Aortic Stenosis By Guy P Armstrong, MD, Waitemata District Health Board and Waitemata Cardiology, Auckland Reviewed / Revised Jul 2022 | Modified Sep 2022 View Patient Education Etiology Pathophysiology Symptoms and Signs Diagnosis Prognosis Treatment Key Points Topic Resources Aortic Stenosis Murmur (Crescendo... Aortic Stenosis Types of Severe Aortic Stenosis Aortic Stenosis Aortic stenosis (AS) is narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole.