Overview of Congestive Heart Failure (CHF)
Congestive heart failure, or heart failure, is a condition in which the heart is unable to adequately pump blood throughout the body and/or unable to prevent blood from "backing up" into the lungs.
In most cases, heart failure is a process that occurs over time, when an underlying condition damages the heart or makes it work too hard, weakening the organ. Heart failure is characterized by shortness of breath (dyspnea) and abnormal fluid retention, which usually results in swelling (edema) in the feet and legs.
Normal Blood Flow of the Heart
The heart consists of four chambers: the right atrium, the left atrium, the right ventricle, and the left ventricle, and four major valves: the mitral valve, the tricuspid valve, the aortic valve, and the pulmonary valve. Atria are relatively thin-walled chambers that receive blood from the circulatory system and from the lungs. Ventricles are muscular chambers that pump blood into the circulatory system and into the lungs.
Blood passes from the atria into the ventricles through two processes. During the "resting phase," when the ventricles are not contracting, the tricuspid and mitral valves open and allow some of the blood that has accumulated in the atria to flow passively through the valves into the ventricles. Then, the atria contract and actively pump blood out through the valves and into the ventricles. Once the ventricles fill with blood, they contract, pumping blood to the lungs and the rest of the body.
When the left ventricle cannot adequately pump blood out of the left atrium, or when one or more of the heart valves becomes leaky or narrowed (stenotic), blood can "back up" into the lungs, causing "left-sided" heart failure. When this occurs, the lungs become congested with fluid (called pulmonary edema), causing difficulty breathing and interfering with the movement of oxygen from the lungs into the bloodstream, causing fatigue.
When an abnormality or condition affects the flow of blood through the right ventricle, pressure in the blood vessels increases and fluid is forced from the blood vessels into body tissues. This "right-sided" heart failure causes swelling (edema), usually in the feet and legs, and sometimes, in the abdomen.
Incidence and Prevalence of Congestive Heart Failure
According to the American Heart Association, nearly 5 million people experience heart failure and about 550,000 new cases are diagnosed each year in the United States. Heart failure becomes more prevalent with age and the number of cases is expected to grow as the overall age of the population increases.
The condition affects 1% of people aged 50 years and older and about 5% of those aged 75 years and older. African Americans experience heart failure twice as often as Caucasians. About 10% of patients diagnosed with heart failure die within 1 year, and about 50% die within 5 years of diagnosis.