What is atherosclerosis?
Atherosclerosis is clogging or hardening of the arteries or blood vessels by plaques of fatty materials. Atherosclerosis can progress gradually and block the arteries making blood flow difficult.
Atherosclerosis is the usual cause of cardiovascular disease (heart attacks, strokes, and peripheral vascular disease). In America, cardiovascular disease is the No 1 killer.
Causes of Atherosclerosis
The real cause of atherosclerosis is not full understood. But it is usually initiated by the inflammation of damaged endothelial cells of the arteries.
The endothelial cells are thin layer of cells that lined the arteries. They help to keep the inside of arteries toned and smooth, which keeps blood flowing. The damage to endothelial cells according to experts is caused by high blood pressure, smoking, or high cholesterol.
Bad cholesterol or LDL (low density lipoprotein) can pass in between endothelial cells of the arteries. When the bad cholesterol, or LDL, pass in between the damaged endothelial cells, it crosses the damaged endothelium, and enter the wall of the artery once inside the wall the LDL is prone to oxidation. The entrance the cholesterol into the walls of artery is as a result of immune response by the damaged endothelial cells through attraction of monocyte white blood cells.
Once inside the vessel wall, the monocyte cells are transformed into macrophages. The macrophages' on ingestion of oxidized LDL triggers a series of immune responses which over time can produce an atheroma.
The immune system's specialized white blood cells (macrophages and T-lymphocytes) absorb the oxidized LDL, forming specialized foam cells. If these foam cells are not able to process the oxidized LDL, and recruit HDL (high-density lipoprotein) particles to remove the fats, they grow and eventually rupture, leaving behind cellular membrane remnants, oxidized materials, and fats (including cholesterol) in the artery wall. This attracts more white blood cells, resulting in a snowballing progression that continues the cycle, inflaming the artery. The presence of the plaque induces the muscle cells of the blood vessel to stretch to compensate the additional bulk, and the endothelial lining thickens, increasing the separation between the plaque and lumen. This eventual offsets the narrowing caused by the growth of the plaque thus, causing the wall to stiffen and become less compliant to stretching with each heart beat.
From the explanation above it could be seen that any thing that:
Damages endothelial cells
Increases low-density lipoprotein (LDL) or very low density lipoprotein (VLDL)
Lows high density lipoproten HDL or
Alters the function of HDL
is considered a risk factor of atherosclerosis. Many risk factors that can lead to atherosclerosis. Some of the factors can be changed while some can't be changed.
The factors include:
1. Genetic disorder: genetic abnormalities like familial hypercholesterolemia are know to be risk factor of atherosclerosis.
2. Cigarette smoking: smoking tobacco increases the risk of developing atherosclerosis by 200% after several pack years. This is because some ingredients in cigarette are responsible for damages made to endothelial cells of the arteries.
3. Gender: Before age 60, men are more likely to have heart attacks than women are. After age 60, the risk is equal among men and women.
4. Age: Risk is higher in men who are 45 years of age and older and women who are 55 years of age and older.
3. Diabetes or impaired glucose tolerance: The risk of developing atherosclerosis is seriously increased for diabetic persons. But it can be lowered by keeping diabetes under control. Most diabetic patients die from heart attacks caused by atherosclerosis.
5. High blood cholesterol: Cholesterol, a soft, waxy substance, comes from foods such as meat, eggs, and other animal products and is produced in the liver. Age, sex, heredity, and diet affect cholesterol. Total blood cholesterol is considered high at levels above 240 mg/dL and borderline at 200-239 mg/dL. High-risk levels of low-density lipoprotein (LDL cholesterol) begin at 130-159 mg/dL.
6. High triglycerides: Most fat in food and in the body takes the form of triglycerides. Blood triglyceride levels above 400 mg/dL have been linked to coronary artery disease in some people. Triglycerides, however, are not nearly as harmful as LDL cholesterol.
