Atherosclerosis

What is atherosclerosis?

Atherosclerosis is the process of cholesterol plaque buildup in arteries. It can lead to a narrowing of the arteries that can significantly reduce the blood supply to vital organs such as the heart, brain, and intestines. In atherosclerosis, the arteries are narrowed when fatty deposits called plaques build up inside. Plaques typically contain cholesterol from low-density lipoproteins (LDL), smooth-muscle cells and fibrous tissue, and sometimes calcium.

As a plaque grows along the lining of an artery, it can sometimes rupture, leading to formation of a blood clot inside the artery, which can totally block blood flow. As a result, the organ supplied by the blocked artery starves for blood and oxygen. The organ's cells may either die or suffer severe damage.

Atherosclerosis is the main cause of death and disability in industrialized nations, including the United States. This is because atherosclerosis is the underlying medical problem in most patients with any of the following illnesses:

• Coronary artery disease — In this chronic (long-lasting) disease, atherosclerosis narrows the coronary arteries, the arteries that supply blood to the heart muscle. This can lead to the chest pain called angina. It also increases the risk of a heart attack, which occurs when a coronary artery is blocked completely.
• Stroke — A blood clot (thrombus) may form inside a brain artery that has been narrowed by atherosclerosis. Once this thrombus forms, it cuts off the blood supply to part of the brain, causing a thrombotic stroke. Currently, about 75% of strokes in industrialized countries are thrombotic strokes.
• Abdominal pain and bowel infarction — When atherosclerosis narrows arteries that supply blood to the intestines, it can cause abdominal pain. Complete, sudden blockage of intestinal blood supply can cause a bowel infarction. A bowel infarction is similar to a heart attack, but it involves the intestines rather than the heart.
• Atherosclerosis of the extremities — Atherosclerosis can narrow the major arteries that supply blood to the legs, especially the femoral and popliteal arteries. This is often called peripheral artery disease (PAD) or peripheral vascular disease (PVD). The femoral and popiteal arteries are affected in 80% to 90% of people with this problem. The reduced blood flow to the legs may result in a crampy leg pain during exercise called intermittent claudication. If blood flow is compromised severely, parts of the leg may become pale or cyanotic (turn blue), feel cold to the touch and eventually develop gangrene.
• Other conditions — Atherosclerosis may be a factor in the development of an aortic aneurysm or renal artery stenosis (narrowing of the kidney arteries).

Factors that increase your risk of developing atherosclerosis include:

• high blood cholesterol level
• high level of LDL (bad) cholesterol
• high levels of triglycerides
• high levels of lipoprotein(a)
• high blood pressure (hypertension)
• diabetes
• family history of CAD at a younger age
• cigarette smoking
• obesity
• physical inactivity
• inflammation, often detected by high levels of C-reactive protein, a marker in the blood.

Symptoms of atherosclerosis

Atherosclerosis usually doesn't cause any symptoms until blood supply to an organ is reduced. When this happens, symptoms vary, depending on the specific organ involved:

• Heart — Symptoms include the chest pain of angina and shortness of breath, sweating, nausea, dizziness or light-headedness, breathlessness or palpitations.
• Brain — When atherosclerosis narrows brain arteries, it can cause dizziness or confusion; weakness or paralysis on one side of the body; sudden, severe numbness in any part of the body; visual disturbance, including sudden loss of vision; difficulty walking, including staggering or veering; coordination problems in the arms and hands; and slurred speech or inability to speak. If symptoms completely disappear within an hour or a bit longer, the episode is called a transient ischemic attack (TIA). When atherosclerosis completely blocks the brain arteries and/or the above symptoms last longer, it's generally called a stroke.
• Abdomen — When atherosclerosis narrows the arteries to the intestines, there may be dull or cramping pain in the middle of the abdomen, usually beginning 15 to 30 minutes after a meal. Sudden complete blockage of an intestinal artery often causes severe abdominal pain, sometimes with vomiting, bloody stool and abdominal swelling.
• Legs — Narrowing of the leg arteries from atherosclerosis is known as peripheral artery disease. It can cause cramping pain in the leg muscles, especially during exercise. If narrowing is severe, there may be pain at rest, cold toes and feet, pale or bluish skin and hair loss on the legs.

Diagnosing atherosclerosis

Your doctor will review your medical history, your current symptoms and any medications you are taking.

Your doctor will ask you about your family history of heart disease, stroke and other circulatory problems, and your family history of high blood cholesterol. He or she will ask about cigarette smoking, your diet, and how much exercise you get.

Your doctor will measure your blood pressure and heart rate. He or she will examine you, paying special attention to your circulation, sometimes listening to the arteries in the neck. The exam includes feeling for pulses in your neck, wrists, groin, and feet. Your doctor may check the blood pressure in your legs, to compare it to the pressure in your arms. The ratio of your blood pressure at your ankle to the blood pressure inside your elbow is called an ankle-brachial index or ABI.

Signs of poor impaired circulation include:

• weak pulses
• cool skin that is pale or blue in the lower legs and feet
• bruits (the rough sound of turbulent blood flow through narrowed arteries) heard with a stethoscope in the neck, abdomen and groin
• an ABI of 0.9 or lower.

