clinical symposia - cardiovascular strand Flashcards
what is a DVT and where fo they normally form?
deep vein thrombosis
- formation of blood clot in deep vein
- leg - femoral or popliteal vein
- pelvis
why are veins predisposed to clots?
low pressure, low flow velocity with valves to prevent backflow
how do veins move blood back to the heart?
against gravity
- valves prevent backflow
- contraction of skeletal muscles compresses veins (skeletal muscle pump)
how might a clot form in DVT?
normal = laminar flow, rbc and platelets not in contact with endothelium stasis = stagnation of flow, platelets in contact with endothelium, activated clotting factors not diluted by rapid flow, thrombus forms
why does the leg swell in DVT?
thrombus causes a venous obstruction, leading to pooling of blood in the vein
increased hydrostatic pressure promotes fluid retention in tissue space (oedema)
what are the symptoms and signs of a DVT?
warmth redness engorged superficial veins unilateral swelling pain tenderness
what is a dependent oedema?
common in elderly patients with lack of motility
usually is symmetrical swelling
chronic
managed with compression stockings and elevation of limbs
what is cellulitis?
bacterial infection
usually unilateral
acute onset
accompanied with fever and general illness
what is nephrotic syndrome?
disease of kidneys causing severe proteinuria
lack of albumin in blood stream = fluid pools in interstitial space, severe oedema
accompanied with other kidney symptoms
what is Virchow’s triad?
thrombus is result of delicate interplay of
- changes in blood flow
- changes in blood vessel wall
- changes in blood constituents
what is an embolus?
material (blood clot, fat, air, amniotic fluid or foreign body) that is carried by the blood from one point in circulation to lodge at another point
why might a pulmonary embolus cause chest pain?
inflammation due to ischaemia/infarction in lung tissue sufficient to irritate parietal pleura (which has neve endings, intercostal nerve supply)
what score is used to asses DVT risk?
Wells score
why may a pulmonary embolus cause hypoxaemia?
ventialtion perfusion mismatch
what investigations could be done for a DVT?
d-dimer
doppler ultrasound - DVT
v/q scoring
CTPA - pulmonary embolism
what is a d-dimer test?
fibrin break down product
very sensitive but not specific (can be caused by more than just a thrombus)
what is a doppler ultrasound?
will demonstrate presence or absence of clot
in high probability cases can do without performing d dimer
what is v/q scanning?
not that common nowadays
nuclear medicine technique
radioactive uptake measured - can show areas of reduced perfusion (embolism)
what is CTPA?
computed tomography pulmonary angiogram
venus canula + IV contrast injected
pulmonary artery tree opacified - can see where embolus is
what is treatment for a DVT/ pulmonary embolism?
in 1st instance - injectable low molecular weight heparin (acts on factor II and factor Xa)
once confirmed - DOAC’s (direct oral anticoagulants) Xa inhibitors
if really bad = thrombolysis with TPA Ateplase to dissolve fibrin and remove clot
give 3 factor Xa inhibitors?
rivaroxaban
apixaban
edoxaban
what is angina?
crushing central chest pain that radiates to arms and jaws
precipitated by physical exertion and relived by rest or GTN spray
(also called chronic coronary syndrome)
what is the usual cause of angina?
myocardial ischaemia because of atherosclerosis or anaemia (not enough blood flowing through vessles)
what might decrease O2 supply?
coronary artery disease
coronary artery spasm
microvascular disease
anaemia
what might increase O2 demand?
exercise tachycardia hypertension heavy meal cold weather
what happens during a heart attack?
- most caused by coronary artery disease (narrowing due to gradual build up of atheroma (fatty material) within the walls)
- if the atheroma becomes unstable, a piece may break off and lead to a blood clot forming
- this clot can block the coronary artery, starving the heart of blood and oxygen, causing damage to the myocardium
what is a myocardial infarction type I?
plaque rupture/erosion with occlusive thrombus or almost occlusive –> cell death
what is myocardial infarction type II?
no plaque rupture/erosion, extreme form of angina - O2 supply and demand mismatch that’s severe enough to cause cell death
- very severe anaemia
- major haemorrhage
- vasospasm (ie after cocaine)
- non-atherosclerotic coronary destruction
how might ischaemia lead to heart failure?
impaired contraction of myocardium > abnormal electrical activity of heart cells > dangerous arrhythmia > heart failure if severe enough
what change in vichrows triad causes myocardial infarction ?
change in vessel wall
what investigations would be performed for a MI?
