Aneurysms, ishcaemic limb and occlusions Flashcards
What is an aneuyrsm?
A localised enlargement of the abdominal aorta such that the diameter is> 3 cm or> 50% larger than normal diameter (normal diameter = 2cm).
- True aneurysms involve all three layers (intima, media & adventitia)
- Most are infrarenal (below the renal arteries)
What are the risk factors for an aneurysm?
Risk Factors:
- Smoking
- Hypertension
- Dissection producing a false lumen
- Family history
- Male
- Age
- Atherosclerosis (e.g. angina, myocardial infarction, stroke, claudication)?
- Hyperlipidaemia
- Connective tissue disorders: Marfan’s syndrome, Ehlers-Danlos syndrome
- Inflammatory disorders: Behcet’s disease, Takayasu’s arteritis
- DIABETES thought to be protective
What are the presenting symptoms of aneuryms?
- Unruptured
- NO SYMPTOMS usually
- Usually an incidental finding on imaging
- 5% of AAA associated with GI malignancy
- May have pain in the back, abdomen, loin or groin - RUPTURED
- Abdominal pain often radiating to back
- Pain may be sudden or severe
- Syncope
- Shock (hypovolaemic)
What signs of an aneurysm can be found on physical examination?
- Pulsatile and laterally expansile mass on bimanual palpation of the abdominal aorta
- Abdominal bruit
- Retroperitoneal haemorrhage can cause Grey-Turner’s sign (flank bruising)
- Bleeding due to rupture can cause hypovolaemic shock - low BP/ high HR
What investigations are used to diagnose/ monitor an aneurysm?
- Bloods
- FBC, clotting screen, renal function (baseline renal function before CT angiogram and liver function
- CRP/ESR - raised if inflammatory AAA
- Group & save and cross-match - vital if ruptured AA -> prep for surgery - Imaging
- Ultrasound - can detect aneurysm but CANNOT tell whether it is leaking or not, fast & reliable
- CT angiogram with contrast - can show whether an aneurysm has ruptured, required if carrying out an endovascular repair - Screening programme: A single abdominal ultrasound is offered to all males aged ≥ 65
How is an aneurysm managed?
- < 3cm: discharge
- Surveillance
- For asymptomatic aneurysms < 5.5cm
- Optimise cardiovascular risk factors e.g. smoking cessation
- (Patients with AAA >4.4cm but <5.5cm found on routine screening should be monitored every 3 months, on top of referral to vascular surgeons within 12 weeks) - Elective surgical repair
- Patient is symptomatic
- Patient is asymptomatic with a AAA >5.5cm
- Patient is asymptomatic with a AAA >4.0cm and has grown by >1cm in 1 year
= 2 week referral to vascular surgery
- Endovascular aortic repair (EVAR)
Ruptured/symptomatic AAA
1. High flow oxygen
2. IV access & urgent bloods, cross match at least 6U
3. Permissive hypotension (aim for BP ≤100mmHg)
4. Immediate transfer to local vascular unit:
- Stable: CT angiogram & EVAR (endoleak complication)
- Unstable - open repair in theatre
What complications may arise following an aneurysm?
- Cardiovascular
- Rupture of AAA (high mortality rate)
- Thromboembolism –> can lead to leg pain
- Fistulas e.g. aortovenous/aortoenteric - Renal
- Ureteric obstruction - due to pressure effect, present with renal colic - Impaired sexual function
- Impotence and retrograde ejaculation due to damage to nerves
What is an ischaemic limb/ occlusion?
“blockage in the arteries of the lower extremities, which markedly reduces blood-flow”
- occurs due to atherosclerosis causing stenosis of arteries (other than brain and heart, most commonly legs) via a multifactorial process involving modifiable and non-modifiable risk factors.
What is the aetiology behind an ishcaemic limb/ occlusion?
Acute limb ischaemia- a sudden decrease in arterial perfusion in a limb, due to thrombotic (DUE TO PAD) or embolic causes (CARDIAC ORIGIN - more common e.g. prosthetic heart valve, AF), can be a result of compartment syndrome secondary to trauma -SURGICAL EMERGENCY
1. Thrombosis (40%) – rupture of atherosclerotic plaques
2. Embolism (40%) – most commonly in a patient with atrial fibrillation
3. Vasospasm – e.g. Raynaud’s phenomenon
4. External vascular compromise:
- Trauma
- Compartment syndrome
What are the risk factors of limb ischaemia/ occlusion?
- Smoking
- Diabetes
- Hypertension
- Hyperlipidaemia
- Physical inactivity
- Obesity
- AF (embolic ALI)
What signs of an ishcaemic limb/ occlusion can be found on physical examination?
- Atrophic shiny skin
- Hairless
- Brittle toenails
- Punched-out ulcers (often painful)
- Colour change when raising leg (to Buerger’s angle)
- Assess sensory and motor function
What are the presenting symptoms of limb ishcaemia/ occlusion?
- Features of Critical Limb Ischaemia
- Often associated with ulcers or gangrene
- Rest pain - burning pain, alleviated on standing
- Night pain (relieved by dangling leg over the edge of the bed) - The 6Ps of acute limb ischaemia
- Pulseless
- Painful
- Pale
- Paralysis
- Paraesthesia
- Perishingly cold
What investigations are used to diagnose/ monitor an ishcaemic limb/ occlusion?
- Bedside
- ECG -check for AF
- ABPI (Ankle-Brachial Pressure Index) -FIRST LINE
- ABPI < 0.8 = do NOT apply a pressure bandage because this will worsen ischaemia
- The ratio of the systolic BP in the lower leg to that in the arms (brachial pressure).
- Lower blood pressure in the legs (result in a ABPI < 1) is an indicator of peripheral arterial disease (PAD)
- Higher ABPI may indicate calcified, stiff arteries causing FALSE NEGATIVES - seen in diabetes - Bloods
- FBC - anaemia will worsen ischaemia, clotting and group and save
- U&Es - assess rhabdomyolysis, required prior to CT
- Creatine Kinase - elevated in rhabdomyolysis
- Full cardiovascular risk assessment including lipid profile, - Colour Duplex Ultrasound
- Shows site and degree of stenosis
- Sound waves measuring blood flow through arteries/veins
- Non-invasive and cheap
- Poor visualisation below the knee - Contrast enhanced CT angiogram / Magnetic resonance angiography
- Assesses extent and location of stenoses
- Vital pre-operatively, perform urgently in ALI
- Gold-standard for demonstrating anatomy
- Contrast agents can be nephrotoxic
How is an ishcaemic limb managed?
Critical limb ischaemia:
1. Conservative
- Smoking cessation
- Supervised exercise programme
- Comorbidities should be treated, including:
- hypertension
- diabetes mellitus
- obesity
2. Medical
- Start patient on statin - 80mg Atorvastatin
- Clopidogrel 75mg in PVD preferred to aspirin
3. Surgical
- Severe PAD or critical limb ischaemia may be treated by:
- Endovascular angioplasty or stenting
- bypass surgery
- Amputation reserved for patients with critical limb ischaemia who are not suitable for other interventions such as angioplasty of bypass surgery or if revascularisation failed
4. Acute limb ischaemia:
- IV fluids & analgesia
- IV unfractionated heparin (whilst awaiting transfer to vascular centre)
- Surgical embolectomy or intra-arterial thrombolysis +/- thromboplasty
- If limb is no longer viable –> amputation (Rutherford III)
Describe the epidemiology of ischaemic limb/ occlusion?
- 55-70 yrs = 4-12% affected
- 70+ yrs = 15-20% affected
- More common in MALES
- Incidence increases with AGE
