Atrial Fibrillation ECG Characteristics

Atrial fibrillation (AFib) is a common type of arrhythmia characterized by the replacement of normal P waves with irregular, rapid, and chaotic electrical activity known as fibrillatory waves or F waves. These F waves typically range in frequency from 350 to 600 beats per minute and vary in size, shape, and amplitude, reflecting the disorganized electrical impulses in the atria.

Key ECG Features of Atrial Fibrillation

One of the most notable features of AFib on an electrocardiogram (ECG) is the absence of consistent P waves, which are replaced by these irregular F waves. The ventricular response is also typically irregularly irregular, meaning there is no predictable pattern to the R-R intervals. In untreated cases, the ventricular rate often ranges between 100 and 160 beats per minute, contributing to the sensation of a racing, fluttering heartbeat.

Heart Rate and Rhythm Variations

However, in certain situations such as complete atrioventricular (AV) block, the ventricular rate may become completely regular. This occurs because the AV node blocks most of the rapid atrial impulses, allowing only a fixed number to pass through to the ventricles, resulting in a more organized but still abnormal rhythm.

QRS Complex Morphology

In most cases of AFib, the QRS complex appears normal in shape, indicating that the ventricular conduction system is functioning without delay. However, when intraventricular conduction delay occurs, the QRS complexes may become wide and bizarre in appearance, mimicking bundle branch block patterns. This phenomenon, known as aberrant conduction, can complicate the interpretation of the ECG but is not uncommon in patients with AFib.

Understanding Atrial Fibrillation

Atrial fibrillation, often abbreviated as AFib, is a serious disruption of the heart's electrical system. It involves the replacement of coordinated atrial contractions with rapid, disorganized electrical impulses. This leads to ineffective atrial pumping and an irregular, often rapid heartbeat. AFib is associated with a range of symptoms including palpitations, fatigue, dizziness, and shortness of breath, and it significantly increases the risk of stroke and heart failure if left untreated.