Your doctor will order blood tests to measure your total, LDL and HDL cholesterol levels, triglyceride level, fasting blood sugar, hemoglobin A1c (a measure of blood sugars over the prior three months), and sometimes hs-CRP C-reactive protein, a marker for inflammation), and Lp(a) (lipoprotein(a), a fatty particle linked to a heightened risk of heart attack). A routine electrocardiogram (EKG) occasionally will uncover electrical changes in the heart that indicate poor blood flow to the heart muscle. Your doctor may order an EKG performed during an exercise stress test if you have any symptoms suggestive of coronary artery disease.

Imaging tests such as CT scans or MRIs can sometimes be done (or reviewed if already done for a different reason). They can reveal calcium buildup (a sign of atherosclerosis) in arteries of the heart, the aorta, carotid arteries to the brain, or in the abdomen. A calcium score test is a CT scan of the heart to look for this buildup in the heart arteries. A carotid ultrasound is an ultrasound looking for cholesterol plaque or blockage in the arteries to the brain.

Expected duration of atherosclerosis

Atherosclerosis is a long-term condition that continues to worsen over many decades without changes in lifestyle and medication if necessary.

Preventing atherosclerosis

You can help to prevent atherosclerosis by changing your risk factors for the illness. You should practice a lifestyle that promotes good circulation and combats atherosclerosis:

• Avoid cigarette smoking. If you smoke, it is essential that you quit.
• Maintain a healthy weight. Obesity, especially a concentration of body fat around the waist, has been linked to unhealthy levels of HDL cholesterol and triglycerides.
• Eat a healthy diet that is rich in vegetables and fruits. Avoid saturated and trans fats. Use monounsaturated (olive) and polyunsaturated (sunflower, safflower, peanut, canola) oils for cooking. Dietary protein should come primarily from fish and plant sources (soy, beans, legumes).
• Exercise regularly.
• Control high blood pressure. You may have to take medication to do this. If you have never been diagnosed with high blood pressure, you should have it checked every two years.
• If you have diabetes, you need to work even harder on controlling weight, exercising more, lowering LDL cholesterol and triglyceride levels, and keeping blood pressure less than 140/90.
• If you do not have diabetes, you should have a fasting blood sugar test every few years if you have risk factors for diabetes (being overweight, having high blood pressure or high cholesterol) starting at age 45.
• Work with your doctor to maintain proper cholesterol levels. If you have never been diagnosed with cholesterol problems, you should have your cholesterol checked every five years starting at age 20.

Treating atherosclerosis

There is no cure for atherosclerosis, but treatment can slow or halt the worsening of the disease. The major treatment goal is to prevent significant narrowing of the arteries so that symptoms never develop and vital organs are never damaged. To do this, you would begin by following the healthy lifestyle outlined above.

If you have high cholesterol that cannot be controlled by diet and exercise, your doctor will likely recommend medication. The most common medicines used to lower cholesterol are statin drugs, also known as HMG-CoA reductase inhibitors. Statins block an enzyme called HMG-CoA reductase, which controls the production of cholesterol in the liver. Examples include:

• lovastatin (Mevacor)
• simvastatin (Zocor)
• pravastatin (Pravachol)
• fluvastatin (Lescol)
• atorvastatin (Lipitor)
• rosuvastatin (Crestor).

Many other non-statin classes of medication exist as well. These medications have been shown to reduce risk of heart events. they include:

• ezetimbe, which blocks absorption of cholesterol
• bempedoic acid, which instructs the liver to make less cholesterol
• PCSK9 inhibitors, which increase LDL receptors on the liver, helping to clear circulating LDL from the bloodstream.

Anti-clotting medications such as aspirin, or other antiplatelet drugs such as clopidogrel (Plavix), are often used as well. They can increase the risk of bleeding, so careful selection of which agent and for how long is needed.

Once symptoms of atherosclerosis-related organ damage develop, the specific treatment depends on the organ involved:

• Heart — Treatments for coronary artery disease include medications to manage symptoms of angina (nitrates, beta-blockers, calcium channel blockers) and prevent heart attacks (aspirin and beta-blockers); balloon angioplasty often with wire mesh stents; and, less commonly, coronary artery bypass surgery.
• Brain — Treatment to help prevent transient ischemic attacks (TIAs) and stroke usually includes one or more antiplatelet medications such as aspirin, dipyridamole and clopidogrel (Plavix). If a carotid artery is very narrow, a procedure to open the artery may be recommended.
• Abdomen — When atherosclerosis narrows arteries that supply the bowel, the patient may be treated with balloon angioplasty with or without stents or a bypass arterial graft.
• Legs — The mainstays of treatment for peripheral artery disease are quitting smoking, exercise (usually a walking program), and aspirin. People with severe arterial narrowing may be treated with balloon angioplasty with or without stents, laser angioplasty, atherectomy or bypass grafts.

When to call a professional

It is possible to have atherosclerosis for many years without having symptoms. If you experience symptoms of an atherosclerosis-related medical condition, contact a doctor immediately.

Prognosis

Atherosclerosis leads to the number one cause of death in the United States and many other countries: cardiovascular disease. However, people with atherosclerosis are living longer with better quality of life than ever before. For many, this is disease can be prevented. Even those people genetically programmed for atherosclerosis can delay the beginning and worsening of the disease with a healthy lifestyle, the right foods, and medication to lower LDL cholesterol.

Additional info

National Heart, Lung, and Blood Institute (NHLBI)
http://www.nhlbi.nih.gov/

American Heart Association (AHA)
http://www.heart.org/

American College of Cardiology
http://www.acc.org/