Peripheral vascular disease Flashcards
What is an aneurysm?
Dilation of a vessel by more than 50% of its normal diameter
What is normal aortic diameter?
1.2-2cm anterior posterior therefore aorta >3cm is aneurismic
What is a true aneurysm?
The vessel wall is in tact- involves dilation of all 3 layers, intima, media and adventicia
What is a false aneurysm?
There is a breach in the vessel wall meaning surrounding structures act as a vessel wall
What are the 2 shapes of aneurysm?
Secular - most likely to rupture
Fusiform - most common
What are myotic aneurysms?
Secondary to infectious process and invole all 3 layers of the artery wall => weakness and rapid dilation
What is the pathogenesis of AAA?
Medial degeneration
1) Regulation of elastin/collagen in the artery wall
2) Aneurysmal dilation increasing aortic wall stress
3) Progressive dilation=> ruptue?
What are the risk factors for AAA?
Age, gender, smoking, hypertension and atherosclerosis
What is the prevalence of AAA?
8% in males over 65
Male: Female = 9:1
25% of people with AAA also have popliteal aneurysms which tend to clot leading to limb ischemia and amputations
Ruptured AAA is the 7th most common cause of death in males in the UK
How does AAA present?
75% assymptomatic and identified on imaging to other pathology (often renal failure) Surveillanc eprogramme for men over 65.
25% are symptomatic and present with:
1) Pain mimicing reanl cholic or MI
2) Trashing- forming a clot in the lumen which embolises and travels to distal arteries causing peripheral pain/ischemia
3) Rupture- sudden onset, central/epigastric pain. May radiate through to the back and mimic renal cholic, MI collapse
What would you find on examination of someone with a ruptured AAA?
May look well Hypo.hyper/normatensive Pulsatile mass +/- tender Transmitted pulses possibly seen or felt in the back Reduced or no peripheral pulses
What are the outcomes of ruptured AAA?
75% will not make it to hospital
Reteroperitoneal rupture- better survival as the peritoneum contains the rupture
Free intraperitoneal rupture into abdominal organs is rapidly fatal
Of the 25 % who make it to hospital, there is a 50% operative mortality
When should you intervene in a AAA?
1) Symptomatic, trashing, rupture
2) Assymptomatic = >5.5cm AP diameter. The risk of rupture begins to climb above 5.5cm
>0.5cm in 6 months expansion or >1cm in a year is worrying
How are AAA imaged?
U/S- assymptomatic screening or surveillance. Shows AP diamer and involvement of illiac arteries
CT andiogram- give conrast into the vein and time the contrast in the arteries. Give shape, size and illiac involvement. Allows for management and planning as some stents are unique t patients
What is the only way to identify a ruptured AAA?
CT scan
What are the surgical interventions for AAA?
Open repair (traditional) 25% Endovascular aneurysm repair (EVAR)
How is an AAA open repiar carried out?
1) Laparotomy and a clamp to aorta and illiacs. Open aneurysm sac.
2) Dacron graft used- can have a tube or bifurcated graft
3) The graft must not touch the bowel as the stitchig doesn’t dissolve and will irritate the bowel=> close aneurysm sac over the graft
4) Planned hospital stay ~7-10 days. Rupture ~1 month
How is an endovascular aneurysm repair carried out?
1) Much less invasive as you exclude AAA from the inside of the vessel. Grafts are inserted via a peripheral artery
2) X ray guided with modular components
3) Planned 3 days hospital stay. Rupture 7-10 days in hospital
What are the disadvantages of EVAR?
Require life long follow up and if the patient changes shape the graft may slip or not fit => leaks
15-20% of EVAR patients will need further intervention later in life
WHat is acute limb ischemia?
Sudden loss of blood supply to a limb. Occlusion of native artery r bypass graft => excruciating pain
Why is acute limb ischemia more common in the legs than arms?
The arms have a collateral blood supply
How do you determine between acute and acute on chronic limb ischemia?
A acurate history and examination.
Really important as the management and urgency are different.
What are the causes of a sudden artery occlusion?
Embolism- usually from heart (MI, AF or VF)
Atheroembolism at the site of occlusion
Arterial dissection (intima tears and this can block the artery)
Trauma- dislocation and fractures- especially knee
Extrinsic compression due to tumour/malignancy
WHat are the clinical features of lower limb ischemia? (6 Ps)
Pain- excrutiating Pallor- shet white initially Pulseless- no peripheral pulses Perishingly COLD- no blood flow Paraesthesia- numbness and tingling Paralysis- poor prognosis