What is atherosclerosis?

Atherosclerosis¹ is a disease in which plaque (made up of fat, cholesterol, calcium, and other substances found in the blood) builds up in and on the walls of your arteries (blood vessels that deliver oxygen-rich blood from the heart to the rest of the body).

While healthy arteries are flexible and elastic, atherosclerosis can cause the arteries to harden and narrow, further restricting blood flow. Plaque buildup can also restrict the flow of oxygen-rich blood to the heart and other parts of the body.

While atherosclerosis is often considered to be a heart problem, it can affect arteries anywhere in the body. While preventable and treatable, atherosclerosis can lead to serious complications. In some cases, plaque can burst, triggering a blood clot². If left untreated, atherosclerosis can lead to potentially fatal problems, including heart attack³, stroke⁴, or even death.

Atherosclerosis causes

The exact cause of atherosclerosis isn’t known⁵. While the disease is slow and progressive, sometimes starting to develop in childhood, atherosclerosis develops faster as you age.

Atherosclerosis can start when the inner layer of an artery is damaged or injured. This damage may be caused by:

• Smoking
• High amounts of certain fats or lipids (triglycerides) in the blood
• High cholesterol⁶
• High blood pressure (hypertension⁷)
• High amounts of sugar in the blood due to insulin resistance or diabetes⁸
• Inflammation from diseases, such as arthritis⁹, lupus¹⁰, or infections, as well as inflammation of unknown cause When an artery has been damaged, plaque may begin to build at the injury site, causing the artery to narrow over time. Eventually, an area of plaque can rupture (break open).

When plaque ruptures, blood cell fragments called platelets stick to the site of the injury. These fragments may clump together to form blood clots, further narrowing the arteries and limiting the flow of oxygen-rich blood to the rest of the body.

Risk factors for atherosclerosis

The factors¹¹ that increase the risk of developing atherosclerosis include many of the same factors as those that may cause damage or injury to the arteries.

Aside from these factors, obesity, a family history of early heart disease, lack of exercise, and an unhealthy diet put you at an elevated risk for developing atherosclerosis.

Atherosclerosis of the aorta

In some cases, atherosclerosis develops in the aorta (the main artery that carries oxygen-rich blood away from the heart to the rest of the body). This is called atherosclerosis of the aorta or arteriosclerotic aortic disease¹².

Like all blood vessels, the wall of the aorta is made up of living cells that require nutrients and oxygen. Many nutrients seep from the inside of the blood vessel through the arterial walls to nourish the rest of the blood vessel.

When the arterial lining is covered with plaque, these nutrients can no longer seep through sufficiently. Cells no longer receive oxygen, causing some of them to die. As atherosclerosis progresses and cells continue to die, the walls of the aorta progressively weaken.

When a critical relationship is reached between the pressure in the center of the blood vessel, its wall’s tension, and the strength of the wall itself, the arterial wall begins to dilate (grow larger) where plaque has built up. As the vessel continually widens, its wall’s tension increases, leading to even further dilation.

The end result of this dilation is an aneurysm. The majority of aortic aneurysms¹³ are abdominal aortic aneurysms¹⁴. When small, these aneurysms rarely rupture; however, they can grow very large without causing symptoms.

Atherosclerosis symptoms

Atherosclerosis develops gradually. Especially if your atherosclerosis is mild, you won’t experience any signs or symptoms¹⁵ of the disease until an affected artery is so narrowed or clogged that it can’t adequately supply blood to your organs and tissues.

The signs and symptoms experienced as a result of moderate to severe atherosclerosis depend on which arteries are affected¹⁶.

• Coronary arteries: These arteries supply oxygen-rich blood to the heart. When plaque constricts or blocks these arteries (which causes a disease called ischemic heart disease¹⁷) you may experience angina¹⁸, chest pain or discomfort that occurs when your heart doesn’t receive enough oxygenated blood. Other symptoms of ischemic heart disease are shortness of breath and arrhythmias¹⁹ (irregular heartbeats). When plaque forms in the heart’s smallest arteries (called coronary microvascular disease²⁰, or MVD), you may experience angina, shortness of breath, sleep problems, fatigue, and a lack of energy.
• Carotid arteries: These arteries supply oxygen-rich blood to the brain. If plaque constricts or blocks these arteries (which causes carotid artery disease²¹), you may experience symptoms of a stroke²², including sudden weakness, paralysis or numbness of the face or limbs, confusion, trouble speaking or understanding speech, dizziness, or loss of coordination.
• Peripheral arteries: When plaque builds up in the major arteries that supply oxygen-rich blood to the legs, arms, and pelvis, it’s called peripheral artery disease²³. When these arteries are constricted or blocked, you may experience numbness, pain, or even dangerous infections in the affected limbs.
• Renal arteries: The renal arteries supply oxygen-rich blood to the kidneys. When plaque builds up in these arteries, chronic kidney disease²⁴ may develop. Early kidney disease often has no signs or symptoms. As the disease progresses, however, it causes a slow loss of kidney function, which may result in tiredness, changes in urination frequency, loss of appetite, nausea, swelling in the hands or feet, itchiness or numbness, and trouble concentrating.

Complications from atherosclerosis

The complications²⁵ associated with atherosclerosis also depend on which artery is blocked:

• Coronary artery disease: Caused by the narrowing or blockage of arteries close to the heart; can lead to angina, a heart attack, or heart failure
• Carotid artery disease: Caused by narrowing or blockage of the arteries close to the brain; can lead to a transient ischemic attack²⁶ (or TIA, sometimes called a mini-stroke) or stroke
• Peripheral artery disease: Caused by circulation problems results from the narrowing or blockage of arteries in the arms or legs; can make you less sensitive to heat and cold, increasing your risk of burns or frostbite; in some cases, can cause tissue death (gangrene²⁷)
• Aneurysms: If a blood clot in an aneurysm dislodges, it may block an artery at some point in the future. While most people with aneurysms experience no symptoms, a burst aneurysm can cause life-threatening internal bleeding.
• Chronic kidney disease: The narrowing or blockage of the arteries leading to your kidneys can affect kidney function, keeping waste materials from exiting your body.

As with any condition, it’s important that you see your healthcare provider if you believe that you have atherosclerosis or experience any new or worsened symptoms.