ATHEROSCLEROSIS

ATHEROSCLEROSIS - Manoj Singh, MD
BASICS
DESCRIPTION
The common form of arteriosclerosis in which deposits of yellowish plaques (atheromas) containing cholesterol, lipoid material, and lipophages are formed within the intima and inner media of large and medium-sized arteries
ALERT
Geriatric Considerations
• Atherosclerosis happens to all who live long enough.
• Effects and complications can be minimized and/or delayed by avoiding all risk factors possible.
Pediatric Considerations
Fatty streaks and deposits in the intima of the aortas of all children begin as early as 3 years of age.
GENERAL PREVENTION
Treat or control modifiable risk factors.
EPIDEMIOLOGY
• Incidence/prevalence in the United States
- Common, but declining steadily
- The effects on the brain, heart, kidneys, extremities, and other vital organs form the leading cause of morbidity and mortality in the United States and most Western countries.
- Complications of atherosclerosis account for half of all deaths, and one third of the deaths in persons 35-65 years of age.
• Predominant age: 35 and older
• Predominant sex: Male > Female
RISK FACTORS
• Modifiable
- Hypertension
- Tobacco smoking
- Diabetes mellitus (considered equivalence of CHD)
- Obesity
- Physical inactivity
- Decreased high-density lipoprotein (HDL) cholesterol
- Increased low-density lipoprotein (LDL) cholesterol
- Comorbidities that may increase risk
 Hypothyroidism
 Elevated homocysteine levels
 High testosterone levels in women
 Low testosterone levels in men
• Nonmodifiable
- Male gender
- Increasing age
- Family history of premature atherosclerosis
Genetics
There is a probable genetic link; many risk factors for atherosclerosis (lipid metabolism, hypertension, and diabetes) are clearly inheritable.
ETIOLOGY
• Biochemical, physiologic, environmental factors that lead to thickening and occlusion of the lumen of arteries
• Aging (some degree of atherosclerosis is universal)
• One or more of the risk factors listed under "Risk Factors"
ASSOCIATED CONDITIONS
• Essential hypertension
• Coronary arteriosclerosis
• Congestive heart failure
• Cerebrovascular accident
• Atrial arrhythmias
• Ventricular arrhythmias
• Renal failure, chronic
• Aortic dissection
• Thrombosis and embolism, arterial
• Atherosclerotic occlusive disease

DIAGNOSIS
SIGNS AND SYMPTOMS
• Characteristically silent until atheromas produce
- Stenosis
- Thrombosis
- Aneurysm
- Embolus
• For lists of possible symptoms see the following topics
- Essential hypertension
- Coronary arteriosclerosis
- Congestive heart failure
- Cerebrovascular accident
- Atrial arrhythmias
- Ventricular arrhythmias
- Renal failure, chronic
- Dissecting aneurysm
- Thrombosis and embolism, arterial
TESTS
Lab
• Associated with elevated serum cholesterol
• Elevated LDL and low HDL
Imaging
Extensively calcified atherosclerotic plaques may be identified in major blood vessels on radiography.
Diagnostic Procedures/Surgery
• Associated with hypercholesterolemia; elevated LDL and low HDL
• Arterial Doppler studies (carotid, renal)
• Angiography
• Ankle-brachial index (ABI)
Pathological Findings
• Early changes (simple), potentially reversible
- Accumulation of lipid-laden cells in the intimal layer of the artery (usually monocytes/macrophages from circulating blood)
- Lipid streaks in aorta and coronary arteries
• Late changes (complicated) usually reversible
- Atheromatous plaques with necrosis, fibrosis, calcification
- Weakening of elastic lamellae
- Neovascularization
- Arterial obstruction
- Thrombosis
• Oxidized low-density lipoprotein induces vascular smooth muscle cell apoptosis and cell death.
• Alteration of endothelial function involving mostly nitrous oxide pathways promotes platelet adhesion and aggregation, local clotting, and vascular growth and alters vascular tone.
