Hyperlipidaemia and atherosclerosis

Question 1

What is hyperlipidaemia

Answer 1

elevated levels of triacylgylceride (TAG) and cholesterol in blood

Question 2

Define chylomicrons

Answer 2

Chylomicrons
Transport exogenous fats from intestines to tissues

VLDL, IDL & LDL
Transport endogenous fats from liver to tissues

HDL
Transport endogenous cholesterol from tissues to liver

Question 3

Difference between primary and secondary hyperlipidaemia

Answer 3

• Primary hyperlipidaemia - mainly due to genetic deficiency
• Secondary hyperlipidaemia – due to lifestyle and other metabolic diseases.

Question 4

Explain the structure of lipoprotein

Answer 4

• Nonpolar core:
  triacylglycerols and cholesteryl esters
• Amphiphilic surface:
  Apoproteins, phospholipid & cholesterol.

Question 5

Outline causes of hyperlipiademia

Answer 5

nutrition, genetics, medications & metabolic diseases. Genetic causes include; increased sensitivity to dietary cholesterol,

Question 6

how is hyperlipaemia diagnosed

Answer 6

• Blood test under fasting conditions

Question 7

Describe treatment for hyperlipidaemia

Answer 7

• Healthy balance diet : replace saturated nfats diet with fruits and vegetables
• regular exercise
• limit alcohol, ,
• avoid smoking

Medications

• stains: inhibits cholesterol biosynthesis (take for lifelong, if stopped can reverse the cholesterol

-Aspirin: inhibit platelet activation (prescribe at low dose)
periodic test to check liver functionats

• Ezetimibe: Blocks the absorption of cholesterol from food and bile. Taken as a combination with statins if the level is not reduced
• Bile acid sequestrants:
• Fibrates:
• Nicotinic acid or niacin or vitamin B3: Inhibits lipolysis in adipocytes and reduce lipid synthesis in the liver
  Usually high concentrations are required
  side effects include skin rash, hepatotoxicity and hyperglycaemia

Question 8

what is the difference between atherosclerosis and arteriosclerosis

Answer 8

Atherosclerosis is hardening of arteries due to plague while
arteriosclerosis is hardening of arteries due to non-plaque factors

Question 9

What is the major cause of atherosclerosis

Answer 9

hyperlipidaemia

Question 10

Describe the different stages of progression of atherosclerosis

Answer 10

1. Endothelial cell injury
   - High LDL levels, smoking and high blood pressure can cause
   - cause irritation or damage or dysfunction to endothelial cells
2. Migration of LDLs
   - Endothelial dysfunction allows the migration of excessive LDL into intima
   - LDLs get oxidised to form oxidised LDL
3. Adhesion, migration & transformation of monocytes
   - Damage to endothelium expresses signalling molecules that attract monocytes to the damaged site.
   - Monocytes binds to endothelial cells and then transform into macrophages
4. Engulfing ox-LDLs
   - Macrophages engulf all the oxidised LDLs and become foam cells
   - Macrophages & Foam cells release growth factors
5. Migration and proliferation of SMCs
   - Growth factors enhance the migration and proliferation of SMCs
   - Dead cells release the lipid core
6. Expansion and occlusion
   - Initially the plaque grows towards the Tunica externa
   - Then grows towards the lumen
   - At a final stage, plaque can rupture and activate platelets and lead to thrombosis

Question 11

What are the risk factors of atherosclerosis

Answer 11

Family history Physical inactivity
genetic factors Poor diet (high calorie, fat)
Ageing Heavy stress
Gender (male) Alcohol

Modifiable factors
- Hyperlipidaemia
- Metabolic diseases (e.g. DM & obesity)
- Smoking
- Hypertension

Question 12

How is atheroclerosis diagnosed

Answer 12

• Blood test
• Electrocardiogram

Question 13

How is atherosclerosis treated

Answer 13

SAME as hyperlipidaemia

• Anti-hypertensives: ACE inhibitors, calcium channel blockers & diuretics
• Anti-platelet drugs to prevent thrombosis
• Surgical procedures (coronary angioplasty, carotis angioplasty)