blunt aortic trauma - lieberman's eradiology learning...

Medell K. Briggs, HMS IV

Gillian Lieberman, MD

Blunt Aortic Trauma: Blunt Aortic Trauma: A Radiologic DiagnosisA Radiologic Diagnosis

Medell K. Briggs, HMS IVGillian Lieberman, MD

Harvard Medical School

July 2004

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You are a 1You are a 1stst year Radiology year Radiology resident…resident…

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Patient KS: HistoryPatient KS: History

• 23 yo male involved in high speed MVA• KS’s motorcycle collided with truck and

KS was thrown from vehicle• EMS found KS alert, but

hemodynamically unstable at scene

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Patient KS: Physical ExamPatient KS: Physical Exam

• Vitals: Temp 97.8 Pulse 110s BP 190/60• HEENT-PERRL, TMs clear• CV-RRR, Norm S1 and S2• Lungs- CTAB with equal breath sounds• Abd- Soft, ND, NT with no palpable pulsatile

masses• Ext- Numerous upper and lower extremity

injuries with lack of palpable left dorsalis pedis pulse

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Patient KS: Portable CXRPatient KS: Portable CXR

PACS, BIDMC

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You immediately …You immediately …

• Call the CT techs to ensure a chest CT with contrast is being obtained

• Page the ER resident to alert her of your findings

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•• What is your primary concern?What is your primary concern?

•• Why is a Chest CT with contrast so Why is a Chest CT with contrast so imperative?imperative?

•• Are any additional studies necessary?Are any additional studies necessary?

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Thoracic Aorta AnatomyThoracic Aorta Anatomy• Ascending aorta

relatively unfixed and mobile

• Descending aorta fixed and immobile due to intercostal arteries and ligamentum arteriosum

Image: Gray’s Anatomy

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Blunt Aortic InjuryBlunt Aortic Injury

• Aorta is most common vessel injured by blunt trauma of chest

• Due to rapid deceleration events – High speed MVA– Fall from significant heights

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Blunt Aortic InjuryBlunt Aortic Injury

• Blunt chest trauma is the most common cause of acute tear through the aortic wall

• An acute, traumatic tear extending through the intima, media, and adventitia is termed: – aortic transection, aortic

rupture, aortic disruption– Tears can involve one or

more layers

Adventitia

Media

Intima

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Blunt Aortic InjuryBlunt Aortic Injury• Incomplete aortic

transections tend to form pseudoaneurysms– Evolve from spared adventitia– Increased hemodynamic

stability due to maintenance of blood flow

– Still emergency due to possible rupture --> death

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Aortic Aortic TransectionTransection: : EpidemiologyEpidemiology

• Results in immediate death in 80-90% of cases (Marx: Rosen’s Emergency Medicine, 2002)

– Due to complete transection and rapid exsanguination at accident site

• Scene survivors also have high rate of mortality– Hemodynamically unstable: mortality rate <90%– Hemodynamically stable: mortality rate as low as

25% (Gotway, Thoracic Aorta Imaging with Multislice CT, 2003)

• Due to pseudoaneurysm formation, rapid diagnosis, and surgical intervention

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Aortic Aortic TransectionTransection: Sites of : Sites of InjuryInjury

• Aortic isthmus: 80-90%

• Ascending aorta: 5-10%

• Descending Aorta near diaphragmatic hiatus: 1- 3% (Marx: Rosen’s Emergency Medicine, 2002)

Image: www.jvasbr.com

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Aortic Aortic TransectionTransection:: Mechanism of InjuryMechanism of Injury

• Aortic Isthmus Injury- sudden deceleration causes mobile aortic arch to swing forward resulting in:

1. Whiplash Effect: shearing force at isthmus

2. Bending stress at isthmus: due to flexion of arch on left mainstem bronchus and pulmonary artery

3. Osseous Pinch: inferior & posterior rotation of anterior chest wall structures (manubrium, 1st rib) cause pinching and shearing of isthmus as it strikes the vertebral column

