Atherosclerosis (ath-er-o-skler-O-sis) is a disease in which plaques that are made up of fat, cholesterol, calcium and other substances, build up in artery walls. Over time, the plaques harden, narrow the opening of the arteries and restrict the blood flow.
When these fatty plaques rupture (break open), they form a thrombus (blood clot) that can further limit, or even block the flow of oxygen-rich blood to organs and other parts of the body.
Atherosclerosis can occur in arteries anywhere in the body but is most serious when it leads to a reduced or blocked blood supply to the heart or to the brain. If it occurs in one of the two main coronary arteries that supply blood to the heart this results in a heart attack. When thrombosis occurs in one of the arteries to the brain, it causes a stroke.
At what age does atherosclerosis occur?
Atherosclerosis is a complex process, often starting in childhood and progressing with age. Our latest research has shown that the origins of heart disease and vessel disease can begin even earlier – in the foetus. Those babies born ‘small for dates’, that is in the lowest five per cent of birth weights at term delivery, appear to be at high risk of high blood pressure, diabetes and cardiovascular disease later in life. Our Clinical Research Group has planned a series of novel intervention studies, mainly with fish oils, to see if we can reverse this risk factor with early intervention.
Atherosclerosis progresses as we age and often shows no symptoms until middle or older age. Detecting heart and blood vessel problems at an early stage and designing interventions to treat abnormalities, has the potential to hundreds of thousands of lives each year.
Risk factors for atherosclerosis
90 per cent of New Zealanders have one modifiable risk factor for heart disease. Much of the burden caused by cardiovascular is preventable. The major modifiable risk factors include tobacco smoking, high blood pressure, high blood cholesterol, insufficient physical activity, obesity, diabetes, poor nutrition, and excessive intake of alcohol. Other risk factors that are beyond our control include age, gender, family history and ethnicity.
What causes atherosclerosis?
Arteries are blood vessels that carry blood from the heart throughout the body. They're lined by a thin layer called the endothelium, a layer of cells that keeps the inside of arteries smooth, allowing blood to flow easily.
Atherosclerosis starts when the endothelium becomes damaged - usually caused by risk factors such as high blood pressure, smoking, or high cholesterol. When the endothelium is damaged, LDL or ‘bad’ cholesterol begins to accumulate in the artery wall. To combat this, the body sends macrophage - a type of white blood cell - to clean up the cholesterol. Sometimes the cells get stuck at the affected site. Over time this results in plaque build up, made up of bad cholesterol and macrophage white blood cells.
As atherosclerosis progresses, the plaque gets bigger and, when it gets big enough, it can create a blockage.
At the Heart Research Institute, we’re trying to understand how atherosclerosis develops and to find innovative ways of preventing, detecting and treating cardiovascular diseases that result.
By understanding the causes of atherosclerosis (diabetes, cholesterol, smoking, high blood pressure and family history) we can better improve human health.
Heart research costs millions. No research costs more.
Find out about Women and Heart Disease and Heart Disease in the Māori Community.