Abstract
The function of the heart is to circulate blood in closed circuit to the lungs, where blood is oxygenated, and out to the body, where oxygen provides fuel for cellular metabolism. To accomplish this task, blood is pumped by the right heart system from the body to the lungs. Once oxygenated in the lungs, blood is returned to the left heart, where it is then pumped out to the body. Although described as a biological pump, the heart is actually two biological pumps in series, composed of a right and left heart. Each unit of the heart is composed of an atrial and ventricular chamber; their synchronized contractions result in the forward flow of blood out of the heart. Crucial to the appropriate function of the heart are four valves (the mitral, aortic, tricuspid, and pulmonic) that function in concert to maintain forward flow of blood across the heart. Diseases affecting the heart valves result in either obstruction to forward flow (stenosis) or reversal of flow across an incompetent valve (regurgitation). In either case, significant morbidity and mortality will result if no treatment is offered to the patient. © 2005 Humana Press Inc.