Acute heart failure refers to a condition in which the heart's function is suddenly impaired, causing it to beat too weakly to effectively transport oxygenated blood throughout the body. Heart disease can lead to acute heart failure via cardiac structural changes such as narrowed blood vessels, enlarging of the heart itself, stiffening of its muscles, etc. Symptoms include chest pain and tightness, difficulties or discomfort with breathing, cough, swelling in the extremities, and unconsciousness, and must be met with emergency medical care immediately.