Definition of Fibrillation

Heart Disease (Coronary Artery Disease) Slideshow

Fibrillation: In matters of the heart (cardiology), fibrillation is incoordinate twitching of the heart muscle fibers.

The difference between fibrillation and flutter is that fibrillation is not well organized while flutter is.

For example, atrial flutter is regular, organized but over-rapid contraction of the atrium of the heart. By contrast in atrial fibrillation, the atrium quivers incoordinately and ineffectually.