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

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 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 General

Presentation

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

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 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 Ruptured

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 History

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 1 st degree relative with AAA

Risk Factors for Rupture Female sex – 2 to 4x more likely Larger initial diameter Lower FEV 1 Current smoking Higher mean bp

Examination

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

How to Proceed

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

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

Management

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

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

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

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

Indications for Operative Intervention

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

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

Magic Number 5.5 cm

< 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 Small AAAs

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 Epidemiology

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 Biology

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

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 Medical Therapy

Pre-op Evaluation

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 Elective AAA

Comorbid Conditions

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

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

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)

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

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

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