Atherosclerosis is a condition characterized by the gradual hardening and narrowing of arteries. This occurs due to the buildup of plaque within the artery walls. Plaque consists of fat, cholesterol, calcium, and other cellular waste products. This slow-developing disease often begins in childhood and can affect arteries throughout the body. Imagine rust accumulating inside a water pipe, progressively restricting water flow.
How Plaque Develops in Arteries
Plaque formation in arteries often begins with damage to the endothelium, the inner lining of an artery. This damage can be caused by factors like high cholesterol, elevated blood pressure, or tobacco smoking. Once the endothelium is compromised, low-density lipoprotein (LDL) cholesterol can infiltrate the artery wall.
The body’s immune system responds by sending white blood cells (monocytes) into the artery wall. These monocytes transform into macrophages, which consume the accumulated LDL cholesterol, becoming “foam cells.” As foam cells, cholesterol, calcium, and fibrous tissue accumulate, they form an atherosclerotic plaque.
This expanding plaque causes the artery wall to thicken and harden, narrowing blood flow. The plaque is often covered by a thin, fibrous cap. If this fibrous cap ruptures or erodes, the plaque’s contents are exposed to the bloodstream, triggering a blood clot. This clot can block blood flow, leading to serious health events.
Key Risk Factors for Atherosclerosis
Several factors can initiate or accelerate atherosclerosis, categorized as modifiable or non-modifiable. Modifiable risk factors are factors individuals can influence. High LDL cholesterol contributes to plaque formation by infiltrating damaged artery walls. High blood pressure places increased stress on the arterial lining, making it more susceptible to damage.
Smoking directly harms the endothelium, promoting inflammation and plaque buildup. Diabetes (high blood sugar) can damage blood vessels over time. Obesity increases the likelihood of developing other risk factors like high blood pressure and diabetes. An unhealthy diet, particularly one high in saturated fats and low in fruits and vegetables, and a lack of physical activity also play a role.
Non-modifiable risk factors are characteristics that cannot be changed. Age is a significant factor, as the risk of atherosclerosis increases over time. Family history and genetics also play a role, indicating a predisposition. Males generally face a higher risk of developing coronary artery disease earlier than females, though the risk balances out in older age.
Resulting Cardiovascular Diseases
When atherosclerosis progresses, it can lead to various cardiovascular diseases, depending on which arteries are affected and how severely blood flow is restricted. If plaque accumulates in the coronary arteries, which supply blood to the heart muscle, it results in Coronary Artery Disease (CAD). Symptoms of CAD can include angina, a type of chest pain, shortness of breath, or heart palpitations, and can lead to a heart attack if blood flow is severely cut off.
Atherosclerosis in the carotid arteries, located in the neck and supplying blood to the brain, can cause Carotid Artery Disease. This condition may lead to a stroke, characterized by sudden weakness, numbness, or difficulty speaking, or a transient ischemic attack (TIA). These events occur when blood flow to parts of the brain is interrupted.
When arteries in the limbs are affected, it leads to Peripheral Artery Disease (PAD). Individuals with PAD often experience pain or cramping in their legs, particularly during walking, known as claudication. This reduced blood flow can also impair wound healing. Atherosclerosis in the renal arteries, supplying blood to the kidneys, can contribute to chronic kidney disease or elevated blood pressure.
How Atherosclerosis Is Diagnosed
Doctors employ several methods to diagnose atherosclerosis, often beginning with a thorough physical examination. During this exam, a healthcare provider might listen for abnormal whooshing sounds, called bruits, in the arteries using a stethoscope, which can indicate narrowed vessels. They may also check for weak or absent pulses in the body, especially the limbs.
Blood tests are conducted to measure cholesterol (including LDL) and blood sugar levels, as high levels indicate atherosclerosis risk. Inflammatory markers, such as C-reactive protein, are also assessed, since inflammation plays a role in plaque development. These tests provide insights into metabolic state and predispositions.
A non-invasive test called the Ankle-Brachial Index (ABI) compares blood pressure measurements in the ankle and arm. A significant difference in these pressures can suggest narrowed arteries in the legs, a common sign of peripheral artery disease. This simple test helps evaluate blood flow limitations in the extremities.
Imaging tests visualize plaque and blockages in arteries. An ultrasound can visualize blood flow and detect narrowing in arteries, such as the carotid arteries in the neck. Computed Tomography Angiography (CTA) uses X-rays and a contrast dye to create detailed images of arteries, revealing plaque and blockages. A coronary angiogram, a more invasive procedure, involves threading a thin tube into the heart’s arteries to inject dye, directly showing any narrowing or blockages.