Atrium (heart) now used for an appendage of the atrium. Humans have a four-chambered heart consisting of the right atrium, left atrium, right ventricle, and left ventricle. The atria are the two upper chambers. The right atrium receives and holds deoxygenated blood from the superior vena cava, inferior vena cava, anterior cardiac veins and smallest cardiac veins and the coronary sinus, which it then sends down to the right ventricle (through the tricuspid valve) which in turn sends it to the pulmonary artery for pulmonary circulation. The left atrium receives the oxygenated blood from the left and right pulmonary veins, which it
Artificial heart valve require replacement (but typically less in younger patients). There are three major types of mechanical valves – "caged-ball", "tilting-disk" and "bileaflet valve " – with many modifications on these designs. The first artificial heart valve was the caged-ball, which utilizes a metal cage to house a silicone elastomer ball. When blood pressure in the chamber of the heart exceeds that of the pressure on the outside of the chamber the ball is pushed against the cage and allows blood to flow. At the completion of the heart's contraction, the pressure inside the chamber drops and is lower than beyond the