Vascular Flashcards
Define a DVT
The formation of a blood clot in the deep veins of a limb, most commonly affecting those of the legs or pelvis.
What are the 3 components of Virchow’s triad?
- Stasis of blood flow
- Endothelial injury
- Hypercoagulability
What is a provoked DVT?
Occurs in the presence of risk factors (inherited or acquired)
What is an unprovoked DVT?
Occurs in the absence of a risk factor.
Are provoked or unprovoked DVTs more common?
Provoked (80%)
What is Virchow’s triad?
3 factors that are critically important in the development of venous thrombosis
Give some acquired risk factors for a DVT
- Surgery
- Malignancy
- Pregnancy
- COCP
- Smoking
- HRT
- Obesity
- Immobilisation >3 days (e.g. post-surgical)
- Long haul flights
- Previous VTE
- Chronic medical conditions (e.g. heart disease, endocrine)
- Increased age
- Acute infections
Which surgeries are particularly risky for DVTs?
Orthopaedic, abdominal and pelvic (risk increased with length of procedure)
Which stage is pregnancy is the biggest risk for DVTs?
Post-partum
What are some inherited risk factors for DVTs?
- First degree relative with a history of VTE
- Thrombophilias
- Antiphospholipid syndrome
- Factor V Leiden
What is Factor V Leiden?
A mutation in human factor V which causes a state of hypercoagulability.
Due to this mutation, protein C (an anticoagulant protein that usually inhibits the pro-clotting activity of factor V) is unable to work.
What is antiphospholipid syndrome?
An autoimmune disease (mostly affects young women). The body makes antiphospholipid antibodies which affect the nomral clotting process, leading to dangerous clotting in arteries and veins.
What is a thrombophilia?
Thrombophilia is a blood disorder that makes the blood in your veins and arteries more likely to clot.
What is the most common inherited form of thrombophilia?
Factor V Leiden
Give some symptoms and signs of a DVT
- Unilateral leg pain and swelling
- Pitting oedema
- Tenderness over deep veins of leg
- Heavy ache in affected area
- Warm skin in area of clot
- Pain may be worse when foot is dorsiflexing
- Asymptomatic
What is the standard diagnostic test for a DVT?
Duplex ultrasound
What test can be used for initial screening in a DVT?
D-dimer
What does a positive d-dimer test mean?
A positive test means the D-dimer level in the body is higher than normal and suggests someone might have blood clots.
What is Well’s score?
The Wells score is a number that reflects your risk of developing deep vein thrombosis
How many points in the Well’s score indicates a likely DVT?
2 points or more
What bloods should be done in the context of a DVT?
- D dimer (urgent)
- FBC
- U&Es
- LFTs
Pathway for investigations in the context of DVT
What is the purpose of a duplex ultrasound?
duplex ultrasound is a test to see how blood moves through your arteries and veins.
Duplex US example with a DVT:
What are the 3 main goals when treating a DVT?
- Prevent clot from getting bigger
- Prevent clot from breaking loose and travelling to lungs
- Reduce chances of another DVT
What is the 1st line pharmacological treatment for anyone with a DVT/PE (as long as no contraindications)?
DOACs e.g. apixaban, rivaroxaban, edoxaban
If DOACs are contraindicated, what is given instead in the context of a DVT/PE?
Warfarin
Which patient population are DOACs contraindicated in?
Patients with severe hepatic disease
What class of drug are enoxaparin, tinzaparin and dalteparin?
LMWH
What type of anticoagulant is given prior to having an USS in a DVT?
LMWH
N.B. LMWH have 2 doses – prophylactic and treatment dost (look at local trust guideline)
What is the target INR on warfarin?
2-3
What is the recommended length of treatment for a provoked 1st VTE (with risk factors)?
3 months
What is the recommended length of treatment for an unprovoked VTE?
Lifelong
What are the 3 main complications a patient can develop following a DVT?
- PE
- Post-thrombotic syndrome
- Bleeding associated with anticoagulation
What % of people with an untreated DVT go on to develop a severe PE?
10%
How does a DVT lead to a PE?
