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Yr3 Surgery: Vascular > Peripheral Vascular Disease > Flashcards

Flashcards in Peripheral Vascular Disease Deck (52)
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1
Q

Define atherosclerosis

Which arteries does it affect?

A

Hardening and narrowing of arteries due to accumulation of lipids in the intima of medium & large sized arteries resulting in the thickening and hardening of arterial walls

2
Q

State 3 components of an atherosclerotic plaque

(recap pathological processes)

A
  • Cells: macrophages, leucocytes, smooth muscle cells
  • Intra & extra cellular lipids
  • Extracellular matrix: collagen, elastin, proteoglycans
3
Q

Remind yourself of the pathophysiology of atherosclerosis

A

Atherosclerotic plaque formation has two steps: formation of fatty streak followed by formation of a simple plaque

Fatty Streak

  1. Chronic endothelial insult leads to endothelial dysfunction/damage
  2. Lipids, mainly from LDLs, and monocytes accumulate in intima
  3. Lipids are oxidised and ingested by macrophages to form foam cells
  4. Foam cells secrete cytokinies which attract more inflammatory cells and stimulate smooth muscle proliferation
  5. Smooth muscles migrate to lesion from media and start to proliferate- now called a fattty streak

Formation of simple plaque

  1. Number of foam cells & SMC increases causing plaque to grow
  2. Some smoooth muscle cells take up lipids
  3. Smooth muscles cells lie over plaque, beneath endothelium, forming a roof
  4. Roof reinforced by collagen, elastin & other amtrix proteins to form fibrous cap
  5. Endothelium stretches as plaque continues to grow creating gaps which platelets adhere to
  6. Centre of plaque undergoes necrosis
  7. Dead cells release cholesterol and cholesterol crystals appear in plaque
  8. Small blood vessels grow into plaque from adventitia
4
Q

Remind yourself of at least 5 (out of 8 ways) a plaque can become complicated

A
  • Ulceration: fibrous cap eroded from underneath and atheroma core, which is highly thrombogenic, is exposed
  • Thrombsis on plaque: often on ulcerated plaque
  • Spasm at site of plaque: thrombi release vasoconstrictors
  • Embolisation
  • Calcification
  • Haemorrhage: if one of new vessels in plaque ruptures it can suddenly expand the plaque leading to oclusion or alternatively the pressure from haemorrhage may cause plaque to rupture
  • Aneurysm
  • Rupture of atherosclerotic artery
5
Q

Summarise the process of atherosclerosis

A
  • Endothelial dysfunction/damage due to chronic inflamation and activation of immune system in arterial wall
  • This causes accumulation of lipids in intima of medium & large arteries and causes further inflammation
  • Plaque formation
  • Plaques can become complicated and casue:
    • Stenosis
    • Rupture giving off a thrombus which blocks a distant vessel
6
Q

State some risk factors for atherosclerosis

Highlight which is greatest risk factor

A
  • Age
  • Family history
  • Male
  • Hypertension
  • Smoking (x9) *BIGGEST!!
  • Alcohol
  • Poor diet (high trans-fat, little fruit & veg intake, little omega 3 consumption)
  • Hypercholesterolaemia
  • Hyperlipidaemia
  • Low exercise
  • Obesity
  • Diabetes
7
Q

Explain why smoking is a risk factor for peripheral arterial disease

A

Numerous ways in which smoking increases risk of peripheral arterial disease:

  • Nicotine causes vasopasm of vessels
  • Carbon monoxide, present in inhaled smoke, is taken up by haemoglobin to form carboxyhaemoglobin which dissociates slowly meaning the haemoglobin is unavailable for oxygen carrying and hence contributes to tissue hypoxia
  • Increases platelet adhesion & fibrinogen levels which increase risk of thrombosis formation
  • Decreased HDL, increases lipids
8
Q

State some potential complications/end results of atheroscerlosis (i.e. what can it cause/lead to)?

A
  • Angina
  • ACS
  • TIA & stroke
  • Peripheral arterial disease
  • Chronic mesenteric ischaemia
9
Q

What are the 3 main patterns of presentation of peripheral arterial disease we see?

