Deck1 Flashcards
Why screen?
- Benefits the patient
- Benefits the NHS (saves cost and resources)
- Benefits society
What is screening?
Screening looks at everyone in a defined population to see if they have an occult condition, that is amenable to preventative or mitigating treatment prior to events with serious consequences occurring. It must have a suitable screening test.
What is the NSC and what is its purpose?
The National Screening Committee. It reviews evidence and provides recommendations on screening to the UK governmants
What are 5 aspects of NSC guidelines?
- Programme standards
- Failsafe procedure
- KPIs
- Incident management guidance
- Leaflets and patient information resources
What is targeted screening?
Screening of high-risk individuals because of lifestyle factors, genetics or other healthcare conditions.
Goes beyond demographics such as age or sex
What are the 5 key considerations for screening programme implementation?
- The condition (occult, sequelae) and population
- The test - acceptable, safe, defined cutoff.
- Intervention - effective, RCTs
- Screening programme - efficient, cost-effective, RCTs
- Implementation criteria - plans for QA, risk management, patient pathway, standards etc.
Define stroke
Rapidly developing clinical symptoms of vascular origin, and/or local/global loss of brain function
How long do TIAs last?
Less than 24 hours, however most last less than 60 mins
What are the 2 causes of cerebral infarct in stroke?
Thromboembolism - e.g. cardiac clot, carotid atheroma, proximal embolism, dissection, web
In-situ thrombosis - intracranial atheroma, intracranial dissection
What percentage of strokes are due to infarct?
85%, 15% are due to haemorrhage
What are some common stroke mimics?
The 5 S’s:
Seizure, syncope, space occupying lesion, sepsis, somatisation
- Also migrane and hypoglycaemia
What is the NIHSS?
Stroke severity scale
- less than 3 = minor stroke
3 - 6 = moderate stroke
> 7 = possible large vessel occlusion
What are 3 established stroke treatments?
- Thrombolysis - within first 3 hours ideally, but 3 - 4.5 is okay
- Thrombectomy - within first 6 hours
- Aspirin - within 48 hours
What is Paget-Schroetter syndrome?
Axillary and subclavian V DVT due to venous thoracic outlet syndrome
What are treatments for venous thoracic outlet syndrome?
Thrombolysis followed by first rib resection
What is the order of veins/arteries of the arm, lateral to medial?
CRUB:
Cephalic, radial, ulnar, basilic
What is CEAP?
The classification of severity of venous symptoms, ranging from 0 = no symptoms to 6 = active ulcers
What percentage of leg ulcers are arterial vs venous?
70% venous, 10% arterial, 10% mixed, 10% other
What are the treatments for DVT?
Thromboprophylaxis - both mechanical and pharmacological
- heparin
- must balance VTE risk with bleeding
How is DVT diagnosed?
Wells score > 2
D-Dimer blood test
Proximal ultrasound
What is May Thurner syndrome?
Right iliac A compresses the Left iliac V
What are treatments for May Thurner Syndrome?
- Conservative - compression and anti-coagulants
- Interventional - Left iliac V stenting
- Surgical - Palma procedure or in-line bypass
What are the benefits of calf DVT scanning?
- it doesn’t rely on clot propagation theory
- ESVS is considering treatment of calf DVT
- identification and treatment may prevent progression to proximal DVT or PE
What are the disadvantages of calf DVT scanning?
- poor sensitivity and specificity
- requires extra training and time scanning
- over-diagnosis, PE is rarer in calf DVT, balance with bleeding
- not recommended by NICE
What is 2 / 3 point compression scan?
Compression at CFV, (mid FV) and PopV
- relies on clot propagation theory
Name some anti-platelet medication?
Aspirin, clopidogrel
What is the VOYAGER trial?
Demonstrates that aspirin and rivaroxaban have beneficial outcomes after limb revascularisation.
Major bleeding risk was not significantly different according to 1 criteria, however was according to another
Name some anti-coagulants?
Warfarin, rivaroxaban
What is an example of a thromboprophylaxis?
Heparin
What are thromboprophylactic drugs?
Drugs that reduce the risk of VTE
What is the time-line for DVT diagnostics?
Wells score on presentation, if > 2:
- proximal vein DVT US scan (within 4 hours)
- if US is -ve, perform D-Dimer
- offer repeat US scan after 6 - 8 days if D-Dimer is +ve but US -ve.
When does clot look completely echolucent?
Fresh thrombus = 1 - 2 Days
When does thrombus start to become echogenic?
After 2 weeks
How may renal artery stenosis present?
Unresponsive hypertension
Smaller kidney (>2cm length)
How is a renal artery stenosis diagnosed?
PSV > 200cm/s or renal-aortic-ratio (RAR) > 3.5
- downstream turbulence or low RI may also be present
How is a coeliac artery stenosis diagnosed?
PSV > 270cm/s or RAR > 3.5
- downstream turbulence or low RI may also be present
What does the coeliac artery bifurcate into?
Hepatic artery (right) and splenic artery (left)
Explain the pathophysiology of mesenteric ischaemia?
