A left atrium of 41 mm is considered enlarged. A cardiac ultrasound allows you to measure the inner diameter of each atrium and ventricle of the heart. A left atrium of 41mm is considered enlarged. Under normal circumstances, the left atrium of a man is under 40mm and the left atrium of a woman is under 38mm. Left atrium 41mm is considered to be enlarged in both men and women, but the magnitude of the increase is small and does not have a great impact on the patient’s health. Therefore, patients will not have obvious abnormal feelings, but need to actively find the cause of the disease, for the cause of the treatment to prevent further deterioration of the condition. At the same time, regular review should be done to dynamically observe the development of the condition. Therefore, if you find that the left atrium is 41mm, you need to cooperate with the doctor to complete the relevant examinations and make a clear diagnosis, and you should not judge the condition on your own based on a single result.