Lower Extremity Vascular Trauma - Lieberman's …eradiology.bidmc.harvard.edu/LearningLab/cardio/Rork.pdf* Small stable hematoma * Unexplained hematoma * Injury to an anatomically

Arteriovenous Fistulas: Complications of a Gunshot Wound

Jillian Rork, MS III Gillian Lieberman, MD

February 2011

Jillian Rork, Harvard Medical School, MSIIIGillian Lieberman, MD

Goals of the Presentation

With the help of our index patient, we will: 1) Review the vascular anatomy of the lower extremity 2) Learn the diagnostic tests available to evaluate for extremity vascular trauma3) Generate a differential diagnosis of lower extremity vascular pathology in the setting of trauma4) Learn the radiologic findings of extremity vascular trauma on CT angiogram. 5) Learn the limitations of CT angiogram in assessing vascular trauma


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Index Patient Presentation

• HPI: 21 yo M s/p gun shot wound to the left upper medial thigh with no exit wound. Absent PT/DP pulses at the scene.

• ROS: Pain at entry site. Denies pain and numbness in left calf and foot. All other systems are normal.

• PMH: Bipolar Disorder, Attention Deficit Disorder

• Medications: None• Allergies: Morphine


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Index Patient: Physical ExamT: 98.8 HR: 83 BP:145/72 RR: 22 O2 sat: 100% • Neuro/Psych: A&O x3, NAD• Cardiac: Regular rate & rhythm, no m/r/g• Pulmonary: Clear to auscultation, normal effort • Extremities:

• Entry wound in left medial thigh, no exit wound • Pulses: RLE femoral, popliteal, PT and DP – Palpable

LLE femoral popliteal, PT and DP – Palpable• No femoral bruit/thrills• No lower extremity edema, compartments soft • Strength and sensation intact bilaterally


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Clinical Questions

With an overall benign exam, does our patient need further evaluation for vascular trauma?

What are the clinical signs of arterial injury in extremities?

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Clinical Signs of Arterial Injuries in the Extremities

Clinical Signs of Arterial Injures in ExtremitiesHard Signs Soft Signs* Absent or diminished pulses* Active hemorrhage* Large expanding or pulsatile hematoma * Bruit/thrill* Distal ischemia

* Small stable hematoma * Unexplained hematoma * Injury to an anatomically related nerve * Proximity of an injury to a major vessel

Compton C, Rhee R. Peripheral vascular trauma. Perspect Vasc Surg Endovasc Ther 2005; 17: 297-307.


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-Clinical signs of arterial injuries are divided into Hard Signs and Soft Signs

-Our patient merits further workup since his injury is near major vessels – the femoral artery and vein

Clinical Signs of Arterial Injuries in the Extremities: Pulse or No Pulse

While it is important to remember the hard and soft clinical signs of arterial injuries, a major take away point from our patient is:

Palpable pulses does NOT exclude vascular injury

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Objectives of Imaging Our Patient

The objectives of imaging our patient is to assess the following:

What is the path of the projectile?

Is there osseous and/or soft tissue injury?

Is there vascular trauma?


Wilson, A. Gunshot Injuries: What Does a Radiologist Need to Know? Radiographics. 1999 Sept-Oct; 19(5): 1358-68. 8

Continue to the next slide for a discussion of possible imaging modalities

Menu of Imaging Tests

Plain film

Reveals osseous fractures that could jeopardize adjacent vessels, but not vasculature itself

Ultrasound (US)

Color-flow duplex scanning demonstrates the integrity of vessels and flow velocity/directionality; however, US is extremely operator dependent

Conventional angiography

Identifies vascular injury and has interventional capacity; however, this is an invasive procedure and does not provide information regarding the foreign body pathway or osseous/soft tissue structures

X-ray Computed Tomography (CT) Angiogram

Identification of vascular injury, osseous damage, and foreign body location

MRI

Identification of vascular injury and soft tissue damage; however, this is an expensive, more time-consuming imaging modality


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Despite the broad menu, CTA is the test of choice for our patient. Continue onto the next slide to learn more about CTA versus conventional arteriography

Conventional Angiography vs CTA

Studies comparing CTA of the extremities with conventional angiography have found CTA to be:

