Unhealthy heart, conceptual image. The main blood vessels of the heart include the vena cava (upper left), where blood arrives form the body. Blood is pumped from the left side of the heart via the lungs to the right side of the heart using the pulmonary system of blood vessels (upper right). The oxygenated blood is then pumped to the rest of the body through the main artery, the aorta (arched, upper centre), which has three smaller arteries branching from it at top centre. The heart muscle itself is supplied with fresh blood through the coronary arteries, seen on the surface of the heart. A poor diet and lack of exercise can lead to an unhealthy heart.