We expect to begin implanting the device in people for clinical study in the fall of 1991. Many cultures have regarded the heart as the center of a person's being. In the coming century, scientists hope to beat heart disease by a prudent combination of prevention and an arsenal of cardiovascular spare parts. Ricki Lewis has a Ph.D. in genetics and teaches biology at the State University of New York at Albany. The human heart is built of four chambers.
Valves keep blood flowing in the proper direction.
Blood that has given up its oxygen to the tissues enters the heart at the right atrium. It passes through a valve to enter the right ventricle, from which it crosses a valve to enter the pulmonary artery. The blood then travels through the lungs, picking up oxygen and losing carbon dioxide. The newly oxygenated blood then flows through the pulmonary vein to the left atrium of the heart. The blood passes through another valve to enter the left ventricle, from which it exits the heart through a valve into the aorta, the largest artery.