A
  • Intermittent claudication
  • Critical limb ischaemia
  • Acute limb-threatening limb ischaemia
10
Q

Define peripheral arterial disease

A

Atherosclerosis, causing narrowing, of the arteries supplying the limbs & periphery

11
Q

Define critical limb ischaemia

A

End stage of peripheral arterial disese where there is an inadequete supply of blood to the limb to allow it to function normally at rest

12
Q

Define intermittent claudication

A

Pain that occurs during exertion due to ischaemia in a limb; relieved by rest. Typically a crampy, achy pain associated with muscle fatigue.

Pts typically describe the pain in their calf when walking beyond a certain intensity.

13
Q

Which muscles are most commonly affected by intermittent claudicaiton?

A

Calf muscles (although more proximal muscles may be affected)

14
Q

Explain why peripheral arterial disease can lead to intermittent claudication

A

Narrowing of arteries leads to decreased blood flow to muscle

15
Q

State some differential diagnosis for pain in lower limb during exertion

A
  • Spinal stenosis
  • Lower limb arthritis
  • Musculoligamentous injury
  • Acute limb ischaemia/acute on chronic limb ischaemia
16
Q

Which arteries in lower limb most commonly have atheroma?

A
  • Superficial femoral artery (80%)
  • Aorto-iliac (15%)
  • Calf arteries (5%)
17
Q

80% of pts present with calf claudication, 18% present with calf, thigh and buttock claudication. 2% present with Leriche’s sydnrome.

What is Leriche’s syndrome?

A

Symptoms due to occlusion in distal aorta or proximal common iliac arteries causing triad of:

  • Bilateral thigh & buttock claudication
  • Absent femoral pulses
  • Male impotence
18
Q

State some key questions to ask when taking a history from pt with suspected peripheral arterial disease

A
19
Q

What is the ‘claudication distance’?

A

Distance someone can walk before claudication occurs

20
Q

Discuss what you might find on examination of someone with peripheral arterial disease

A
  • Weak peripheral pulses
    • Radial
    • Brachial
    • Carotid
    • Aorta
    • Femoral
    • Popliteal
    • Dorsalis pedis
    • Femoral
  • Delayed capillary refill
  • Pallor
  • Cold
  • Skin changes (e.g. ulceration, hair loss [not mvery accurate/useufl])
  • Bruits e.g. carotid
  • Buerger’s Test
21
Q

What classification is used to grade chronic leg ischaemia?

Describe this classification

A

Fontaine classification

22
Q

Discuss what investigations you would do if you suspect peripheral arterial disease, include:

  • Bedside
  • Bloods
  • Imaging/other

*For each, justify why doing them

A

Bedside

  • Blood glucose: diabetes = risk factor
  • Urine dipstick: diabetes= risk factor
  • ECG: if suspect may have coronary artery disease

Bloods

  • FBC: anaemia can precipitate claudication, may see polycythaemia vera
  • Lipids:risk factor
  • HbA1c: diabetes= risk factor

Imaging/other

  • ABPI (ankle-brachial pressure index): compare systolic blood pressure in brachial artery with arteries in lower limb
  • Arterial doppler: waveform is monophasic in PAD when should be biphasic
  • Angiography (CT or MRI): look for narrowing of vessels
  • Treadmill testing: measure blood flow before an after rest
23
Q

What investigations should you consider in a pt <50yrs with minimal risk factors who presens with peripheral arterial disease?

A
  • Thrombophilia screen
  • Homocysteine (**lower homocysteine level has been associated with reduced risk of cardiovascular events)
24
Q

For ABPI, discuss:

  • What it is/definition
  • How it is calculated
  • Normal & abnormal result
A
  • Ratio of systolic blood pressure in ankle vs the arm
  • Doppler probe held over brachial artery and BP cuff inflated to occlude flow; as cuff is deflated doppler signal reappears and systolic BP is recorded. Similar pressure readings taken from dorsalis pedis & posteiror tibial arteries with a cuff just above the ankle. ABPI should be measured in each leg. See equation in image:
  • Results (different places say different things). Teach me surgery says:
    • Normal >0.9
    • Mild 0.8-0.9
    • Moderate 0.5-0.8
    • Severe <0.5

If going to remember one number remember <0.9 = arterial disease

25
Q

When, and why, is exercise testing done in peripheral arterial disease?

