• Normal coronary blood flow: 1 mL per gram of myocardium per minute
• Oxygen extraction from coronary bed: 75% at rest, 100% during stress
• Coronary flow primarily during diastole
• Mean coronary resistance is 3-6 times the totally vasodilated value, implying extreme vasodilator reserve
• Atherosclerosis progression: Intimal incorporation of lipids → expanding plaque with fibrosis and calcification → finally rupture of plaque causing thrombosis → acute infarction
• Subtotal occlusions important in pathogenesis of unstable angina
• Usual pattern
-Short, proximal stenoses of left coronary artery
-In right coronary artery, disease more diffuse, involving proximal and middle portions of artery
-Patients with type 1 diabetes mellitus have diffuse disease
• Blood flow may be adequate at rest; exercise and stress may produce ischemia
• Acute coronary insufficiency (angina pectoris): Immediate decrease in myocardial work
• After only 15 minutes of reversible ischemia, may take 24-48 hrs for complete recovery
• Coronary artery disease responsible for 20% of all deaths
• Cardiovascular disease accounts for > 40% of all deaths
• Atherosclerosis identified in up to 50% of autopsies of patients in second decade of life
• Risk factors
• Coronary mortality rate directly proportional to number of vessels affected and LV function
• Retrosternal chest pain
-Frequently radiates down left arm, left neck, occasionally right arm, mandible, ear
• Exercise, cold exposure, eating can precipitate symptoms
• Stable, progressive, or unstable angina
• Pulmonary edema from ischemia (poor prognosis)
• Some have no symptoms (silent myocardial ischemia)
-Normal in 50% of patients
-May have inverted T waves, ST segment abnormalities, or Q waves at rest
• Consider other causes of chest pain, including gastroesophageal reflux disease, aneurysms, aortic dissection
• Risk reduction: Smoking cessation, hypertension control, lipid reduction
• Percutaneous transluminal coronary angioplasty (> 90% successful but repeat interventions common)
• Operative therapy: Complete revascularization associated with improved outcome
• Evaluate carotid bruits, renal function, respiratory status, coagulation studies
Conventional Coronary Artery Bypass Grafting (CABG)
• Internal mammary (preferred), saphenous vein, or radial artery used to bypass on average 3-4 coronary vessels
• Graft patency affected by smoking, low-density lipoprotein
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