Aortic Emergencies

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Aortic Emergencies

• David Peterson
• February 3, 2005

2
Objectives

• Define aortic dissection AAA and demonstrate
  their clinical relevance
• Review pathophysiology and classification
• Discuss diagnostic modalities
• Discuss management options
• Series of questions and cases

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PERSPECTIVE

• 1955 DeBakey outlined principles that remain
  basis for surgical treatment of aortic dissection
• Medical treatment of aortic dissection was first
  advocated in the 1960s and is indicated for
  certain types of dissections

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Aortic Dissection

• longitudinal cleavage of the aortic media
  created by a dissecting column of blood
• Rosens Emergency Medicine

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(A) Normal blood flow in the aorta. (B)
Dissection occurs when the inner lining of the
aorta tears and the blood flow dissects between
the layers of the aortic wall
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Aortic Dissection
John Ritter Age 54 DEAD
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Epidemiology

• Underreported
• Hypertension is the most common risk factor
  associated with aortic dissection and is seen in
  most patients
• Incidence 5-10/ 1,000,000 and rising
• Mortality 1-2/hour (33 in 1st 24 hrs)
• High rate of misdiagnosis 28
• One study suggests EPs suspect AD in lt50 of
  cases
• Sullivan et al. Am J Emerg Med 18 46-50. 2000
• Variable presentation including MI
• Lack of suspicion for AD is 1 cause of
  misdiagnosis

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Epidemiology

• History of cardiac surgery present 18 and
  bicuspid aortic valve in 14 of all patients with
  aortic dissection
• more often in proximal dissections
• Atherosclerosis rarely involved at site of
  dissection
• Aortic dissection uncommon before age 40 except
• Congenital heart disease, Ehlers-Danlos or Marfan
  syndrome, giant cell arteritis and possibly
  pregnancy
• 44 of patients with Marfan syndrome develop
  aortic dissection and account for 6 of such
  cases

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Ehlers-Danlos
10
Marfan Syndrome
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Anatomy and Physiology

• Each contraction the heart swings side to side
  resulting in flexion of both ascending aorta and
  descending aorta
• Descending aorta flexes just distal to left
  subclavian artery where mobile aorta is tethered
• At 70 heartbeats per minute sequence occurs 37
  million times a year causing repetitive stress on
  the aorta

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Anatomy and Physiology

• The aortic wall has three distinct layers the
  intima, the media, and the adventitia
• The media is comprised of elastic tissue and
  smooth muscle
• MEDIA Middle
• INTIMA Inside

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Pathophysiology

• Requires 3 basic features
• Abnormal media
• Blood entry into media by intimal tear
• Pressure forces favoring propagation

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Pathophysiology
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Pathophysiology

• Arterial Obstruction is caused by 2 mechanisms
• By compressing from the expanding hematoma
• From occlusion of lumen by intimal flap
• This results in peripheral complications
• Cerebral ? CVA, syncope
• Spinal ? Neuro deficits
• Cardiac ? MI, tamponade, AR
• Respiratory ? Hemoptysis, pleural effusion
• GI ? Hematemesis, dysphagia, mesenteric ischemia
• Renal ? ARF, HTN
• Limbs ? Extremity ischemia

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CT AD Intimal Flap
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Pathophysiology

• Intimal tears occur in 96 of all AD cases
• Felt to occur 2o to shearing forces and
  hemodynamic stresses
• Propagation factors
• Degree of HTN
• Slope of pulse wave (dP/dT)
• Spontaneous cure rupture back into true lumen
  (rare)

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Aortic dissection bursts into the pericardium

• Pericardial Tamponade

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• Hemopericardium and tamponade can occur with
  dissection into pericardial sac

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The tear progresses down to and occludes the
coronary artery precipitating an MI

• Almost always an inferoposterior MI RCA

21

• Coronary artery involvement in 1 ? presents as
  MI
• 0.1-0.2 of MIs are complicated by incorrect
  admin of lytics in
• setting of AD

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The tear can disrupt the aortic valve, producing
acute valvular insufficiency, a common cause of
acute CHF and increased risk of death
AR
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Clinical Presentation

• Sudden, severe chest pain (76-90)
• Migratory CP is highly specific (71)
• Back pain (53), abd pain
• Other Sx depending on site of involvement
• Syncope (9)
• Neuro Sx (6-13)
• Mesenteric ischemia
• Renal failure
• Can be painless in up to 15 (chronic)