A

Useful if there is difficulty in determining the exact severity of intermittent claudication; can see at what intensity of exertion claudication occurs.

26
Q

You may get falsely high ABPI readings in arteries which are….

A

Heavily calcified as these vessels may be incompressible so blood flows through them at high cuff pressures (which would falsely elevate your ABPI)

27
Q

Discuss the management of intermittent claudication

A
  • Lifestyle:
    • Stop smoking!!
    • Reduce alcohol
    • Healthy diet
    • Exercise
    • Weight loss
  • Exercise rehabilitation/supervised exercise programme
  • Optimise control of comorbidities (hypertension, diabetes etc..)
  • Pharmacological:
    • Statin: atorvastain 80mg (ALL)
    • Antiplatelet: clopidogrel 75mg (ALL)
    • Naftidrofuryl oxalate (consider in those with poor QoL)
  • Endovascular revascularisation= angioplasty +/- stent (shorter segments <10cm, high risk, aortic-iliac disease)
  • Surgical revascularisation (longer lesions >10cm, multifocal disease, disease that is purely infrapopliteal):
    • Bypass with autologous vein or prosthetic material
    • Endarterectomy
28
Q

Which pts with intermittnet claudicaiton may be considered for surgery?

A

NICE guidance states that surgical intervention can be offered in suitable patients if (i) risk factor modification has been discussed; and (ii) supervised exercise has failed to improve symptoms.

29
Q

What can you give as an alternative to clopidogrel in pts with intermittent claudication?

A

Aspirin plus dipyridamole

30
Q

How does naftidrofuryl oxalate help intermittent claudication?

A

Peripheral vasodilator

31
Q

Give 3 ways in which exercise rehabilitation can help with symptoms of intermittent claudication

A
  • Improves walking technique
  • Optimises collateral blood distribution
  • Improves capillary perfusion
32
Q

We always measure cholesterol before starting a pt with PAD on a statin; true or false?

A

FALSE- Heart Protection Study showed that statin treatment reduced CVA events & mortality regardless of initial cholesterol or degree of reduction so don’t measure cholesterol just start statin

33
Q

Discuss presentation of critical leg ischaemia

A
  • Pain at rest for > 2 weeks
  • Pain at night relieved by dangling foot out of bed
  • Ulceration of leg
  • Gangrene of leg
34
Q

Critical limb ischaemia can be defined in 3 ways; state these

A
  • Ischaemic rest pain for greater than 2 weeks duration, requiring opiate analgesia
  • Presence of ischaemic lesions or gangrene objectively attributable to the arterial occlusive disease (Fig. 1)
  • ABPI less than 0.5
35
Q

Discuss the management of critical limb ischaemia

A
  • Urgent referral to vascular team
  • Analgesia
  • Urgent revascularisation by:
    • Angioplasty & stenting
    • Bypass surgery
  • Amputation if revascularisation not possible or gangrene
36
Q

Describe Buerger’s test

What may you see in someone with peripheral arterial disease?

A

Buerger’s test involves lying the patient supine and raising their legs until they go pale and then lowering them until the colour returns (or even becoming hyperaemic). The angle at which limb goes pale is termed Buerger’s angle; an angle of less than 20 degrees indicates severe ischaemia

37
Q

What is sunset foot?

A

Idea that chronic critically ischaemic limbs may appear pink due to compensatory vasodilation the so-called sunset foot

38
Q

State the 6 P’s of critical limb ischaemia

A
  • Pain
  • Pallor
  • Pulseless
  • Perishingly cold
  • Paraesthesia
  • Paralysis
39
Q

What is acute life-threatening limb ischaemia?

What is acute on chronic limb ischaemia?

