Thrombosis, embolism and shock Flashcards Preview

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Flashcards in Thrombosis, embolism and shock Deck (18)
1

Thrombosis

The formation of a solid or semi-solid mass from the
constituents of the blood while moving within the vascular system during life.

2

Locations where thrombi may form

Arteries
Veins
Capillaries

3

Factors that promote thrombosis

Virchow’s triad:

1. Abnormalities of the vessel wall

2. Abnormalities of blood flow

3. Abnormalities of the blood’s constituents

4

Abnormalities of the vessel wall

Heart-
Myocardial infarction
Rheumatic endocarditis
Veins-
Trauma
Inflammation
Chemicals - sclerosants
(irritant substances injected
to obliterate varicose veins)
glucose
(atheroma in diabetes mellitus)
Capillaries-
Inflammation

5

Abnormalities of blood flow

Arteries-
Turbulence
aneurysms, plaques, spasm
Heart-
Atrial fibrillation
Aneurysms
Veins-
Local problem
compression
inactivity
(postoperative bed rest; economy class syndrome)
General problem
heart failure
circulatory shock

6

Abnormalities of the blood constituents

Increased viscosity
Polycythaemia
Dehydration
Chronic hypoxia
Polycythaemia rubra vera
Hyperproteinaemia
Multiple myeloma
(Tumour of plasma cells in bone marrow with accumulation of immunoglobulins in plasma)
Abnormalties of clotting
Pregnancy (prevents bleeding when placenta detaches)
Some (older) contraceptive pills
Following trauma (liver produces more clotting factors)
Thrombocythaemia
Tumours
Inherited

7

Fate of thrombi

Resolution
Fibrinolysis. Very common fate.
Organisation
Incorporation into a scar (mural nodule or web)
by macrophages and fibroblasts. Vessel lumen
remains narrowed or occluded
Intimal cell proliferation, capillary invasion
and recanalisation. Vessel again becomes patent.
Detachment
Thromboembolism

8

Embolism

The transport of abnormal material (solid, liquid, gas)
by the blood stream and its impacting in a blood vessel

9

Types of emboli

Thrombi
Fat
Gas
Tumour material
When tumour penetrates blood vessel parts may break away to form metastases.
Infective agents
Includes fragments of vegetations growing on heart valves in infective endocarditis.
Atheroma
Fragments of atheromatous plaque may break off
Amniotic fluid
uterus may force amniotic fluid and squames from infant into uterine veins of mother.
Foreign bodies
intravenous drug abuse
iatrogenic

10

Gas emboli

Infusions
Vascular surgery
Caisson disease
On ascending from the depths
too rapidly, bubbles of N2 form
in the blood stream and on
entering the bones and joints
cause the pain known as “the
bends.”

11

Shock

Shock is a physiological state characterized by a significant, systemic reduction in tissue perfusion, resulting in decreased tissue oxygen delivery and insufficient removal of cellular metabolic products, resulting in tissue injury

12

Hypovolaemic shock

- haemorrhage – internal or external
severe burns

13

Cardiogenic shock

large acute myocardial infarction
other acute cardiac disease

14

Septic shock

endotoxins from Gram negative bacteria
exotoxins from Gram positive bacteria
both lead to dilation of blood vessels

15

Anaphyllactic shock

severe form of allergic reaction
- food, antibiotics, insect stings

16

Neurogenic shock

spinal cord trauma
regional anaesthesia

17

Obstructive shock

cardiac tamponade
tension pneumothorax
massive pulmonary embolism

18

Clinical features of shock

low systolic blood pressure: 90 beats/min
respiratory rate: 29 breaths/min
urine output: low
metabolic acidosis
hypoxia
cutaneous vasoconstriction or vasodilation
anxiety, agitation, indifference, lethargy, obtunded