From the Guidelines
The most common cardiac structure driving atrial fibrillation (AF) is the pulmonary veins (PVs).
Key Findings
- The PVs are the most frequent source of rapidly firing foci that initiate paroxysmal AF, due to their unique anatomic and electrophysiological features 1.
- The electrical properties of PVs, including smaller L-type Ca2+-current and inward-rectifier current, but larger delayed-rectifier K+-currents, increase the likelihood of spontaneous ectopy and re-entry 1.
- Abnormalities in intracellular Ca2+ handling proteins and enzymes in PVs can also contribute to the development of AF 1.
- Other potential sources of abnormal activity include the posterior LA, ligament of Marshall, coronary sinus, venae cavae, septum, and appendages, but the PVs are the most common site 1.
Mechanisms
- The mechanisms of AF involve a combination of focal and reentrant activities, with the PVs playing a key role in initiating and maintaining the arrhythmia 1.
- The autonomic tone, particularly the shift towards vagal predominance, can also contribute to the development of AF 1.
- Age and cardiovascular diseases can produce complex electrical and structural changes in the atria and PVs, creating a stable arrhythmogenic substrate that facilitates the perpetuation of AF 1.
From the Research
Cardiac Structure Driving Atrial Fibrillation (AF)
- The most common cardiac structure driving atrial fibrillation (AF) is the pulmonary veins in the left atrium, due to their distinct anatomical and electrophysiological properties 2.
- The left atrium is also identified as a key location for high-frequency reentrant sources that may organize AF 3.
- Structural remodeling, including atrial fibrosis, is a main mechanism for AF persistence, and the left atrium is a critical site for this process 4, 5.
- Ectopic foci in the pulmonary veins are recognized as a trigger of AF, and their electrical isolation by ablation is a cornerstone of invasive AF treatment 4, 2.
- The relationship between clinical presentation and basic mechanisms of AF is complex, and involves interactions between atrial and ventricular function, as well as electric and structural remodeling 6.