Vascular Surgery Flashcards
Define Abdominal Aortic Aneurysm
An abnormal localised dilation of the abdominal aorta > 3cm (or 50% over normal diameter)
Most Commonly it affects the Infrarenal aorta (95%) with iliac involvement in 30%
Aetiology of Abdominal Aortic Aneurysm
Collagen and elastin degeneration in the arterial wall. Often associated with
- atherosclerosis
- inflammatory (chronic inflammatory infiltrate in the vessel wall)
- Traumatic
- Infective
- Arteritis
- Connective Tissue Diseases e.g Marfans Syndrome and Ehlers-Danos type IV
Most common site of AAA
Infrarenal aorta (95%) with iliac involvement in 30%
Risk Factors for Abdominal Aortic Aneurysm
- Smoking
- Hypertension
- Family History (10 x increased risk if 1st degree relative FHx)
- Coronary Artery Disease
- Popliteal Artery Aneurysms
- Male (4-6 x increased risk)
Risk of Rupture is related to diameter: Laplace’s Law.
AAAs risk of rupture:
5-5.9: 3.3% per year
6-6.9: 9.4% per year
7-7.9: 24% per year
What is Laplace’s Law?
a principle of physics that the tension on the wall of a sphere is the product of the pressure times the radius of the chamber and the tension is inversely related to the thickness of the wall.
What is an AAAs risk of rupture
AAAs risk of rupture:
5-5.9: 3.3% per year
6-6.9: 9.4% per year
7-7.9: 24% per year
How prevalent are AAAs in population
5% of >60s
15% >80s
Epidemiology of AAAs
5% of >60s and 15% >80s in population have AAAs
It is 4-6 x more common in men
Causes about 6000 deaths/ year in UK
Typical History for AAA
OFTEN ASYMPTOMATIC
If ruptures: Most common reason for presentation
- epigastric and/or back pain.
- Collapse
Those reaching hospital often have a leak tamponaded within retroperitoneum
tamponade= collection of blood
INTACT ANEURYSMS MAY CAUSE SYMPTOMS:
- Back Pain (Vertebral erosion)
- Lower Limb Ischemia (distal embolisation)
- Massive GI bleed (erosion into the duodenum)
- High output cardiac failure (aortocaval fistula)
What is aortocaval fistula
Spontaneous rupture of an AAA into the adjacent vena cava
Symptoms of intact abdominal aortic aneurysm
INTACT ANEURYSMS MAY CAUSE SYMPTOMS:
- Back Pain (Vertebral erosion)
- Lower Limb Ischemia (distal embolisation)
- Massive GI bleed (erosion into the duodenum)
- High output cardiac failure (aortocaval fistula)
Symptoms of ruptured AAA
- epigastric and/or back pain.
- Collapse
Those reaching hospital often have a leak tamponaded within retroperitoneum
tamponade= collection of blood
Findings on Examination of AAA
Pulsatile mass above umbilicus.
If leaking or ruptured:
- abdominal/ back tenderness
- pallor
- Tachycardia
- Hypotension
- Hypovolaemic Shock
Investigations for AAA
Acute Presentation:
- Bloods: FBC, U&Es, Clotting, URGENT CROSS MATCH,
- ECG
- CXR
- Bedside USS: (Confirm presence and size)
If stable…(if unstable emergency repair)
- CT
N.B Screening for AAA
CT or MR angiography: to delineate aneuysm prior to treatment
Management of AAA
CONSERVATIVE
- regular US follow up
- management of Cardiovascular Risk Factors
[RADIOLOGICAL
1. EVAR (Endovascular treatment by stent placement)- only some AAA are suitable (have satisfactory neck and landing site for endograft)]
SURGICAL TX with tube or bifurcation grafts
suitable in Emergency, asymptomatic >5.5cm, Symptomatic or rapidly expanding
