Coronary heart disease: a non-communicable disease — AQA GCSE Combined Science
Test yourself on Coronary heart disease: a non-communicable disease with AQA GCSE practice questions.
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Coronary heart disease: a non-communicable disease explained
Coronary heart disease occurs when fatty deposits narrow the coronary arteries, reducing blood flow to heart muscle.
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Treatments include drugs such as statins, which lower blood cholesterol, and anticoagulants, which reduce clotting; mechanical devices such as stents, which hold arteries open, and artificial pacemakers, which correct irregular heartbeats; and heart transplants. Evaluating means weighing benefits against drawbacks. Stents restore blood flow quickly but carry risks of infection or thrombosis. Statins reduce heart attack risk but may cause muscle pain and must be taken long term. Transplants can restore heart function but donor hearts are scarce and immunosuppressant drugs are needed. A judgement should compare options for a named patient, considering effectiveness, risk, cost, availability and quality of life.
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.
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.
In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. Students should understand the consequences of faulty valves. Faulty heart valves can be replaced using biological or mechanical valves.
Heart valves keep blood flowing one way through the heart. A valve that cannot open fully is stiff or narrowed, so blood cannot pass easily and the heart must work harder to push blood through. A leaky valve does not close tightly, so blood flows backwards instead of moving on. Both faults reduce the efficiency of the heart's pumping, which can cause breathlessness, tiredness and fluid build-up. Faulty valves can be replaced with biological valves, taken from an animal or a human donor, or mechanical valves made from materials such as metal or polymer. Biological valves may wear out sooner, while mechanical valves are durable but usually require long-term medication to reduce clotting.
In the case of heart failure a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery.
Heart failure means the heart cannot pump blood effectively around the body. A donor heart, or a donor heart and lungs together, can be transplanted to replace the failing organs. Donor organs are scarce, so patients may wait a long time and must be matched to reduce rejection. While waiting, an artificial heart can be fitted. It is a mechanical pump that takes over the pumping action, keeping the patient alive until a donor organ becomes available. Sometimes an artificial heart is used temporarily to let the patient's own heart rest, which may help it recover. Artificial hearts are used only occasionally because of risks such as infection, blood clots and bleeding, and because they need a power supply.
Your focus
- Describe how drugs, mechanical devices and transplants are used to treat cardiovascular diseases.
- Compare the advantages and disadvantages of each treatment option using appropriate criteria.
- Reach and justify a conclusion about the most suitable treatment for a given patient.
Show all 12 objectives
- Describe how fatty material builds up in the coronary arteries and narrows them.
- Explain how reduced coronary blood flow leads to a lack of oxygen for the heart muscle.
- Compare stents and statins in terms of how they reduce the effects of coronary heart disease.
- Describe how a faulty heart valve can fail to open fully or can leak.
- Explain the consequences of faulty valves for blood flow and heart function.
- Compare biological and mechanical replacement valves.
- Describe what is meant by heart failure and how it affects blood pumping.
- Describe donor heart and heart-lung transplantation as treatments for heart failure.
- Explain how and why artificial hearts are used whilst waiting for a transplant or to rest the heart.
Coronary heart disease: a non-communicable disease exam tips
Marking Points
- Stents are inserted into narrowed coronary arteries to keep them open, improving blood flow and reducing angina, but surgery carries risks such as infection or blood clots.
- Statins reduce cholesterol production in the liver, lowering the risk of fatty deposits forming, but can cause side effects such as muscle pain and need long-term use.
- Anticoagulants reduce blood clotting, lowering the risk of heart attack or stroke, but can cause excessive bleeding if a wound occurs.
- Artificial pacemakers correct irregular heart rhythms by sending electrical impulses, but require surgery and battery replacement.
- Heart transplants can restore heart function when other treatments fail, but donor hearts are scarce and immunosuppressant drugs must be taken for life.
- Evaluation should compare treatments using criteria such as effectiveness, risk, cost, availability and impact on daily life, then reach a justified conclusion.
- 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.
- States that valves normally keep blood flowing in one direction through the heart.
- Describes a valve that cannot open fully as stiff or narrowed, so blood flow through it is restricted.
- Describes a leaky valve as one that does not close tightly, allowing blood to flow backwards.
- Explains that both faults make the heart work harder and reduce the efficiency of blood circulation.
- Names biological and mechanical replacement valves and gives a relevant difference between them.
- Links valve replacement to restoring one-way blood flow and improving symptoms.
- State that heart failure occurs when the heart cannot pump blood effectively around the body.
- Name a donor heart transplant, or a heart and lungs transplant, as a treatment that replaces the failing organ(s).
- Explain that donor organs are in short supply, so patients may wait a long time for a suitable match.
- Describe an artificial heart as a mechanical pump that keeps a patient alive while they wait for a transplant.
- Explain that an artificial heart can allow the patient's own heart to rest and so aid recovery.
- Recognise that artificial hearts are used only occasionally because of risks such as infection, blood clots or bleeding, and the need for a power supply.
Examiner Tips
- 💡Use a table or clear paragraphs to separate advantages and disadvantages before writing your evaluation.
- 💡Refer to a specific treatment and a specific patient context, such as an elderly patient with narrowed arteries, to make the evaluation relevant.
- 💡Use comparative language such as 'more effective than' or 'carries a greater risk than' to show evaluation rather than description.
- 💡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.
- 💡Use the phrase 'blood flows backwards' for a leaky valve and 'blood cannot flow through easily' for a valve that cannot open fully.
- 💡When asked about consequences, link the faulty valve to the heart working harder and to symptoms such as breathlessness or tiredness.
- 💡For treatment questions, compare biological and mechanical valves using one advantage and one disadvantage of each.
- 💡Use the phrase 'whilst waiting for a heart transplant' when describing the main purpose of an artificial heart.
- 💡Link each treatment to its purpose: transplant replaces the organ, artificial heart supports the patient temporarily.
- 💡When asked to evaluate, give both a benefit and a risk of artificial hearts rather than only one side.
Common Mistakes
- Listing advantages and disadvantages without a conclusion; finish with a justified judgement comparing the options.
- Treating all drugs as having the same effect; distinguish statins, which lower cholesterol, from anticoagulants, which reduce clotting.
- Ignoring non-medical factors such as cost, waiting lists or lifestyle; include these when evaluating treatments.
- Confusing the coronary arteries with the aorta or pulmonary artery: the coronary arteries branch from the aorta and supply the heart muscle itself.
- Thinking a stent cures coronary heart disease: a stent holds one narrowed artery open but does not remove the underlying disease process.
- Believing statins dissolve existing fatty deposits: they mainly lower cholesterol and slow further deposition.
- Saying a leaky valve blocks blood flow: a leaky valve allows backflow because it does not seal properly.
- Confusing a valve that cannot open fully with a leaky valve: the first restricts forward flow, the second allows reverse flow.
- Assuming all replacement valves last equally well: biological valves tend to wear out sooner, while mechanical valves are more durable but may need medication to reduce clotting.
- Saying an artificial heart cures heart failure permanently; correct this by stating it is usually a temporary measure to keep the patient alive or rest the heart.
- Confusing a heart transplant with a coronary bypass or stent; correct this by stating that a transplant replaces the whole heart (or heart and lungs) with donor organs.
- Claiming donor organs are always immediately available; correct this by explaining that demand exceeds supply, so waiting times can be long.