Coronary artery disease (CAD) develops when the coronary arteries (major blood vessels) that supply the muscles of the heart with blood, oxygen and nutrients become damaged or diseased. Plaques (cholesterol-containing deposits) in a patient’s arteries, as well as inflammation, are usually to blame. When plaque builds up, it narrows the coronary arteries and decreases blood flow to the heart. This decreased flow may cause a patient to experience angina (chest pain), shortness of breath, or other symptoms. A complete blockage may cause a myocardial infarction (heart attack). Since CAD often develops over decades, the patient may only become aware of the condition following a significant blockage or a heart attack.
Symptoms
Narrow coronary arteries are unable to supply enough oxygenated blood to the heart, especially during physical exercise. As plaque continues to accumulate in the coronary arteries, the patient may develop any of the following signs and symptoms:
- Angina (chest pain) → The patient may experience pressure or tightness in their chest, as if there were someone were standing it. This pain usually occurs on the middle or left side of the chest and can be triggered by physical or emotional stress.
- Shortness of breath → This is due to the heart’s inability to pump enough oxygenated blood to meet the body’s demands.
- Heart attack → If a coronary artery becomes completely blocked, the patient will suffer a heart attack. The classic signs and symptoms of a heart attack include crushing pressure in the chest and referred pain in the shoulder or left arm, sometimes with shortness of breath and sweating. It is possible for a heart attack to occur without any apparent signs or symptoms.
Causes
Coronary artery disease begins with damage to the innermost layer of a coronary artery, sometimes as early as childhood. The damage can be caused by:
- Smoking
- High blood pressure
- High cholesterol
- Diabetes or insulin resistance
- Sedentary lifestyle
Following the damage of the internal wall of the artery, plaque made of cholesterol and other cellular waste products accumulate at the site of injury (atherosclerosis). If the surface of the plaque ruptures, platelets will clot in an attempt to repair the artery. The resulting clot can block the coronary artery, leading to a heart attack.
Risk Factors
Risk factors for coronary artery disease include:
- Age → Increases a patient’s risk of damaged and narrowed arteries.
- Sex → Men are generally at greater risk of CAD; the risk for women increases after menopause.
- Family history → A family history of heart disease is associated with a higher risk of CAD. A patient’s risk is highest if their father or a brother was diagnosed with heart disease before the age of 55 or if their mother or a sister developed it before the age 65.
- Smoking → Smokers have a significantly higher risk of heart disease. Exposing others to second-hand smoke increases their risk of CAD.
- High blood pressure → Uncontrolled high blood pressure can cause arteries to harden and narrow the channel through which blood can flow.
- High blood cholesterol levels → High levels of cholesterol in the blood can increase the risk of plaque formation and atherosclerosis. High cholesterol can be caused by a high level of low-density lipoprotein (LDL) cholesterol. A low level of high-density lipoprotein (HDL) cholesterol can also contribute to the development of atherosclerosis.
- Diabetes → Type 2 diabetes and CAD share similar risk factors, such as obesity and high blood pressure.
- Overweight or obesity → Excess weight typically exacerbates other risk factors.
- Physical inactivity → Lack of exercise also is associated with CAD and some other risk factors, as well.
- High stress → Unrelieved stress may damage arteries as well as exacerbate other CAD risk factors.
- Unhealthy diet → Eating excessive food high in saturated fat, trans fat, salt and sugar can increase the risk of CAD.
Risk factors can often occur in clusters and may build on one another, for example obesity can lead to type 2 diabetes and high blood pressure. It is possible for CAD to develop without any classic risk factors. Researchers are studying other possible factors, such as:
- Sleep apnea → This disorder causes you to repeatedly stop and start breathing during sleep, which causes sudden drops in blood oxygen levels. This results in increased blood pressure and cardiovascular strain.
- High sensitivity C-reactive protein (hs-CRP) → hs-CRP is a normal protein that appears in higher amounts during inflammatory responses. It is thought that narrowing of coronary arteries correlated to higher hs-CRP levels in the blood.
- High triglycerides → This is a type of fat (lipid) in your blood. High levels may raise the risk of coronary artery disease, especially for women.
- Homocysteine → High levels of homocysteine may increase risk of CAD.
- Preeclampsia → This condition can develop in women during pregnancy and causes high blood pressure and higher protein levels in urine. It can lead to a higher risk of heart disease later in life.
- Alcohol use → Excessive alcohol use can cause heart muscle damage and can worsen other CAD risk factors.
- Autoimmune diseases → Inflammatory rheumatologic conditions can lead to an increased risk of atherosclerosis.
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