A piece of the blood clot breaks off and travels through the blood and the right side of the heart into the pulmonary arteries, increasing pulmonary arterial pressure
How may a small PE present?
Often asymptomatic
How may a medium size PE present?
- SOB
- Pleuritic chest pain
- SOB
- Tachycardia
How may a large PE present?
- Syncope
- Hypotension
- Right heart failure
- Sudden death
Why does a large PE lead to these symptoms?
Large clots suddenly increase the pulmonary arterial pressure, increasing afterload. This pressure cannot be matched by the pressures produced by the right ventricle → right heart failure.
What is post-thrombotic syndrome?
Chronic venous hypertension for weeks/months after the DVT. This leads to symptoms e.g. limb pain, swelling, hyperpigmentation, dermatitis, ulcers, venous gangrene and lipodermatosclerosis
What % of people with a DVT develop post-thrombotic syndrome?
Up to 50% (within 2 years)
What is lipodermatosclerosis?
Changes in the skin of the lower legs.
What is peripheral arterial disease typically caused by?
Typically caused by atherosclerosis of the arteries supplying the limbs
What is chronic limb ischaemia?
When the reduction in arterial supply to the limbs becomes symptomatic
What are the risk factors for PAD?
- Smoking
- Obesity
- Diabetes
- Hyperlipidaemia
- HTN
- Increasing age
- Family history
- Physical activity
What is intermittent claudication?
Cramping type pain in the calf/thigh/buttock after walking a fixed distance (claudication distance) relieved by rest within minutes.
What is ischaemic pain?
A burning type of pain that occurs due to hypoxia of the tissues
When is ischaemic pain worse?
At night
What are symptoms of PAD?
- Intermittent claudication
- Ischaemic pain
- Weakness of muscles
- Loss of sensation
- Hair loss
What are the 4 stages of PAD?
I - asymptomatic
II - intermittent claudication
III - ischaemic rest pain
IV - ulceration or gangrene (or both)
What are some signs seen in PAD?
- Ulceration (severe)
- Hair loss
- Pale lower limbs/feet
- Gangrene (severe)
- Thickened toenails
What is the Buerger’s test used for?
Buerger’s test is used to assess the adequacy of the arterial supply to the leg (in a PAD/vascular examination).
Describe the steps of the Buerger’s test
- Patient supine on bed
- Lift up leg to 45 degrees and hold for 1 minute (if the pain allows)
- Observe the elevated leg for; a) pallor, b) venous guttering
- Drop the leg down over the side of the bed
If the leg exhibits pallor when lifting it up to 45 degrees in Buerger’s test, what does this indicate?
The development of pallor indicates that peripheral arterial pressure is unable to overcome the effects of gravity, resulting in loss of limb perfusion (i.e. PAD).
What is Buerger’s angle?
The angle when lifting the leg at which the leg develops pallor.
Describe the results of Buerger’s test on a healthy individual
In a healthy individual, the entire leg should remain pink, even at an angle of 90º.
What does a Buerger’s angle of less than 20 degrees indicate?
Severe limb ischaemia
What is an ABPI?
A non-invasive method of assessing peripheral arterial perfusion in the lower limbs by calculating the ratio between the systolic blood pressure in the arm (brachial) and the lower limb (dorsalis pedis/posterior tibial).
Which arteries are involved in an ABPI?
- Brachial
- Dorsalis pedis
- Posterior tibial
What 3 pieces of equipment are required for an ABPI?
- Doppler
- Sphygmomanometer
- US gel
How should the patient be positioned during an ABPI?
Lying flat
Describe the steps of measuring the brachial pulse in an ABPI
- Place cuff around arm (as if to measure BP)
- Position doppler at 45 degrees to brachial artery until you can hear a reliable pulse
- Inflate cuff until you can no longer hear pulse, and then another 30 mmHg
- Deflate cuff slowly and note down the pressure at which you first hear the pulse return
- Repeat on other arm and note down the highest of the two
Which brachial pressure is used in an ABPI?
The highest out of the L and R arm
Where is the posterior tibial artery located?
