AQA Biology 4.2.2.4
Coronary heart disease
The heart's own blood supply can slowly clog up. See what happens as a coronary artery narrows, then weigh up drugs, devices and transplants for real patients.
Combined Science · Foundation tier
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An old garden hosepipe.
A hosepipe has been used for years. Gunk has slowly built up on the inside wall, all the way along. The tap is turned on exactly as far as before.
If you had to guess, does more water come out of the end now, or less?
How CHD develops
Fatty material builds up. Flow falls. The muscle runs short of oxygen.
Healthy. A wide lumen. Plenty of blood, and so plenty of oxygen, reaches the heart muscle.
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.
Risk factors such as smoking, a diet high in saturated fat, and lack of exercise are linked to a higher rate of CHD. Risk rises with age because fatty material has longer to build up.
Treatments · drugs, devices, transplants
Every treatment has a cost as well as a benefit.
Statins · a drug
Reduce blood cholesterol, which slows the rate at which fatty material is deposited.
For: no surgery. Against: taken long term; side effects in some people; slow to act; don't clear what is already there.
Stents · a device
A mesh tube that holds a coronary artery open, so blood can flow to the heart muscle. The fatty material stays.
For: quick recovery; flow restored at once. Against: risks of the operation; the artery can narrow again.
Faulty valves
A valve may not open fully, so less blood gets through, or may leak, so blood flows backwards. Either way less oxygenated blood reaches the body: the person is tired and breathless. Faulty valves can be replaced with biological or mechanical valves.
Transplants and artificial hearts
In heart failure, a donor heart, or heart and lungs, can be transplanted. Artificial hearts are occasionally used to keep a patient alive while waiting for a transplant, or to let the heart rest as an aid to recovery.
Against: a shortage of donors; risk of rejection, so drugs to suppress the immune system for life. Artificial hearts are temporary, with risks of blood clots and infection.
Choose a treatment · and defend it
Three patients. What would you recommend?
High blood cholesterol. Early fatty build-up in the coronary arteries, but no symptoms yet.
Think again · what a stent does
“A stent clears the fat out of the artery.”
Your call
ChooseA stent is fitted in a narrowed coronary artery. What happens to the fatty material?
Sort
Drug, mechanical device or transplant?
The spec asks you to weigh these three kinds of treatment. Place each one.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Explain
- Fatty material, narrowing, less blood, less oxygen for the heart muscle: in that order.
- Evaluate
- Advantages and disadvantages of each option, then a judgement with a reason.
- Suggest
- Apply what you know to a new patient or symptom.
Key fact
In coronary heart disease, fatty material builds up inside the coronary arteries, narrowing them and reducing the flow of blood, so the heart muscle lacks oxygen. Statins, stents and transplants each have advantages and disadvantages.
Key note · AQA 4.2.2.4
Coronary heart disease
- CHD: layers of fatty material build up inside the coronary arteries, narrowing them.
- Less blood flows through the coronary arteries, so the heart muscle lacks oxygen.
- Statins reduce blood cholesterol and slow fatty build-up. Stents hold arteries open; the fatty material stays.
- Faulty valves: may not open fully, or may leak. Less oxygenated blood reaches the body. Replace with biological or mechanical valves.
- Heart failure: donor heart, or heart and lungs. Artificial hearts: while waiting for a transplant, or to let the heart rest.
- Evaluate: drugs (no surgery, long term) vs devices (quick, surgery risk) vs transplant (donors, rejection, lifelong drugs).
Photograph this card. Tomorrow, cover it and say each line first.
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Patients described here are invented for practice. Diagrams are schematic and not to scale.