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by Parlikar U

Cardiovascular Disease

Atherosclerosis: At the ‘Heart’ of the Matter

The main function of the cardiovascular system is to transport blood throughout the body. Cardiovascular disease occurs when blood flow becomes obstructed. Atherosclerosis, a build-up of deposits on the inside of arteries, is a primary cause.
Blocked Coronary Artery
Blocked Coronary Artery
© 2011 Nucleus Medical Media, Inc.
Atherosclerosis is a gradual disease process. Normal, healthy arteries start out smooth. During early adulthood, fatty particles from the blood make their way into the inner layer of the artery. They build up and form fatty streaks. Injuries to the internal lining from smoking, high blood pressure, or diabetes, make it more likely that fatty particles will build up.
As time goes on, fat from low-density lipoproteins (LDLs) continues to build up. The lipids react with oxygen and are taken over by smooth muscle cells of the artery. The cells develop a foamy appearance. The foam cells attract platelets from the blood stream as well as calcium deposits and cell debris. The wall of the artery becomes inflamed as white blood cells try to heal the injured area. In the meantime, a fiber-like cap forms over the fatty mixture and creates a hardened lesion called an atherosclerotic plaque. As the plaque continues to grow, it narrows the affected artery slows the flow of blood through it.
Atherosclerosis
Atherosclerosis
© 2011 Nucleus Medical Media, Inc.
At times, the fibrous caps covering atherosclerotic plaques may rupture. When this occurs, blood cells called platelets are exposed to the contents of the plaque. This causes them to collect and form a clot at the site of the rupture—a process called thrombosis. Sometime these clots can grow large, leading to the total obstruction of flow in the artery. Pieces of the clot, called emboli, may also break off and travel downstream.
Blood Clot Blocking Blood Flow
Blood Clots
© 2011 Nucleus Medical Media, Inc.
Atherosclerosis can eventually lead to the following conditions:
  • Cerebrovascular Disease (Stroke) —A stroke occurs when brain cells die because they are not getting enough oxygen via the bloodstream. Eighty percent of strokes are caused by blockage of an artery leading to the brain.
    Ischemic Stroke
    Stroke
    © 2011 Nucleus Medical Media, Inc.
  • Coronary Heart Disease
    • Angina —Narrowing of the coronary arteries, which carry blood to the heart muscle, may create a supply and demand problem for the heart. Myocardial ischemia results when demand for oxygen is greater than its supply. This often occurs at times of exertion. Most patients experience myocardial ischemia as chest pain, also known as angina.
      Angina: Most Common Areas of Pain
      Angina: Most Common Areas of Pain
      © 2011 Nucleus Medical Media, Inc.
    • Heart Attack (Myocardial Infarction) —Heart attack refers to the death of heart cells due to lack of oxygen. Most heart attacks occur when a large clot forms in a coronary artery, cutting off the flow of blood to the heart. Complications include congestive heart failure and cardiac arrhythmias, which result from the abnormal conduction of electrical signals through heart tissue.
      Heart Attack
      Heart Attack
      © 2011 Nucleus Medical Media, Inc.
    • Congestive Heart Failure (CHF)—CHF occurs when the heart is unable to pump enough blood to the body. It is usually the result of a heart that has weakened over time, often because of long-standing coronary heart disease, high blood pressure, or both. Other causes include myocardial infarction or abnormalities of the heart valves.
  • Peripheral Vascular Disease —Peripheral vascular disease refers to the narrowing of arteries that carry blood to the legs. Patient with severe arterial narrowing often have pain and fatigue when they walk. An aneurysm or bulge in an artery may also occur due to its weakened wall. Aneurysms can occur anywhere, but when associated with atherosclerosis, they most commonly occur in the abdominal portion of the aorta.
Other cardiovascular conditions unrelated to atherosclerosis include:
  • Congenital defects of the valves, chambers, and great vessels
  • Some types of irregular heart beats, known as arrhythmias
  • Inflammation or infections of the valves or pericardial sac that surrounds the heart
  • Cardiac tumors
  • Venous conditions such as varicose veins, thrombophlebitis, and deep venous thrombosis

RESOURCES

American Heart Association http://www.heart.org

Texas Heart Institute http://texasheart.org

CANADIAN RESOURCES

Health Canada http://www.hc-sc.gc.ca

Heart and Stroke Foundation of Canada http://www.heartandstroke.ca

References

American Heart Association. Atherosclerosis. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/Cholesterol/WhyCholesterolMatters/Atherosclerosis%5FUCM%5F305564%5FArticle.jsp. Updated May 1, 2013. Accessed May 9, 2013.

Heart and Circulation. In: Fox SI, ed. Human Physiology. 4th ed. Dubuque, Iowa:Wm. C. Brown Publishers;1993:328-367.

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