2.3.1 Coronary Heart Disease

• Cardiac muscle cells


  Cells that make up the heart
• Cardiac muscle cells, like all cells in the body, need a supply of blood to deliver oxygen, glucose and other nutrients and remove waste products such as carbon dioxide
• Coronary arteries


  Blood vessels that supply blood to the heart
• The coronary arteries branch off directly from the aorta
• The heart needs to constantly respire, so it is vital that it receives oxygen
• Coronary heart disease (CHD)

  A condition where layers of fatty material build up inside the coronary arteries
• Sources of cholesterol in the body

  • Dietary cholesterol (from animal products eaten)
  • Cholesterol synthesised by the liver
• If a coronary artery becomes partially or completely blocked by fatty deposits


  It loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts
• Reduced blood flow through the arteries


  Results in a lack of oxygen for the heart muscle
• Angina


  Severe chest pains caused by partial blockage of the coronary arteries
• Heart attack


  Occurs when cells in an area of the heart cannot respire aerobically due to complete blockage of a coronary artery
• Treatment of CHD using stents

  1. Threaded up through the groin to the blocked vessel

  2. Tiny balloon inflated to push metal/plastic stent against artery wall

  3. Balloon and tube removed
• Stents


  • Effective at reducing risk of heart attack by widening lumen to increase blood flow
  • Procedure is relatively simple
  • Last a long time
  • Risk of blood clots (thrombosis)
• Treatment of CHD using statins


  1. Block an enzyme in the liver needed to make cholesterol

  2. Slow down rate of fatty material building up in blood
• Statins


  • Reduce levels of 'bad' (LDL) cholesterol, reducing risk of CHD, heart attacks and strokes
  • Can increase levels of 'good' (HDL) cholesterol
  • Must be taken regularly and long-term
  • Can have undesirable side effects
• Heart valves


  Play a vital role in ensuring blood is pumped from the ventricles to the arteries
• Faulty heart valves

  • Can stiffen, preventing full opening to let blood flow through
  • Can develop a leak, allowing blood to flow in the wrong direction
• Replacing faulty heart valves

  1. Using biological valves from cows or pigs

  2. Using mechanical valves
• Heart transplant

  Replacing the heart with an artificial one made from plastic and metal
• Artificial hearts

  • May be used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
  • Less wait time as they are manufactured
  • Less chance of immune system rejection
  • Don't always work as well as real hearts at pumping blood
  • Increased risk of blood clots