Abdominal Aortic Aneurysms

1. Abdominal Aortic Aneurysms Elizabeth Pensler, DO Vascular Surgery Kansas City Review April 3-5th 2014

2. Definition of Aneurysm • Focal and persistent dilatation of the diameter of an artery of 150% or more • Transverse diameter of 3 cm or greater

3. Normal aortic diameter gradually decreases from the thorax (28 mm in men) to the infrarenal location (20 mm in men)

4. Types of Aneurysms • True vs. False (pseudoaneurysm) • True: involves all 3 layers of the arterial wall • False: Presence of blood flow outside of normal layers of arterial wall. Wall of false aneurysm is compose of the compressed, surrounding tissues.

7. Types of AneurysmsEtiology • Degenerative • Incorrectly termed atherosclerotic • Not typically assoc. with occlusive disease • Complex degenerative process • Calcification and atherosclerotic pathology present

8. Inflammatory • Triad ab or back pain, pulsatile (+/- tender) abdominal mass, elevate ESR • Dx made - periaortic inflammatory rind on CT

9. Post-dissection- up to 20% of aneurysms are related to previous dissection. Overtime, develops into true aneurysm • Traumatic • Developmental Anomalies- persistent sciatic arteries, aberrant right subclavian artery • Infectious- Can be primary or secondary infections. • Congenital- Tuberous sclerosis, aortic coarctation, Marfan’s.

10. Crawford Aneurysm Type

11. Epidemiology • 15,000 Deaths per year USA • 13th leading cause of death in USA • 1.8-6.6% of patients in Autopsy series! • Strong male predominance 3:1 - 8:1 • Racial distribution Whites > Blacks

12. Increasing Incidence of AAA • Inc. 2.6X from 2.62 deaths per 100,000 in 1981 to 6.82 per 100,000 in 2000 • Hospital admissions rose 3X • Increases in both elective admissions (from 3.05 to 7.80 per 100 000) and emergency admissions (from 7.44 to 11.23 per 100 000) • Br J Surg 2003 Dec;90(12):1510-5BestVA; Price JF; Fowkes FG

13. Genetic predisposition • 15-20% have 1st degree relative with AAA • 11.6x more common in persons 1st degree • Duplex 25% males and 7% females have AAA if 1st degree relative has AAA • 69% risk of AAA in offspring of women with AAA! • Females rise from 14% to 35% in affected families

14. AAA: Associated conditions • Emphysema: Strongest independent risk factor for rupture of a known AAA • Destruction elastin matrix in lung and aortic wall may have a common cause (e.g. alpha 1 antitrypsin deficiency)

15. Range of Potential Rupture Rates for a Given Size of Abdominal Aortic Aneurysm • AAA Diameter (cm) Rupture Risk (%/yr) • <4 0 • 4-5 0.5-5 • 5-6 3-15 • 6-7 10-20 • 7-8 20-40 • >8 30-50

16. Operative Mortality of AAA Repair • 3 – 5% for open repair • 1% for EVAR

17. Assessing the AAA patient • Normal - aorta 1-2.4cm & iliac 0.6-1.2cm • Aneurysm - Aorta >3cm & iliac > 2cm • Average expansion rate approximately 0.33 cm per year. • Risk Factors for aneurysm • Older age, male gender, white race, positive family history, smoking, HTN, hypercholesterolemia, PVD, CAD. • Ultrasound • used to diagnose and monitor AAA until aneurysm approaches size at which repair considered. • Computed Tomography • used in preop assessment of AAA.

18. Ruptured AAA • No significant overall change in mortality with open repair from 1991-2006 • Overall mortality for ruptured AAA = 90% • Mortality rate for patients who arrive at hosptial alive = 40-70% • High postop mortality rate due to MI, renal failure, and multi-organ failure • Ischemia-reperfusion injury, hemorrhagic shock, lower torso ischemia • rEVAR significantly reduces mortality of ruptured AAA patients (31 vs 50%)

19. Screening for AAA • US Preventive Services Task Force • Men 65-75 yo who have ever smoked • Not for or against men 65-75yo who never smoked • Does not recommend screening for women • Society of Vascular Surgery, Medicare Screening • Men smoked at least 100 cigarettes during their life • men and women with a family history of AAA • Only screen patients candidates for repair.

20. Choosing between Surgery & Observation • Risk for AAA rupture without surgery • Operative risk of repair • Patient’s life expectancy • Personal preferance of patient

21. 1. Risk of Rupture • Size matters: • Aneurysm > 5cm 6-16% • > 7cm 33% annual rupture rate • Wall stress analysis • Saccular aneurysm have higher rate of rupture • HTN, COPD, active smoking independent predictors of rupture • (+) family hx tend to rupture • Expansion rate

22. 2. Operative Risk of Repair • Mortality after: • elective open AAA ~ 5% • EVAR 1% • 6 independent RF’s for mortality Open repair • Creatinine > 1.8, CHF, EKG detected ischemia, Pulmonary dysfunction, older age, female gender. • Cardiac, pulmonary, renal, and GI risks with each proceudre.