Moore et al. Am J Card. 891235-1238 2002 Hals.
Emerg Med Reports 2000
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Risk Factors for AD

• Hypertension (60-90)
• Age 50-70 yo
• Male (31)
• CTDs (Marfans 5, Ehlers-Danlos)
• Turners, Coarctation, Ebsteins Anomaly
• Congenital bi-/tricuspid AV
• Family Hx or previous dissection
• Cocaine, metamphetamine
• Iatrogenic
• Trauma

Hals. Emerg Med Reports 2000
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Classification

• DeBakey
• Type I involve ascending aorta, arch, and
  descending aorta
• Type II ascending aorta proximal to L subclavian
  artery
• Type IIIa descending aorta only above diaphragm
  only
• Type IIIb descending aorta only extension below
  diaphragm

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DeBakey
27
Stanford

• Type A involvement of ascending aorta
• Type B no involvement of ascending aorta
• 62.5 of pts w/ AD have a Type A
• Involvement of ascending aorta is of prognostic
  and therapeutic importance

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Diagnosing AD

• Clinical suspicion above all
• 3 clinical variables shown to be useful
• Aortic pain (immediate onset, tearing, ripping)
• Mediastinal widening / aortic widening on CXR
• Pulse or BP differentials
• Likelihood of AD
• Ø of above variables ? 7 risk of AD
• Pain or widening alone ? 31 39 risk of AD
  respectively
• gt 2 variables or isolated BP / pulse diff ? gt 83
  risk of AD
• Von Kodolitsch et al. Arch Intern Med. 160
  2977-82. 2000
• Diagnostic modalities
• ECG, CXR, CT, TEE, Angiogram, MRI

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ECG findings in AD

• 85 will be abnormal
• LVH
• Non-specific ST-T wave changes
• MI (RCA most common)
• Bottom line
• not sensitive or specific
• beware thrombolysis until AD excluded

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CXR findings in AD

• 80-90 will be abnormal
• Most findings non-specific
• Mediastinal widening (59-75)
• Calcium sign (pathognomonic)
• Double density aorta
• Obliteration of aortic knuckle
• Loss of PA window
• Tracheal deviation to right
• Depressed left main stem bronchus
• New left pleural effusion
• Apical cap
• Size disparity of ascending descending aorta

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CXR
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TEE

• Rosen 98 sensitive, 77 specific
• Moore et al 88 sensitive
• 1st test in Europe and Japan
• Advantages
• Can differentiate Type A B dissections
• Rapid, can be done at bedside
• No contrast or radiation
• Can detect AR and pericardial effusion
• Disadvantages
• Availability, operator dependence
• Limited info on distal aorta

Moore et al. Am J Card. 891235-1238. 2002
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TEE Aortic Dissection
Intra-operative TEE echo demonstrating high
velocity jet striking aortic wall at point of
intimal injury
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CT scanning

• Dynamic helical CT nearly 100 sensitive and
  specific (dye) (Moore et al 93 sens)
• Advantages
• Availability, can differentiate Type A B
• Able to identify sealed-off false lumens
• Able to identify other pathology (eg PE)
• Disadvantages
• Dye reactions (1/10,000 fatal)
• No info on AV function or intimal tear location
• No info about extension into other arteries

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CT Aortic Dissection
CT of abdominal aorta show intimal flap (dark
line)with true lumen anteriorly and false lumen
posteriorly
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CT Aortic Dissection
Stanford Type A Aortic Dissection
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CT Aortic Dissection
Stanford Type A Aortic Dissection
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Angiography

• 81-87 sensitive, 96 specific
• Previous gold standard
• Advantages
• Anatomical delineation of aortic tree
• Ability to demonstrate AR
• Can differentiate Type A B dissections
• Disadvantages
• False ves due to false lumen thrombosis
• Invasive, time consuming, expensive

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Angiography
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MRI

• Near 100 sensitivity and specificity
• No role in critical pts but good for serial
  follow-up
• Advantages
• Excellent anatomical delineation, info on AR,
  intimal tear location, type and extent of AD
• Disadvantages
• Time-consuming
• Unable to monitor pt

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MRI
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Intravascular U/S

• New technique intravascular U/S probe
• Currently evolving uses include
• Identification of unstable plaques in CAD
• Diagnostic and therapeutic use in AD
• 3-D imaging of aorta surrounding structures
• Guidance of intra-vascular stent placement less
  invasive procedure than classic surgery
• Fenestration of intimal flap
• Not available at most centers at this time

Chavan et al. Circulation 96 2124-2127. 1997
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IVUS Aortic Dissection
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So what test do I order 1st?

