Abdominal Aortic AneurysmsAlexandre d’Audiffret, M.D. FACS.West Virginia University
What is an AAA?• Localized dilatation ofthe abdominal > 50% ofnormal diameter• Normal infrarenal aorticdiameters– Males – 21.4 +/-3.6mm– Females – 18.7 +/-3.3mm• AAA > 3.0cm indiameter
Who is at risk?• 4-5% of patients > 60 years ofage• 4-66 fold greater in males thanfemales• Age, gender, smoking mostclosely correlated with AAAprevalence
Abdominal Aortic Aneurysms• Ruptured AAA 13 th overall leadingcause of death• Elective AAA repair – 40,000 + /year• AAA rupture risk most closelycorrelated with AAA size
Symptoms• 75% Asymptomatic• Symptoms– Pain– Pressure on adjacent structures– Embolization– Thrombosis
Screening• Palpable, pulsatile abdominal mass• PESensitivitySpecificity29% AAA < 4cm 84%57% AAA > 4cm 96%• Overall PPV – 17% to 36%
DiagnosisPlain Radiograph• Can detect thin rim of calcium in 70%of AAA• Accurate measurement in 67% ofcases• Negative of technically inadequatestudy cannot exclude AAA
DiagnosisCT• More expensive than US• Better than US for size, location• Can image iliac, hypogastric arteries• With contrast can image flow channel• Inflammatory AAA• Ruptured AAA
DiagnosisMRI• Expensive• Patient suitability/compliance• Comparable to CT
DiagnosisAortography• Expensive• Invasive• Underestimates AAA size because ofluminal thrombus• Should NOT be routinely utilized– PAD, Renal or Visceral Artery Stenosis
When to repair• Operative morbidity and mortality(elective operative mortality 90% mortality. 50% ifpatient makes it to the OR.
Abdominal Aortic Aneurysms• Few would disagree that AAA > 6cm pose a significant risk of ruptureand repair is indicated• Recommendations for repair ofsmall AAA (< 5.5cm) vary:– > 5 cm– > 4.5 cm– > 4.0 cm
Abdominal Aortic Aneurysms• Rupture risk– 5.5cm-6.5 cm: 23%at 3 years– 6.5cm-6.9 6.9 cm: 27% at3 years– 7.0 cm : 40% at 2years2520151050Yearly rupture risk of infrarenal AAA4 5 5.5 6 6.5 7 7.5 8
UK Small Aneurysm Trial• Prospective, randomized trial• Open surgical repair vs.ultrasound surveillance andselective repair• 126 vascular surgeons, 93 UKHospitals• September 1991 through October1995
UK Small Aneurysm Trial• Ages 60-76• Fit for elective operation• Asymptomatic, infrarenal AAA• 4.0 to 5.5 cm in diameter byultrasound
UK Small Aneurysm Trial/ Adams Study Treatment andFollow-up• Operations per local / vascularsurgeon protocol within 3months of randomization– 1 month post-opop– All deaths within 2 weeks ofoperation were attributed to AAArepair
UK Small Aneurysm TrialTreatment and Follow-up• Ultrasound surveillance– 4.0 to 4.9 cm : every 6 months– 5.0 to 5.5 cm : every 3 months• Indications for operation insurveillance group– > 5.5 cm– Growth rate > 1 cm per year– Symptoms
UK Small Aneurysm TrialMethods• All patients directly contacted at endof trial to check survival status• Primary End-Point : DEATH• Secondary Endpoints:– Aneurysm rupture– Death from surgical repair of AAA
UK Small Aneurysm TrialResults• Mean follow-up– 4.6 years• Compliance –– Operation : 92%– Surveillance : 94%• Time to operation in surveillance group2.9 years• Necropsy – 29% of patients who diedduring the study period
UK Small Aneurysm TrialResults• Operative Mortality– Early Surgery – 5.8%– Surveillance – 7.1%• Median Aneurysm Growth Rate– 0.33cm/yr
UK Small Aneurysm TrialResults• Ruptured AAA’s– 10 : > 5.5cm– 8 : 5.0 to 5.5 cm– 7 : 4.0 to 4.9 cm• Mean Risk of Rupture for AAA 4.0 to5.5 cm:1.0% per year
UK Small Aneurysm TrialConclusionsFor AAA 4.0 to 5.5 cm• Elective operation NOT associatedwith survival advantage• US surveillance safe alternative• 39% in surveillance group did NOTrequire operation during studyperiod
Treatment of Aortic Aneurysms:How Should the UK Small Aneurysm TrialAffect Decision-Making?CONCLUSIONS• US surveillance is appropriate forpatients with AAA 4.0 to 5.5 cm:• Compliant patients• Aggressive surveillance program• Best option unclear for womenreported to have a higher rupturerate.
Treatment of Aortic Aneurysms:How Should the UK Small Aneurysm TrialAffect Decision-Making?CONCLUSIONS• Elective operative repair for patientswith AAA 4.0 to 5.5 cm may beindicated:– Good risk patients unlikely to becompliant with or unable to be followedin an aggressive US surveillanceprogram.
Abdominal Aortic Aneurysms• Treatment– Conventional Open repairvs. Endovascular repair
Conventional Open Repair• Mortality – 2.6%• 7 day LOS• 90 days to return topre-op QOL• Follow-up at 1 and 12months• Need for re-intervention - < 3%
Technical Points• Retro-peritoneal versus trans-abdominalabdominalapproach.– Difficult neck (suprarenal clamping),Condition of the right common iliac, re-operation, pulmonary status.– If suprarenal exposure needed during a trans-abdominal approach, the medial visceralrotation is the only approach.
Technical points• Prep thigh and Torso from knees to nipples.• Midline incision: Xyphoid to pubis• Evicerate patient, mobilize the ligament ofTreitz. . Continue the retroperitoneal dissection.Watch the L ureter as it cross the left iliacbifurcation. When applying clamps, 1 st the iliacsthen the Aorta. Beware of the iliac veins, avoidclamping right at the bifurcation.• Retro peritoneal approach, the incision is fromthe lat border of the rectus mideway between thepubis and the umbilicus extending to the tip ofthe 12 th rib. Patient in right decubitus position.
Technical Points• Post-op op complication:– Renal failure = increase Cr (in complete failure goesup 1 point per 24 hours)– Mesenteric ischemia ( colon) = persistent acidosis• When to reattach the IMA (patent without back bleeding,evidence of a large Arc of Riolan).– Lower extremity ischemia– Stroke: if severe carotid stenosis present consider acombined case, versus pre-opendarterectomy.– MI– Bleeding: anastomotic site, splenic injury should beconsider in retroperitoneal approaches. If patientrequires more than 2 units of blood, call vascularsurgeon.