Coronary heart disease: a non-communicable disease: In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle. Stents are used to keep the coronary arteries open. Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit.

The idea

Coronary arteries supply the heart muscle itself with oxygenated blood. In coronary heart disease, fatty material called atheroma builds up in the artery wall, so the lumen narrows. Blood flow through the coronary arteries falls, so heart muscle cells receive less oxygen and cannot respire aerobically at the required rate; this causes chest pain and can lead to a heart attack. A stent is a mesh tube inserted into the narrowed artery, often via a balloon catheter, and expanded to hold the artery open, restoring blood flow. Statins are medicines that lower blood cholesterol, slowing further fatty deposit. They reduce risk but do not clear existing deposits, and treatment is long term.

What earns the marks

• Names the coronary arteries as the vessels that supply the heart muscle with oxygenated blood.
• Describes fatty material building up inside the coronary artery wall and narrowing the lumen.
• Links narrowing to reduced blood flow and therefore reduced oxygen delivery to heart muscle.
• Explains that stents are inserted and expanded to keep the coronary artery open and restore blood flow.
• Explains that statins lower blood cholesterol, slowing the rate at which fatty material is deposited.
• Recognises that statins reduce risk but do not remove existing fatty deposits, so they are usually taken long term.

Common mistakes and how to put them right

• Confusing the coronary arteries with the aorta or pulmonary artery.

  Put it right: The coronary arteries branch from the aorta and supply the heart muscle itself.

• Thinking a stent cures coronary heart disease.

  Put it right: A stent holds one narrowed artery open but does not remove the underlying disease process.

• Believing statins dissolve existing fatty deposits.

  Put it right: They mainly lower cholesterol and slow further deposition.

Exam tips

• Use the chain 'narrowed lumen → reduced blood flow → less oxygen to heart muscle → reduced aerobic respiration' when explaining consequences.
• When comparing treatments, give one benefit and one drawback of each, such as stents acting quickly but carrying surgical risk, while statins are tablets but take time to act.
• Read the command word: 'describe' needs the sequence of events, while 'explain' needs the causal links between narrowing, oxygen supply and heart muscle function.