Atrial fibrillation occurs when action potentials fire very rapidly within the pulmonary veins or atrium in a chaotic manner. The result is a very fast atrial rate — about 400 to 600 beats per ...

Left atrial enlargement (LAE) is when the left side of the heart enlarges or swells, leading to breathlessness, fatigue, and other symptoms. It often affects people with high blood pressure and ...