• Moore et al CT is initial test of choice
  followed by TEE to clarify Dx or better delineate
  surrounding anatomy AR
• Moore et al. Am J Card. 891235-1238. 2002
• In Calgary, TEE is considered highly accurate and
  available, and should be considered a 1st line
  test
• Peter Giannacarro

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Can we predict outcomes?

• Pulse deficit is independent predictor of 5-day
  mortality RR 2.73, 95 CI 1.7-4.4
• Stat sig trend of increasing mortality with
  increasing number of pulse deficits
• Bosssone et al. Am J Card 89 851-855. 2002
• Mortality predictors
• Age gt 70 (OR 1.7, 95 CI 1.05-2.77)
• Abrupt onset CP (OR 2.6, 95 CI 1.22-5.54)
• Hypotension/shock/tamponade (OR 2.97, 95 CI
  1.25-3.29)
• ARF (OR 1.77 95 CI 1.80-12.6)
• Pulse deficit (OR 2.03 95 CI 1.25-3.29)
• Abnormal ECG (OR 1.77 95 CI 1.06-2.95)
• Rajendra et al. Circulation. 105 200-206. 2002

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Management

• ABCs and then 2 basic principles
• Control the slope of pulse wave (dP/dT)
• 1st control your HR, then lower the pressure
• Surgery if indicated
• All Type A dissections need urgent OR
• Controversies New Ideas
• Surgery for Type B dissections
• Intravascular repair

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Medical Tx

• Control HR
• IV BBs aim for HR 60-80 bpm
• Esmolol 500 mcg/kg bolus, then titrate infusion
  50-200 mcg/kg/min
• Metoprolol 5 mg IVP q5min
• Propranolol 1mg IVP q5min

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Medical Tx

• Control BP
• aim for BP 100-120 mmHg sys or min BP reqd to
  maintain end-organ perfusion
• Nitroprusside 0.5 mcg/kg/min titrate up prn
• Monotherapy
• Labetalol 20 mg IVP, then 20-80 mg q5-10 min
  until in target HR, then 1-2 mg/hr

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Surgical Tx

• Indicated for
• All Type A dissections
• Type B w/ complications
• Aortic rupture
• Severe distal ischemia
• Refractory HTN
• Progressive dissection despite Tx
• Intractable pain
• Mortality for Type A repair is 7-12
• Co-morbidities increase mortality
• 5 yr survival is 77 Type A 88 Type B

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Why not operate on all?

• Medical Tx of Type B has 20 mortality
• Surgical Tx of Type B has 10-15 mortality, and
  3.5-36 risk of paraplegia
• This may be changing with advent of endovascular
  repair, fenestration procedures, and IVUS

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AAA
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AAA some facts

• Incidence rising 2 gt65 yo
• 9 men for every 1 female
• Most have no antecedent Sx
• 50-80 mortality rate
• Misdiagnosed in 30-60 of cases

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Definitions

• Aneurysm irreversible localized dilatation of
  an artery to gt 1.5 original diameter (3cm in abd
  aorta)
• Types of aneurysms
• True involves intima, media, and adventitia
• Pseudoaneurysm only intact bulging layer is
  adventita
• Inflammatory aneurysm surrounding fibrosis and
  adhesions

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Pseudoaneurysm

• Damged intima media
• Adventitia prevents rupture

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Anatomy

1. Aorta
2. Inf phrenic
3. R hepatic
4. Common hepatic
5. Gastroduodenal
6. Inf pancreatico-duodenal
7. L common iliac
8. L renal
9. Splenic
10. L gastric

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Risk Factors for AAA

• Age 50-70
• Male (91)
• White
• Atherosclerosis
• HTN
• Smoking
• Family Hx
• Loss of elastin / CTDs (Marfans)

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Clinical presentation

• Unruptured vs. Ruptured
• Unruptured
• Vague abd pain / back pain / pulsations /
  fullness
• SMA syndrome (wt loss, vomiting)
• Renal colic, radicular Sx, embolic phenomena
• Ruptured
• Classic abd pain, pulsatile mass, hypotension
• Atypical
• Back or flank pain hematuria
• LLQ pain GI bleeding
• Sx of high-output failure

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Physical Findings

• Pulsatile abd mass
• Palpate each sid of aorta if gt2.5 cm w/u
• PPV 43
• Other findings neither sensitive or specific

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How do to Diagnose AAA

• Clinical suspicion
• Diagnostic imaging
• Abd U/S
• CT abd
• Angiography
• MRI
• What test, when, and for whom?

