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The heart is a strong muscle whose main role is to pump oxygenated blood to the different parts of the body, including the vital organs like the brain and the kidneys. This function goes on with every heartbeat several times a minute, normally from 60 to 100 times, 24 hours a day. As such, the heart muscle (or myocardium) cells need oxygen, too, which is in turn supplied by the blood flowing through the coronary arteries making up the main blood supply to the heart.
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What is Ischemic Heart Disease?
Ischemia is a condition when cells do not get enough blood supply and therefore lack oxygen resulting in cell damage. Ischemic heart disease develops when the blood supply to the organ is not enough and the demand or need exceeds the supply. Since the heart is constantly pumping against the resistance of the walls of the smaller vessels, and needs more energy and oxygen during times of stress and exercise, the demand for more oxygenated blood increases. Failure to meet this demand results in ischemic heart disease, or myocardial ischemia, where cell damage may eventually lead to heart failure.
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The most common cause of a significant reduction in the blood supply to the heart is coronary artery disease, or a decrease in the diameter of the arteries supplying the heart muscles. This usually occurs when there is excess lipid or fat deposition inside the walls of these blood vessels, a condition also known as atherosclerosis, usually due to high fat diet.
With constant thickening and hardening of the lipid deposits in the arteries, plaques may form and rupture, which may lead to blood clot formation. These blood clots may further reduce the diameter of an artery or totally block blood flow, leading to cell damage or ischemia.
Other less common causes of myocardial ischemia are coronary artery spasm or sudden contractions of the coronary arteries, sudden decreases in blood volume, infectious diseases and other illnesses such as hypertension that may lead to a decrease in blood supply to the heart.
Risk factors that may lead to ischemic heart disease are advancing age, family history, smoking, lack of exercise, obesity, diabetes and high blood pressure.
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Some people do not experience any symptoms of heart disease. In others, the most common symptom is angina or chest pain behind the breast bone or on the left side of the chest which may have different characteristics such as:
- Stabbing, pricking or burning pain
- Constricting or squeezing pain
- Chest tightness or heaviness
- Choking sensation
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The pathophysiology of ischemic heart disease also involves the possible complications that can arise from the series of changes evolving from the disease. The most common complication is heart failure since the damaged tissues cannot pump blood effectively. Heart failure in turn leads to inadequate perfusion of other organs, the most sensitive of which are the kidneys and the brain.
Another complication arising from poorly functioning muscle cells is the development of a heart block with abnormal heart rate and rhythm which can also result in heart failure.
The most dreaded complication from heart disease is a heart attack which may sometimes be a sudden, fatal attack. During such event symptoms of angina may be accompanied by shortness of breath, cold clammy skin and loss of consciousness. Without immediate medical help a heart attack can end in permanent disability or death.
Understanding the pathophysiology of heart disease is important to be able to prevent the cause of disease, recognize symptoms and seek immediate medical help to avoid the complications.
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Mayo Clinic, “Myocardial Ischemia", http://www.mayoclinic.com/health/myocardial-ischemia/DS01179
Mayo Clinic, “Coronary Artery Disease", http://www.mayoclinic.com/health/coronary-artery-disease/DS00064