Thrombotic Disorders Flashcards
1
Q
Venous thrombo-embolism
A
the process of blood clot formation in the veins
2
Q
Diagram terminology page
A
insert
3
Q
Provoked Venous thrombo-embolism definition
A
clear precipitating cause from history or tests
4
Q
Unprovoked Venous thrombo-embolism definition
A
no clear cause
5
Q
Thrombophilia definition
A
where the blood in the body clots more easily than normal
6
Q
Why do venous thrombo-embolisms occur? What are the main categories called?
A
Virchow’s triad
circulatory stasis
vascular injury
hypercoagulable state
7
Q
Virchow’s triad
insert
A
insert picture
8
Q
Why do venous thrombo-embolisms occur?: circulatory stasis:
A
- where the blood is not flowing in the way it
should be - bed rest, hence valves in veins aren’t used
as they should be so blood flow becomes
stagnant, clotting proteins become more
activated and a blood clot forms - lower limb ortho surgery
- major abdominal surgery
- pregnancy
- long haul flights/long car journeys
9
Q
Why do venous thrombo-embolisms occur?: hypercoagulable states:
A
- the body is in a state of producing clotting
proteins more than they normal should,
which can activate the clotting processes in
the body - smoking
- oestrogens (oral contraceptives, HRT)
- active cancer
- inherited and acquired thrombophilias
10
Q
Why do venous thrombo-embolisms occur?: Vascular Injury:
A
- direct damage to a vessel carrying blood
- limb trauma (including surgery)
- foreign bodies
- cannula, pacemaker wires
- sepsis
- bacteria, toxins
- previous DVT
- May Thurner Syndrome = pinch where iliac
vein and artery overlap so narrowed left
iliac vein due to pressure from right iliac
artery
11
Q
What is the most common inherited thrombophilia? Related %s.
A
- Factor V Leiden
- mutation of the factor V gene
- 5% of UK population
- only 10% of people with Factor v Leiden
have thrombosis hence genotype vs
phentotype factors
12
Q
What is the 2nd most common inherited thrombophilia?
A
- prothrombin thrombophilia
- mutation of Factor II gene
13
Q
Other Inherited thrombophilias:
A
- protein C deficiency
- protein S deficiency
- hereditary anti-thrombin deficiency
- congenital dysfibrogenemia
14
Q
When to test for inherited thrombophilias?
A
- if patient has had an unprovoked DVT or
PE and those who have a first degree
relative who has had DVT or PE if it is
planned to stop anticoagulation treatment - do not routinely offer thrombophilia
testing to first degree relative of people
with a history of DVT or PE and
thrombophilia - do not offer testing for hereditary
thrombophilia to people who are
continuing anticoagulation treatment
anyway - do not off thrombophilia testing to people
who have had a provoked DVT or PE
15
Q
Why do we not test everybody for inherited thrombophilias?
A
- expensive
- there are many more inherited
thrombophilias than what we can test
them hence do not want to falsely reassure
patients
16
Q
Acquired Thrombophilias:
- most common?
- is?
- affects men or females more?
- associated with
- risks
A
- most common is antiphospholipid
syndrome - autoimmune disorder: antibodies attack
phospholipids - more female than men
- 10-15% associated with systemic lupus
erythematous have antiphospholipid
syndrome - increased risk of pregnancy complications:
miscarriage, stillbirth, pre-eclampsia
17
Q
When to consider testing for antiphospholipid antibodies in patients?
A
patients who have has an unprovoked DVT or PE if it is planned to stop anticoagulation treatment
18
Q
Acquired thrombophilias:
- 2nd most common/
- is? (1)(4)
A
- acquired dysfibrinogenaemia
- fibrinogen is a part of clotting cascade,
helps to form a stable plug - fibrinogen is dysfunctional due to:
- severe liver disease (most
common)***
- autoimmune disease (Rh arthritis)
- plasma cell dyscrasias
- certain cancers (eg cervical)
19
Q
Insert Vascular injury diagram illiac veins
A
insert
20
Q
Most common site for deep vein thrombosis
A
- leg > arm
- calf = popliteal and tibial veins
- thigh = femoral and iliac veins
21
Q
DVT in legs signs:
A
- unilateral calf swelling
- heat
- pain
- erythema (redness)
- hardness
22
Q
Why are DVTs easy to miss?
