Congestive heart failure (CHF), also known as heart failure, is a condition where the heart muscle is unable to pump sufficiently to maintain blood flow to meet the body's needs. It is classified by the New York Heart Association system from Class I (no symptoms) to Class IV (symptoms at rest). The American College of Cardiology/American Heart Association categorizes heart failure into four stages from asymptomatic structural heart disease to end-stage disease. Common causes include ischemic heart disease, hypertension, diabetes and obesity. Symptoms vary depending on whether the left or right side of the heart is affected but may include shortness of breath, fatigue, swelling and coughing. Diagnosis involves imaging, blood tests and physical exams.