3D coloured computed tomography (CT) scan of the heart (top), kidneys (left and right centre) and aorta (main artery, large red tube descending from heart) showing aortic dissection. An aortic dissection, or tear in the aorta, typically occurs when the inner layer of the artery?™s wall weakens. Left untreated, the tear can enlarge allowing blood to pass through the tear into the middle layer of the artery wall, causing the layers to separate from one another (dissect). This can lead to the formation of a new channel, called a false lumen (green), between the two layers. The false lumen disrupts blood flow to the rest of the body, which can cause severe pain, shortness of breath, dizziness and a loss of vision. Aortic dissection can be fatal if left untreated. Treatment options include medication and surgery.