Understanding Aortic Stenosis Aortic stenosis is one of the most common and serious valve diseases. It occurs when the aortic valve opening becomes narrowed, making it harder for blood to leave the heart and reach the body. At first, the heart compensates. Over time, that compensation fails — and symptoms appear. Aortic stenosis prognosis: What 6 facts should you know? Heart-valve-surgery.com n.d. https://www.heart-valve-surgery.com/aortic-stenosis-prognosis.php (accessed Feb