Vascular And Transplant Flashcards
Describe the pathophysiology of diabetic foot
Describe in terms of effects on vasculature, effects on neurology, and local effects of hyperglycaemia.
Vasculature
-
Microvascular disease
- Hyperglycaemia causes vasoconstriction, inflammation, and thrombosis
- Reduced endothelial NO, increased Reactive oxygen species, “advanced glycation products” all cause thickened capillaries
- Macrovascular disease Diabetes often part of the metabolic syndrome that drives macrovascular disease
Neurology
- Sensory neuropathy Disease of the vasa nervorum from microvascular disease
-
Autonomic neuropathy
- Denervation of sweat glands causes dry skin and cracks
- Inability to vasodilate in response to infection
- Motor neuropathy Atrophy of small muscles causes change in weight distribution and eventual dislocation of MT heads; subluxation of the 1st MTP is classic
- Visual impairment Contributes to trauma and ulceration
Tissue effects in hyperglycaemia
- Impaired chemotaxis and phagocytosis due to chronic glycosylation of neutrophils
- Ideal bacterial substrate
Causes of perepheral vascular disease
Commonest
- Atherosclerosis
Rare
- Burgers Disease (smokers)
- Persistant sciatic artery
- Popliteal entrapment (pop art in medial head of gastrocnemius)
- Cystic adventitial disease (abnormL development of mucin producing mesenchymal cells cause cytic degeneration inadventitia)
- Fibromuscular dysplasia
What are the common sited of atheroma deposit
Sites of stress/strain or high turbulence
- Ostia
- coronoary
- Mesenteric
- Renal
- Bifurcation
- Carotid
- Aortic
- Iliac
- SFA
- popliteal
How can you assess severity of Perepheral disease on history
This can be done with the Fontaine stage
1 = Asymptomatic
2 = Intermittent Claudication
3 - rest pain
4 - Tissue loss
Rutherford Scale can also be used but is more cumbersome than the Fonatine
0 = Asymptomatic
1 = mild claudcation
2 = moderate claudcation
3 = severe claudcation
4 = rest pain
5 = mild tissue loss
6 = major tissue loss
What are the important things to ask/exmine for PVD patient?
History
- Claudication symptoms, distance, duration
- Smoking
- Cardiac risk assessment
- Stroke
- PMH - IHD, CAD, MI, CKD, DM, obesity, Hyperlipidemia
Exam -
- Inspect for trophic changes - hair loss, shiny skin, hypertrophic nails
- Tissue loss
- exam all pulses and capillary refill
- ABPI
What are normal values of ankle and toe pressures? When would you be worried about critical iscahemia?
ANKLE PRESSURE
Normal - 90% of systemic BP
60-80 mmHg needed for healing
50 mmHg - Critical ischaemia
ABPI
- >1.2 -> ?calcification check toe pressure
- 0.9-1.2 = normal
- 0.6-0.9 = cludication
- <0.5 = critical ischaemia
- <0.3 = rest pain
TOE PRESSURE (normally about 30 mm Hg less than ankle)
- pressure <30mmHg = critical
- TBPI
- >0.8 = normal
- <.3 = critical
How does arterial flow velocity change with stenosis
Normal –> 150cm/s —-> triphasic
<50% stenosis —-> 200cm/s —–> triphasic
50-75% stenosis —> 200-400cm/s —> triphasic/biphasic
>75% stenosis —> >400cm/s —> monophasic, dampened
Outline the utility of common investigations for PVD
ABPI
- cheap, can be done in clinic
- good screenig for PVD
Duplex US (B/colour/power/spectral mode)
- Cheap, noninvasive
- good for superficial vessels - very good for common femoral and distal popliteal
- sensitive and specific
- not good for small vessels and large or deep vessels (supra-inguinal) or tortuous vessels.
CTA
- Good for emergency situation and when MRA not appropriate
- radiation involved
- CT cannot reliably differentiate between contrast and organic narrowing particularly in small vessels.
MRA
- better than CTA
- Contrast toxicity particulalrly in CKD 3 and above (nephrogenic systemic fibrosis for whihc the nly treatment is renal transplant.
Angiography
- Gold standard
- used only when endovascualr intervention is planned
- Complications
- Procedure related - hematoma, dissection, AV fistula, Pseudoaneurysm
- Contrast related - nausea, vomiting, alleric reaction, renal impairement
What are the types of endoleak and their usual management?
Type 1 endoleak
- leak between the vessel wal and the graft
- Intervene
Type 2
- Back bleeding (lumbar, IMA, median sacral)
- Intervene if expanding
Type 3
- Fabric or metal failure
- intervene
Type 4
- Porous graft
- Observe
Type 5
- Serous leak (expansion by >5mm in absnce of leak)
- observe
What size Aneurysm will you intervene on?
AAA
- 5.5cm
- enalrging >1cm /yr or symptomatic
Iliac = 3cm
Femoral = 3.5 cm
Pop = 2 cm
Splenic/Visceral - 2 or any size in women of child bearing age.
Criteria for EVAR of aortic aneurysm
EVAR has better short term outcome compared to open repair at cost of poorer long term result. Results of UK EVAR1 and DREAM trials show that by 4 years post op EVAR and open outcomes are comparable, and after that open outcomes are superior to EVAR.
For AAA, patients needd pre-op CT angio.
- IMA should be expendable (rely on marginal vs re-implant)
- Atleast 1 internal iliac should be patent
- neck - >1cm landing zone
- neck diamteer <3cm
- Angle <60degree
For Iliac
- neck >1cm long
- Diamter >8mm - <24mm
- not tortuous
Complication of EVAR
EVAR specific
- Endoleak
- graft migration
- Kinking/occlusion
- hematoma
- pseudoaneurysm
- AV fistula
- Dissection
AAA realted
- MI
- stroke
- ischaemic bowel
- Acute renal failure
