What causes Arterial fibrillation?
Abnormal heart rhythms that occur sporadically or persistently are known as atrial fibrillation and flutter. When these very fast electrical discharge patterns occur they cause the atria to contract extremely rapidly which in turn causes the ventricles to contract faster and much less efficiently than is normal. The contractions are so fast that the walls of the arterial will quiver which decreases the amount of blood pumped to the ventricles.
Symptoms of these disorders may include weakness, fainting or shortness of breath. In an elderly person this condition may cause heart failure, shock or chest pain. If the ventricle rate is less than 120 beats per minute it is possible that no symptoms will be present. But if the rate is higher it can produce unpleasant palpitations or even chest discomfort. At higher rates or with atrial fibrillation, it is quite possible that the person will be aware of the irregularities in their heart rhythms.

What is Arterial flutter?
 Arterial flutter produces an arterial rhythm and ventricular rhythm that are both regular. The ventricles tend to beat more slowly than the atria. This is caused by the atrio-ventricular node and the bundle of HIS which can not properly conduct electrical impulses at such a fast rate. Thus only every second to fourth impulse gets through causing the ventricles to beat too fast to fill completely with blood. This in turn causes inadequate amounts of blood to be pumped out of the heart. As the blood pressure falls, heart failure may occur.
Usually no symptoms are present, but it is generally the result of some problems like  rheumatic heart disease, high blood pressure, alcohol abuse, coronary artery disease or the excessive use of a thyroid hormone which is often taken for hyperthyroidism. With arterial fibrillation which causes the atria to not empty completely into the ventricles with each heart beat, there is a possibility over time that some blood may stagnate inside the atria and form clots. When this happens pieces of the clot have been known to break off and pass into the left ventricle. These pieces will then continue into the general circulation where they can block smaller arteries. These small blockages are called emboli. In most cases this will occur after arterial fibrillation has converted to a normal rhythm whether normally or with treatment from a doctor. These blockages, when they occur in an artery in the brain have been known to cause strokes. In rare cases, a stroke is the first sign of this condition.
Treatment: The possible treatment is to control the rate at which the ventricles contract and also to restore a normal heart rhythm. Electric shock known as cardioversion is the best treatment and in some cases a normal rhythm is restored using anti-arrhythmic drugs.