Coronary heart disease (CHD) is a condition in which the CORONARY ARTERIES — the blood vessels that supply the heart muscle itself with oxygen and glucose — become narrowed and partially or completely blocked.
The heart muscle is always active, always respiring — it needs a continuous supply of oxygen. If this supply is reduced or cut off, the heart muscle cannot function properly.
CHD is one of the leading causes of death in the UK and worldwide.
How CHD Develops — Atherosclerosis
CHD develops through a process called ATHEROSCLEROSIS:
1. Over many years, fatty substances (mainly cholesterol) build up in the walls of the coronary arteries.
2. These fatty deposits are called PLAQUES or ATHEROMAS.
3. The plaques harden over time, making artery walls less elastic.
4. The lumen (central channel) of the artery becomes progressively NARROWER.
5. Blood flow to the heart muscle is reduced.
6. If a plaque ruptures, a BLOOD CLOT can form at that site — this can completely block the artery.
Complete blockage = HEART ATTACK. The heart muscle supplied by that artery receives no oxygen and begins to die. This causes severe chest pain, shortness of breath and can be fatal.
Risk Factors for CHD
Several factors increase the risk of developing CHD:
HIGH BLOOD CHOLESTEROL — excess cholesterol deposits in artery walls forming plaques.
HIGH BLOOD PRESSURE — damages artery walls, making them more susceptible to plaque formation.
POOR DIET — high in saturated fats and salt raises cholesterol and blood pressure.
LACK OF EXERCISE — physical activity strengthens the heart and helps control weight and cholesterol.
OBESITY — associated with high blood pressure, high cholesterol and type 2 diabetes.
NON-LIFESTYLE FACTORS (cannot be changed):
GENETICS — family history of CHD significantly increases risk.
AGE — risk increases with age as arteries gradually narrow.
SEX — males tend to develop CHD at younger ages than females (though risk equalises after menopause).
Treatments for CHD
Several treatments can reduce the effects of CHD:
STATINS (medication):
Drugs that reduce the level of LDL cholesterol in the blood.
Slows the build-up of plaques in arteries.
Taken daily — can significantly reduce heart attack and stroke risk.
Side effects: muscle pain in some patients.
STENTS (surgical):
A small metal mesh tube inserted into a narrowed coronary artery.
Holds the artery open, restoring blood flow.
Inserted during a procedure called angioplasty — a thin tube is passed through a blood vessel to the narrowed area.
Effective but does not treat the underlying cause.
BYPASS SURGERY:
A healthy blood vessel from another part of the body (e.g. leg vein) is grafted around the blocked section of coronary artery.
Creates a new route for blood to reach the heart muscle.
Major surgery with risks, but effective for severe blockages.
HEART TRANSPLANT:
Replacing the entire diseased heart with a donor heart.
Last resort for severe heart failure.
Risks: immune rejection, waiting time for a suitable donor.
Patient must take immunosuppressant drugs for life to prevent rejection.
⚠️ Common Mistake
A STENT holds a narrowed artery open — it does NOT bypass the blockage. A BYPASS SURGERY creates a new route around the blockage using a grafted blood vessel. Students often confuse these two treatments.
📌 Key Note
CHD = narrowed coronary arteries (atherosclerosis/plaques). Risk factors: smoking, high cholesterol, high blood pressure, poor diet, lack of exercise. Treatments: statins (lower cholesterol), stents (hold artery open), bypass surgery (reroute blood).
🎯 Matching Activity — Match the CHD Treatment to How it Works
Match each treatment to its mechanism. — drag the symbols on the right to match the component names on the left.
Statins
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Stent
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Bypass surgery
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Heart transplant
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Replaces the diseased heart — last resort, risk of rejection
Metal mesh tube inserted into a narrowed artery to hold it open
Grafts a healthy blood vessel around the blocked coronary artery
Drugs that lower LDL cholesterol in the blood — slow plaque formation
🎯 Test Yourself
Question 1 of 3
1. What causes coronary heart disease?
2. How does a stent treat coronary heart disease?
3. Which of the following is a lifestyle risk factor for CHD that CAN be changed?
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