Comparable in accuracy

More time-efficient

Less invasive

Less expensive

Literature Highlight: In a prospective study of 139 patients, CT angiography was used as the initial imaging modality in the setting of trauma to the extremities

Sensitivity 95.1% for proximal arterial injuries in the upper and lower extremities

Specificity 98.7% for proximal arterial injuries in the upper and lower extremities


Soto JA, Munera F, Morales C, et al. Focal arterial injuries of the proximal extremities: helical CT arteriography as the initial method of diagnosis. Radiology. 2001; 218: 188-194. 10


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Before reviewing our patient’s CTA images, it is imperative we review lower extremity vascular

ANATOMY

Images modified from Hansen, JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

Lower Extremity Arterial Vasculature Jillian Rork, MS III Gillian Lieberman, MD

Image modified from Hansen JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

The “Must Know” Arteries

Femoral Artery

•Superficial femoral artery

•Deep artery of thigh

Popliteal Artery

Anterior tibial artery

Posterior tibial artery

Fibular artery

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Posterior Crural Compartment: Artery Names and Locations


Posterior Crural CompartmentImage modified from Hansen, JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

LateralMedial

o The popliteal artery divides into the anterior tibial and the posterior tibial artery

o The posterior tibial artery gives rise to the fibular artery

o The posterior tibial artery courses medially while fibular artery courses laterally

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Anterior Crural Compartment: Artery Names and Locations


Anterior Crural CompartmentImage modified from Hansen JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

Lateral Medial

The anterior tibial descends and gives rise to the dorsalis pedis artery

The perforating branch of fibular artery supplies the lateral malleolus

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Vascular Anatomy of Anterior Thigh Compartment


Image modified from Hansen, JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

Superficial and deep femoral arteries and veins travel through the anterior compartment of the thigh (outlined in purple)

*Remember: Keep this image in mind when reviewing our patient’s axial CTA images !

Medial Lateral

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Vascular Anatomy of Crural Compartments


Image modified from Hansen JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com. Date accessed 2/15/11.

Anterior Compartment (Purple)

-Anterior tibial artery and vein

Posterior Compartment (Teal)

-Posterior tibial artery and vein

-Fibular artery and vein

Lateral Compartment (Yellow)

-None

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Lateral Medial

*Remember: Keep this image in mind when reviewing our patient’s axial CTA images !

Index Patient: Pelvic CTA Image Jillian Rork, MS III Gillian Lieberman, MD

PACS, BIDMC 17

Axial CTA of the pelvis shows TWO contrast enhanced vessels (femoral artery and femoral vein) on the patient’s left side. The patient’s right side shows only ONE contrast enhanced vessel (femoral artery).

Blue Arrow: Femoral Artery Yellow Arrow: Femoral Vein

Right Left

Index Patient: Pelvic CTA Interpretation

If the CTA was timed properly, only the arteries should be filled with contrast. Thus, either our test is faulty OR our patient has a connection between an artery and vein in his left lower extremity, causing contrast to enter the venous system.

Blue Arrow: Femoral Artery

Yellow Arrow: Femoral Vein

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Index Patient CTA: IV Contrast in Superficial Femoral Vein


Yellow = Superficial Femoral Vein

Blue Arrow = Superficial Femoral Artery

Purple Arrow = Deep Femoral Artery

PACS, BIDMC 19

As we continue down our patient’s leg, we note the bifurcation of the femoral artery into the superficial femoral artery and deep femoral artery. We also note contrast in the superficial femoral vein

Index Patient CTA: Arteriovenous Fistula


PACS, BIDMC 20

As we continue down the axial CTA, we notice a stream of contrast between the superficial femoral artery and vein. This is suggestive of an arteriovenous (AV) fistula between the artery and vein, which would explain why veins contain contrast

Orange Arrow = Fistula between Superficial Femoral Artery and Vein

Index Patient CTA: Thrombus/Intimal Flap


PACS, BIDMC 21

This axial CTA of the lower extremity distal to the AV fistula shows an opacity in the superficial femoral vein, suggestive of either a clot or intimal flap.

In addition, please note the increased diameter of the left thigh, suggestive of internal hemorrhage and soft tissue swelling

Yellow Arrow = Clot or Intimal Flap

Index Patient CTA: Foreign Body Jillian Rork, MS III Gillian Lieberman, MD

PACS, BIDMC 22

Distal to the AV fistula, we find a foreign body – the bullet. Please note the streak artifact created by the foreign body; this will be important

when discussing the limitations of CTA studies.