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Plain Films

• Initial screening
• Findings in 60-75
• Calcified wall
• Paravertebral soft tissue mass
• Loss of psoas shadow
• Loss of renal silhouette
• Erosion of vertebral bodies
• Negative study does NOT exclude Dx

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Ultrasound

• Test of choice, esp in unstable pts
• Advantages
• 100 sensitive specific for AAA
• Rapid (5 min vs. 80 min for CT)
• can be done at bedside
• non-invasive
• Disadvantages
• Poor at identifying rupture
• Technically difficult in obesity / bowel gas

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AAA Ultrasound
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Computed Tomography

• 100 sensitive specific for AAA
• Advantages
• Able to detect ruptures
• Obesity bowel gas dont limit study
• Surrounding anatomy
• Disadvantages
• Unstable pts
• Time
• IV contrast (can do without)
• Not 100 sensitive for rupture

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CT Ruptured AAA

• The CT scan done with of oral and intravenously
  contrast demonstrates opacification of the aorta
  as well as inferior vena cava
• The arrow head points to the presence of the
  retroperitoneal hematoma, extending into the
  adjacent paraspinal retroperitoneal tissues

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CT Ruptured AAA
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Angiography

• NOT a ED screening tool
• Tends to underestimate AAA size
• May aid in planning of surgery (e.g. renal a.
  stenosis)
• Helical CT can produce 3-D images may replace
  angiography

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Angiography
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MRI

• Not useful in acute setting
• Excellent anatomical delineation
• Used primarily prior to elective repair

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MRI
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ED Management

• Depends on context
• Incidental Dx of AAA
• Ruptured AAA in stable pt
• Unstable pt with ruptured AAA
• Basic principles
• ABCs
• Surgical referral for all
• Elective surgery has 5 mortality
• Emergent surgery in non-ruptured AAA 25
  mortality
• Emergent surgery for RAAA 50 mortality
• Controversies
• Role of volume resuscitation

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Fluid Resuscitation

• Evidence in penetrating trauma for forgoing
  aggressive volume resusitation
• Bickell et al. N Eng J Med 1994 (331) 1105-1109
• Fluids can cause dilutional coagulopathy
• Ø studies compare ED resus strategies in AAA
• Recent Cochrane Review no evidence to support
  any specific fluid resus strategy in setting of
  traumatic hypovolemic shock
• Kwan et al. Coch Data Sys Rev. 2002
• Recommendations are to aim for min BP necessary
  to maintain end-organ perfusion use blood
  products early

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Natural Hx

• Formation ? enlargement ? rupture ? DEATH
• How can we intervene?
• Primary prevention
• Early management observation
• Elective surgery
• Emergency surgery

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Risk of Rupture

• Risk factors
• Size of AAA
• COPD
• HTN
• smoking
• What is the risk of rupture?
• lt4 cm 1-1.2
• 4-5 cm 1-3
• One study suggests surgeons estimate risk of
  rupture gt2x published risk
• Lederle. Arch Intern Med 156 1007-009. 1996

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Current Surgical Indications

• All symptomatic aneurysms
• All saccular aneurysms
• Poor risk pt w/ AAA gt6 cm
• Good risk pt w/ AAA gt5 cm
• Young, good risk pt w/ AAA 4-5 cm
• Sternbergh et al. Surg Clin NA 78 827-834. 1998

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Elective repair of small AAAs

• 5 yr survival 76 vs 30 for emergent
• 2 recent RCTs suggest no survival benefit from
  immediate surgery for AAAs 4-5.4 cm
• RR 1.21 95 CI 0.95-1.54
• Lederle et al. N Eng J Med 346 1437-44. 2002
• RR 0.94 95 CI 0.75-1.17
• UK Small Aneurysm Trial Participants. Lancet 352
  1649-55. 1998

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AAA Repair
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AAA Repair
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AAA Repair
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AAA Repair
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Traditional vs Endovascular

• Endovascular repair advantages
• Less invasive
• Decd blood loss, procedure times, ICU stays,
  hospitalization time, and recovery time
• Decd morbidity but not mortality
• Disadvantages
• Expense, limited long-term experience but may be
  less durable than conventional repair
• Utility
• Clear morbidity advantage in elderly, high risk
  pts demonstrated in recent observational study
• Sicard et al. Ann Surg 234 427-37. 2001
• No good evidence to support use in small AAAs or
  younger pts
• Brewster. Surgery 131 363-7. 2002

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Late complications

• Graft infection
• Early or late (up to years after)
• 30-50 mortality
• Staphylococcus epidermidis
• Present w/ sepsis /- AEF
• Tx is abx, graft excision, bypass
• Aorto-enteric fistula (AEF)
• Can form anywhere (usually duodenum)
• Acute or chronic GIB
• Tx is graft replacement

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The End

• Questions?