23. 3. Patient’s Life Expectancy • Very difficult to assess due to patient’s co-morbidities • Typical 60yo surviving AAA repair has 13year life-expectacy • 70yo has 10year life-expectancy • 80 yo has 6 year life-expectancy.

24. 4. Personal Preference of Patient • Fear of AAA vs. Fear of surgery • Anecdotal experiences of friends and family • Procedures provided in community by interventional specialists and surgeons.

25. Medical Management of AAA • Smoking Cessation- Single important modifiable RF • Exercise Therapy- Benefit small aneurysms • Beta Blockers- May decrease the rate of expansion? • ACE inhibitors- Evidence is mixed, however, implicated in less aneurysm rupture. • Doxycycline • Antibiotic activiety against chlamydia species • Suppresses expression of MMP • Statins - associated with reduced aneurysm expansion rates. Decreases MMP-9 in aneurysm wall.

26. EVAR vs. OPEN • EVAR-1 and DREAM Trials • Randomized AAA > 5.5 cm to EVAR vs. open repair • Lower 30-day mortality for EVAR (1.6% EVAR vs. 4.6% open) • Peripop mortality and severe complications 4.7% EVAR & 9.8% open repair (DREAM) • Similar all-cause mortality at 2 years • Higher rate secondary interventions in EVAR • Total cost of Tx & 4 yrs of f/u inc. for EVAR.

27. Open Repair • Transabdominal Approach • Previous retroperitoneal surgery • Ruptured AAA • Exposure of mid/distal portions of visceral vessels or R renal artery • R internal or external iliac artery • Co-existant abdominal pathology • Left-sided vena cava • Retroperitoneal Approach • Mult. Previous intraperitoneal procedures • Abd wall stoma, ectopic/ anomaly of kidney • Inflammatory aneurysm • Proximal aortic access, endarterectomy of viceral/renal arteries needed • Obese patients • Fewer GI complications

29. Open Repair-Complications • Cardiac • Pulmonary • Renal • Lower Extremity Ischemia • Spinal Cord Ischemia • Incisional Hernia • 14.2% ventral hernia, 9.7% SBO • Graft Infection

30. Open Repair Complications:Colon Ischemia • Collaterals from SMA, IMA, internal iliac artery, and profundafemoris supply sigmoid colon • Mortality 40-65%, full-thickness necrosis 80-100% • Occurs in 0.6-3% of elective and • 7-27% of ruptured AAA (much more common endoscopically than clinically)

33. Colon Ischemia • Signs and Symptoms • Bloody bowel movements • Persistent acidosis & shock • Treatment • Ischemia limited to mucosa submucosa- npo, IVF, IV abx • Transmural ischemia- bowel resection, fecal diversion, creation of ostomy, washout of abdomen, IV abx.

34. Open Repair- Concomitant Pathology • Treat most life-threatening process FIRST • Avoid simult. OR  prosthetic graft infection • If secondary procedure can be staged without increased risk - do aneurysm repair first • Clean procedures (ie:nephrectomy, oophrectomy) can be performed simultaneously • GI procedures should not occur at same time • Abort surgery if metastatic disease or abscesses which increase risk for graft infection discovered.

35. Inflammatory AAA • Perianeurysmal fibrosis & inflammation • 5% of AAA • Treatment of AAA resolves the periaortic inflammation in 53% (open & EVAR) • Duodenum, left renal vein, and ureters often involved in inflammation. • PreOp ureteral stent placement recommended

37. Infected AAA • 0.65% of AAA • Can be primary or secondary infection • Potential causes of infection: • Continguous spread of local infxn, septic embolization from distal site, bacteremia. • In the past syphilis and steptococcal species was common: • Now: staph and salmonella. • With HIV and wide-spread abx use- can be caused by any bacterial or fungal infection • Dx: fever, abdominal/back pain, high ESR, bacteremia.

38. EVAR

39. Types of Endoleak

40. Types of Endoleak • Type I • Usually identified and treated @ time of stent graft implantation • Must be treated if found on post-op imaging • Associated with high likelihood of AAA rupture • Type II • 10-20% of post-op CT scan show Type II leak • 80% resolve spontaneously at 6 months • Indication to treat: persistent leak, aneurysm growth • Transcatheter tx (coil embolization) • Type III • 0-1.5% incidence • Strong predictor of rupture • Tx: re-establish continuity by additional component to bridge gap or cover hole. • Type IV • Majority resolve within one month of stent graft implantation

41. EVAR complications • Stent-graft infection • Net infection rate of 0.43% • Pelvic ischemia • Internal iliac occlusion during EVAR • Si/sx: buttock claudication (most common 16-50%), buttock necrosis, colon necrosis, spinal ischemia, lumbosacral plexus ischemia, ED (15-17%). • Ischemic colitis < 2%

42. Discussion • “No significant difference between endovascular repair and open repair in rate of overall survival at a median of 6.4 years.” • Significantly higher rate of reinterventions in EVAR group than open group • Study limited by difference in f/u between the open and endovascular group.