Posterior to the medial malleolus
Describe the steps of measuring the ankle pressure in an ABPI
- Place cuff around ankle
- Place doppler at posterior tibial artery (posterior to medial malleolus) until you can hear a reliable pulse
- Inflate cuff until you can no longer hear the pulse and then another 30 mmHg
- Deflate cuff slowly and note down the pressure at which you first hear the pulse return
- Repeat on dorsalis pedis artery
- Note down highest of the two readings (i.e. only use L or R)
- Repeat on other leg
How do you calculate the right ABPI?
Right ABPI = highest of right ankle pressures (dorsalis pedis OR posterior tibial) / highest of arm pressures
What is a normal ABPI?
1.0-1.2
What ABPI indicates severe arterial disease/critical limb ischaemia?
<0.5
What are the 2 imaging options in PAD?
CT or MR angiography
What should all patients presenting with intermittent claudication be offered as conservative manaegment?
A supervised exercise program (3 months)
If there is no improvement following a supervised exercise program in PAD patients, what is then advised?
Vascular surgery
What is the most important lifestyle modification in the context of PAD?
Smoking cessation (also weight reduction)
If patient presents with rest pain or gangrene/ulceration, what is the immediate management plan?
Urgent referral to vascular surgery
What 2 drugs are most important in the medical management of CVS risk factors?
- Statin therapy (high dose atorvastatin)
- Antiplatelet therapy (clopidogrel)
What is the favoured surgical treatment for PAD?
Angioplasty
What are some complications of chronic limb ischaemia (seen in PAD)?
- Sepsis (2ary to infected gangrene)
- Acute-on-chronic ischaemia
- Amputation
- Reduced mobility and quality of life
What is the 5 year mortality rate in those diagnosed with chronic limb ischaemia?
50% (this is also due to the associated CVS risk factors)
What is acute limb ischaemia?
A sudden decrease in limb perfusion that threatens the viability of the limb. It is complete or partial occlusion of the arterial supply to a limb which can lead to rapid ischaemia and poor functional outcomes within hours.
Mortality rate of acute limb ischaemia?
THIS IS A SURGICAL EMERGENCY – 20% mortality rate associated with this.
What is the main cause of acute limb ischaemia?
Embolus - a thrombus from a proximal source travels distally to occlude the artery
What are 2 other causes of acute limb ischaemia?
- Thrombus
- Trauma (least common)
What are some conditions which may lead to an embolus?
- AF
- Post MI
- AAA
- Prosthetic heart valves
Describe how a thrombus can form and lead to acute limb ischaemia
Atheromatous plaque in the artery ruptures and a thrombus forms (can be acute or chronic) → occlusion of vessel
How can trauma lead to acute limb ischaemia?
Fractures, compartment syndrome
What symptoms are seen in ALI (6 P’s)?
- Pallor
- Pulseless
- Perishingly cold
- Paraesthesia
- Pain
- Paralysis
Management of ALI?
- A-E assessment and early surgical input
- Surgical (depends on underlying cause of occlusion):
- Embolectomy
- Local intra-arterial thrombolysis
- Angioplasty
- Artery bypass surgery
- Amputation (this is last resort)
Define an aneurysm
An aneurysm is an abnormal dilatation of a blood vessel by more than 50% of its normal diameter
Define an AAA
An AAA is a dilatation of the abdominal aorta >3 cm.
Who is AAA screening routinely offered to?
All men in UK during the year they turn 65
Why is AAA screening not routinely offered to women or men <65?
As risk is much smaller in these groups
What are some symptoms of an expanding/burst AAA?
- Abdominal pain
- Back or loin pain
- Distal embolism producing limb ischaemia
Burst:
- Sudden onset abdominal/flank/back pain
- Syncope
- Pulsatile abdominal mass
What are the 2 surgical repair options for AAA?
- Open repair
- Endovascular repair (EVAR)
Management of a burst AAA?
- A-E approach
- Permissive hypotension (BP <100 mmHg)
- Unstable – open approach
- Stable – EVAR
- 80% of people with a burst AAA will die before reaching hospital
What is permissive hypotension?
Refers to managing trauma patients by restricting the amount of resuscitation fluid and maintaining blood pressure in the lower than normal range if there is continuing bleeding during the acute period of injury.
