Vascular Surgery Flashcards
How is ABPI calculated
Foot artery occlusion pressure / brachial systolic pressure
ABPI >1.1 indicates
Calcified or incompressible vessels e.g. diabetes and renal failure
ABPI 0.7-0.9 indicates
Mild ischaemia
ABPI 0.4-0.7 indicates
Moderate ischaemia
ABPI <0.4 indicates
Critical ischaemia
What is the most accurate investigation for imaging the arterial system
Intra-arterial digital subtraction angiography (IADSA)
What is the investigation of choice for imaging the lymphatic system
Lymphoscintigraphy
How is lymphoscintigraphy performed
Radiolabelled colloid is injected into the webspace between the 2nd and 3rd toes and images obtained with a gamma camera
What are the 3 histological layers of an artery
- Tunica intima
- Tunica media
- Tunica adventitia
What are the 2 types of artery
- Elastic conducting arteries
2. Muscular distributing arteries
Describe the tunica intima
- Innermost layer
- Single layer of endothelial cells orientated in the direction of flow
Describe the tunica media
- Middle layer
- Composed of elastin and collagen fibres with vascular smooth muscle cells
Describe the tunica adventitia
- Outermost layer
- Connective tissue
What are the histological differences between the thoracic and abdominal aorta
Thoracic aorta has >30% elastin compared to <20% in the abdominal section
What crosses the abdominal aorta anteriorly
- Splenic vein
- Body of pancreas
- 3rd part of duodenum
- Left renal vein
What lies immediately to the right of the abdominal aorta
- IVC
- Right ureter
- Azygous vein
What lies immediately to the left of the abdominal aorta
- Left sympathetic trunk
- Left ureter
Define an aneurysm
Pathological dilatation of an artery to >1.5x its normal diameter
What is the diameter of the aorta
2cm
Define a true aneurysm
Dilatation of an artery involving all layers of the arterial wall
Define a false aneurysm
Pulsatile, expansile swelling due to a defect in an arterial wall, with blood outside of the lumen, surrounded by a capsule of fibrous tissue or compressed surrounding tissue
List the causes of aneurysms
- Degenerative (atherosclerotic) - MOST common
- Inflammatory
- Congenital (Berry aneurysm)
- Mycotic (bacterial, IE)
- Infective
Where is the most common site of atherosclerotic AAA
Infrarenal
Mortality rate for elective AAA repair
5%
In whom is elective AAA repair offered
Those with a AAA >5.5cm
What percentage of AAAs involve the iliac arteries
30%
What percentage of AAAs are asymptomatic
75%
Where does a AAA typically rupture and what does this cause
- Posterior wall
- Retroperitoneal haematoma (bruising of the flanks/scrotum
Who is screened for AAA in the UK
65 year-old men
What histological changes are seen in AAAs of those with Marfan’s
Cystic medial necrosis
How much blood should be cross-matched for ruptured AAA repair
10 units
What type of AAA repair is preferred if there is iliac involvement
- Open
- Trouser Y-graft
List the immediate complications of AAA repair
- Primary Haemorrhage
- Distal embolisation (ischaemic leg, trash foot)
List the early complications of AAA repair
- Haemorrhage (reactionary, secondary)
- MI
- Renal failure (esp if proximal clamp above renal vessels)
- Multi-organ failure/DIC/ARDS
- Colonic ischaemia
- Pneumonia
- Stroke
- DVT/PE
- Paraparesis due to spinal ischaemia
How much heparin is to be used prior to cross-clamping of the aorta
3000 units
What bacteria cause myoctic aneurysms
- Staph aureus
- Salmonella
- Streptococcus
List the late complications of AAA repair
- Late graft infection
- Aortoenteric fistula
- Anastomotic aneurysm
What are the requirements of conventional EVAR
Aneurysm needs to have a proximal neck of at least 5mm above the aneurysm and below the renal arteries
What type of endovascular graft can be used in those aneurysms not suited for conventional EVAR
Fenestrated EVAR (very expensive)
What are the follow-up implications for EVAR
Long-term due to high risk of late complications e.g. endoleak
Describe type 1 endoleaks
Leak from stent-graft attachment site
Describe type 2 endoleaks
Leak due to retrograde flow through visceral or lumbar arteries into aneurysm sac (most common type)
Describe type 3 endoleaks
Due to structural failure of the stent-graft e.g due to holes
Describe type 4 endoleaks
Due to graft porosity and usually settles with time
Describe type 5 endoleaks
Aneurysm sac continues to expand with time, but no leak is identified (endotension)
What is the 2nd most common site of atherosclerotic aneurysm
Popliteal artery
How do popliteal aneurysms present
- Aneurysm thrombosis or distal emboli leading to limb ischaemia
- Rupture is rare
How are popliteal aneurysms treated
- Ligation and vein bypass graft, OR
- Endovascular stent
What percentage of those with a popliteal aneurysm will also have a AAA
30%
What is the most common type of visceral artery aneurysm
Splenic artery aneurysm
What are the indications for surgery in popliteal aneurysm
- Symptomatic
- Limb ischaemia
- Asymptomatic with thrombus
List the branches of the external iliac artery
- Inferior epigastric artery
- Deep circumflex iliac artery
List the branches of the femoral artery
- Superficial circumflex iliac artery
- Superficial epigastric
- Superficial and deep external pudendals
- Profunda femoris
Describe the course of profunda femoris
- Largest branch of the femoral artery
- Arises posteriorly/posterolaterally
- Descends medially to enter adductor compartment
- Gives of medial and lateral circumflex femoral, then 3 perforators
- Ends as 4th perforator
Outline the bounds of the popliteal fossa
- Lateral = biceps femoris above, lateral head of gastroc and plantaris below
- Medial = semimembranosus and semitendinosus above, medial head of gastroc below
- Floor = popliteal surface of femur, posterior ligament of knee, popliteus mucle
- Roof = superficial and deep fascia
What is the deepest structure of the popliteal fossa
Popliteal artery
What is the most superficial structure of the popliteal fossa
Tibial nerve
What flanks the dorsalis pedis artery in the foot
- Medial = EHL tendon
- Lateral = EDL tendons
What does the posterior tibial artery divide into
Medial and lateral plantar arteries
What is the most common caused of PVD
Atherosclerosis with thrombosis
Outline the structure of an atherosclerotic plaque
- Superficial fibrous cap
- Intra-intimal area with accumulation of lipids, smooth muscle cells, foam cells
- Basal zone with lipid accumulation and tissue necrosis
What is thromboangitis obliterans also known as
Buerger’s disease
What is the classic demographic of Buerger’s disease
Progressive obliteration of distal arteries in young men who smoke heavily
How is Buerger’s disease managed
- Smoking cessation
- Sympathectomy to relieve arterial spasm
- Antibiotics
- Foot care
- Analgesia
- Prostaglandins for acute ischaemia
List the symptoms of acute limb ischaemia
- Pain
- Pulseless
- Pallor
- Paraesthesia
- Paralysis
- Perishing cold
What is the time-frame for resolution of acute limb ischaemia
4-6 hours
Outline the principles of managing acute limb ischaemia
- Resuscitation
- Immediate anticoagulation (5000 units heparin IV)
- Analgesia
- Restore arterial continuity
- Identify and correct any underlying source of embolus
What is the investigation of choice in acute limb ischaemia if diagnosis in doubt
Arteriography
Describe the clinical appearance of a limb with <6 hours ischaemia
White
Describe the clinical appearance of a limb with 6-12 hours ischaemia
Mottled limb with blanching on pressure