From the Guidelines
Yes, everyone has an atrial appendage, which is a normal anatomical structure present from birth. The atrial appendage is a small, ear-shaped pouch or sac that protrudes from each atrium of the heart. Most people have both a left atrial appendage (LAA) and a right atrial appendage (RAA), which serve as reservoirs that can expand to accommodate increased blood volume. The left atrial appendage is particularly significant clinically because it can be a site where blood clots form in patients with atrial fibrillation, potentially leading to stroke if these clots dislodge and travel to the brain, as noted in the guidelines for the primary prevention of stroke 1. Some key points to consider about the atrial appendage include:
- The left atrial appendage is a common site for thrombi formation in patients with atrial fibrillation, which can increase the risk of ischemic stroke 1
- The presence of an atrial appendage is not a disease or condition in itself, but rather a normal part of the heart's anatomy
- Variations in size and shape of the atrial appendages can occur between individuals, but they are standard anatomical features of the human heart. The clinical significance of the atrial appendage is highlighted in the context of atrial fibrillation, where the risk of stroke can be reduced by procedures to close or remove the left atrial appendage, as mentioned in the guidelines for the primary prevention of stroke 1.
From the Research
Atrial Appendage Presence
- The presence of an atrial appendage is not explicitly stated in the provided studies as a universal feature in all individuals.
- However, the studies discuss the left atrial appendage (LAA) and right atrial appendage (RAA) in the context of atrial fibrillation, stroke, and thromboembolism, implying that these structures are present in the population being studied 2, 3, 4, 5, 6.
Anatomical Variations
- A study on the macroscopic morphology of the right atrial appendage in humans found that it is triangle-shaped with a mean area of 2.73 cm2, and has a dense net of muscle fascicules inside the chamber 5.
- The left atrial appendage is described as a unique cardiac structure with distinct anatomic and functional features, differing from the left atrium in structure, function, and hormonal activity 6.
Clinical Significance
- The left atrial appendage is identified as the source of more than 90% of cardiac-based emboli, particularly in atrial fibrillation, highlighting its clinical significance in stroke prevention 2, 3, 6.
- The presence of an atrial appendage is relevant to the development of thromboembolic events, and its occlusion has emerged as a therapeutic alternative to oral anticoagulation in patients with atrial fibrillation 3.