Heart Surgery Patient Guide
Circulation of Blood, Part 2
As the de-saturated blood passes through the lungs, the carbon dioxide that was added to the red blood cells by the body's organs is exchanged for a new supply of oxygen. The newly oxygenated blood then flows from the lungs to the left atrium, which is the receiving chamber on the left side of the heart. The valve located in the left atrium is the mitral valve. As the left atrium fills with the newly oxygenated blood, the mitral valve remains closed.
As the pressure changes within the left atrium and left ventricle, the mitral valve opens, allowing the oxygenated blood to flow into the left ventricle. As the left ventricle fills, the pressures in the left atrium and left ventricle begin to change. Once the left ventricle is filled, the mitral valve closes as the left ventricle begins to contract. By closing at this time, the mitral valve prevents the oxygenated blood in the left ventricle from flowing back to the lungs.
The left ventricle is the pumping chamber of the left side of the heart and is the most muscular portion of the heart. When you hear some say their blood pressure is 120 over 80, it is the left ventricle that is generating these pressures. As the left ventricle contracts, the oxygenated blood leaves the heart and crosses the aortic valve, which is the valve that helps to control the flow of blood out of the heart to the body. The oxygenated blood leaving the left ventricle and crossing the aortic valve enters the main artery of the body, known as the aorta. The aorta then travels to the body's organs via branches that carry the blood to the individual organs. Once the left ventricle has emptied, the aortic valve closes to keep the blood that has just been pumped out from re-entering the heart.
The valves of the heart open and close in a sequential fashion and are critical to normal heart function. Various conditions can affect the function of the heart valves. In general, the two main categories of valve problems are: a) Stenosis and (b) insufficiency or regurgitation. Stenosis is a condition in which the valve narrows and does not open fully. Insufficiency or regurgitation is a condition that prevents the valve from fully closing. Both stenosis and insufficiency may over time cause problems and eventually require surgery to either repair the valve if possible, or replace the valve if a satisfactory repair cannot be performed.