Congestive heart failure is a complex clinical syndrome characterized by abnormalities of left ventricular function and neurohormonal regulation. It occurs when the heart cannot pump enough blood to meet the body's needs. The pathophysiology involves compensatory mechanisms like increased sympathetic discharge and activation of the renin-angiotensin-aldosterone system which initially help but eventually worsen the heart's function. Congestive heart failure can be classified based on cardiac output level and the side of heart involved. Treatment focuses on relieving symptoms through diuretics, vasodilators, and other drugs while also arresting disease progression with ACE inhibitors, beta-blockers, and aldosterone antagonists.