Abdominal Aortic Aneurysm

Key Feature


Abdominal Aortic Aneurysm


Essentials Of Diagnosis

  • Defined as an aortic diameter > 3 cm.
  • Most are asymptomatic,detected during a routine physical examination or imaging performed for anoother reason 
  • Sever back and abdominal pain and hypotension indicate rupture
  • Concomitant atherosclerotic occlusive disease of lower extremities in 25 %
General Considerations

  • More then 90% of abdominal aneurysms originate below the renal arteries many extend into the common iliac arteries.
  • Half are <5 Cm in diameter.
  • On routine ultrasound surveillance,two third will increase in size to require repair.
  • Yearly rupture risk is 2% for 4 to 5.4 cm aneurysms ,7% for 6 to 6.9 cm aneurysms,25% for 7 cm aneurysms
  • Patients with chronic obstructive pulmonary disease are more likely to experience rupture are small aneurysms.
  • More then one third of patients with popliteal aneurysms have abdominal aortic aneurysms. 
Demographic
  • Aortic aneurysms is present in 5-8% of the population older than 65.
  • Incidence has tripled over the last 30 years. 
Clinical Finding

Symptoms & Signs
  • Asymptomatic aneurysms prominent aortic pulsation on routine physical examination and incidental finding on abdominal ultrasonogram or CT scan,coexisting renal or lower extremity arterial occlusive disease present in 25% ,popliteal artery aneurysms in 15%.
  • Symptomatic aneurysms : midabdominal or lower back pain (or both).
  • Inflammatory aortic aneurysms : Low grade fever,elevated sedimentation rate and recent upper respiratory tract infection.
  • Infected aneurysms (rare) : Fever of unknown origin.peripheral emboli,positive blood cultures,caused by septic emboli to a normal aorta or bacterial colonization of an exisiting aneurysms.
  • Ruptured aneurysms : Severe back,abdominal or flank pain and hypotension ; 90% patients die before reaching the hospital are in the perioperative period.
Differential Diagnosis 
  • Asymptomatic abdominal aortic aneurysms: intraabdominal tumor,iliac aneurysms,Or mesenteric artery aneurysms.
  • Symptomatic/Ruture abdominal aortic aneurysms: acute myocardial infarction,Aortic dissection,Renal stones,Gastrointeritis,Bowel obstruction,and bowel infarction.
Diagnosis
Laboratory Tests
preoperative evaluation : Electrocardiogram,Serum Creatinine,Hematocrit and Hemoglobin and type and acrsross match.

Imaging Studies


  • Abdominal Ultrasonography : Indicated for screening and for monitoring aneurysm growth (annually for aneurysms > 3.5 cm in diameter)
  • Abdominal Radiograph : Curvilinear calcification are much less accurate
  • Contrast - enhanced CT scanning : precisely sizes the aneurysm,define it`s relationship to the renal arteries.
  • MRI : as sensitive and specific as CT and useful is renal insufficiency precludes contrast-enhanced CT.
  • Aortography/CT angiogram : indicated before elective aneurysmrepair when arterial occlusive disease of the visceral or lower extremity arteries is suspected or when endograft repair is being considerd .
  • Preoperative Evaluation : Assessment of cardiac risk and ultrasound examination of the carotid arteries.

Medication

  • Beta-Blocker and oral Roxithromycin ,300 mg daily for 30 days,Decrease the expansion rate of small  aneurysm.

Surgery

  • In asymptomatic good risk patients,surgery advised when  aneurysm diameter > 5 cm.
  • In poor risk patients,surgery advised when  aneurysm diameter > 6 cm.
  • Urgent repair advised for symptomatic  aneurysms irrespective diameter.
  • Ruptured  aneurysms require emergent surgery.
  • Open repair : Surgical reaction and synthetic graft replacement for most thoracic,abdominal,juxtarenal,and infrarenal aortic  aneurysms with diameter > 5 cm.
  • Endovascular Repair : Uniiliac or bifurcated endovascular stent grafts,deployed via the common femoral arteries,can be considered for infrarenal  aneurysms with favorable anatomy.
  • Endovascular repair can be done by a percutaneous route or by bilateral inguinal incisions under epidural anesthesia,and thus has made repair of aortic  aneurysms feasible in elderly high risk patients.
  • Long-Term durability of endovascular grafts needs to be established.

Therapeutic procedure 

  • Physical examination.
  • Ultrasonogram of abdominal aorta every 6 month.

Follow Up

  • Open repair : Yearly physical examination.
  • Endovascular repair : Routine surveillance,CT abdomen,and physical examination.

Complication

  • Open repair : Acute myocardial infraction,Arrhythmia,Bleeding,Respiratory failure,Limb ischemia,Renal failure,stroke,Ischemic colitis,Bowel infraction,Liver dysfunction,acalculous cholecystitis,Grafts infaction,Graft enteric fistula.
  • Endovascular Repair : Persistent filling of the  aneurysm(Endoleak),Graft Migration,Graft Thrombosis,Graft Infaction (Rare),Renal failure,conversion to open repair.

Prognosis

  • Mortality following elective open or endovascular repair is 1-5 %
  • A patient with >5 cm aortic aneurysmand life expectancy of > 1 year has a 3 fold greater chance of dying of rupture than of dying from surgical reaction .
  • 5 year survival after surgical repair is 60-80 %.
  • 5-10 will develop another aortic aneurysm adjacent to the graft or in the thoracic aorta.

When to Refer

  • Any patient with an aneurysm_> 4.0 cm .
  • Any patient with a symptomatic or suspected ruptured abdominal aortic aneurysm.

When to Admit

  • All patients with symptomatic or suspected ruptured abdominal aortic aneurysms or suspected infected aneurysms.

Prevention

  • Blood pressure Control.
  • Cardiovascular risk assessment and treatment.
  • Smoking cessation .
  • Screening of family members older than 65.

Evidence

Practice Guidelines

  • Brewster DC et al : Guideline for the treatment of abdominal aortic aneurysms.Report of a subcommittee of the joint Council of the American association for the vascular surgery and Society for Vascular surgery.



Abdominal Aortic Aneurysm Abdominal Aortic Aneurysm Reviewed by Gyano Tech on November 27, 2018 Rating: 5

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