Atrial fibrillation is the most common sustained cardiac arrhythmia. In arrhythmia the atria beats rapidly, chaotically and ineffectively. It is a kind of heart malformation that occurs due to abnormal rhythm of the heart.
A coordinate contraction of all the heart muscles at once, which is required for the pumping cycle leads to a normal rhythm of the heart. But abnormal rhythm of the heart results from cardiac impulses that have gone wild and violent with the auricular muscle mass and ventricular muscle mass, which are respectively called Atrial fibrillation and Ventricular fibrillation.
Since auricular muscle mass is entirely separated from the ventricular muscle mass and insulated from each other by fibrous tissue, these two fibrillations are entirely independent of each other.
The mechanism of atrial fibrillation is identical with that of ventricular fibrillation except that the process occurs in the atrial muscle mass instead of ventricular mass. A very frequent cause of atrial fibrillation is atrial enlargement. It results due to heart valve lesions that prevent the atria from emptying adequately into the ventricles.
In atrial fibrillation the atria become useless as primer pumps for the ventricles. Even so, blood flows positively through the atria into the ventricles and the efficiency of ventricular pumping is decreased only 20 to 30 percent.
Therefore in contrast to the lethality of ventricular fibrillation, a person can live for months together or even years with atrial fibrillation though at a reduced efficiency of overall heart pumping. The onset of atrial fibrillation can cause palpitation. It may precipitate or aggravate cardiac failure in, patients with an abnormal heart, especially that with mitral stenos is or poor left ventricle function.
Heart has four chambers, left & right ventricles and left & right atria which are synchronized to act together. A condition in which synchronism does not take place is known as fibrillation. Fibrillation of atrial muscles called as atrial fibrillation, fibrillation of the ventricular muscles is termed as ventricular fibrillation. In atrial fibrillation the ventricles functions normally, but respond with an irregular rhythm. In atrial fibrillations circulation is maintained, although not as efficiently. Ventricular fibrillation is more dangerous, as the ventricles are unable to pump the blood. There are many methods of correcting fibrillation mechanically, including A.C. defibrillation & D.C. defibrillation.
This process of applying counter shock is called A.C defibrillation. A.C. defibrillation cannot be successfully used to correct atrial fibrillation.
D.C. defibrillation is more successful to treat ventricular fibrillation, and can also be used for correcting atrial fibrillation. The D.C. method requires fewer repetitions and is less likely to harm the patient.