Purple Arrow = Bullet

Index Patient CTA: Popliteal Arteries


PACS, BIDMC 23

As we continue down the lower extremity CTA, we note both popliteal arteries contain contrast, suggesting adequate perfusion distal to the AV fistula.

No veins contain contrast on this image

Blue Arrow = Popliteal Artery

Index Patient CTA: Crural Perfusion

Pink Arrow = Posterior Tibial Artery

Blue Arrow = Fibular Artery

Yellow Arrow = Anterior Tibial Artery


PACS, BIDMC 24

Posterior Compart

Anterior Compart

Lateral Compt

This lower extremity axial CTA shows all three vessels of the calf (posterior tibial, anterior tibial, and fibular artery) contain contrast, suggesting adequate perfusion and thus decreased risk of ischemic limb. Remembering the crural compartments

make it easier to determine the location of the three arteries.

Causes and Complications of Arteriovenous Fistulas

Cause

Simultaneous injury of an adjacent artery and vein

Mechanism

Venous pressure is lower than arterial pressure; thus, arterial contents will flow into the venous system

Flow through an arteriovenous fistula is continuous

Physical exam

Accentuation of the bruit and thrill detected over fistula during systole

Long-standing complications

Venous congestion

High-out cardiac failure

Hemmila MR, Wahl WL, “Chapter 13. Management of the Injured Patient.” Doherty GM.: CURRENT Diagnosis & Treatment : Surgery, 13th Edition: http://www.accesssurgery.com/content.aspx?aID= 5212736

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Comparison Patient 1: Subacute Arteriovenous Fistula


• This volume-rendered CT angiogram shows an AV fistula between anterior tibial artery and vein (long arrow)

• The anterior tibial artery is enlarged above the level of arteriovenous fistula and smaller distally (short arrows)

• Dilated veins are shown throughout image, suggesting a subacute or chronic process

• Retained BB pellet indicated by short arrow

Gakhal MS, Sartip KA. CT angiography signs of lower extremity vascular trauma. Am J Roentgenol. 2009 Jul; 193 (1): W49-57. 26

CTA Signs of Arterial Injury

Extravasation of contrast material

Pseudoaneurysm

Vessel caliber reduction

Spasm

Dissection or partial-thickness wall injury

External compression

Thrombus/Intimal Flap


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In addition to AV fistuals, CTA can show other signs indicative of arterial injury:

On the following slides, we will show examples of each

Comparison Patient 2 Extravasation on CTA

• On this coronal CTA of the right lower extremity, note the active contrast extravasation (large arrow) from the superficial femoral artery

• This sometines described as a ‘contrast blush’

• A small hole measuring approximately 1mm was discovered during surgery and repaired with primary sutures



Comparison Patient 3: Pseudoaneurysm on Angiogram


• Pseudoaneurysms are leaks contained by surrounding tissues and local fibrosis

•Simply said: A contained rupture

• Pseudoaneurysm wall is NOT formed by vascular tissue, but develops from organized thrombus, associated fibrosis, and surrounding tissues

Imaged modified from Windsor JA, Schweder P, “Chapter 37. Complications of Acute Pancreatitis.” Zinner MJ, Ashley SW: Maingot’s Abdominal Operations, 11th Edition: http://www.accesssurgery.com/context.aspx?aID=130125.

Selective mesentric angiogram showing a pseudoanuerysm related to the left gastric artery

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Comparison Patient 4: Pseudoaneurym on CTA



This volume-rendered CTA and reformatted coronal CTA of the right lower extremity show a small pseudoaneurysm arising from the proximal anterior tibial

artery (arrows).

Comparison Patient 5: Vessel Caliber Reduction

Image A: Sagittal reformatted CT angiographic image of lower extremity shows loss of opacification of popliteal artery (white arrow).

Image B: Conventional arteriogram confirms loss of opacification of popliteal artery suggestive of transection (black arrow).

A B


Miller-Thomas MM, West OC, Cohen AM. Diagnosing traumatic arterial injury in the extremities with CT angiography: pearls and pitfalls. Radiographics. 2005 Oct; 25 (Suppl1):S133-42. 31

Comparison Patient 6: Vessel Caliber Reduction

Coronal and sagittal CTA of lower extremity showing focal lumen narrowing of left popliteal artery. During surgical exploration, an intimal flap was found at this site and repaired.



