What is heart disease? Heart disease, or cardiovascular disease, is a general name for a wide variety of diseases, disorders and conditions that affect the heart and blood vessels. Heart disease is the number one cause of death in the United States, according to the Centers for Disease Control and Prevention (Source: CDC). The heart is composed of muscle tissue that requires a steady supply of oxygen in order to pump blood effectively throughout the rest the body. Heart diseases can damage the coronary arteries, which provide oxygen-rich blood to the heart muscle. Heart diseases can also impair the functioning or structure of the heart and blood vessels. Coronary artery disease causes most heart attacks and is the most common form of heart disease. The types of heart disease include: Atherosclerosis is a buildup of cholesterol, calcium and blood clotting material on the walls of the arteries. The material that builds up is called plaque. Cardiac arrhythmia is an abnormal heart rhythm. Cardiomyopathy is a weakened and enlarged heart muscle. Congenital heart defect is a problem with the structure of the heart. Coronary artery disease is a narrowing of the coronary arteries that supply the heart. Heart attack (myocardial infarction) is a lack of oxygenated blood to the heart muscle. Heart failure is a condition in which the heart has been damaged from a heart attack or other type of heart disease. Heart valve disorder is a malfunctioning heart valve that causes abnormal stress on the heart. Myocarditis is an infection of the middle layer of the heart wall. Pericarditis is an infection of the lining that surrounds the heart. Left untreated, heart disease can result in serious complications, such as lethal cardiac arrhythmias, severe heart failure, cardiac arrest, and death. Some complications can occur suddenly and require immediate treatment. Immediate emergency treatment best minimizes the risk of complications. Seek immediate medical care (call 911) if you, or someone you are with, have chest pain, difficulty breathing, or palpitations, which may be combined with dizziness, sweating, fainting, and anxiety.