Aneurysms and carotid artery surgery Flashcards
When does a dilatation of the aorta become classified as an aneurysm?
When it dilates to an increase of > 50% (normal diameter of the aorta = 2cm)
Where are the majority of aneurysms found?
95% are infrarenal abdominal aneurysms - Located in the part of the abdominal aorta below the kidneys
Whats the difference between true and false aneurysms?
True - disease affects all 3 layers of the aorta wall
False - usually only affects outer layer, usually caused by trauma
What can cause aneurysms?
Degenerative disease
Connective tissue disease
Infection (mycotic aneurysm)
Trauma
What are the risk factors for aneurysms?
Male Age Smoking Hypertension Family History Genetics
How can asymptomatic aneurysms be found?
Clinical exam - pulsatile mass (false a etc)
After family member diagnosis
Screening - all males over 65yo get US
Incidentally in a scan for something else
What is the criteria for a successful screening regime?
Definable disease Prevalence Severity of disease Natural history is understood Reliable detection Early detection confers advantage Treatment options available Cost effective Feasibility Deemed acceptable - complaincy
What classifies as a small aneurysm?
3-4.4cm
Annual USS scans
What classifies as a medium aneurysm?
4.5-5.5cm
3 monthly USS scans
What classifies as a large aneurysm?
> 5.5cm
Immediately referred to vascular surgeon
What are some unusual presentations of aneurysms?
Distal embolisation Aortocaval fistula Aortoenteric fistula (connection between aorta and intestines/stomach/oesophagus) Ureteric occlusion Duodenal obstruction
How do we assess patient fitness for aneurysm surgery?
Full history and exam - comorbidity, function Full blood tests ECG ECHO Pulmonary function tests Myocardial perfusion scans Cardio-pulmonary exercise testing End of the bed test? Patient preference
What are some pros of cranial ultrasound?
No radiation
No contrast - safe in renal failure
Cheap
What are some cons of cranial ultrasound
Operator dependent
Inadequate for surgical planning
What are some pros of CTA and MRA when planning surgery?
Quick
Not operator dependent
What are some cons of CTA or MRA for planning surgery?
Contrast used
Radiation
What is done to assess aneurysm before surgery?
Ultrasound
Computed tomography angiography
Magnetic resonance angiography
What procedure involves making a large incision in the abdomen to expose the aorta and aneurysm sac?
Laparotomy - from xiphisternum to pubic symphysis
What are some complications of open surgery on aneurysms?
General anaesthetic use Big operation - healing time, infection Incisional hernia Damage to nearby anatomy Risk of preoperative MI Renal failure Colonic ischaemia
Describe endovascular repair (EVAR) of aneurysms
Small incision in groin, where special instruments are inserted through a catheter in the femoral arteries to thread them up to the aneurysm. At aneurysm, surgeon places stent and graft to support aneurysm.
What are some complications of EVAR?
Damage to veins/arteries/nerves on insertion Rupture of aneurysm Endoleak Femoral artery dissection/pseudoaneurysm Distal emboli/ischaemia
What could surgery on aneurysms lead to clinically?
DVT/PE
MI
Stroke
Death
What are some general complications following both EVAR and open surgery?
Wound infection Bleeding Pain Scarring (Radiation/contrast if used)
What are endoleaks?
Blood leaks back into aneurysm sac following EVAR, 5 types:
I - gap between graft and vessel at seal
II- increased pressure forces blood out
III- defect or misalignment of endograft
IV - porosity of graft
V- permeability of graft allows transmission of pressure into sac
What is a type I endoleak?
I - gap between graft and vessel at seal, requires urgent attention
What is a type II endoleak?
II- increased pressure forces blood out
MOST COMMON
What is a type III endoleak?
III- defect or misalignment of endograft, requires urgent attention
What is a type IV endoleak?
IV - porosity of graft, occurs soon after procedure
What is a type V endoleak?
V- permeability of graft allows transmission of pressure into sac
ENDOTENSION, controversial
What is there a risk of in EVAR?
Incomplete removal of blood can lead to Abdominal compartment syndrome
Why must you prep abdomen before surgery?
Acts as a tamponade normally, which is lost following anaesthetics
What is atherosclerosis of the carotid arteries associated with clinically?
Transient ischaemic attacks
Stroke
What can cause cerebral infarctions?
AF Carotid atheromatous plaque rupture Endocarditis MI Carotid artery injury/dissection Drug abuse Haematological disorders e.g. sickle cell Primary intracerebral haemorrhage
What % of strokes are due to ischaemia?
84%
What % of strokes are due to haemorrhage?
16% (primary intracerebral +subarachnoid haemorrhages)
What is Virchows triad?
Three broad range of factors associated with thrombosis:
Hypercoagulability
Haemodynamic changes - stasis, turbulence
Endothelial damage/dysfunction
What are some risk factors for carotid artery atherosclerosis?
Smoking Diabetes Hypertension Family history Male sex Previous DVT Hyperlipidaemia Hypercholesterolaemia Obesity Age
How can we diagnose stroke?
History and examination
CT
Carotid USS - measure flow and direction
What is poiseuilles law?
Flow depends on resistance and radius of the vessels
As radius decreases, velocity increases
What therapy is suggested to those with carotids artery atherosclerosis?
Smoking cessation Control of hypertension Antiplatelet agents e.g. aspirin, clopidogrel Statins Diabetic control
If severe:
Carotid endarterectomy
Stenting
What is the circle of willis?
circulatory anastomosis that supplies blood to the brain and surrounding structures.
Describe Carotid endarterectomy
clamp above and below diseased section, remove plaque and repair artery to create open channel
What is the general rule with superficial and deep vessels?
Superficial - continue following bifurcation
Deep - end and supply area
What are some complications of Carotid endarterectomy ?
Wound infection Bleeding Scarring Anaesthetic risks Nerve damage
What are the nearby nerves that can be damaged during Carotid endarterectomy, and how would damage present?
Vagus nerve - PS control of lungs, GI tract
Hypoglosseal nerve - numb lips and tongue
Glossopharyngeal nerve - loss of voice
What is the hypoglosseal nerve responsible for?
Lip and tongue innervation
What is vagus nerve responsible for?
Parasympathetic control of hearts, lung, GI tract etc
What is the glossopharyngeal nerve responsible for?
Voice
What are some possible complications of Carotid endarterectomy?
Plaque rupture
Hypoperfusion
Clotting
When should surgery be considered?
Symptomatic but 50-69% stenosis
Asymptomatic but >70% stenosis