• Ascending Aorta Injury1. Waterhammer Effect: aortic

compression results in explosive rupture of ascending aorta due to increased intraaortic pressure

2. Shearing stress: heart displacement into left posterior chest causing tear above aortic valve

Image: www.jvasbr.com

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Aortic Aortic TransectionTransection: : Clinical FeaturesClinical Features

• Symptoms (Uncommon and nonspecific)– Interscapular or retrosternal pain

• 25% of patients (Marx: Rosen’s Emergency Medicine, 2002)

– Dyspnea, hoarseness, dysphagia

• Physical Exam (rarely signs of chest trauma)– Generalized hypertension

• Secondary to aortic isthmus sympathetic afferent nerves causing reflex htn due to stretch stimulus

– Pseudocoarctation• Compression of aortic lumen by periaortic hematoma

– Often no clinical signs of chest trauma

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Aortic Aortic TransectionTransection: : Diagnostic Imaging ModalitiesDiagnostic Imaging Modalities

• CXR• CT• Angiography • Transesophageal echocardiogram

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Patient KS: CXRPatient KS: CXR• Sensitive Indicators:

– Widened mediastinum– Indistinct aortic knob

• Less Sensitive Indicators:– Displaced trachea– Widened R paratracheal

stripe– Widened paraspinal line

• Not So Sensitive Indicators:– Depression of left main

bronchus– Left hemothorax/effusion– Left apical pleural cap

PACS, BIDMC

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Diagnostic Imaging: CXRDiagnostic Imaging: CXR

• Widened Mediastinum– Defined as >8cm on supine

AP CXR– Sensitivity 81-100%– Specificity 60%

• Numerous differentials: achalasia, hematoma/hemorrhage, lymphadenopathy, neoplasm(Reed, Gamuts of Radiology, 2003)

– Normal CXR has NPV of 98%

(Rivas, L, Multislice CT in Thoracic Trauma, 2003)

PACS, BIDMC

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Diagnostic Imaging: CTDiagnostic Imaging: CT• Conventional CT failed at

diagnosing aortic injury• Helical and new multislice

CT have proven great success in diagnosis

• Able to assess polytraumatized patient

• Uses nonionic contrast• Reformations similar to

angiographic projections• Sensitivity 100%• Specificity 96%(Rivas, L, Multislice CT in Thoracic Trauma, 2003)

PACS, BIDMC

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Patient KS: CTPatient KS: CT

• Direct Signs– Pseudoaneurysm– Intimal flap– Abnormal aortic

contour– Active contrast

extravasation– Abrupt changes in

aortic caliber

• Indirect Signs– Mediastinal

hematoma– Periaortic

hematoma

PACS, BIDMC

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Patient KS: CTPatient KS: CT• Direct Signs

– Pseudoaneurysm– Intimal flap– Abnormal aortic


extravasation– Abrupt changes

in aortic caliber



hematoma

PACS, BIDMC

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Patient KS: CTPatient KS: CT• Direct Signs

– Pseudoaneurysm– Intimal flap– Abnormal aortic


extravasation– Abrupt changes in

aortic caliber



hematoma

PACS, BIDMC

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Patient KS: CTPatient KS: CT

• Reformations– Give full

visualization of ascending and descending aorta

– Can be reformatted in oblique, sagittal, or coronal views for better localization and visualization

PACS, BIDMC

Pseudo- aneurysm

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Diagnostic Imaging: CTDiagnostic Imaging: CT

PROs CONs-High sensitivity & specificity

-Pulsation artifacts

-Non-invasive -IV contrast-Provides info on other injuries-Rapid and easily accessible

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Diagnostic Imaging: Diagnostic Imaging: AngiographyAngiography

• Traditional imaging modality for aortic transections

• Enables intricate visualization of aorta and provides precise localization of aortic defects

• Sensitivity 100%• Specificity 97%

(Marx: Rosen’s Emergency Medicine, 2002)

• 1-10% procedure complication rate (Mechem, ICU Management of Trauma Patients, 2004)

• Thoracic aortograms quickly being phased out by multislice CT– No longer performed at

BIDMC! Image: Samett, EJ, 2003.

