Dramatic comparison of the difference between a healthy aortic valve and a defective one. Labels for the aorta, aortic valve, blood flow and ventricle. Shows aortic valve open, allowing the blood to flow freely from the ventricle to the aorta. Enlargement of normal closed aortic valve, preventing backflow of blood into the ventricle. Contrasts two images of a defective aortic valve infected with bacterial endocartitis, preventing valves from closing properly, allowing blood to flow backward into the heart.