Coronary heart disease (CHD), or coronary artery disease, develops when the coronary arteries become too narrow. The coronary arteries are the blood vessels that supply oxygen and blood to the heart. CHD tends to develop when cholesterol builds up on the artery walls, creating plaques These plaques cause the arteries to narrow, reducing blood flow to the heart. A clot can sometimes obstruct the blood flow, causing serious health problems. Coronary arteries form the network of blood vessels on the surface of the heart that feed it oxygen. If these arteries narrow, the heart may not receive enough oxygen rich blood, especially during physical activity. CHD can sometimes lead to heart attack. It is the “most common type of heart disease in the United States,” where it accounts for more than 370,000 deaths every year. If pieces of plaque break off or rupture, platelets will cluster in the area in an attempt to repair the blood vessel. This cluster can block the artery and reduce or block blood flow, which may lead to a heart attack.