Blockages of the Coronary Arteries
The coronary arteries run along the surface of the heart and supply the heart muscle with blood and oxygen. Coronary artery disease develops when these arteries become blocked and can no longer deliver enough blood and oxygen to the heart muscle. Cholesterol-containing deposits (plaques) are the usual cause of this condition.
When plaques build up, the coronary arteries become narrowed, causing the heart muscle to receive less blood. Diminished blood flow may cause chest pain (angina) or shortness of breath. Complete blockage of a coronary artery can cause a heart attack.
Symptoms
When blockages develop in the coronary arteries, there is inadequate blood flow to the heart muscle. This lack of circulation becomes most obvious to a patient when there is increased physical activity. Typical symptoms of inadequate coronary circulation include the following:
(1) Chest pain (“angina”). A pressure or tightness in the chest, as if someone were standing on your chest. The pain, referred to as angina, is usually triggered by physical or emotional stress. It typically goes away within minutes after stopping the stressful activity.
(2) Shortness of breath. If the heart can't pump enough blood to meet the body's needs, shortness of breath occurs with exertion.
(3) Heart attack. If a coronary artery becomes completely blocked, a heart attack (“myocardial infarction”) may occur. The classic signs and symptoms of a heart attack include “crushing” chest pain, pain in the shoulder or arm, shortness of breath, and sweating.
If such symptoms are experienced, one should seek immediate medical attention.
Causes
Coronary artery disease is caused by damage to the inner layer of a coronary artery. The damage may be caused by various factors, including:
- Smoking
- High blood pressure
- High cholesterol
- Diabetes
- Radiation therapy to the chest
Once the inner wall of an artery is damaged, fatty deposits (mainly cholesterol) accumulate at the site of injury in a process called “atherosclerosis”. If the surface of these plaques breaks or ruptures, blood cells (called “platelets”) accumulate at the site to try to repair the artery. Accumulation of this platelet clump at the site of a plaque can block a coronary artery completely and lead to a heart attack. This is the rationale for recommending antiplatelet medications for patients at high risk for heart attack.
Risk factors
Risk factors for coronary artery disease include:
Male Sex: Men are generally at greater risk of coronary artery disease. However, the risk for women increases after menopause.
Family history: A family history of heart disease is associated with a higher risk of coronary artery disease, especially if a close relative developed heart disease at an early age.
Smoking: Nicotine constricts the blood vessels, and carbon monoxide can damage their inner lining, making them more susceptible to atherosclerosis. The incidence of heart attack in smokers is at least 3x higher than for non-smokers.
High blood pressure: Uncontrolled high blood pressure can result in thickening of the artery wall, thus narrowing the channel through which blood can flow.
High blood cholesterol levels: High levels of cholesterol in the blood can increase the risk of formation of plaques and atherosclerosis.
Diabetes: Diabetes is associated with an increased risk of coronary artery disease.
Obesity.
Lack of exercise.
High stress: Emotional stress may damage the lining of the arteries and increase the risk of plaque formation in the wall of the coronary artery.
As one might expect, a combination of risk factors increases the chance of developing coronary artery disease. “Metabolic syndrome” is an example of this. This “syndrome” consists of high blood pressure, high triglycerides, elevated insulin levels and accumulation of excess body fat at the waist.
Sometimes, patients who are thin, have normal blood pressure, don’t smoke, have no family history of coronary artery disease and have normal levels of blood cholesterol nevertheless develop coronary artery disease. This leads some people to the conclusion that the risk factors that we generally recognize as causing coronary artery disease, may not be the only risk factors after all. Other “possible risk factors” have been proposed to explain such cases. These include the following:
C-reactive protein: a normal protein that appears in higher amounts when there's swelling somewhere in the body. High CRP levels may be a risk factor for heart disease. It is thought that as coronary arteries narrow, there is more CRP in the blood.
Homocysteine: an amino acid that the body uses to make protein and to build and maintain tissue. It is thought by some that excessive levels of homocysteine may increase the risk of coronary artery disease.
Fibrinogen: a protein in the blood that is important for normal clotting of the blood. Excessive fibrinogen, however, may increase clumping of platelets, causing a clot to form in a coronary artery, leading to a heart attack.
Lipoprotein (a): this substance forms when a low-density lipoprotein (LDL) particle attaches to another type of protein in the blood. Lipoprotein (a) may interfere with the body's ability to dissolve blood clots. High levels of lipoprotein (a) may be associated with an increased risk of coronary artery disease and heart attack.
Sleep apnea: a condition characterized by repeated stopping and starting of breathing while a person is sleeping. This results in a dropping of oxygen levels in the blood, an elevation of blood pressure, and a strain on the heart which may lead to coronary artery disease.
Treatment of Coronary Artery Disease
Treatment consists of modifying the risk factors that cause coronary artery disease. Weight reduction, management of hypertension and diabetes, stopping cigarette smoking, increasing physical activity, and lowering cholesterol levels through diet and medications are all very important treatment recommendations for patients with, or at risk for, coronary artery disease. Interventions such as coronary angioplasty and stenting or coronary artery bypass surgery are treatment options available for patients who are not adequately treated with less invasive options
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