Pulsatile Abdominal Mass

1. Pulsatile Abdominal Mass Presley Regional Trauma Center Department of Surgery University of Tennessee Health Science Center Memphis, Tennessee

2. General • Underlying condition may range in severity from benign to life-threatening • Either attributable to a large blood vessel or from another mass that is simply in close proximity to a blood vessel

3. General • AAA = most feared cause of a PAM • Present in 3 to 9% of population • 15K deaths per year • Incidence and penetrance of aneurysms vary according to age and race

4. Presentation

5. Asymptomatic • More common • Often discovered on abdominal or pelvic scans done for other indications • Plains films may reveal a calcified aortic shell

6. Ruptured • Pronounced symptoms • Condition may range from hemodynamic instability to class IV shock • Traditional presentation • hypotension • back or abdominal pain • PAM • occurs less than 50% of the time

7. Ruptured • Overall mortality = 77 to 94% • 50% mortality prior to reaching hospital • Most leak into the left RP = contained rupture • Free rupture usually results in death either at home or en route to the hospital

8. History • Helpful in determining risk for AAA • Factor associated with increased risk • advanced age, greater height, CAD, atherosclerosis, high cholesterol, HTN, smoking duration (7.6x more likely; ex-smokers 3x more likely; RR increases by 4% for each year), male, FH • Lower risk • women, African Americans and diabetics

9. Factors • Occur almost exclusively in elderly males • Rarely seen in patients younger than 50 • mean age 72 • Male:female = 4:1 to 6:1 • 12 to 19% of patients with AAA will have 1st degree relative with AAA

10. Risk Factors for Rupture • Female sex – 2 to 4x more likely • Larger initial diameter • Lower FEV1 • Current smoking • Higher mean bp

11. Examination

12. PE • Key to detecting an AAA prior to the advent of modern radiologic tests • Palpation of an AAA is safe and has not been reported to precipitate rupture • Not very accurate in detecting AAA • depends primarily on the size of the AAA • those >5 cm are detectable in 76% of pts

13. How to Proceed

14. Unstable Patient • For the unstable patient with a painful, pulsatile abdominal mass no further study or workup is necessary • For patients with stable (but not necessarily normal) vitals, CTA can be helpful

15. Stable Patient • For the stable patient with a PAM, furhter work-up is always indicated • Duplex ultrasonography • unreliable in detecting rupture • CTA of the chest, abdomen and pelvis

16. Management

17. Stable Patient • Once the Dx is made, the subsequent course of action is determined by the clinical presentation and the size • It must be emphasized that if the patient becomes hemodynamically unstable at any point, operative intervention is necessary • Must evaluate discomfort and/or pain

18. No Pain • Patient with PAM and known AAA • Hemodynamically stable • Without complaints of pain • Must be categorized based on the size of the aneurysm

19. Pain • With pain in the abdomen, back, testicles or femoral region, index of suspicion must be high for a symptomatic or ruptured AAA (even if hemodynamically stable) • Other causes should be considered • Dx must not be delayed • interval between onset of symptoms and subsequent Dx and operation may have a direct bearing on overall survival

20. Considerations • Whether the risk associated with AAA repair exceeds the risk of rupture in a given period • What other factors are present that may affect this decision

21. Indications for Operative Intervention

22. Basic Physics • Law of Laplace best describes aneurysm expansion and rupture • Tangential stress (t) placed on cylinder filled with fluid is determined by t = Pr/d • P = pressure exerted by the fluid, r = internal radius of the cylinder and d = thickness of the cylinder wall

24. So … • When the aorta expands, its radius increases and wall thickness decreases • geometric increase in tangential stress • as an aneurysm grows from 2 to 4 cm in diameter, t increases fourfold • Elastic tissue in the aorta attenuates with age • When t > elastic capacity = rupture

25. Magic Number 5.5 cm

26. Small AAAs • < 5 cm • For a patient with a small AAA with stable vitals and no abdominal pain – serial US and optimization of medical management • Usually do not rupture • Grow at 0.2 to 0.4 cm per year

27. Epidemiology • Over the past several decades, the number of AAAs (especially smaller ones) detected has increased • Increased serendipitous detection in the course of scans done for other indications • The progressive aging of the population

28. Biology • Evaluating the role various proteolytic enzymes play in processes involving the structural elements in the aortic wall • Investigating the importance of the immune system, specifically the macrophage, in the development of AAAs

29. Biology • Determining how hemodynamic and biomechanical stress affects aortic wall remodeling • Identifying molecular genetic variables that contribute to AAA development

30. Medical Therapy • Perioperative β blockade - cardioprotective • Anti-HTN – no level I data • Lipid-lowering drugs – requires further study • long-term statin use after successful AAA surgery has been associated with reduced mortality • Smoking cessation = mandatory

31. Pre-op Evaluation

32. Elective AAA • Must determine expected benefit of repair in relation to the estimated risk • Detailed H&P • ECG • Routine lab work • Appropriate imaging - approach • Optimize patient medically

33. Comorbid Conditions

34. CAD • Common • Leading cause of both early and late mortality after AAA repair • ACC/AHA guidelines • Clinical predictors of major perioperative CV risk – defined as MI, CHF or death – may be divided into 3 categories • major, intermediate and minor

35. Significance • Major predictor requires that the Sx or disease be managed appropriately before non-emergency surgery • Intermediate predictor is associated with increased risk of periop cardiac complications and requires current status be fully investigated

36. Significance • Minor predictor is indicative of CV disease but has not been shown to independently increase the risk of periop CV complications • Once clinical predictors have been evaluated, additional factors involving the patient’s ability to perform various activities (from ADLs to strenuous sports)

38. METs • Quantification of the energy required to perform an activity = metabolic equivalents • The number of METs of which a patient is capable directly correlates with the ability to perform specific tasks • Patients who are unable to attain 4 METs are considered to be at high risk for periop Cv events and long-term complications

40. Benefit • 2 large RCT to evaluate if pre-op coronary intervention (CABG or PTCA) improved mortality in elective major vascular surgery • No difference with respect to periop (30 days) MI in either group • At 2.7 years there was no difference in mortality between the groups

41. So … • There is no need of pre-op coronary revascularization in patients with stable CAD • In stable patients, without evidence of heart failure, there may be no role for pre-op intervention as long as aggressive medical therapy can be initiated