Transcript Coronary heart disease - VBIOLOGY

Forms of cardiovascular disease
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Coronary heart disease
Strokes
Gangrene
Aneurisms
Forms of coronary heart disease
• Angina
Chest pain after exertion
Spreads to neck, jaws, arms, back
Shortage of blood to heart (no muscle death)
Cramp
• Heart attack (myocardial infarction)
moderately large coronary artery blocked
sudden severe chest pain
can be treated
• Heart failure
Blockage of main coronary artery
gradual damage
heart becomes steadily weaker
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Embolism
• A clot breaks off
• It may lodge elsewhere
Coronary artery – Heart attack
Brain - Stroke
•Gangrene
•A thrombus has broken off (embolised) and travelled via the left
ventricle to the left leg, where it has blocked an artery, cutting off
the blood supply to the foot.
An occlusive stroke
An artery is blocked
Aneurysm
• Atherosclerosis narrows
lumen of an artery
• Increases blood pressure
• This weakens the wall
• Balloons out and may burst
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Strokes due to aneurysm
• Aneurysm in brain artery
• Haemorrhage within brain
• Stroke
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Platelets
• An electron micrograph of a
platelet.
• It looks like a chocolate chip
cookie. The chocolate chips are
granules that contain a variety of
mediators.
• When activated, platelets
release the granules to
promote...
coagulation,
change of shape
stickiness
• They plug small vascular holes.
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Cholesterol
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Useful in small amounts
Stabilises membranes
Used in synthesis of Vitamin D
Used in synthesis of hormones
(testes, ovaries, adrenal glands)
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Lipoproteins
• Very low density lipoproteins (VLDLs) Bad
(cholesterol from liver to tissues for storage)
• Low density lipoproteins (LDLs) Bad
(made from VLDLs in tissues, cholesterol from liver to tissues)
• High density lipoproteins (HDLs) Good
(cholesterol from tissues to liver)
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Coronary heart disease
• An undamaged artery
Endothelial
cells
Elastic
lamella
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Smooth
muscle
Coronary heart disease
Endothelial
cells
Phagocytes
invade
• Damage to artery
• Due to hypertension?
• Phagocytes invade wall
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Elastic
lamella
Smooth
muscle
Coronary heart disease
• LDLs in blood plasma
enter artery wall
• LDLs carry cholesterol
from the liver
• They deposit cholesterol
• The cholesterol and LDLs
are attacked by the
phagocytes
• The damage prevents
LDLs returning to the
plasma so they deposit
more cholesterol
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Coronary heart disease
• The phagocytes release
growth factors
• These stimulate the
growth of smooth muscle
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Coronary heart disease
• Plaque of fibrous fatty
tissue builds up
• Platelets stick to it
• They release clotting
factors (thromboxanes)
• The endothelium normally
releases prostaglandins to
prevent clotting
• At the site of an
atheromatous plaque the
balance is wrong
• The blood clots
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Progress of a thrombosis
A thrombosis
Mild  Severe
Arteriosclerosis
• Calcification of the
deposit
• Often in aorta or
coronary arteries
• This causes hardening
of arteries
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Calcification
Risk factors
• Diet – avoid saturated fat
• Exercise – see exercise unit
• Gender – oestrogen increases HDL,
testosterone increases LDL
• Heredity – choose parents carefully
• Stress – avoid it!
• Age – arteriosclerosis inevitable as you
get older
• Hypertension –stress, obesity,
smoking, excessive drinking, lack of
exercise, salt intake
• Smoking
- carbon monoxide, nicotine, clotting
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CHD and Cholesterol/Blood pressure/Smoking
• Relative risk (death rates per 10,000 people years)
• Factors increase each other’s effects
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59.7
30.3
29.6
23.3
10.7
11.2
Nicotine
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Nicotine binds to some acetylcholine receptors
reduces arteriole diameter
increases adrenaline release
increases blood pressure
increases heart rate
decreases blood supply to extremities
increases stickiness of platelets
Increases fat levels
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Nicotine
ACh
Carbon monoxide
• Carbon monoxide (and nicotine) damage the
endothelium
• Binds to haemoglobin and reduces oxygen transport by
15% in smokers
Other effects of smoking
• decreases antioxidant concentration (eg Vitamin C
• and E)
this increases the damage done by free radicals released by
phagocytes
• Raises number of platelets
• Increases ratio of VLDLs and LDLs to HDLs in the blood
Saturated fat
• Decreases number of LDL receptors on liver cells
so they stay in circulation
• Increases blood cholesterol concentrations
• Increases ratio of LDLs to HDLs
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CHD and age
Prevention
• Screening
• Encouraging lifestyle changes
• Problem:
long term nature of cardiovascular
diseases – no symptoms until damage is
already done
Treatment
Pacemaker
helps maintain rhythm
• Bypass Surgery
using leg blood vessel
21000 in UK in 1992
• Transplant Surgery
since 1967
140 in UK in 1992