- Stenosis or compression reduces blood flow to bowel
- Tissue oxygen debt after eating
- Causes pain and weight loss
What are the 2 types of mesenteric ischaemia patients?
- Atheroma = elderly, smokers
- Coeliac artery compression syndrome = young, females
- diaphragm impinges on coeliac artery
- causes severe pain after eating
- pain varies with respiration
What are flow characteristics of the portal vein?
High flow, low resistance
What is the function of the Circle of Willis?
To provide collateral circulation and redundancy within cerebral circulation
What does the ICA bifurcate into?
The MCA and the Posterior communicating artery
- also the ACA (trifurcation)
What does the basilar A bifurcate into?
The posterior cerebral arteries
Why does TCD use a large sample volume?
To penetrate better through the skull
How can TCD waveforms be used?
Changes in TCD velocity reflect changes in flow if diameter is unchanged.
Increased PI = increased resistance (e.g. increased intracranial pressure)
Increased PI may indicate brain death
Decreased PI = ?proximal stenosis
What type of probes are used for TCD?
Low-frequency, phased array
Why is no angle correct used for TCD measurements?
RCTs and studies where performed using non-imaging TCD without angle correct
How does angle correct impact PSV?
It increases it
What is PI?
A measure of the proportion of diastolic flow.
What is a normal adult MCA TAM velocity?
55 - 65 +/- 12 cm/s
(for children normal can be up to 100)
Why is TCD used in paediatric sickle cell disease?
To assess for silent strokes and to assess for stroke risk
What is a normal adult MCA PI?
0.9 +/- 0.24
What can change MCA velocities and PIs?
Hyperaemia, vasospasm, hypo/hyperventilation, stenoses, ICP, liver failure
Why can blood vessels look large using TCD?
Refraction and attenuation of the US beam by the cortical and middle bone = Beam divergence
What percentage of people have an intact Circle of Willis?
20%
What is a normal MCA PI?
And what is a raised MCAPI?
Normal = 0.9 (+/- 0.24)
Raised = > 1.2
What are TCD criteria for intractranial stenoses?
PSV > 160cm/s
MeanV > 100cm/s
What is the Lindegaard Ratio?
Mean MCA velocity / mean iICA velocity
(use TCD probe for both measurements)
Why use the Lindegaard ratio?
To investigate vasospasm, post sub-arachnoid haemorrhage.
LR > 3 suggests vasospasm
- LR helps distinguish between general hyperaemia from focal vasoconstriction
What are some uses of TCD?
R to L cardiac shunt
Microemboli detection
Vasospasm, post-subarachnoid haemorrhage
Functional reserve testing
Intracranial stenosis detection
What is moyamoya?
A network of small arteries rather than conventional, larger arteries = constricts blood flow to the brain
Which vessels are usually affected in paediatric sickle cell disease?
The iICA and MCA
Why is TCD using in sickle cell?
Children with sickle cell disease have a high risk of stroke
Silent stroke in 16 - 20%
They then have a very high (67%) change of recurrent stroke
- If detected, transfusion reduces risk of recurrence to 10%
What were the key outcomes from the STOP trial?
If all MCA, dICA, ACA and Basilar A meanV < 170cm/s = normal
If all between 170 - 200 cm/s = conditional
If MCA or dICA > 200cm/s = abnormal
What are associated with silent infarcts?
Intra- and extra- cranial stenoses, and vessel tortuousity
How do velocity measurement from phased and linear array probes compare?
Linear arrays generally measure higher velocities (up to 17%)
- due to ISB and angle effects
What tests contribute to the sickle cell stroke risk assessment?
TCD, MRI and Blood tests
What are some CLTI / ALI risk classification systems?
Fontaine, Rutherford, WIfI
What physiological tests may indicate CLTI?
ABPI < 0.4 or TP < 30mmHg
What are some example medical managements for CLTI?
Antiplatelets, Anti-hypertensives, anticoagulants, statins, anti-diabetic agents
Lesions of which vessels have poor endovascular outcomes?
Diffuse tibial disease and PopA + Trifurcation occlusions
Also, long or heavily calcified lesions of fem-pop segment
What is the first line treatment for CFA disease?
Endarterectomy
What is the first line treatment for AI disease?
Endovascular stenting
What is acute limb ischaemia (ALI)?
Rapid onset ischaemia (< 2 weeks)
What are the two categories of ALI?
- Thromboembolism - e.g cardiac clot or carotid
- In-situ thrombosis - e.g. PopA aneurysm or plaque ulceration
What medical managements are used for ALI?
IV heparin
Pain relief
Anti-platelets
What is thrombolysis and when can it be used?
Thrombolysis involves delivering streptokinase (fibrin degrader) via a catheter directly to the clot
It can be used within 4 - 6 weeks of presumed thrombus formation
- may take up to 24 hours
What are the different types of thrombectomy?
Aspiration (suction)
Maceration (Jetstream)
Balloon embolectomy - usually for cardiac source
What is trash foot?
Atherosclerotic plaque fragmentation into distal vessels
How do cardiac and artery embolisms vary?
