Atherosclerosis

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What is Atherosclerosis?

Atherosclerosis is the most prevalent disease in the industrialized world. According to published data from Pfizer pharmaceuticals, atherosclerosis is the leading cause of illness and death in Canada. One in five deaths is due to atherosclerosis in its various forms; heart attacks account for half of these deaths (10% of all deaths in Canada) and strokes for another third (7%).

Atherosclerosis is the build-up of plaque inside of large- and medium-sized arteries, which deliver oxygenated blood to vital organs and tissues in the body. When plaque build-up occludes blood flow, it can lead to coronary heart disease, heart attacks and strokes.

How does plaque develop? The most widely accepted theory for the mechanism of plaque development is the “response to injury hypothesis.” This model presumes a multifactorial cause of plaques, beginning with damage to the innermost part of the artery called the endothelium. Over the years, endothelial cells can be stimulated to produce abnormal growth and plaque development through a variety of mechanisms. Plaque development is thought to start early in childhood, and continue in adulthood based on genetics and lifestyle.

Symptoms of Atherosclerosis:

Although atherosclerosis is a long process that begins in childhood, it remains asymptomatic until adulthood, typically starting in men in their 40s and women after menopause.

Signs of atherosclerosis depend on the area affected. In the heart, atherosclerosis can cause angina (heart pain) due to decreased blood flow, eventually leading to a heart attack when a blood vessel is obstructed.

In the kidney, it can reduce blood flow, which can lead to high blood pressure, causing kidney damage, and in subsequent years, lead to kidney failure.

In the brain, it can lead to strokes.

Peripheral vascular disease is another side effect of atherosclerosis. This is common below the knee but can occur above anywhere in the body. Compromised blood flow to the lower leg causes claudication, which can be painful when the leg demands more blood flow; for example when walking or exercising. This pain improves with rest.

Causes and risk factors of Atherosclerosis

Genetically men tend to have a higher incidence of atherosclerotic lesions compared to women. High cholesterol, triglycerides and elevated blood pressure (either systolic or diastolic) contribute to the development of atherosclerosis.

Lifestyle risks include cigarette smoking, obesity, stress and behaviour patterns, unhealthy diet and physical inactivity, and the use of alcohol and oral contraceptive. Diseases that lead to higher risk of atherosclerosis include diabetes mellitus, elevated homocysteine levels, hyperlipidemia and high blood pressure.

 Complications of the disease:

Atherosclerotic plaques can become unstable, break off and block smaller arteries. This blockage may cause strokes or heart attacks depending on where in the body the ruptured plaque comes to a halt.

How it is diagnosed:

Regular physical examinations are critical for optimum health. Physicians will order tests depending on the age of the patient, symptoms and family history.

A standard blood test can determine blood lipid, glucose and hemoglobin A1C levels.

Doppler ultrasounds may be completed, with focus on the area of interest. For example, carotid artery ultrasounds will be performed when it is suspected that there is impeded blood flow to the brain.

An ankle-brachial index is most commonly completed when an individual complains of pain in their leg with walking or exercise, which is alleviated by rest. Brachial (arm) blood pressures are compared with pressures in the ankle. If a significant difference in pressure is found, steps are taken to reduce the difference. Patients may be asked to being an exercise regimen, being medication and/or go for vascular surgery.

Electrocardiograms (ECGs) may also be ordered to check heart rhythm.

Stress tests can determine the amount of energy required from the heart during exercise compared with at rest. If a patient experiences discomfort during the test, additional measures are taken to alleviate the discomfort. For example, the patient may have to start medications and or undergo vascular surgery.

Cardiac catheterization and angiograms are invasive procedures that determine which blood vessels are blocked. A special dye that is visible by an X-ray machine is injected into the blood vessels of the heart. An X-ray machine takes a series of images (angiograms), offering a look into the blood vessels [i]If a blockage is found, the surgeon may use a variety of techniques to relieve the blockage; angioplasty, stents and balloon valvuloplastys are such examples.




Treatments of Atherosclerosis

Current treatment recommendations may involve lifestyle adjustments, prescription medications and vascular surgery.

Lifestyle adjustments include exercise, smoking cessation, consuming healthy diets, maintaining a healthy weight, and reducing stress and alcohol consumption.

Prescription medications are intended to reduce blood cholesterol and lower blood pressure, and anti-coagulants may be used to prevent the formation of blood clots.

If diet and medications are unable to prevent the progression of atherosclerosis then vascular surgery may be required. Angioplasty, stents and bypass surgeries may be the only options to prevent adverse complications.

 

[i]Webpage: http://www.mayoclinic.org/home/ovc-20262384)

 

References

 

  1. Atherosclerosis and Arteriosclerosos.Human Pathology and Experimental Animal Methods and Models. Rodney A. White. 1989 CRC press.
  2. W. D Reitsma. 1979 ExcerptaMedica, Amsterdam.
  3. Atlas of Heart Diseases.Atherosclerosis: Risk Factors and treatment.Volume X. Virgil Brown MD.1996 by Current Medicine Inc.
  4. Atherosclerosis and Coronary Artery Disease.Volume 2. Valentin Fuster, Russell Ross. Eric J. Topol. 1995 Lippincot, Raven Publisher.
  5. Atlas of Atheroscleross: Risk Factors and Treatment 4th Scott. M, Gruraj MD PhD. 2005 Current Medicine.
  6. Webpage: http://www.mayoclinic.org/home/ovc-20262384).
  7. Webpage: https://www.kidneyresearchuk.org/health-information/ckd-information/atherosclerotic-renovascular-disease
  8. Webpage: http://www.pfizer.ca/sites/g/files/g10017036/f/201410/Atherosclerosis.pdf
  9. Webpage: http://www.heart.org/HEARTORG/
  10. Webpage: https://en.wikipedia.org/wiki/Atherosclerosis
  11. Webpage: http://www.webmd.com/heart-disease/what-is-atherosclerosis