disease characterized by an inadequate supply of oxygen-rich blood to the heart muscle (myocardium) because of narrowing or blocking of a coronary artery by fatty plaques (see atherosclerosis). If the oxygen depletion is extreme, the effect may be a myocardial infarction ( heart attack); if the deprivation is insufficient to cause infarction (death of a section of heart muscle), the effect may be angina pectoris, or spasms of pain in the chest. Both conditions can be fatal because they can cause heart failure or ventricular fibrillation—an uncontrolled and uncoordinated contraction of the ventricles (the lower chambers of the heart) that induces sudden death. Middle-aged men, especially those with a family history of the disease, are particulary vulnerable to developing coronary heart disease, as are individuals with hereditary conditions such as familial hypercholesterolemia (a disorder in which the body's tissues are incapable of removing cholesterol from the bloodstream). coronary artery bypass surgery or balloon angioplasty may be necessary if medications and diet and lifestyle changes such as frequent exercise and cessation of smoking are not effective.