3D CT scan of the aortic valve in the heart, showing incomplete closing of the valve. This is known as aortic insufficiency, and leads to oxygenated blood flowing back into the heart, causing lowered levels of oxygen in the bloodstream around the body. This causes breathlessness and other symptoms of poor circulation. The aortic valve is a tricuspid valve, formed of three flaps, which normally opens to pump blood around the body through the aorta. Treatment is generally with a valve replacement. CT scanning uses X_rays to build up a 3D picture of internal tissues.