2.3.2 Coronary Artery Disease
Failure of the coronary arteries to deliver an adequate supply of blood to the myocardium is called coronary artery disease（CAD）.Its major cause is the accumulation of plaque that causes the wall of the artery to harden（arteriosclerosis）and lose elasticity，causing reduced blood flow to your heart muscle.This plaquelike substance is composed of cholesterol，lipids，and cellular debris（atheroma）.With partial occlusion，localized areas of the heart experience oxygen deficiency（ischemia）.When the occlusion is total or almost total，the affected area of the heart muscle dies（infarction）.
The clinical signs and symptoms of myocardial infarction（MI）typically include intense chest pain（angina pectoris），profuse sweating（diaphoresis），paleness（pallor），and labored breathing（dyspnea）.An abnormally rapid heart rate（tachycardia）or an abnormally slow heart rate（bradycardia）may also accompany an MI.
When angina cannot be controlled with medication，surgical intervention may be necessary.In percutaneous transluminal coronary angioplasty（PTCA），a deflated balloon is passed through a small incision in the skin and into the diseased blood vessel.When the balloon inflates，it presses the occluding material against the lumen walls to force open the channel（Fig.2-3）.A more invasive procedure involves rerouting blood around the occluded area using a vein graft that bypasses the obstruction（coronary artery bypass graft，CABG）（Fig.2-4）.In this procedure，one end of the graft vessel is sutured to the aorta and the other end is sutured to the coronary artery below the blocked area.This graft reestablishes blood flow to the heart muscle.
Fig.2-3 Percutaneous Transluminal Coronary Angioplasty
Fig.2-4 Coronary Artery Bypass Graft(https://www.daowen.com)
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Task 4 Decide whether the following statements are true（T）or false（F）according to the text.
1.Coronary artery disease results from insufficient blood supply to the cardiac muscle.（ ）
2.Hardening of the walls of the coronary artery is less likely to be induced by the accumulation of plaques.（ ）
3.This plaquelike substance in the coronary artery consists of cholesterol，lipids，and cellular debris.（ ）
4.With partial occlusion，the cardiac muscles in localized areas die.（ ）
5.In coronary artery bypass graft surgery，the graft vessel is used to carry（ ）blood from the aorta to a point in the coronary artery distal to the blocked area.