What may cause the atria to quiver in atrial fibrillation?

In atrial fibrillation, the quivering of the atria is primarily caused by rapid atrial impulses. This arrhythmia is marked by disorganized electrical signals in the atria, leading to a fast and chaotic contraction of the atrial muscles. As a result, the atria do not contract effectively but instead flutter or quiver, which significantly decreases their ability to pump blood efficiently into the ventricles.

The rapid impulses in atrial fibrillation originate from ectopic foci, which are areas in the atria that generate electrical signals independently of the normal conduction pathway. This disruption leads to the ineffective and irregular rhythm characteristic of atrial fibrillation, overwhelming the atrial muscle with continuous rapid firing without coordinated contraction.

Understanding the role of these rapid impulses is crucial for recognizing the mechanisms behind atrial fibrillation and its potential effects on hemodynamics, including the risk of stroke and other complications due to blood stagnation in the quivering atria.