The heart consists of four chambers that work together in perfect harmony to ensure smooth and continuous operation to provide every part of the body with blood carrying oxygen and many nutrients needed by tissues and organs. The upper two chambers of the heart are called atria while the lower two chambers are called ventricles. The right atrium receives "used", unoxygenated blood from the body and the right ventricle pumps it to the lungs. The left atrium receives the oxygenated blood from the lungs and the left ventricle pumps it out to a major artery called the aorta, which then delivers the blood to the body through an intricate network of blood vessels.
Congestive heart failure (CHF) usually results from myocardial (heart muscle) dysfunction as well as progressive cardiac remodeling (alteration of structure and function of the heart). When the heart muscle is not able to pump enough blood to satisfy the metabolic needs of the tissues, blood moves through the heart and body more slowly resulting in increased pressure in the heart. In response to the decline of pumping capacity, compensatory mechanisms are activated in an effort to maintain cardiac function, such as the renin-angiotensin-aldosterone system and the sympathetic nervous system. These systems may continue to be activated for months or years. During this time, there are no overt signs of heart failure and the individual is considered to be asymptomatic. Over time, it is thought that the compensatory mechanisms themselves can cause further damage to the heart and circulation through a process called remodeling that results in enlargement of the heart, thickening and/or thinning of cardiac walls, and further declining capacity of the heart to pump. As the heart becomes weaker and the pumping becomes increasingly less effective, a transition takes place and the individual develops symptomatic heart failure. As pressure in the heart and lungs build up, the kidneys are affected and may cause the body to retain fluid. If the fluid buildup continues in the legs, feet, lungs, and organs, the body becomes "congested" with fluid; hence, "congestive heart failure".
Heart failure may be due to a primary disease of the heart muscle that is called cardiomyopathy, or may be secondary to diseases that affect the heart muscle such as hypertension, coronary heart disease, or various diseases of the heart valves. Heart failure may develop gradually over many years or may occur quickly following a heart attack or a disease of the heart muscle.
Heart failure may be either left-sided or right-sided:
Left-Sided Heart Failure
Left-sided heart failure, also called left ventricular heart failure, is a failure of the left ventricle (the larger chamber that pumps blood to the body) to function properly, which forces the left side to work harder in order to pump the correct amount of blood. This may result in fluid accumulating in the lungs (pulmonary edema) and, with the ensuing edema (fluid retention), the patient experiences shortness of breath. This is the most common type of heart failure.
