Pathophysiology of thrombosis and embolism + Rheumatic fever/heart disease Flashcards
What term is used to describe normal blood flow?
laminar - smooth
what is stasis?
stagnation of blood flow
Define turbulence
forceful or unpredictable flow
3 parts of virchow’s Triad? what do they mean?
- Changes in the blood vessel wall
- Changes in the blood constituents
- Changes in the pattern of blood flow
they are factors causing thrombosis
example of problem that can cause changes to the blood vessel wall?
atheromatous coronary artery
Hypercholesterolaemia falls under which of virchow’s triad?
changes in blood constituents
examples of problems that cause changes in pattern of blood flow
stasis:-
DVT
post op
turbulent:-
atheromatous plaque
aortic aneurysm
define thrombus
a solid mass from the constituents of the blood within the vascular system disrupting the laminar flow of blood. It brings platelets in close contact with the vascular wall. Fibrin meshwork - RBCs become trapped
difference between a thrombus and a clot?
thrombus forms inside a healthy vessel - it is an abnormal clot
blood clot is a response to injury of vascular tissue - occurs outwith vessels
describe the pathogenesis of thrombosis
endothelial injury, stasis or turbulent blood flow and hypercoagulability of blood
what do the consequences of thrombosis depend on?
site, extent and collateral circulation
what is collateral circulation?
alternate circulation around a blocked artery or vein via another path such as nearby minor vessels
what sort of clinical situations can arise from thrombosis
DVT
Ischaemic limb
Myocardial infarction
define thromboembolism
thrombus that has propagated (increased/moved) throughout the body
Define emboli
detached intravascular solid, liquid or gaseous mass
Types of embolus? (11)
systemic/arterial thromboembolus venous thromboembolus fat embolus Gas embolus Air embolus Tumour septic material amniotic fluid bone marrow foreign bodies - IV cannulae, sutures trophoblast - pregnant women
Describe systemic/arterial thromboembulus:-
causes, travel, consequences
caused by mural thrombus (mural means they adhere to the wall of a blood vessel - associated with MI or left atrial dilatation + AF). Also by aortic anuerysms, atheromatous plaques, valvular vegetations (lesions)
travels to wide variety of sites - lower limbs most common, brain, other organs
consequences depend on vulnerability of affected tissues to ischaemia, calibre of occluded vessel (diameter) and colateral circulation but usually infarction occurs
Describe venous thromboembulus:-
causes, travel, consequences
originate from DV thromboses (lower limbs)
most common form of thromboembolic disease
travel to pulmonary arterial circulation
often have multiple venous thromboses that can become one large one
consequences depend on size of embolus: can be silent, pulmonary haemorrhage/infarction, right heart failure, sudden death.
What can having multiple pulmonary embolisms over time lead to?
pulmonary hypertension
and R ventricular failure
Risk factors fro DVT and PTE (7)
cardiac failure severe trauma/burns post-op/ post-partum (after birth) nephrotic syndrome (kidney) oral contraceptives increasing age bed rest/immobilisation
define and give examples of air emboli
when air bubble moves into venous system e.g head and neck wounds surgery Central venous lines
give example of situation where gas embolus occurs
decompression syndrome - divers’ disease - N2 forms as bubbles which lodge in capillaries
give example of situations where fat emboli can arise
after major fractures or vigorous CPR
lipid molecules leak out of the bone marrow
what is rheumatic heart disease
a complication of rheumatic fever in which the heart valves are damaged.
It can sometimes cause - neurological symptoms
- commonly affects children aged 5-15 and boys more so than girls
presentation of rheumatic fever
polyarthritis of large joints (wrists, elbows, ankles, knees)
skin rashes
fever
what is pancarditis?
inflammation of the entire heart (epicardium, endocardium and myocardium). Heart murmurs are common in the acute phase.
how can rheumatic fever cause damage to the heart?
by combination of antibody-mediated and T cell mediated reactions
if pancarditis in the acute rheumatic fever phase progresses over time what can a person develop?
chronic rheumatic heart disease, mainly manifesting as valvular abnormalities
what is virtually the only cause of mitral stenosis?
rheumatic heart disease
what does RHD rarely cause?
aortic stenosis
Diagnosis/ investigations of rheumatic heart disease
evidence of strep pyogrenase needed - throat culture, antigen test
ECG - heart block
blood tests - increased inflammatory markers and white cell count
management of rheumatic fever
no cure
antibiotics to treat bacterial infection
corticosteroids if evidence of myocarditis
NSAIDs