Cardiac = mainly platelet thrombus
Artery = atherosclerotic debris or cholesterol rich emboli
Cardiac thrombus embolectomy is more effective
Should PAD be screened for?
No
However REASON trial suggests targeted screening e.g. 50 - 79 with multiple risk factors - using ABPI
What are differential diagnoses for intermittent claudication?
Spinal stenosis, osteo arthritis, ileofemoral venous obstruction
What is the first-line treatment for IC?
BMT, supervised exercise and lifestyle advice
How is antithrombotic treatment altered in patients with high bleeding risk?
Use single, not dual, antiplatelet
Why are ABPIs not used for graft surveillance?
Most graft stenoses are clinically silent and difficult to detect with ABPI
When do most bypass grafts fail?
Highest risk is in first month (5-15%) - operative complications
80% of grafts fail within the first 2 years
What lesions are considered for treatment in bypass graft patients?
> 75% stenoses
What are the main causes of graft occlusion < 1 month?
Technical problems of operation or insufficient run-off
What are the main causes of graft occlusion < 1 year?
Myointimal hyperplasia at anastomoses or stenosis within the vein graft
What are the main causes of graft occlusion > 1 year?
Progression of distal atherosclerosis
What are some of the causes of ALI?
Embolism, thrombosis, aneurysm, dissection, trauma
What is the most common presentation of ALI?
In-situ thrombosis
What is the key question when considering management of ALI patients?
Is the ALI embolic or thrombotic of origin
Which category of ALI is generally most serious?
Embolic - there aren’t the collaterals developed that might be present in thrombosis patients.
What are the 6 Ps of ALI?
Pulselessness
Pallor
Parasthesia
Paralysis
Perishingly cold
Pain
What is the initial management of ALI?
IV heparin - reduce risk of further embolism or clot propagation
Which ALI is time critical?
Rutherford IIb
Which ALI is irreversible?
Rutherford III
How do you distinguish between Rutherford IIb and Rutherford III ALI?
Rutherford IIb will still have audible venous flow within the leg
What is thrombolysis?
Catheter directed delivery of streptokinase to the site of the clot
- dissolves fibrin to remove the clot
- can take up to 24 hours
- can be performed up to 4 - 6 weeks after presumed clot formation
What are the domains of the angiosome concept?
ATA = top of the foot
PeroA = heel
Med plant A = medial aspect of sole
Lat plant A - lateral aspect of sole
What is 50% NASCET equivalent to?
70% ESCT
What is 70% NASCET equivalent to?
83% ECST
When is ECST useful?
When there is a large bulb
What are limitations of ECST?
Limited by angiography accuracy
What is NASCET stenosis?
1 - (residual lumen / distal ICA)
What is ECST stenosis?
1 - (residual lumen diameter / bulb diameter)
Where do the renal arteries arise?
Between the SMA and IMA
Where does the coeliac artery arise?
Above the SMA (almost at the level of the diaphragm)
What percentage of patients have multiple renal arteries per side?
20%
What is typical renal artery blood flow?
~ 1000 - 1200 ml/min
Why are low frequencies used to examine renal arteries?
Better penetration and reduce aliasing
What impact does diabetic nephropathy have on renal artery blood flow?
Increased resistive index, decreased renal blood flow
What are 3 conditions that may be detected by renal US assessment?
- Diabetic nephropathy (Increased RI)
- Renal vein thrombosis (Pulsatile arterial flow, no venous signal)
- Renal artery stenosis
What are 2 causes of renal artery stenosis?
- Atheromatous - usually proximal renal artery
- Fibromuscular dysplasia - affects mid-distal renalA
- usually young women
- can cause hypertension without loss of renal function
Which arteries are commonly affected by fibromuscular dysplasia (FMD)?
Carotid and renal arteries
What are some indications for renal artery stenosis?
Renal artery PSV > 180/200 cm/s
RAR > 3.5
Interlobar artery acceleration time > 70ms
What conditions make renal assessment easier?
- Patient in a fasted state
- Breath hold while imaging
What are some limitations of renal artery US assessment?
Low renal blood flow
Movement / patient unable to hold breath
Depth
Poor views
How can ultrasound be used for kidney transplant patients?
- Assess suitability of target iliac vessels (stenosis, calcification)
- Assess for AVF post-biopsy
- Assess for venous thrombosis
- Flow changes can indicate rejection (increased RI)
Where does the IMA arise?
Beneath the renal As, slightly to the left of the aorta mid-line
What does the coeliac artery bifurcate into?
Hepatic A (Right) and Splenic A (Left)
Why should SMA and IMA analysis be performed fasted?
Eating can change velocities and waveforms
What are stenosis criteria for abdominal aorta branches?
Coeliac A: PSV > 200cm/s
SMA: PSV > 270cm/s or SMA:A > 3.5
Renal A: PSV > 200cm/s or RAR >3.5
What is acceptable coverage?
> 70%
What is achieveable coverage?
> 80%
What is a lacunar artery?
An end artery in the brain
