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Coronary heart disease

Causes, risk factors and treatments. Topic 5 of 7 in Organisation.

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1. Coronary heart disease (CHD)

Coronary arteries can develop atherosclerosis — fatty material (including cholesterol) builds up in the artery walls, narrowing them and reducing flexibility.

This restricts oxygenated blood reaching heart muscle cells → cells can’t respire properly → can die → heart attack.

Risk factors: high blood pressure, smoking, excess alcohol, poor diet, high cholesterol, heredity, stress, lack of exercise.

Plaque building up in an artery

Cut across

An artery cut across, almost blocked by fatty plaque in its wall.

Cut lengthways

An artery cut lengthways: plaque has built up in the wall and ruptured, and a blood clot has formed on it.
Fatty material (plaque) builds up in the artery wall, under its lining. The lumen narrows, so less blood can flow through. If the plaque ruptures, platelets gather on it and form a blood clot, which can block the artery completely.

Treatments:

  • Statins — drugs that lower blood cholesterol.
  • Stents — small mesh devices inserted into a narrowed artery to hold it open (less invasive, faster recovery).
  • Heart bypass — a section of blood vessel from elsewhere in the body (often a vein from the leg) is used to reroute blood around a blockage.
  • Lifestyle changes — balanced diet, quitting smoking, reducing alcohol, healthy weight, regular exercise.

How a stent is fitted

  1. A stent: a short tube made of a metal mesh.

    1 of 4 A stent

    A stent is a small, expandable tube of metal mesh. It starts folded up small, so it can be threaded through the blood vessels to the narrowed artery.

  2. A narrowed artery with fatty plaque in its wall and a balloon on a catheter inside the narrowed section.

    2 of 4 Balloon angioplasty

    A thin tube (catheter) is passed through a blood vessel, usually in the wrist or groin, to the narrowed coronary artery. A small balloon on its tip is inflated, squashing the fatty plaque against the artery wall and widening the artery.

  3. A folded stent on a balloon catheter, positioned inside the narrowed section of the artery.

    3 of 4 The stent goes in

    A stent, folded tightly around a balloon, is moved into the narrowed section. Inflating the balloon opens the stent out against the artery wall.

  4. The opened stent left in place, holding the narrowed section of the artery open.

    4 of 4 The artery stays open

    The balloon is deflated and removed, but the stent stays in place. It holds the artery open, so blood can flow freely to the heart muscle again.

Other heart problems:

  • Faulty valves — don’t open/close properly, causing backflow, breathlessness, fatigue; treated by valve replacement (biological or mechanical).
  • Pacemaker problems — irregular pacemaker cells can be corrected with an artificial pacemaker.
  • Septal defect (“hole in the heart”) — gap between the two sides lets oxygenated and deoxygenated blood mix; repaired surgically.
  • Heart failure — may require a heart or heart-lung transplant.

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