7. High blood pressure: Blood pressure of 140 over 90 or higher makes the heart work harder, and over time, both weakens the heart and harms the arteries.
8. Physical inactivity: Lack of exercise increases the risk of atherosclerosis. It's found that people who exercise more have high HDL production.
9. Obesity: Excess weight increases the strain on the heart and increases the risk of developing atherosclerosis even if no other risk factors are present.
10. Dyslipoproteinemia: (unhealthy patterns of serum proteins carrying fats & cholesterol) also increases the risk of developing atherosclerosis.
11. High serum concentration of low-density lipoprotein (LDL) and very low density lipoprotein (VLDL). Because more cholesterol will be deposited at the damaged endothelial cells.
12. Low serum concentration of functioning high density lipoprotein (HDL)
13. Vitamin B6 deficiency
14. Dietary iodine deficiency and hypothyroidism, which cause elevated serum cholesterol and of lipid peroxidation.
15. High intake of saturated fat (may raise total LDL cholesterol)
16. Intake of trans fat (may raise total LDL cholesterol while lowering HDL cholesterol)
17. High carbohydrate intake
18. Elevated serum levels of homocysteine
19. Elevated serum levels of uric acid
20. Elevated serum insulin levels
Symptoms of atherosclerosis
Atherosclerosis usually causes no symptoms until middle or older age.
Atherosclerosis is asymptomatic for decades because the arteries enlarge at all plaque locations, therefore there is no effect on blood flow. Even most plaque ruptures do not produce symptoms until enough narrowing or closure of an artery, due to clots, occurs. It only become symptomatic after severe narrowing or closure impedes blood flow to different organs enough to induce symptoms. Most of the time, patients realize that they have the disease only when they experience other cardiovascular disorders such as stroke or heart attack. These symptoms, however, still vary depending on which artery or organ is affected. Symptoms differ depending upon the location of the atherosclerosis
Erectile dysfunction is also one of early indications of atherosclerosis because the first stage of atherosclerosis endothelial dysfunction affect the penis first.
In the coronary (heart) arteries: Chest pain, heart attack, or sudden death.
In the carotid (brain) arteries: Sudden dizziness, weakness, loss of speech, or blindness.
In the femoral (leg) arteries: Disease of the blood vessels in the outer parts of the body (peripheral vascular disease) causes cramping and fatigue in the calves when walking.
In the renal (kidney) arteries: High blood pressure that is difficult to treat.
Treatment of atherosclerosis
In atherosclerosis, once a blockage has developed, it's generally there to stay.
Hence its medical treatments often focus on alleviating symptoms. Though treatments to decrease the plaque rather than simply treating the symptoms is more effective.
Non-pharmaceutical means like change of lifestyle and change of diet are usually the first method of treatment. Before medication, surgery and any form of treatment is employed.
1. Change life style
Changing lifestyle risk factors that lead to atherosclerosis will slow or stop the process. That is by engaging in regular exercise, stop smoking, and stop alcohol consumption. These lifestyle changes won't remove blockages, but they’re proven to lower the risk of heart attacks and strokes.
2. Change of diet
Avoiding certain diets and embracing others have proven to prevent the development of atherosclerosis. Eatting diets high in fruits and vegetables decreases the risk of cardiovascular disease and death. Diets rich in trans-fats and saturated fats should be avoided.
3. Medication
Drugs for high cholesterol and high blood pressure will slow and perhaps even halt the progression of atherosclerosis, as well as lower your risk of heart attacks and stroke.
A group of medications referred to as statins are widely prescribed for treating atherosclerosis. They have shown benefit in reducing cardiovascular disease and mortality in those with high cholesterol with few side effects.
4. Other physical treatments include:
Angiography and stenting
REFERENCE:
https://en.m.wikipedia.org/wiki/Atherosclerosis
http://www.m.webmd.com/heart-disease/what-is-atherosclerosis
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