Aortic valve disease is when the valve between the aorta (main artery to the body) and the left ventricle (pumping chamber in the heart) doesn’t work properly. Sometimes, the valve doesn’t close all the way, causing blood to flow backward into the heart (regurgitation), or the valve is narrow and doesn’t allow enough blood to leave the heart and flow to the body (stenosis). The disease is either present at birth or develops over time.