Heart failure is defined as the inability of the heart to pump enough blood to meet the body's needs. It occurs when there is insufficient cardiac output to supply the metabolic demands of the body's tissues and organs. Heart failure is commonly termed congestive heart failure since symptoms of increased venous pressure are often prominent. It can result from several cardiac diseases and causes reduced pumping ability of the heart. The body initially tries to compensate through mechanisms like the Frank-Starling mechanism and neurohormonal activation, but eventually the heart cannot keep up with demands and clinical heart failure ensues.