Thromboembolic Disease and Stroke Flashcards
how do clots form pulmonary embolisms
thromboemboli detach and travel through the right side of the heart to block vessels in the lungs
where do clots usually form in the veins
venous valve pockets and other areas of stasis
define a DVT
Formation of thrombi within the lumen of the vessels that make up the deep venous system
where does a distal VT (vein thrombosis) form
in the calves
where does a proximal VT form
popliteal vein or femoral vein (closer to the heart)
what is the significance of the location of a DVT
proximal closer to heart so more likely to cause PE
what does VTE stand for
venous thromboembolism
what are the three components of virchow’s triad
hypercoagulable state
circulatory stasis
endothelial injury
what can cause a hypercoagulable state
Malignancy
Pregnancy and peripartum period
Oestrogen therapy
Inflammatory bowel disease
Sepsis
Thrombophilia
what can cause circulatory stasis
Left ventricular dysfunction
Immobility or paralysis
Venous insufficiency or varicose veins
Venous obstruction from tumour, obesity or pregnancy
what can cause endothelial injury
Venous disorders
Venous valvular
damage
Trauma or surgery
Indwelling catheters
the risk factors for VTE are predisposing and exposing. describe the exposing risk factors
(acute conditions or trauma)
surgery, trauma, acute illness, acute heart failure, acute resp failure, central venous catheterisation, cancer, inflammatory disease
what are the predisposing risk factors for VTE
(patients characteristics)
history of VTE, chronic heart failure, advanced age, varicose veins, obesity, Immobility or paresis,
Myeloproliferative disorders,
Pregnancy/peripartum period, Inherited or acquired thrombophilia,
Hormone therapies,
Renal insufficiency, CANCER AND INFLAMMATORY DISEASES
what factors lead to a provoked VTE
transient/ reversible or continuing/ irreversible factors
what is a thrombus
clot that stays in situ
what is an embolus
clot that has dislodged
what is the difference between venous and arterial clots
arterial platelet rich, veins fibrin rich due to stasis of blood
what are the symptoms of a PE
breathlessness, cough, haemoptysis, sharp stabbing chest pain, dizzyness/fainting
what causes an unprovoked VTE
no identifiable cause- idiopathic
what are the consequences of a VTE
fatal PE, risk of recurrent VTE, post thrombotic syndrome (PTS), chronic thromboembolic pulmonary hypertension, SOB, right sided heart failure, reduced quality of life
what is post thrombotic syndrome characterised by
pain, oedema, hyperpigmentation, eczema, varicose collateral veins, venous ulceration
how is post thrombotic syndrome treated
with compression stockings
describe the progression of chronic thrmoboembolic pulmonary hypertension
asymptomatic,
progressive dyspnoea , SOB and hypoxaemia,
right sided heart failure
what causes chronic thromboembolic pulmonary hypertension
original embolic material is replaced over time with fibrous tissue that is incorporated into the intima and media of the pulmonary arteries. this may occlude the pulmonary artery, leading to pulmonary artery resistance and, ultimately, right heartfailure.
how is chronic thromboembolic pulmonary hypertension treated
pulmonary thromboendarterectomy- surgery to remove clots from pulmonary arteries
and
anticoagulants
what does D-dimer show
breakdown product of cross linked fibrin, released when clot forms
how is used to investigate a DVT
ultrasound
what does a doppler ultrasound show
how blow flows through a vessel
what does the ability to compress a vein suggest
that there is not a clot above it as pressure is not too high to compress
what is venography and when is it used
uses contrast dye and X ray ( or magnetic resonance imagine) to image vascular system
used when ultrasound negative but patients symptoms are positive
what other than a clot can raise D-dimer
recent surgery/illness
what does the wells score show
calculates the pre-test probability of a DVT
what action plan should follow a low wells score
check D-dimer, no imagine if negative
what action plan should follow a mod/high wells score
imaging regardless of D-dimer
what does negative imaging and positive D-dimer require
repeat imaging
what factors are considered for a wells score
active cancer, calf/leg swelling, collateral superficial veins, pitting oedema, localised pain, paralyses, recently bedridden
what factors are considered for a wells score for PE
clinical signs of DVT, PE most likely diagnosis, HR>100, immobilisation, previous DVT/PE, haemoptysis, malignancy
what does the revised geneva score indicate
probability of PE in patients
what factors are considered in the geneva score
age, previous DVT/PE, surgery, active cancer, unilateral limb pain, haemoptysis, HR, pain on lower limb deep venous palpation AND unilateral oedema
what is considered the gold standard of imagine
CT pulmonary angiogram
angiogram (X-ray of blood vessels)
what are other imaging methods used for DVT/PE
chest X-ray (can show pleual effusions and sometimes infarct)
V/Q scan (ventilation/perfusion) Demonstrates mismatched perfusion defects
how are DVTs and PEs treated (drugs)
anticoagulants, thrombolysis, analgesia
low molecular weight heparin, warfarin
Direct oral anticoagulants; dabigatan, apixaban, rivoraxaban, edoxaban
how are DVTs and PEs treated (medical interventions)
compression stockings, IVC filters
what conditions are screened for DVT/PEs
cancers, thrombophilia
what are factor Xa inhibitors and what do they do
anticoagulant drugs that stop thrombin being formed by blocking factor Xa
what is fragmin
anticoagulant (administered via infection)
what anticoagulant tends to be favoured in cancer
fragmin
what is phlegmasia
Arterial compromise secondary to extensive DVT
