Because the right subclavian artery branches out from the aorta before the left subclavian artery under normal anatomy, it is acceptable for the blood pressure of the right hand to be slightly higher than that of the left hand. However, if the blood pressure exceeds 20 mmHg, the possibility of vascular disease is considered, for example, aortic coarctation can lead to a large difference in blood pressure between the extremities, with the right hand blood pressure being 20 mmHg higher than the left; aortitis or aortic ulcer can also cause the blood pressure of the left and right hands to be different. In addition, aortic plaque or aortic stenosis can also cause the blood pressure of the right hand to be 20 mmHg higher than that of the left hand; in addition, stenosis of the left subclavian artery, stenosis of the axillary artery, and stenosis of the brachial artery can also cause the blood pressure of the right hand to be 20 mmHg higher than that of the left hand. if a large difference in blood pressure between the upper extremities is found when measuring blood pressure, vascular disease should be considered.