Atrial Fibrillation

Learn about Atrial Fibrillation, the most common chronic arrhythmia. It is characterized by disorganized atrial contraction and electrical activity.

Overview

Atrial Fibrillation is the most common chronic arrhythmia. It is characterized by disorganized atrial contraction and electrical activity. It occurs when the atrial chambers of the beat rapidly and irregularly, resulting in tachycardia and an irregular heart rhythm. 

Pathophysiology

Atrial Fibrillation (AF) can be associated with abnormal atria due to underlying cardiac diseases, such as ischemic heart disease, hypertension, valvular heart disease and cardiomyopathies, or non-cardiac causes such as electrolyte disturbances, pulmonary embolism, and acute infections. Fibrosis and inflammation that causes morphological changes in the atria can cause a difference in refractory periods within the atrial tissue, promoting electrical re-entry resulting in AF.

Audio

On auscultation, a variable intensity of S1 between beats and an irregular rhythm is heard.

ECG

The key ECG findings of AF include the absence of P waves and the presence of an irregularly irregular rhythm. 

When the inter-R period is too short, there is not enough time for the previous mechanical pump diastolic cycle to complete and restart a new mechanical pump systolic cycle. Even though the ECG tracing shows a new cycle, not all are “conducted” into a mechanical pump action which results in heart sounds. The ECG signals that do not correspond with mechanical action are referred to as “non-conducted narrow complexes”.

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