What is atrial flutter?

Updated: Nov 09, 2018
  • Author: Jesse Borke, MD, FACEP, FAAEM; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Atrial flutter is the second most common tachyarrhythmia, after atrial fibrillation. This condition has traditionally been characterized as a macroreentrant dysrhythmia with the re-entrant loop just above the atrioventricular (AV) node in the right atrium. Atrial rates are generally between 240 and 360 beats per minute (bpm) without medications.

The electrocardiogram (ECG) usually demonstrates a regular rhythm, with P waves that can appear sawtoothed (see the image below), also called flutter waves, usually best visible in lead II. The QRS complex is narrow if there is no aberrancy. Because the AV node cannot conduct at the same rate as the atrial activity, some form of conduction block is often seen, typically 2:1 (most common), 3:1, or 4:1. This block may also be variable and cause atrial flutter to appear as an irregular rhythm.

Twelve-lead ECG showing atrial flutter with variab Twelve-lead ECG showing atrial flutter with variable block.

Atrial flutter can arise from conditions that lead to atrial dilatation. These include chronic left-sided congestive heart failure, pulmonary embolus, valvular heart disease (especially mitral and tricuspid diseases), and septal defects. Metabolic conditions such as hyperthyroidism and alcoholism can also cause atrial flutter. Rarely, atrial fibrillation or atrial flutter may be due to pericardial disease or effusion or caused by carbon monoxide intoxication.

Twelve-lead ECG of type I atrial flutter. Note neg Twelve-lead ECG of type I atrial flutter. Note negative sawtooth pattern of flutter waves in leads II, III, and aVF.

See Atrial Flutter and Pediatric Atrial Flutter for complete information on these topics.

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