CTA Imaging Shortcomings

Poor arterial opacification

Transit of contrast bolus and timing of image

Vessel underfilling from injury or poor cardiovascular health

Atherosclerosis

Displaced fracture fragments

Artifacts from metal/foreign bodyStreak artifacts are the major limiting factor



Please proceed to next slide for example

Example of Streak ArtifactsJillian Rork, MS III Gillian Lieberman, MD

Non-diagnostic CTA with metallic streak artifact after shotgun injury to the lower extremity

Miller-Thomas MM, West OC, Cohen AM. Diagnosing traumatic arterial injury in the extremities with CT angiography: pearls and pitfalls. Radiographics. 2005 Oct; 25 (Suppl1):S133-42. 34

Index Patient: Surgical Intervention

Patient underwent repair of arteriovenous fistula:

Evidence of through-and-through injury to both the artery and vein with subsequent fistula formation

Vein: Following debridement, 2-inch segment of left greater saphenous vein used to patch femoral vein

Artery: More than 70% had been transected; surgeons divided artery in half and mobilized it to allow for primary reanastomosis

Small strip of vastus medialis muscle (1.5cm x 6cm) was interposed between two repair vessels to prevent re-fistulization


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Index Patient: Post-operative Ultrasound


US color doppler images show no evidence of left superficial femoral arteriovenous fistula; red and blue colors indicate flow in opposite direction and do NOT mix.

There is no other evidence of other abnormalities in the vessels. PACS, BIDMC 36

Conclusions With the help of our index patient, we have:

1) Reviewed the vascular anatomy of the lower extremity

2) Learned the clinical indications for vascular imaging in the setting of a trauma - Palpable distal pulses is NOT enough to exclude vascular injury

3) Learned that CT angiogram is a sensitive and specific test to evaluate for extremity vascular trauma

- Limitations include poor arterial opacification and streak artifacts

4) Learned the radiologic findings of extremity vascular trauma on CT angiogram- Contrast extravasation-Vessel caliber reduction - Pseudoaneurysm- Arteriovenous fistula formation


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Bibliography

BIDMC PACS and Online Medical Records

Compton C, Rhee R. Peripheral vascular trauma. Perspect Vasc Surg Endovasc Ther 2005; 17: 297- 307.

Gakhal MS, Sartip KA. CT angiography signs of lower extremity vascular trauma. Am J Roentgenol. 2009 Jul; 193 (1): W49-57.

Hansen, JT. Hansen: Netter’s Clinical Anatomy, 2nd Edition. Philadelphia, PA: Saunders Elsevier; 2010. www.medconsult.com

Hemmila MR, Wahl WL, “Chapter 13. Management of the Injured Patient.” Doherty GM.: CURRENT Diagnosis & Treatment : Surgery, 13th Edition: http://www.accesssurgery.com/content.aspx?aID= 5212736.

Miller-Thomas MM, West OC, Cohen AM. Diagnosing traumatic arterial injury in the extremities with CT angiography: pearls and pitfalls. Radiographics. 2005 Oct; 25 (Suppl1):S133-42.

Soto JA, Munera F, Morales C, et al. Focal arterial injuries of the proximal extremities: helical CT arteriography as the initial method of diagnosis. Radiology. 2001; 218: 188-194.

Wilson, A. Gunshot Injuries: What Does a Radiologist Need to Know? Radiographics. 1999 Sept-Oct; 19(5): 1358-68.

Windsor JA, Schweder P, “Chapter 37. Complications of Acute Pancreatitis.” Zinner MJ, Ashley SW: Maingot’s Abdominal Operations, 11th Edition: http://www.accesssurgery.com/context.aspx?aID=130125.


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http://www.medconsult.com/

Acknowledgements

Gillian Lieberman, MDJames Knutson, MDKaren Lee, MDDavid Li, MD Emily Hanson


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Documents

Lower Extremity Vascular Trauma - Lieberman's …eradiology.bidmc.harvard.edu/LearningLab/cardio/Rork.pdf* Small stable hematoma * Unexplained hematoma * Injury to an anatomically