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Question 1

• 1. Preexisting conditions associated with an
  increased risk of aortic dissection include which
  of the following?
• A. Coarctation of the aorta
• B. Congenital heart disease
• C. Marfan syndrome
• D. Pregnancy
• E. All of the above

E
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Question 1 Short Answer

• Dissection is the most common and the most lethal
  catastrophe involving the aorta. Aortic
  dissection occurs two to three times more
  frequently in males than in females, and there
  may be a higher incidence in blacks. Although
  aortic dissection has been reported in patients
  as young as 14 months and as old as 100 years,
  the majority of cases occur in patients between
  50 and 70 years of age. Aortic dissection is
  relatively rare before age 40, except in
  association with specific predisposing syndromes,
  such as Marfan syndrome, Ehlers-Danlos syndrome,
  congenital heart disease, familial incidence,
  pregnancy, coarctation of the aorta, Turner's
  syndrome, and trauma. The type of trauma that is
  usually associated with aortic dissection is
  iatrogenic, such as cardiac surgery and cardiac
  catheterization. The incidence of aortic
  dissection is nine times higher in patients with
  a bicuspid valve, compared with a tricuspid
  aortic valve. Aortic dissection occurs more often
  in patients with a history of coarctation.

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Question 2

• 2. Aortic dissection occurs in which layer of the
  aortic wall?
• A. Adventitia
• B. External elastic lamina
• C. Intima
• D. Media
• E. Any layer

D
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Question 3

• 3. Regarding the Stanford classification of
  aortic dissections, which of the following
  statements is true?
• A. The majority of patients have Type B
  dissections.
• B. Patients with Type B dissections tend to be
  older, heavy smokers with chronic lung disease,
  generalized atherosclerosis, and/or hypertension.
  
• C. Type A dissections are less common and are not
  associated with high levels of mortality.
• D. Type A dissections involve the distal aorta.
  
• E. The Stanford classification is based on the
  involvement of the descending aorta.

D
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Question 4

• 4. Regarding clinical features of aortic
  dissections, which of the following statements is
  not true?
• A. Aortic regurgitation occurs in about 50 of
  patients with Type A dissection
• B. In about 20 of patients, neurologic deficit
  is the presenting manifestation.
• C. Pain is the most common presenting complaint.
  
• D. Pulse deficit, a unilaterally weakened or
  absent pulse, occurs in almost 50 of patients
  with proximal dissections.
• E. The most common neurologic abnormality is
  ischemic paraparesis.
• F. Syncope, while rare, can be the sole
  presenting symptom.

E
90
Question 5

• 5. A 66-year-old white male with a history of
  hypertension and a known patent foramen ovale has
  a sudden onset of ripping chest pain that
  radiates to his back, a blood pressure of
  210/120, and a heart rate of 110. Regarding his
  initial treatment, which of the following would
  not be a wise choice?
• A. Labetalol
• B. Nitroprusside alone
• C. Esmolol drip followed by nitroprusside
• D. Intravenous normal saline

B
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Question 6

• 6. Which of the following patients with an acute
  dissection requires immediate surgery?
• A. A 40-year-old pregnant female with a Type A
  dissection
• B. A 68-year-old black male with a progressive
  stroke
• C. A 77-year-old hypertensive white male with a
  Type B dissection
• D. A 56-year-old Hispanic male with elevated
  cardiac enzymes and a Type IIIA dissection
• E. None of the above

A
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Question 7

• 7. Which of the following statements regarding
  laboratory and radiographic evaluation in the
  work-up of aortic dissection is true?
• A. Cardiac enzymes are usually elevated.
• B. Chest x-rays will be abnormal in 80 to 90 of
  cases.
• C. CT scanning requires arterial catheterization
  for delivery of contrast dye.
• D. Aortography is no longer the gold standard.
• E. Transthoracic echocardiography has a
  sensitivity approaching 96

B