Pulsatile mass above umbilicus- abdominal aortic aneurysm
Abdominal aortic aneurysm is a permanent localised dilation of the abdominal aorta and greater than 3cm. 95% of abdominal aortic aneurysm are due to atherosclerosis.Other aetiologies are inflammatory ( variant of atherosclerosis aneurysm ),...
Abdominal aortic aneurysm
Abdominal aortic aneurysm is a permanent localised dilation of the abdominal aorta and greater than 3cm.
Causes of abdominal aortic aneurysm
95% of abdominal aortic aneurysm are due to atherosclerosis.Other aetiologies are inflammatory ( variant of atherosclerosis aneurysm ), traumatic, infective ( mycotic ), and connective tissue disorder, Marfan's syndrome and Ehler- Danlos type IV.
Risk factors for abdominal aortic aneurysm
Risk factors for abdominal aortic aneurysm includes hypertension, smoking and family history.
Presenting complaints for abdominal aortic aneurysm
The majority of patients are asymptomatic, may be found incidentally.Symptoms may be related to vertebral body erosion, distal embolization, thrombosis and rupture).
In emergency setting the patient may present with epigastric or back pain ranging form vague discomfort to excruciating pain or collapse associated with leakage or rupture. Rarely, present with gastrointestinal bleeding due to erosion into the duodenum or high output cardiac failure due to aortocaval fistula.
Examination finding on abdominal aortic aneurysm
A pulsatile mass is felt above the umbilicus. If leaking or rupture, abdominal and back tenderness with pallor, tachycardia, hypotension and hypovolaemic shock.
Pathology of abdominal aortic aneurysm
Atherosclerosis leads to thinning of the media, loss of smooth muscle cells and elastic fibres with progressive replacement of non contractile ineastic collagen leading to generalized dliation of the vessel.Most commonly involve the infrarenal aorta with iliac involvement in 30% of cases.Risk of rupture is related to diameter. e.g > 5.5 cm risk 10-15% per year, if 7cm risk is > 75%. Patients with rupture surviving until arrival in hospital usually have a leak tamponated within the retroperitoneum .
The investigation requires include blood test such as full blood count, urea and electrolyte studies, clotting studies, cross match blood in acute presentation.
Imaging CT scan or ultrasound useful to confirm the presence and size of the aneurysm
Arteriography or MRA may b necessary to measure involvement of the renal arteries prior to treatment.
Management of abdominal aortic aneurysm
The management includes conservative, radiological and surgical. The conservative management includes followed up with regular ultrasound and treatment for cardiovascular risk factors. This is most commonly done with small asymptomatic aneurysm ( < 5.5 cm )
The radiological treatment includes endovascular treatment by stent placement while the surgical approach includes insertion of tube or bifurcation grafts.
Complication of abdominal aortic aneurysm
From disease includes rupture ( most frequent ) , distal embolization, sudden complete thrombosis, infection ( gram negative organisms or staphylococci ) renal failure, gut ischemic, aortic intestinal fistula , arteriovenous fistula from aneurysm eroding into the inferior vena cava.
From surgery includes haemorrhage, embolism, graft thrombosis and graft infection,
Risk of rupture related to sizes of aneurysm.< 50% of patients with a ruptured abdominal aortic aneurysm reach hospital alive and only about 50% of these survive.( overall 80% mortality) .
Elective surgery however have a mortality of < 5% with a 5 year survival of 72%.