Atherosclerosis (or arteriosclerotic vascular disease) is a condition where the arteries become narrowed and hardened due to an excessive build up of plaque around the artery wall. The disease disrupts the flow of blood around the body, posing serious cardiovascular complications.
Arteries contain what is called an endothelium, a thin layer of cells that keeps the artery smooth and allows blood to flow easily. Atherosclerosis starts when the endothelium becomes damaged, allowing LDL cholesterol to accumulate in the artery wall. The body sends macrophage white blood cells to clean up the cholesterol, but sometimes the cells get stuck there at the affected site. Over time this results in plaque being built up, consisting of bad cholesterol (LDL cholesterol) and macrophage white blood cells.
The plaque clogs up the artery, disrupting the flow of blood around the body. This potentially causes blood clots that can result in life-threatening conditions such as heart attack, stroke and other cardiovascular diseases.
The condition can affect the entire artery tree, but mainly affects the larger high-pressure arteries.
Arteriosclerosis and atherosclerosis
Arteriosclerosis and atherosclerosis are different conditions:
- Arteriosclerosis is the stiffening or hardening of the artery walls.
- Atherosclerosis is the narrowing of the artery because of plaque build-up. Atherosclerosis is a specific type of arteriosclerosis.
All patients with atherosclerosis have arteriosclerosis, but those with arteriosclerosis might not necessarily have atherosclerosis. However, the two terms are frequently used with the same meaning.
Causes of atherosclerosis
Atherosclerosis is caused by macrophage white blood cells and fat that accumulate in arteries - the white blood cells are originally sent by the body's immune system to clean up LDL cholesterol pockets.
When they stick to an artery they secrete a molecule called netrin-1, this stops normal migration of the macrophages out of the arteries. As a result, what you have left is a mixture of clumped up cholesterol pockets and white blood cells, this is the plaque that can disrupt blood flow.
A study carried out by researchers at NYU Langone Medical Center is said to have been the first of its kind to explain why macrophages stick to artery walls.
Certain factors that can damage the inner area of the artery (endothelium) and can trigger atherosclerosis include:
- High Blood Pressure
- High levels of cholesterol
- High levels of sugar in the blood
Areas of the artery that are damaged are likely to have plaque build up which can eventually break open. When the plaque breaks open, blood cell fragments called thrombocytes (or platelets) accumulate at the affected area. These fragments can then stick together, forming blood clots.
Diabetes - patients with poorly-controlled diabetes, who frequently have excess blood glucose levels, are much more likely to develop atherosclerosis.
Genetics - people with a parent or sibling who has/had atherosclerosis and cardiovascular disease have a much higher risk of developing atherosclerosis than others.
Air pollution - in 2007, researchers from the University of California in Los Angeles linked exposure to diesel exhaust particles in air pollution to a higher risk of bad cholesterol build-up in the arteries. (Link to article)
Symptoms of atherosclerosis
A symptom is something the patient feels and describes, such as pain, while a sign can be detected by other people, such as a rash.
The first signs of atherosclerosis can begin to develop during adolescence, with streaks of white blood cells appearing on the artery wall. The symptoms of the disease depend on which arteries are affected:
Carotid arteries provide blood to the brain, when the blood supply is limited patients can suffer stroke and may experience:
- Difficulty breathing
- Facial numbness
Coronary arteries provide blood to the heart, when the blood supply to the heart is limited it can cause angina and heart attack, symptoms include:
- Extreme anxiety
- Chest pain
- Feeling faint
Renal arteries supply blood to the kidneys; if the blood supply becomes limited, there is a serious risk of developing chronic kidney disease, and the patient may experience:
- Loss of appetite
- Swelling of the hands and feet
- Difficulty concentrating
Peripheral arterial disease
The arteries to the limbs, usually the legs, are blocked. The most common symptom is leg pain, either in one or both legs, usually in the calves, thighs or hips. The pain may be described as one of heaviness, cramp, or dullness in the leg muscles. Other symptoms may include:
- Hair loss on legs or feet
- Male impotence (erectile dysfunction)
- Numbness in the legs
- The color of the skin on the legs change
- The toenails get thicker
- Weakness in the legs
On the next page we look at how atherosclerosis is diagnosed, how it can be prevented and the available treatments for atherosclerosis.