2: Vascular Disease In Other Sites Flashcards
What is renal-artery stenosis
Narrowing of one or both renal arteries
What are the two possible causes of renal artery stenosis
- Atherosclerosis
- Fibromuscular dysplasia
What % of RAS is due to atherosclerosis
90
What % of RAS is due to fibromuscular dysplasia
10
In which population is atherosclerotic RAS more common
Males over 50
In which population is fibromuscular dysplasia RAS more common
Females under 50
how may renal artery stenosis present clinically
- Renal bruit
- Treatment-resistant HTN
- Features of renal failure
Explain the pathophysiology of renal artery stenosis
Narrowing of the renal arteries causes ischaemic. This results in activation of RAAS system. Aldosterone increases sodium + hence fluid retention. Increases peripheral vascular resistance leading to secondary HTN. Ischaemia also causes ischaemic renal injury and progressive atrophy
What three investigations are important in work-up of RAS
- U+E
- Duplex USS
- CT/MR angiography
How will U+Es present in RAS
Raised creatinine
Hypokalaemia
What is treatment-resistant hypertension and hypokalaemia a good indicator of
Renal artery stenosis
Why is there hypokalaemia in renal artery stenosis
Renal ischaemia causes activation of RAAS and hyper-aldosteronism. This causes exchange of sodium for potassium causing hypokalaemia
What are the indications for duplex USS
- HTN onset before 30
- Resistant to three anti-HTN medications
- Renal dysfunction with ACEi
- Unexplained renal atrophy - difference of more than 1.5cm
On CT angiography if there is stenosis of proximal renal artery segment what does it suggest
Atherosclerotic pathophysiology
On CT angiography if there is stenosis of distal renal artery segment what does it suggest
Fibromuscular dysplasia
What lifestyle factors are used in management of renal artery stenosis
Smoking cessation
Weight loss
Control diabetes and HTN
Why should ACEi not be given to manage blood pressure in renal insufficiency
Due to toxic if renal damage
What is ultimate management of renal artery stenosis
Percutaneous trans-luminal angioplasty
What percentage of the renal artery must be stenosed to require percutaneous trans-luminal angioplasty
60%
Explain why ACEi are contraindicated in patients with renal artery stenosis
Normal system:
PGE2 causes vasodilation of renal artery to control blood flow through glomerulus and Angiotensin II controls efferent arteriole
In RAS:
There is narrowing of the afferent impairing flow. Therefore more reliant on efferent to control flow through glomerulus. If ACEi are used this is lost.
Define acute mesenteric ischaemia
occlusion of blood supply to the small bowel resulting in necrosis and possible perforation
In which age-group is mesenteric ischaemia more common
> 60
What are 4 causes of mesenteric ischaemia
- Thrombosis
- Embolism
- Mesenteric venous thrombosis
- Non-occlusive disease
When is mesenteric vein thrombosis more common
Younger patients w/ hyper-coagulable states
Explain non-occlusive disease as a cause of mesenteric thrombosis
Drop in cardiac output
What are three risk factors for acute mesenteric ischaemia
- Hypercoagulable states
- AF
- Vasculitis
What is the triad of symptoms for acute mesenteric ischaemia
- Severe abdominal pain
- No abdominal signs
- Rapid shock
what is the stereotypical presenting complaint of acute mesenteric ischaemia
Abdominal pain disproportionate to clinical findings
where is the abdominal pain in acute mesenteric ischaemia
Central
if due to embolism describe onset of pain in acute mesenteric ischaemia
Abrupt onset and extremely painful
if due to thrombosis explain symptoms of acute mesenteric ischaemia
Less severe - as there is collateral supply
what artery is occluded in 90% of acute mesenteric ischaemia
Superior mesenteric artery
what does the superior mesenteric artery supply
Midgut
What investigations may be ordered in mesenteric ischaemia
FBC (Raised WBC)
Abdominal X-Ray
CT/MRI
CT angiography
What investigations may be ordered in mesenteric ischaemia
FBC (Raised WBC)
Abdominal X-Ray
CT/MRI
CT angiography (confirmatory)
How should acute mesenteric ischaemia be managed
Emergency laparotomy - remove necrotic segments
What are main complications of acute mesenteric ischaemia
Peritonitis
Sepsis
How common is chronic mesenteric ischaemia
Rare!
In which individuals does chronic mesenteric ischaemia occur
> 60
What is the most common presentation of chronic mesenteric ischaemia and when does this occur
Asymptomatic - when there is occlusion of single artery. More than this causes symptoms
If symptomatic, how does chronic mesenteric ischaemia present
Intestinal angina - dull epigastric pain following meals
What is the problem with chronic mesenteric ischaemia
Pain may cause avoidance of eating which can lea to weight loss
What will be auscultated in chronic mesenteric ischaemia
abdominal bruit
Explain chronic mesenteric ischaemia
stenosis of two or more main gastric arteries causes a post-prandial mismatch between blood supply and metabolic demand
Why is one artery occluded asymptomatic
due to collateral supply from other vessels
What is first line investigation for chronic mesenteric ischaemia
CT abdomen
How is chronic mesenteric ischaemia managed
Nutritional support- regular small meals
Long-term anticoagulant
Revascularisation
What medication is used to control risk factors contributing to carotid stenosis
Clopidogrel
Atorvostatin
ACEi
What is first-line management for carotid stenosis
Carotid endarterectomy
What are the indications for carotid endarterectomy in carotid stenosis
- Symptomatic, Cartoid.a stenosis >70% and life-expectancy >5y
- Asymptomatic and stenosis >80%
if individuals are unfit for carotid endarterectomy what is second-line
Endovascular carotid.a stenting
what is the main risk of carotid artery stenosis
stroke
What are the indications for carotid endarterectomy in carotid stenosis
- Symptomatic, Cartoid.a stenosis >70% and life-expectancy >5y
- Asymptomatic and stenosis >80%
- Symptomatic and stenosis 50-69%
Explain clinical presentation of carotid artery stenosis
asymptomatic. May cause gradual decline condition. Presents suddenly with stroke/TIA