Coronary Heart Disease is also known as atherosclerotic heart disease, coronary artery disease, and ischaemic heart disease. It comes about as the result of atheromatous plaques clogging the arteries that supply the heart's muscle, which is known as the myocardium. The symptoms of coronary heart disease often do not reveal themselves until several decades after the fact, oftentimes in the result of a severe heart attack. After years of accumulation the plaques can rupture, and thus limit the amount of blood that flows to the heart muscle, resulting in the heart attack. Coronary heart disease is the leading cause of sudden death. For men and women of advanced age, it is the most common cause of death.
When it comes to heart disease, atherosclerotic heart disease entails a wide spectrum. At one end you have asymptomatic people whose disease is characterized by atheromatous streaks inside the walls of the coronary arteries. The streaks do not obstruct the blood flow, but rather represent the earliest stage of atherosclerotic heart disease. During this phase of the disease, a coronary angiogram may or may not show any signs that it is present. This is due to the fact that the coronary artery's lumen has not decreased in caliber.
As the years pass, the streaks will increase, becoming thicker and thicker. First the atheromatous plaques expand into the artery walls; then they expand in to the lumen of the vessel. This affects the blood flow through the arteries. Initially, it was thought that atheromatous plaques grow via a slow process. But in recent years, it has been learned that the buildup of plaque might be complimented by small ruptures that cause a sudden increase in plaque owing to the accumulation of thrombus material.
When less than seventy percent of the vessel's diameter is obstructed, symptoms of obstructive coronary artery disease will rarely appear. It is when over seventy percent of the vessel's diameter is obstructed by atheromatous plaques that the person will begin developing symptoms. This stage is called ischemic heart disease. These signs start to make themselves felt during times when the heart is given an increased workload. Exertional angina and decreased exercise tolerance count among the chief symptoms.
As the disease wears on, it may result in an almost total obstruction of the coronary artery's lumen. This limits the flow of blood carrying oxygen to the myocardium. Usually, when afflicted with this phase of the disease, individuals will have suffered from one or several heart attacks. They will also display signs of chronic coronary ischemia. These include symptoms of flash pulmonary edema and angina at rest.
We should be clear that there exists a difference between myocardial infarction and myocardial ischemia. The term "ischemia" refers to the disorder wherein the amount of oxygen that is supplied to a tissue is not sufficient for that tissue's needs. When the myocardium is afflicted with ischemia, it is unable to function properly. When it afflicts large portions of the myocardium, the organ's relaxation and contraction can be impaired. "Infarction" implies that the tissue has died because of a lack of oxygen rich blood.