifocal atrial tachycardia, SVT and wide complex tachycardia.  An electrocardiogram artifact from tremor also can be confused with atrial flutter.

# Epidemiology and Demographics
Atrial flutter is more common in elderly males.  Men are affected 2.5 times more than women.  The incidence of new cases every year in the USA is 200,000.

# Risk Factors
Major risk factors for the development of atrial flutter are elderly age, presence of heart disease and high blood pressure.

# Diagnosis

## History and Symptoms
Common symptoms in patients with atrial flutter are palpitations, fluttery sensation in the chest, breathlessness and lightheadedness.

## Physical Examination
The hemodynamic stability of the patient should be first assessed.  The patient should also be examined for the presence of reversible causes of atrial flutter.

## Electrocardiogram
Characteristic electrocardiographic findings in a patient with atrial flutter include; an atrial rate from 250-350 beats per minute, a "sawtooth" appearance to the tracings due to rapid regular undulations (F waves), and a variable ventricular rate depending on AV conduction.

## Echocardiography
Transthoracic echocardiography (TTE) is used in atrial flutter to evaluate the sizes of left  and right atria.  Transesophageal echocardiography (TEE) is used to evaluate the presence of thrombus and selection of candidates for cardioversion.

# Treatment

## Medical Therapy
The management of atrial flutter is similar to that of atrial fibrillation with primary goals being control of ventricular rate, restoration of sinus rhythm, and prevention of recurrent episodes and thromboembolic episodes. In the setting of unstable hemodynamics immediate electrical cardioversion is recommended.  because of the high success rate and low complication rate radiofrequency ablation is considered superior to medical therapy in atrial flutter.