Atrial flutter and atrial fibrillation are both conditions which affect the upper chambers, or atria, of the heart. In both atrial fibrillation and flutter the atria contract much faster than normal, with the result that blood is not effectively pumped into the lower chambers, or ventricles, of the heart. The rapid atrial contractions of atrial fibrillation occur in an irregular fashion and have a chaotic rhythm, while in atrial flutter the contractions are regular. With atrial fibrillation the ventricles beat irregularly, but, in the case of atrial flutter, they can beat either in a regular or irregular fashion. Both conditions carry an increased risk of heart failure or stroke.
The atria contract so quickly when this happens that upper heart quivering occurs. Normally, the muscles in the walls of the heart chambers contract in response to electrical impulse signals originating from the SA node, or pacemaker, inside the right atrium. The impulses spread through the atria, causing them to contract, before passing through what is known as the AV node and into the ventricles. In atrial fibrillation and flutter, random electrical impulses arise from the heart muscle and override the SA node, causing abnormal contractions.
Similar complications may occur when this happens. The ventricles beat more quickly than usual, although they do not contract as rapidly as the atria. They may not fill properly and the amount of blood ejected from the heart with each beat could decrease, with a risk of heart failure. The atria may not empty completely, and blood remaining in the chambers could clot. If a clot travels out of the heart and lodges in an artery in the brain, a stroke could result.
Atrial flutter is not as common as atrial fibrillation, but both conditions occur more frequently with increasing age. High blood pressure frequently causes both disorders. Symptoms of both atrial fibrillation and flutter can be similar, and may include palpitations, breathlessness, tiredness and chest pain. The pulse in both conditions is typically faster than normal, but is likely to feel irregular in a person with atrial fibrillation and regular in someone with atrial flutter.
Treatment of this condition involves reducing the heart rate and establishing what is called a normal sinus rhythm. This includes attending to any underlying conditions which could be causing the problem, such as a heart defect or hyperthyroidism. Drugs can be used to lower the heart rate and correct the unsynchronized heart rhythm, and medication to prevent blood clots may also be given. A treatment called cardioversion administers electric shocks to restore the heart's normal rhythm. For people with atrial flutter, a method known as catheter radiofrequency ablation may be used to destroy areas of tissue in the heart which are responsible for the abnormal beats.