A
- can be no signs and symptoms
23
Q
Differential Diagnoses for blood clot:
A
- Baker’s cyst = ruptured aneurysm behind
the knee - Cellulitis = inflammation and infection of
skin - Muscular pain/strain after injury
- history is key
24
Q
DVT investigations:
A
- D-dimer test = useful to rule out DVT if low
probability - Doppler ultrasound:
- investigation of choice: quick, safe
- real time 2D images
- colour doppler (duplex) shows
direction and velocity of blood flow
- thrombosed veins non-compressible - contrast venography rarely required, but
can be useful in extensive disease or to
look for anatomical malformations
25
D-dimer test:
- D-dimer is a breakdown product from
fibrin = fibrous mesh component of blood
clots
- only present when the coagulation system
has been activated
- elevated in venous thromboembolism
- very sensitive = negative test can be used
to rule out DVT/PE if low probability
- not very specific = positive test is not diagnostic
- can occasionally be negative in "barn-door"
DVT/PE
- do not use if high clinical probability
26
D-dimer diagram
insert
27
D-dimer may be higher in pregnancy:
pregnancy is a hyper coagulable state
hence more fibrinogen in pregnancy anyway
28
DVT treatment: Calf:
- symptomatic Rx (ibuprofen for pain)
- Repeat ultrasound in 7 days to ensure no
progression
- reality we treat despite:
- anticoagulation with Direct Oral
Anticoagulant (DOAC)
eg: Rivaroxaban, Dabigatran ***
- 3-6 months for 1st event
- lifelong for second event
- warfarin for renal dysfunction
- thrombophilia testing if 1st degree relative
with VTE
29
DVT treatment: Ilio-femoral DVT:
- anticoagulation with Direct Oral
Anticoagulant (DOAC)
eg: Rivaroxaban, Dabigatran ***
- 3-6 months for 1st event
- lifelong for second event
- warfarin for renal dysfunction
- thrombophilia testing if 1st degree relative
with VTE
30
Pulmonary embolism: Microemboli:
asymptomatic
31
Pulmonary Embolism: Small, peripheral:
- pleuritic pain
- breathless
- haemoptysis
32
Pulmonary Embolism: Large, central:
- chest pain
- breathless
- hypoxia
33
Pulmonary embolism: Massive:
- syncope
- shock
- tachycardia
- death
34
investigations for pulmonary embolism:
- Oxygen sat low
- ABG low PaO2
- ECG: sinus tachycardia (fast HR), S1, Q3,
inverted T3, right heart strain
- ***CT pulmonary angiogram (CTPA) is the
investigation of choice in a suspected PE
35
CTPA PE
insert
36
Justifying the use of CTPA:
- CTPA carries a high radiation dose:
- only used if there is a reasonable
likelihood of PE
- consider alternative approach in some
groups of patients
- Wells score used to guide investigation
- Low probability:
- D-dimer first
- CTPA is D-dimer positive
37
Alternative approach to CTPA:
- ventilation - perfusion scan
38
Ventilation - Perfusion Scan
- uses inhaled and injected radioisotopes
- looks for a mismatch of lung ventilation
and perfusion
- limited use if underlying lung disease
39
Contraindications for CTPA:
- severe contrast allergy
- severe renal dysfunction
- high risk from radiation
(pregnant/breastfeeding)
40
PE treatment: Anticoagulation:
- consider co-morbidities, contraindications
and patient preferences (bleeding risk
assessed with HASBLED scoring system
- consider special circumstances: renal
function, extremes of body weight, cancer
thrombosis, APLS
- Large PE: initially ***heparin, usually sc
low molecular weight heparin
(***Enoxaparin)
- then convert to:
- warfarin or
- DOAC (rivaroxaban, dabigataran ***)
- 3-6 months for first event
- lifelong for second event/ persistent
risk factors
- smaller PEs can go straight to DOAC
- thrombophilia testing if 1st degree relative
with VTE
41
29 year old woman, smoker, overweight on combined contraceptive pill, recent trip to USA, acute chest pain, collapsed at home, bought to A&E:
- cold, sweaty, agitated
- pulse 150bpm, BP 75/65, RR 24/min, SO2
91% on 60% O2
- JVP +10cm
- heart sounds normal, chest clear
- chest x ray: normal
Treatment for massive PE:
- IV fluids
- IV heparin infusion
- consider thrombolysis***:
- if a patient has shock and right heart
strain
- benefit vs bleeding risk: 10% risk of
major bleeding
- not because clot looks big on CT
- other options: surgical embolectomy,
catheter fragmentation
42
PE is cause of death in what % of patient post mortems?
10-30%
43
What % of VTE events occur <90 days of hospital discharge?
50%
44
VTE prevention:
- prophylactic low dose sc: heparin:
- low dose rivaroxaban after major joint
surgery
- venous compression stockings
- pneumatic compression stockings (cant
give blood thinners during surgery)
- early mobilisation
- good hydration