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Diagnostic Imaging: Diagnostic Imaging: AngiographyAngiography

Pros Cons-High sensitivity & specificity

-Highly invasive

-Precise localization of defect

-Time consuming

-IV contrast-Must be aware of “fake outs” (i.e. ductus diverticulum)

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Diagnostic Imaging: TEEDiagnostic Imaging: TEE

• Transesophageal echocardiogram (TEE) provides accurate identification of:– Intimal flap– Periaortic hematoma

• Sensitivity 91-100%• Specificity 98-100%

(Vignon, P, TEE in Traumatic Rupture of Aortic Isthmus, 2004.)

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Diagnostic Imaging: TEEDiagnostic Imaging: TEE

Transverse View at Aortic Isthmus•Large arrow- thick “medial flap”

•Arrow heads- localized deformity of aortic wall due to pseudoaneurysm

Color Doppler at Aortic Isthmus•Large arrow- thick “medial flap”

•Similar blood flow velocities on both sides of flap

•Color mosaic is turbulent flow at site of disruption

Images: Vignon, P, 2004.

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Diagnostic Imaging: TEEDiagnostic Imaging: TEEPros Cons

-Extremely fast -Ascending and descending aorta blind spots

-Can be performed at bedside

-Operator and reader DE-pendent

-No IV contrast-Simultaneous eval of cardiac fxn

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Patient KS: SummaryPatient KS: Summary•• What was your primary concern?What was your primary concern?

– Aortic Transection!• Critical injury to radiologically diagnose due to high mortality rate

•• Why was a Chest CT with contrast so imperative?Why was a Chest CT with contrast so imperative?– CXR findings and clinical history of high speed MVA increased suspicion

of a possible aortic transection– To date, multislice CT with contrast is the preferred modality in a trauma

situation due to:• High diagnostic capabilities, rapid assessment, and concomitant

evaluation of additional traumatic injuries

•• Were any additional studies necessary?Were any additional studies necessary?– No. Angiography and TEE are best used as confirmatory studies or

primary diagnostic modalities in extremely stable patients• Numerous factors (i.e. time, invasiveness, expertise needed) limit use

in emergent situations

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ReferencesReferences• Gotway MB, Dawn SK. “Thoracic Aorta Imaging with Multislice CT.” Radiologic Clinics of

North America. 2003 May;41(3).

• Gray’s Anatomy. <www.bartleby.com>.

• Marx: Rosen’s Emergency Medicine: Concepts and Clinical Practice, 5th ed. St. Louis: Mosby, Inc., 2002. pp 401-405.

• Mechem CC. Intensive Care Unit Management of Trauma Patient. 20 April 2004. 21 July 2004. <www.uptodate.com>.

• Reeder MM. Reeder and Felson’s Gamuts in Radiology: Comprehensive List of Roentgen Differential Diagnosis. 4th ed. New York: Springer, 2003.

• Rivas LA, Fishman JE, et al. “Multislice CT in Thoracic Trauma.” Radiologic Clinics of North America. 2003 May;41(3).

• Samett EJ. Aorta Trauma. 10 Jan 2003. 21Jul 2004. <www.emedicine.com>.

• Vignon P, Lang RM. Transesophageal Echocardiography in Rupture of Aortic Isthmus. April 2004. 23 July 2004. <www.uptodate.com>.

http://www.uptodate.com/

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AcknowledgementsAcknowledgements

• Alice Fisher, MD• Vassilios Raptopoulos, MD• Phillip Boiselle, MD• Pamela Lepkowski, Program Coordinator • Gillian Lieberman, MD• Larry Barbaras, Webmaster

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