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Atherosclerosis

Read in Hindi

Dr Sudhir Bhatnagar
Internal Medicine

verified

Atherosclerosis is a condition in which the arteries get blocked because of the deposition of fatty substances, and abnormal cells on the walls of arteries. Though anyone can suffer from atherosclerosis, there are a few risk factors that put a person at a higher risk of developing atherosclerosis.

A block in the arteries is actually caused by the narrowing and thickening of the walls of arteries because of the deposition of fatty substances such as cholesterol along with other cellular waste. The substances that get accumulated along the arteries form a build-up called plaque or atheroma. Plaques are primarily dangerous because they narrow the arteries, restrict the blood flow and can hinder the functioning of several organs. Moreover, plaques can rupture and result in a blood clot that again blocks the blood supply to the heart. These conditions either trigger a heart attack or a stroke affecting the brain.

Atherosclerosis is a slow disease that takes really long time to progress and causes complications. In a few people, plaque formation may start during childhood and may advance rapidly during the 30s. In others, it does not really pose a threat until the 50s or 60s. With all advances in surgical and operative procedures, people who initially show the symptoms of heart attack can prevent the complications in advance. However, people in whom any signs are not seen at an early stage are at a greater risk.

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Stages

Following are the stages of the pathogenesis of atherosclerosis


  1. Endothelial dysfunction - Endothelial dysfunction is the earliest stage that may be attributed to the stretching of endothelial cells of coronary arteries, which leads to a gap in between cells because stretching chemicals are released, which attracts macrophages towards endothelium starts forming fatty streaks.

  2. The early fibro atheroma - In this phase, there is a migration of cells present in smooth muscles to the intima, under the control of platelet-derived growth factor (PDGF), angiotensin II and insulin-like growth factor (IGF) from foam cells.

  3. Atheroma advancement - Plaque is a thin fibrous cap with smooth, low muscle cell (SMC) density, macrophages and abundant lipid rich in tissue factors. During this phase, the fibrous cap is weakened because of which plaque ruptures.

  4. Plaque rupture - Because of an expression of enzymes such as myeloperoxidase, the fibrous cap of plaque is weakened, because of which iron deposition and macrophage calcification occur.

  5. Necrotic core development - During this phase, necrosis in the core region develops.

  6. Plaque erosion - The formation of thrombi because of the rupture of plaque is a characteristic of this phase. The occurrence of calcified plaque is less likely than ruptured plaque. Gross results in the aorta play a vital role in differentiating atherosclerotic lesions.

  7. Gross Findings - Fatty streaks are minimally raised lesions that are bright yellow. These fatty streaks are lipid abundant when stained with oil red O. The white raised areas that are firm in texture are known as fibrous plaque.

Symptoms

Atherosclerosis is a silent condition and may not show any symptoms until the affected artery is sufficiently blocked to disturb the blood flow and deprive the organs and tissues of sufficient blood supply. However, with a partial block of arteries, the following signs may be seen:


  1. Anginal chest pain: Choking type of chest pain at the middle of the chest, sometimes radiating to neck or upper arm. It appears especially during exertion and disappears during rest or sublingual sorbitrate. Angina chest pain appears because of the blockage of arteries supplying blood to heart muscle.

  2. Sudden numbness or weak and dizzy feeling or brief loss of consciousness or loss of function of a part of body because of the blockage of the carotid arteries (in the neck) that supply blood to the brain indicating the possibility of stroke.

  3. Pain in leg muscles while walking because of the blockage of arteries that supply blood to the limbs indicating the possibility of peripheral arterial disease.

  4. Erectile dysfunction may occasionally occur in men because of the hardening of the arteries.

Causes And Risk Factors

Causes


The exact cause of atherosclerosis is unclear. Atherosclerosis is discussed when lipid and fibrous materials accumulate in the large arteries forming lesions. These legions are called as 'foam cells'. These lesions grow to block blood flow and lead to myocardial infarction or stroke. There are several factors that may increase the risk of cardiovascular diseases because of atherosclerosis. Permanent risk factors include an increase in age and a family history of heart disease.