what treatment should be used to treat venous clots
fibrinolysis (as fibrin rich clots) e.g. tissue plasminogen activator (tPA), streptokinase (SK)
what treatment should be used for PE and clots causing stroke/ atrial fibrillation- or patients who have deterioated haemodynamically in hospital
thrombolysis (break down clots) e.g. tissue plasminogen activators
when should pharmacological systemic thrombolytic not be given
when patients with PR are haemodynamically stable
what do compression stockings prevent
post thrombotic syndrome
how long post thrombosis should compression stockings be worn
2 years
what is the only treatment for post phlebitic syndrome
compression stockings
what are IVC filters
mechanical devices which sit in the inferior vena cava and aims to catch any clots that pass dislodge
what are the complications of the IVC filters
can thrombose and rip through walls of IFC into the aorta causing a fistula
what is the burden on VTE as a disease
substantial negative impact on quality of life, lower levels of physical functioning, worse perceptions of health, disability, death
what is a stroke
acute onset of focal neurological symptoms and signs due to disruption of blood supply
what is stroke a complication of
poor vascular health
what do the specific stroke symptoms experienced by a patient let you determin
the area of brain affected
what is the biggest impact a stroke has on a patient
rarely kills but 2/3rds leave hospital with a disability
what are the two types of stroke
haemorrhagic (15-20%) and ischaemic (80-85%)
describe ischaemic stroke
when a clot blocks blood flow to an area of the brain
describe haemorrhagic stroke
when blood vessel tears and bleeding occurs inside or around the brain tissue
what causes a haemorrhagic stroke
raised blood pressure, weakened blood vessel wall due to (structural aneurysm, ateriovenous malformation) or inflammation of the vessel wall (vasculitis)
describe a thrombotic ischaemic stroke
clot blocking artery at the site of occlusion
describe an embolic ischaemic stroke
clot blocking artery has travelled to artery it occludes from somewhere more proximal in the arteries/heart
describe hypoperfusion ischaemic stroke
due to reduced flow of blood due to stenosed artery rather than occlusion of artery
what is a stenosed artery
narrowing of artery due to atherosclerosis
what is the mechanism of atherothrombotic stroke
atherogenesis (adhesion on monocytes and lymphocytes) -> plaque-> vessel stenosis OR plaque rupture -> platelet aggregation -> thrombosis -> ischaemia
vessel stenosis can also lead to ischaemia by reduced blood flow
what are the non modifiable risk factors for stroke
age, family history of stroke/heart disease, gender, race, previous stroke
what are the (potentially) modifiable risk factors of stroke
hypertension (most important), hyperlipidaemia, smoking, atrial fibrillation, diabetes, congestive heart failure, alcohol, obesity, physical inactivity, poor socioeconomic status
what causes a transient ischaemic attack
artery blocked by small clot that endothelium is able to dissolve it and blood flows again
what types stroke benefit from statin therapy
ischaemic not haemorrhagic
where do venous clot usually travel
usually stay in venous system and travels to the lungs..
what could allow a venous clot to enter the arterial system
atrial septal defect, patent foramen ovale
what are the rarer cause in stroke (especially in younger patients)
homocysteinemia (makes vessels weaker), vasculitis, protein S, C, Antithrombin III deficiency, paradoxical embolism (from arterial side), genetic, cardioembolic, cervical artery dissection
what is the immediate treatment for an ischaemic stroke
thrombolysis or thrombectomy (to remove clots and reverse disability)
what are conditions that mimic stroke
hypoglycaemia, seizure, migrane, brain tumours, functional hemiparesis (pretending to have a stroke)
how is a stroke diagnosed
history, examination, brain imaging (differentiating between types); CT, MRI +/- angiography
in ischaemic stroke what investigations are completed to find the cause of the thrombosis or embolism
blood tests (glucose, lipids, thombophillia), asses for hypertension
what is an atheroembolism
embolism from a thrombus forming on an athersclerotic plaque (platelet rich clots)
infarcts in same side as affected carotid artery
what is a cardioembolism
embolism from a clot formed in the heart (usually in left atrium)
infarcts in more than one arterial territory (bilateral)
where do clots affecting multiple areas come from
the heart (cardioembolism)
what tests should be carried out on a suspected atheroembolism
carotid scanning, CT/MR angiography of aortic arch
what tests should be completed on a suspected cardioembolism
ECG-AF?, LVH? (uncontrolled hypertension)
echocardiogram
what should be considered if there is multiple haemorrhages
vascultitis
what is used to investigate the cause of bleeding in a haemorrhagic stroke
imaging; hypertensive? underlying aneurysm?
what is a complication of thrombolysis
bleeding in the brain
what is used to prevent later stroke following a atheroembolic/thromus stroke
antiplatelets (aspirin + dipryridamole) statins for cholesterol diabetes management hypertension management lifestyle advice
what is used to prevent later stroke following a atrial fibrillation stroke
anticoagulant (warfarin (vit k antagonist)
direct acting oral anticoagulants (Rivaroxaban, Dabigatran, Apixaban, Edoxaban)
do antiplatelets work on the clot from the heart
no
what are the surgical managements of a stroke
haematoma (clot within tissues) evacuation, relief of raised intracranial pressure, carotid endarterectomy (unblock the artery)
(70% stenosis in same side internal carotid artery as affected side of brain)
