Cholesterol
Atherosclerosis
Atherosclerosis is the process by which fatty or fibrous deposits build up in the arterial wall to form plaques. The build-up of plaques causes the artery to narrow, which can reduce the blood supply to vital organs such as the heart and brain, depriving them of oxygen and vital nutrients – this is called ischaemia. Damage to the artery due to cardiovascular risk factors such as hypertension or smoking allows cholesterol in the blood to enter the arterial wall. This starts a chain of events that leads to a narrowing within the artery wall due to cholesterol accumulation, known as a ‘plaque’.
Progression of atherosclerosis is the main cause of cardiovascular disease and associated events.1,2 An atherosclerotic plaque can cause complications in a number of ways:
- Plaque growth can lead to a narrowing of the blood vessel and a gradual reduction of blood flow. Many parts of the body can compensate by developing alternative routes of blood supply by collateral blood vessels, but only to a certain extent. If the following tissues receive a less-than-adequate blood supply, adverse symptoms occur:
- Heart: chest pain on exercise, known as angina
- Brain: can lead to transient ischaemic attack (TIA)
- Legs: intermittent claudication
- Plaque rupture exposes cholesterol and parts of the vessel wall to the blood, leading to blood clotting and platelet activation. This can cause thrombus formation that completely blocks the blood flow, or a thrombus that blocks a blood vessel further downstream. This could lead to a myocardial infarction in the coronary arteries, or a stroke in the carotid arteries leading to the brain
- Weakening and widening of the vessel wall can lead to an aneurysm, a bulging or ballooning of the vessel wall. When an aneurysm ruptures, this can result in massive internal bleeding
Lipid modifying treatment, in addition to dietary and lifestyle changes, can slow the progression of atherosclerosis, or even lead to plaque regression.
References:
1. Lusis AJ. Atherosclerosis. Nature 2000; 407: 233-41.
2. World Health Report 2004. World Health Organization. http://www.who.int