- ECG most important (if ST elevation straight for emergency coronary angioplasty)
- coronary angiogram, echocardiography and serum troponin levels during admission
- MRI potentially but not for every patient
what artery supplies the inferior territory of the heart?
80% people is the right coronary artery
other 20% is left circumflex artery
what is troponin testing?
cardiac protein involved in interactions of actin and myosin
released in myocardial damage
three types = C I T (I and T highly specific to cardiac tissue)
what are symptoms of MI?
diaphoresis (excessive sweating)
nausea
chest pain
breathlessness
what is the treatment of MI?
- pain relief with morphine, high flow O2, oral aspirin
- thrombolytic drugs replaced by primary percutaneous intervention (clot removed by tube in arm/ leg and stent placed)
what preventative measures are there for MI?
LIFESTYLE CHANGES statins beta blockers antiplatlet agents ACE inhibitors GTN spray
what do statins do?
inhibit HMG CoA reductase, reducing production of cholesterol
what do beta blockers do?
negatively chronotrophic = prolomg diastole, increasing coronary filling time
negatively inotropic = reduce myocardial O2 demand
reduce sympathetic overactivity - remodeling
prophylaxis against arrythmia
what is GTN spray?
glyceral trinitrate
- increase nitric oxide
- peripheral vasodilation = decreased preload and offload of blood
what is a stroke
rapidly developing loss of brain function due to disturbance in blood supply to the brain
what are the 2 reasons why a stroke my occur
- a blockage by thrombus or embolus: ischemic stroke
- haemorrhage
what is a cerebral ischema/infarction
- blockage of blood vessel due to thrombus or emboli
is a cerebral schema or haemorrhage more common?
ischemia- 80% strokes
people with what kind of clinical features show cerebral ischemia
atrial fibrillation (irregular heartbeat)
heart attack
surgery
how is a cerebral ischemia trigged
emboli from ruptured atherosclerotic plaque, usually from some type of intervention, ends up in carotid arteries
what is the main way we can prevent ischemic strokes
recognise risk factors early
what causes a cerebral haemorrhage
rupture blood vessel when an aneurysm or out-pouching of blood vessel ruptures = bleeding
what is the deadliest type of stroke
cerebral haemorrhage
how do we prevent cerebral haemorrhages
controlling high BP
what is a TIA and what is it also known as
result of temporary disruption of circulation to part of the Brian due to embolism or thrombus in brain arteries
‘mini stroke’
how long is the recovery in a TIA
24 hours
usually know by 3-4 hours
what are the common symptoms of a haemorrhage stroke
loss vision in one eye
weakness/numbness in a limb/part of a limb
unable to speak properly
is time of onset of a stroke important and why
yes- allows us to distinguish between diff types of stroke
why might a person be at risk of having a stroke? why might these factors place someone at risk?
- high BP = promotes atherosclerosis so changing vessel wall and blood flow
- atrial fibrillation = alters blood flow in L atrium, promoting thrombosis and embolism
what kind of drug is someone with atrial fibrillation usually on?
digoxin
hat route would a blood clot take?
left atrium left ventricle aorta brachiocephalic artery R common carotid artery R internal artery
what type of scan allows us to differentiate between a ischemic and haemorrhage stroke? how?
CT scan
Haemorrhage - bleeding = white area with surrounding oedema = black
infarction = dark
why is it important to differentiate between cerebral ischemia and haemorrhage?
symptoms of both very similar
however one is a clot, one is a bleed and so treatment for the 2 will largely differ
where is the common sight of build up for atherosclerosis
carotid arteries
how does a atherosclerotic plaque rupture lead to clot formation?
due to the atherosclerotic plaque ending up int he carotid arteries there is turbulent blood flow in this area. once the plaque ruptures a blood clot can form on top, occulting the artery or embolising to the brain
what scans/investigations take place to confirm a stroke ?
CT scan
echocardiography/ECHO
MRI - look at brain