Atrial Fibrillation

Atrial fibrillation is a rapid chaotic rhythm that originates from multiple sites within both atrial chambers. Small circuits simultaneously exist throughout the atrial chambers in a dynamic changing pattern. These circuits give rise to rapid impulses that bombard the connection between the top and bottom chambers of the heart, the AV node. Only some of these impulses can get through this structure which serves as a natural bottleneck against too rapid stimulation of the bottom chambers, the ventricles. Nonetheless, the ventricles will be stimulated in a more rapid fashion than normal and the pattern will be irregular, also differing from the norm. This rapid, irregular pattern gives rise to the symptoms of atrial fibrillation, such as palpitations, rapid heart beat, chest discomfort, shortness of breath and dizziness. Contributing to the symptoms is the failure of the atria and the ventricles to have coordinated pumping action as they do in the normal situation, which can also lead to a less efficient cardiac pump. In some individuals, failure of the atrial chambers to contract properly can make them more prone to the formation of clot which can travel to distant organs where they may cause damage.

Atrial Flutter

Atrial flutter also involves rapid firing of the electrical impulse as in atrial fibrillation, but the rhythm or heart beat is more regular or organized. The rhythm is due to reentry within the atria. The electrical impulse travels in circles arriving back at the same point, usually around 300 times per minute. Signs and symptoms often experienced with atrial flutter are similar to those of atrial fibrillation, such as a pounding heart rate or pulse, shortness of breath, or dizziness.