Abdominal Aortic Aneurysm Flashcards
How do arterial aneurysms develop?
- proteolytic degradation
increase in proteolytic enzymes compared to inhibitors
increased activity + expression of MMPs
elastin not synthesised - inflammatory response - cytokine activation of proteins
- biochemical stress - atherosclerosis - intimal layer
- genetics - upregulation of genes coding for ECM degradation
Describe the dimensions of the aorta and places where it commonly forms an aneurysm
average diameter = 28mm thoracic –> 20mm infrarenal
an aorta >3cm = moderate aneurysmal
severe if >5cm
>1.8cm iliac artery = aneurysmal
most begin below renal arteries and before bifurcation of iliac
How can aneurysms be classified?
morphology - saccular or fusiform
true or false
location
size
What is the difference between true and false aneurysms?
TRUE =
involvement of all 3 layers (intima + media + adventitia)
eg atherosclerotic, syphilitic, congenital, ventricular (following an MI)
FALSE =
collection of blood leaking out of artery or vein
blood is confined around the vessel by surrounding tissue
eg from trauma, percutaneous surgery, injections
What does an aneurysm look like histologically?
lymphocyte and macrophage infiltration
media thinning
marked loss of elastin
What are the S&S of an aortic aneurysm?
usually asymptomatic unless there is gross expansion or rupture
Expanding AAA back/flank/abdo/groin pain early satiety nausea vomiting urinary symptoms venous thrombosis fever embolic phenomena (affects toes) pulsatile mass syncope
Ruptured AAA central abdo/back pain groin pain syncope paralysis flank mass pulsatile mass shock
What are the indications for surgical intervention with AA disease?
ruptured
symptomatic
asymptomatic + >5.5cm
asymptomatic + >4cm + increased by 1cm within a year
Hows does AAA cause groin pain?
retroperitoneal space invaded
pressure on L/R femoral nerve
refers pain down to the groin
List some DDx for AAA
Skin/soft tissue - sebaceous cysts, sarcoma, lipoma, hernia
GIT - hepatomegaly, carcinoma of stomach/pancreas
Vascular - AAA, retroperitoneal lymphadenopathy
acute abdo, acute pancreatitis, perforation, renal or biliary colic, inferior MI
What are some of the RF for AAA?
M>F >65yrs peripheral vascular disease smoking COPD previous aneurysm CAD hypertension first-degree relative connective tissue disease - Marfan's, Ehlers-Danlos
What are some of the RF for a ruptured AAA?
hypertension elevated peak aortic wall stress cardiac/renal transplant tobacco rapid expansion baseline line aortic diameter decreased FEV1 F>M
What investigations can be used to diagnose AAA?
examination + history
Lab - FBC, U&Es, LFTS + diff to assess transfusion requirements or infection
Imaging
USS - 100% sensitive and 96% specific
AXR - high false negative
CT - 100% sensitive + more accurate in defining extent and morphology of disease
MRI + gadolinium - better imaging but not suitable for unstable patients
Angiography - may miss AAA if laminated thrombus means lack of calcification –> lumen will appear normal
useful for endovascular repair
What are the mortality figures of elective aortic repair vs emergency repair?
elective
4% risk of death after open-surgery
1% risk after endovascular repair
emergency
40-50% risk after open-surgery
Who would benefit more from an endovascular stent rather than elective surgery?
patients with: severe COPD severe cardiac disease active infection medical problems which preclude operative intervention
How are AAA monitored?
with USS
every 3 months if AAA 4.5-5.4cm
every 2 years if AAA 3.0-4.4cm
