After the right ventricle contracts, pressure is low in the chamber. The Tricuspid Valve, which had been closed from the pressure generated from the ventricle's contraction, now opens as the pressure of the blood from the right atrium has built up while the Tricuspid Valve was closed. The right ventricle will again contract, closing the Tricuspid Valve again, and pushing open the Pulmonic Valve. Once the right ventricle completes its contraction, the pressure in the pulmonary artery will be higher than in the right ventricle, and the Valve will close. The valves on the left side of the heart, the Aortic Valve and the Mitral Valve however, are not working properly.
Blood returns from the lungs and empties into the left atrium.
In this illustration, the Mitral Valve opens properly when the left ventricle is finished contracting, and allows blood to flow into the left ventricle easily. When the left ventricle contracts however, blood is shown to flow back into the left atrium through the Mitral Valve. The other valve on the left side of the heart, the Aortic Valve, is also illustrated to have the other main problem associated with heart valves. In this case, the valve is thickened and perhaps calcified. Instead of being easy to open as the left ventricle contracts, the left ventricle must push very hard to open the valve and allow blood to flow out to the rest of the body.