In one sentence, describe what the following article is about:

The key to understanding CHF is the word congestion. Congestion develops when the heart is unable to pump blood as quickly as it should.This may occur because the heart muscle is too weak or because blood vessels throughout the body are narrowed and constricted, causing the heart muscle to become exhausted.  Poorly functioning valves may cause the chamber to dilate from blood back-up, thinning the myocardium, decreasing pumping ability and increasing the workload. Normally, the ventricles of the heart contract (while the atria are relaxing) allowing for the filling and emptying of each chamber. If the muscle wall of the left ventricle cannot contract properly, some of the blood is left in the ventricles. Blood then backs up into the pulmonary vessels, the pressure within those vessels increases and fluid leaks into the lung tissue, producing congestion and eventually pulmonary edema (swelling) .If not corrected, the back-up of blood will soon lead to failure of the right side of the heart. This condition is called congestive heart failure. Congestive heart failure is actually a complication of other cardiovascular conditions rather than a disease in itself. CHF is frequently caused by a defect in myocardial contractions resulting in myocardial failure. However, CHF may also be triggered by acute hypertensive crisis, rupture of an aortic valve cusp or a massive pulmonary embolism. There are a number of things that can be done to treat CHF - these usually involve correcting the underlying cause of the heart failure, such as hypertension or dysrhythmia.  Follow a strict low sodium diet and avoid drinking too much fluid. Get plenty of bed rest and gradually re-introduce slower-paced activity. Avoid emotional stress. Take prescription medications to treat CHF, such as diuretics, vasodilators, dobutamine and ACE inhibitors.

Summary:
Understand what congestive heart failure means. Understand what causes congestive heart failure. Familiarize yourself with the treatment for CHF.