Science Question 7

QUESTION:

 What is atrial fibrillation?

ANSWER :

 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 muscle 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 per cent.
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 those with mitral stenosis or poor left ventricle function.