Heart is a hollow muscular organ that pumps the blood through the circulatory system by rhythmic contraction and dilation. In vertebrates there may be up to four chambers (as in humans), with two atria and two ventricles. he heart is obviously considered the most important organ. So when someone has a heart condition, the situation couldn’t be more serious. Great Big Story reports that Andrew Jones lost the function of his heart. Incredibly, doctors are able to sustain him completely with an artificial heart while he waits for a transplant. He is the only body builder in the world with literally no pulse.