• Decrease in elastin with aging along with collagen degeneration and increased intima-media thickness of arterial wall
TREATMENT
STABILIZATION
• Outpatient until complications occur
• Emphasis on prevention
GENERAL MEASURES
For details, see the following topics
• Essential hypertension
• Congestive heart failure
• Cerebrovascular accident
• Renal failure, chronic
• Dissecting aneurysm
• Thrombosis and embolism, arterial
• Diabetes
• Hyperlipidemia
• Hypothyroidism
Diet
American Heart Association Dietary recommendations are controversial, and have not been proven effective at lowering atherosclerotic risk
• Initial diet, step 1
- Total fat 30% of total calories; saturated fat 10%
- Carbohydrates 50-60% of total calories
- Protein 10-20% of total calories
- Cholesterol 300 mg a day
- Total caloriesamount required to achieve and maintain desirable weight
- Sodium 1,650-2,400 mg
- Alcohol 30 g
• Initial diet, step 2
- Total fat 30% of total calories; saturated fat 7%
- Carbohydrates 50-60% of total calories
- Protein 10-20% of total calories
- Cholesterol 200 mg per day
- Total caloriesamount required to achieve and maintain desirable weight
- Sodium 1,650-2,400 mg
- Alcohol 30 g
- Antioxidants (vitamins A, E, C)
Activity
Encourage physical fitness as this will may progression (5)[B]
Complementary and Alternative Medicine
• Omega-3 fatty acids 1000 mg/d may be effective in lowering risk, but data are conflicting. (6)[C]
• Good evidence exists showing the following do NOT lower atherosclerotic risk:
• Vitamin E [I]
• lowering homocysteine levels (8)[I]
• Chelation therapy (9)[I]
• Anticoagulation (10)[D]
• Garlic (11)[I]
• No evidence that testosterone treatment is beneficial for aortic atherosclerosis (12)[D]
MEDICATION (DRUGS)
For details, see the following topics
• Essential hypertension
• Coronary arteriosclerosis
• Congestive heart failure
• Stroke
• Atrial arrhythmias
• Ventricular arrhythmias
• Renal failure, chronic
• Dissecting aneurysm
• Thrombosis and embolism, arterial
• Angina
• Myocardial infarction
• Arteriosclerotic heart disease
• Atherosclerotic occlusive disease
• Hypothyroidism
• Hyperlipidemia
SURGERY
• Angioplasty
• Stent
• Carotid endarterectomy
• Rotational atherectomy (13)[C]
FOLLOW-UP
PROGNOSIS
Avoiding risk factors has greatly decreased mortality rates in the past decade.
COMPLICATIONS
• Coronary artery disease
• Renal failure
• Cerebrovascular accidents
• Dissecting or ruptured aneurysms
• Congestive heart failure
• Arterial thrombosis
• Gangrene
• Cardiac arrhythmias
• Sudden death
REFERENCES
1. Fauci AS, ed. Harrison's Principles of Internal Medicine. 14th ed. New York, NY: McGraw-Hill; 1998.
2. Guidelines for cardiopulmonary resuscitation and emergency cardiac care. JAMA. 1992;268:28.
3. Hunninghake D, ed. Lipid disorders. Med Clin North Am. 1994;78.
4. Hurst JW, et al. The Heart. 8th ed. New York, NY: McGraw-Hill; 1994.
5. Nordstrom CK, et al. Leisure time physical activity and early atherosclerosis: The Los Angeles Atherosclerosis Study. Am J Med. 115:19-25.
6. Omega-3 fatty acids for intermittent claudication. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
7. Vitamin E for intermittent claudication. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
8. Homocysteine lowering interventions for peripheral arterial disease and bypass grafts. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
9. Chelation therapy for atherosclerotic cardiovascular disease. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
10. Anticoagulants for intermittent claudication. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
11. Garlic for peripheral vascular disease. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
12. Steroid sex hormones for lower limb atherosclerosis. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
13. PTRA for coronary artery disease. The Cochrane Database of Systematic Reviews. 2006, Issue 1.
MISCELLANEOUS
• See also: Aortic Dissection; Arterial Embolus and Thrombosis; Atherosclerotic Occlusive Disease; Congestive Heart Failure; Hypertension, Essential; Renal Failure, Chronic; Stroke (Brain Attack)