Flutter refers to a rapid but organised electrical activity in a heart chamber, more regular than fibrillation but faster than normal rhythm. The term most commonly refers to atrial flutter, though ventricular flutter also exists as a distinct and more dangerous condition.
Atrial flutter is a supraventricular arrhythmia in which the atria beat at around 250 to 350 times per minute, driven by a circular electrical circuit (re-entry circuit) rather than the normal pacemaker. Because the atrioventricular (AV) node cannot conduct every beat, the ventricles typically respond at a ratio (for example 2:1 or 3:1), producing a regular ventricular rate of around 75 to 150 beats per minute. Atrial flutter may feel like palpitations, breathlessness, or fatigue. It is closely related to atrial fibrillation and the two conditions often occur in the same person. Atrial flutter carries a stroke risk and is managed with anticoagulation, rate or rhythm control, and often catheter ablation, which has a high success rate.
Ventricular flutter is a very rapid, regular ventricular arrhythmia at around 200 to 300 beats per minute. It represents a transition between ventricular tachycardia and ventricular fibrillation, with the heart rate so fast that the ventricles cannot fill effectively and cardiac output collapses. Ventricular flutter is a life-threatening emergency that requires immediate defibrillation, either by an AED or by an ICD in people who have one.
For cardiac arrest survivors and those with ICDs, any fast or irregular heart rhythm that causes symptoms should be reported to the cardiac team promptly.
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