A
  • Acute limb ischaemia: clinical features that are less than 14 days duration, often presenting within hours. Has 1 or more of 6P’s
  • Acute-on-chronic ischaemia is a more complex condition whereby there is an acute often embolic event in a patient with previous peripheral arterial disease. These patients are sub-classified as they typically have a longer duration in which the limb is salvageable.
40
Q

What investigations would you do if you suspect acute life-threatening limb ischaemia?

A
  • 1st should be hand-held arterial doppler
  • If doppler signals present, do ABPI
41
Q

Ischaemia in acute life-threatening limb ischaemia may be due to thrombus or emboli; state some features that may suggest each

A
42
Q

Discuss the initial and definitive management of acute limb-threatening ischaemia

A

Initial

  • ABC
  • Analgesia (often IV opiods)
  • IV unfractionated heparin (to prevent thrombus propagation- particularly if not for immediate surgery)
  • Vascular referral

Definitive

  • Intra-arterial thrombolysis
  • Surgical embolectomy
  • Angioplasty +/- stent
  • Bypass surgery
  • Amputation (if irreversible ischaemia)
43
Q

State some potential complications of chronic limb ischaemia

A
  • sepsis (secondary to infected gangrene)
  • acute-on-chronic ischaemia
  • amputation
  • reduced mobility and quality of life
44
Q

Discuss the prognosis of chronic limb ischaemia, inlcude:

  • Prognosis for intermittent claudication
  • Prognosis following below-knee amputations
  • 5 yr mortality for chronic limb ischaemia
A

Over a 5 year period, of those patients with intermittent claudication:

Prognosis Intermittent Claudication

  • Most will have stable claudication
  • 10-20% develop worsening symptoms
  • 5-10% develop critical limb ischaemia

Post-Amputation Prognosis

Two years following a below-knee amputation for chronic limb ischaemia, 15% require a further above knee amputation, 30% have died, and only 40% have full mobility.

Mortality of Chronic Limb Ischaemia

The 5 year mortality rate in those diagnosed with chronic limb ischaemia is around 50%.

45
Q

What may you see on USS if there is plaque in arteries?

A

Calcium deposits lining vessel- white

46
Q

State how to perform ABPI

A
  • Lie pt on bed- head slighlty elevated for comfort
  • Make sure pt has rested for 5 mins before doing ABPI
  • Cover any open wounds/skin with cling film
  • Inflate cuff to 20mmHG above pressure where pulse is no longer heard
  • Slowly deflate cuff until pulse returns then quickly release rest of pressure
  • Repeat for other vessels
47
Q

Which systolic pressures do you use in the ABPI calculation?

A

You calculate ABPI for each leg.

For left leg: use highest of left leg vessel pressures (out of AT, PT, peroneal) divided by highest arm pressure (e.g. if pressure was higher in R arm you would use this brachial pressure even if you are doing the ABPI for left leg)

For right leg: use highest of right leg vessel pressures divided by highest arm pressure

48
Q

State the three main types of waveform we hear/see on doppler ultrasound

Which is best?

A
  • Tri-phasic
  • Bi-phasic
  • Mono-phasic

Triphasic is best, monphasic is worst.

*NOTE: in young health people may hear/see more than triphasic

49
Q

Explain the shape of a triphasic waveform

A
  • First peak= peak systole
  • Second peak (negative) = early diastole (some retrograde flow)
  • Third peak (positive)= late diastole, artery contracts to propel blood forwards

*Go on youtube and remind yourself of how tri-, bi- and mono- phasic sound

50
Q

State some limitations/contraindications of ABPIs

A
  • Pain
  • Ulceration (can cover sound wounds with cling film)
  • DVT at present or in past 6 months!! (risk of disloding clot)
  • Oedema
  • Incompressability (consider toe pressures)
51
Q

Why do you sometimes do toe pressures and calculate TBPI rather than ABPI?

A

Toe vessels less likely to be calcified than leg

Normal toe pressue 60mmHg therefore threshold for normal >0.7

52
Q

Slowly we are moving away from using the term critical ischaemia; what is the new term we are using?

A

Chronic limb threatening ischaemia (CLTI) and acute limb threatening ischaemia (ALTI)