BIOMED SCIE Lecture 9 Cardiovascular Disease IV

• Cardiovascular disease


  Disorders of the heart and the blood vessels
• Types of cardiovascular disease

  • Coronary heart disease: disease of the blood vessels supplying the heart muscle
  • Cerebrovascular disease: disease of the blood vessels supplying the brain
  • Peripheral arterial disease: disease of blood vessels supplying the arms and legs
  • Rheumatic heart disease: damage to the heart muscle and heart valves from rheumatic fever, caused by streptococcal bacteria
  • Congenital heart disease: malformations of heart structure existing at birth
  • Deep vein thrombosis and pulmonary embolism: blood clots in the leg veins, which can dislodge and move to the heart and lungs
• Cardiovascular diseases account for ~36% of yearly deaths in Ireland
• Atherosclerosis


  Damage occurs to the inner lining of an artery and deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances can build up

  
• Cholesterol build up is caused by too much ('bad') LDL-Cholesterol in the plasma


  Once in the subendothelium it becomes oxidised by free radicals released by the endothelium
• Plaque


  The build-up of fatty substances, cholesterol, cellular waste products, calcium and other substances in the artery
• Thrombosis


  Inappropriate activation of the normal haemostatic process within the non-interrupted vascular system, resulting in thrombus (blood clot) formation that blocks blood flow to vital areas

  
• Blood vessel structure


  • The cavity of a vessel is called the central lumen
  • The epithelial layer that lines blood vessels is called the endothelium
  • The endothelium is smooth and minimises resistance

  
• Endothelial dysfunction


  A change in the surface structure of endothelial cells, with presentation of surface adhesion receptors (sticky) which allow rolling and transmigration of white blood cells (monocytes) and adhesion and activation of platelets

  
• Causes of endothelial dysfunction and atherosclerosis


  • Hypertension
  • Diabetes
  • Elevated cholesterol (Raised LDL, low HDL)
  • Age
  • Smoking
  • Obesity
  • Family history
• Response to endothelial injury

  1. Monocyte transmigration through the endothelium

  2. Monocytes differentiate into macrophages

  3. Macrophages ingest lipoproteins and become foam cells

  4. Foam cell/Fatty streak formation

  
• Stages in atherosclerotic plaque development

  • Lipoprotein trapping in the subendothelial space
  • Lipoprotein aggregation (LDL cholesterol)
  • Monocyte transmigration from the bloodstream to the injured site
  • Foam cell formation/fatty streaks – monocytes become macrophages and engulf the lipoprotein
  • Slow plaque build-up over years
  • Plaque rupture

  
• Smoking increases the risk of heart attack by making platelets more active, decreasing HDL cholesterol, and causing endothelial dysfunction
• Hyperglycaemia in diabetes


  Leads to endothelial damage and plaque build-up
• People with diabetes are two to four times more likely to have a heart attack than someone without the disease
• Cardiovascular diseases account for 65% of diabetic-related illnesses that lead to death
• Angina pectoris


  Chest pains caused by partial blockage of the coronary arteries

  
• Myocardial infarction (heart attack)


  Death of the muscle tissue in the heart resulting from blockage of the blood flow in one or more coronary arteries
• Types of stroke


  • Ischaemic stroke: caused by a blood clot, air bubble or fat globule blocking an artery that carries blood to the brain
  • Haemorrhagic stroke: caused by a blood vessel bursting and bleeding into the brain

  
• Treatments for blocked coronary arteries

  1. Stents: restore blood flow

  2. Coronary artery bypass surgery: use a healthy blood vessel to bypass the blocked or diseased area
• The nicotine in cigarettes enhances the influence of adrenaline on the body, which increases blood pressure by constricting your blood vessels
• Silent Heart Attack (Silent Ischemia)


  • Neuropathy and nerve damage leads to a ‘numbness’, the diabetic does not sense touch, heat, cold or pain.• Because of this, the diabetic may be unaware of symptoms, leading to a silent heart attack
• Coronary arteries supply oxygen- rich blood to the heart muscle
• • Haemorrhagic strokes, This haemorrhage may be due to: a vessel bursting within the brain itself a blood vessel on the surface of the brain bleeding into the area between the brain and the skull