Risk Factors


Risk factors that can be controlled by changing lifestyle include:
Smoking: It damages the walls of the arteries, raises blood pressure and reduces good cholesterol (HDL) levels. It causes blood clots by aggregating platelets at the site of damage

  1. Physical inactivity

  2. Dyslipidaemia: High bad cholesterol (LDL), triglyceride and

  3. Low good cholesterol (HDL)

  4. Stress

  5. Obesity

  6. Sleep disorders


The risk of heart disease increases under certain health conditions such as:

  1. High blood pressure (hypertension): Above 140/90
    Researchers suspect that high blood levels of a protein called C-reactive protein (CRP) might increase the risk of atherosclerosis and attacks. High blood levels of triglycerides, especially in women, may increase the risk (Read: 70% of the urban Indian population at risk of heart disease!).

Prevention

There are several diagnostic methods used to confirm atherosclerosis. When you present to the doctor for clinical evaluation, a physical examination is first conducted. When you present to the doctor, a detailed history is taken. Physical examination is conducted. Subsequently, your doctor may recommend you any of the following tests:


  1. Blood Test: A blood test is performed to detect the level of cholesterol, fats and sugar in the blood. Abnormal levels may indicate risk for atherosclerosis.

  2. ECG (Electrocardiogram): ECG detects the electrical activity and rhythmic pattern of the heart. Specific electrical and rhythmic patterns can indicate the possibility of heart disease. If ECG in normal tread mill test detects coronary artery disease (atherosclerosis) in early stage.

  3. Echocardiography: In this test, the sound waves from reflected from the heart muscles create moving picture and offers information about how well the heart is functioning.

  4. CT Scan: A CT coronary angiography can show the thickening and narrowing of arteries of the heart.
    Other tests such as a chest X-ray can be suggested to analyse the structures of heart and blood vessels and detect the signs of heart failure. An ankle-brachial index is taken to compare blood pressure of the ankle with the blood pressure of the arm. An abnormal index may indicate peripheral vascular disease caused by atherosclerosis.

Treatment

Cholesterol-lowering drugs: The primary cause of atherosclerosis is the deposition of cholesterol on the walls of arteries. Moreover, there are various cholesterol-lowering drugs (containing statins and fibrates) that you may be prescribed for getting cholesterol under control. However, these drugs are just to bring cholesterol down to a safe level. To maintain good cholesterol levels, you should have a healthy diet control and involve regular physical activity in your daily routine. Other medications that are used to treat this condition include


  1. Drugs containing may be given for slowing down cholesterol deposition.

  2. Anti-platelet drugs such as aspirin may be prescribed to reduce the chances of blood clot and further narrowing of arteries.

  3. Anticoagulants such as heparin or warfarin may be given to prevent clot formation.


Drugs such as beta-blockers, angiotensin-converting enzyme (ACE) inhibitors and Ca channel blockers may be prescribed for controlling blood pressure and slow down the progression of atherosclerosis.

What if medicines do not work? Are there surgical options?

For severe symptoms or malfunctioning of an organ, the following procedures may be performed:

  1. Angioplasty: This procedure involves widening the blocked arteries with the help of a balloon and stent that compresses the plaque against the artery.

  2. Bypass surgery: The surgeon may graft a healthy blood vessel from some other part of your body to bypass the blockage in the narrowed artery. This allows blood to flow around the blocked or narrowed artery.

  3. Endarterectomy: Sometimes, the fat deposits may be surgically removed from the walls with an endarterectomy.

Lifestyle/management

Following lifestyle modifications are vital for the management of Atherosclerosis-


  1. Diet modifications.

  2. Smoking cessation.

  3. Inclusion of fat-soluble antioxidants in your diet.

  4. Exercise daily.

Prognosis And Complications

Prognosis


Advancement in managing various risk factors such as blood pressure, smoking cessation, diabetes mellitus, diet, and daily exercise has increased atherosclerotic disorders. However, in the case of end-stage organ failures such as stomach stroke with paralysis, heart failure, and disturbed cognition can worsen this disease's prognosis.

Complications


Atherosclerosis can lead to various complications such as peripheral artery disease (PAD), cerebrovascular disease (CVA), abdominal aneurysm, transient ischemic attack (TIA), and stenosis of renal arteries.

References

1. National Institute of Health- Public access. Atherosclerosis [Internet] Available at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2826222/. A (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2826222/)
2. Stat Pearls. Atherosclerosis [Internet] [Updated on August 10, 2020] Available at https://www.ncbi.nlm.nih.gov/books/NBK507799/. (https://www.ncbi.nlm.nih.gov/books/NBK507799/)

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