Heart failure can happen in two ways. The heart muscle may become weak and enlarged (systolic dysfunction). The weakened muscle doesn’t pump enough blood forward when the ventricles contract. Or, the heart muscle may become stiff (diastolic dysfunction). The stiff muscle can’t relax between contractions, which keeps the ventricles from filling with enough blood.

Your heart is a pumping muscle that works nonstop to keep your body supplied with oxygen-rich blood. Signals from the heart’s electrical system set the speed and pattern of the pump’s rhythm. Valves keep the blood moving in one direction, through the heart’s four chambers.

If you have congestive heart failure, knowing your body can help you manage your condition.