Post on 28-Dec-2015
transcript
Pulsatile Abdominal Mass
Presley Regional Trauma CenterDepartment of Surgery
University of Tennessee Health Science CenterMemphis, 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 1st degree relative with AAA
Risk Factors for Rupture
• Female sex – 2 to 4x more likely
• Larger initial diameter
• Lower FEV1
• 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