A ortic F istulas Pathophysiologic Features, - PowerPoint Presentation

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Aortic Fistulas

Pathophysiologic Features,

Imagin

g Findings, and Diagnostic Pitfalls

       

Aishwarya Gulati

1

, Harit Kapoor

2

, Achala Donuru

1, Kunal Gala3, Maansi Parekh1 Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, PA Department of Radiology, University of Kentucky Medical Center, Lexington, KYTata Memorial Hospital, Mumbai, IndiaConflicts of Interest: None

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TABLE OF CONTENTSThoracic Aortic Fistulas

Aortoatrial fistulas

Aortobronchial fistulas

Aortoesophageal fistulas

Abdominal

Aortic Fistulas

Aortoenteric fistulas

Aortocaval fistulas

Incidence and risk factors

Pathogenesis

Imaging modalitiesDirect and ancillary imaging featuresCase examples with clinical and imaging pearlsImaging pitfallsBrief approach to managementSummaryPLUS bonus cases of aberrant subclavian-esophageal fistula & iliac-ureteral fistula

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AortoesophagealInc: 1.7%-2% of TEVARMC: middle to third part of esophagus

Aortobronchial

Inc: 0.5% of TEVAR

MC: left tracheobronchial tree

AortoentericInc: 0.5% to 2.3% of ruptured AAAs (highest if post-EVAR included)MC: 3rd part of duodenum

Aortocaval

Inc: 2%-6% of ruptured AAAsMC: infrarenalINCIDENCE AND TOP RISK FACTORS

Atherosclerotic abdominal aortic aneurysm (AAA), AAA repair or graft infections

Mycotic aneurysmCollagen vascular diseaseMalignancyPost thoracic endovascular aortic repair (TEVAR) or endobronchial stent placementRadiationTraumaAortic aneurysmTraumaLumbar surgeryInferior vena cava (IVC) filter placementInfective endocarditis (IE)Aortic aneurysmInterventions

—eg, atrial appendage closure device, pulmonary vein ablationAortic aneurysm repairEsophageal malignancyForeign body ingestionFierro et al., Cardiol Rev, 2018. Anguera et al., Eur Heart J, 2004. Chiesa et al., Eur J Vasc Endovasc Surg, 2010. Picichè et al. Ann Thorac Surg, 2003. Kieffer et al., Ann Surg,2003. Xiromeritis et al.,Int Surg, 2011. Brewster et al., J Vasc Surg, 1991. Leigh-Smith et al., J Accid Emerg Med, 2000.Increasing incidence >>Inc = incidence, MC = most commonAortoatrialInc: 1.6% of IE cases (up to 5.8% in prosthetic IE)MC: right atrium

Aortic dissection/ aneurysmInterventions—eg, balloon dilatation, surgeryTrauma

AortopulmonaryInc: 4% of thoracic aneurysms at autopsy,imaging incidence unknown

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TICKING BOMBSManifests clinically as “herald” or “sentinel” bleeds, may or may not have a phase of intermittent recurrence that precipitates eventually, or manifests directly with sudden exsanguinationPATHOGENESISDua et al., J. Vasc. Surg, 2014. Picichè et al. Ann Thorac Surg, 2003. Endovascular Aortic Repair (EVAR) incidence increased from 5.2% to 74.0% from 2000 to 2010; however, there has been a concomitant increase in associated complications such as aortic fistulas.

Surgery/ intervention (#1)

Atherosclerosis

Infection

Trauma

Radiation

Vasculitides

Aortitis

Pseudo-aneurysm

Pressure Necrosis

Adhesive Granulation

Fistula formation

Pulsatile pressure on inflamed,  weakened walls

Inappropriately tight sutures

Transmission of pulsatile pressure on surrounding structures

Surgical material

Superimposed infection

Postoperative inflammation

Rupture of aortic wall and fistula formation

DETONATION TIME?

Aortic fistulas can take a long time to develop and

can appear many years to decades after interventions

such as aneurysm repair and adjacent hollow organ stent placement.

PRIMARY FISTULA:

Without prior aortic intervention, rare

SECONDARY FISTULA:

In the setting of prior aortic intervention, more common

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IMAGING MODALITIES CT angiography (CTA)

Modality of choice:

universal availability and quick acquisition

Performance:

can detect bleeds as slow as 0.3-0.5 mL/min. Sensitivity and specificity vary, as findings can be very subtle and nonspecific, especially in the most common scenario of postoperative fistulas: 40%–90% sensitivity, 33%–100% specificity

Multiphasic acquisition is key:

Noncontrast sequence best for detecting wall hematoma and preexisting hyperattenuating hemorrhage or postoperative materialArterial and delayed phases for identifying active bleed

Neutral oral contrast can help enhance identification of an active blush into the bowel lumenElectrocardiographic gating (end-diastole best) can enhance identification of aortic root and ascending aortic fistulas

3D reconstructions aid in surgical planning

Other angiographic modalitiesConventional AngiographyCan be used to better delineate anatomy for surgical planning or therapeutic interventionsCan detect bleeds as slow as 0.5-1.0 mL/min

MR AngiographyLimited use in emergent settings, can be hard to distinguish air from calcium; metal stents cause artifactCan allow quantification of flow through the fistulaTagowski et. al, Radiol Res Pract. 2014 , Vu et al., Radiographics, 2009, Lebenatus et. al, Radiology, 2018, Ananthasubramaniam, Cardiovasc Ultrasound, 2005. Picichè et al. Ann Thorac Surg. 2003 .

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IMAGING MODALITIES Nuclear Medicine

BLEED SCAN

99m

Tc-tagged RBC scan

Best sensitivity - detects bleeds as slow as 0.1–0.5 mL/min.

Poor anatomic resolution and predictability of angiographic control.

INFECTION VERSUS FISTULA 99mTc-HMPAO- or

111In-tagged WBCDifferentiate between infection and fistula in cases of equivocal CT findings.

Sensitivity 60%-100%, specificity 53%-100% (for prosthetic vascular graft infection).

18F-FDG PET/CT Better anatomic detail.Poor utility in the postoperative period. Transesophageal ModalitiesEndoscopy

Usually avoided to prevent clot displacement and precipitate bleeding, particularly in unstable patients. Negative examination result does not rule out fistula. Can be used for treatment.Transesophageal echocardiography (TEE)Unique utility for aortic root and arch fistulas.Can be performed at bedside or intra-operatively to quantify flow.Love et al, JNMT, 2004. Tagowski et. al, Radiol Res Pract. 2014 , Vu et al., Radiographics, 2009, Lebenatus et. al, Radiology, 2018, Ananthasubramaniam, Cardiovasc Ultrasound, 2005. Picichè et al. Ann Thorac Surg. 2003 .

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IMAGING FEATURES

DIRECT FEATURES

(less commonly seen)

INDIRECT/ANCILLARY FEATURES

(more commonly seen)

 

These imaging signs are directly incriminatory. A single sign is enough for a certain diagnosis.

Direct visualization of fistula

Graft migration into communicating organ or structure

Active extravasation of intravenous contrast medium into fistulizing organ or oral contrast medium into aortaThese signs increase suspicion for a fistula. Multiple indirect signs (the greater the better) increase the likelihood of a true fistula. True confirmation is achieved at surgery or angiography only. Abnormal aortic wallAortitis, aneurysm, or pseudoaneurysmMural hematomaDiscontinuous aortic plaquePresence of endovascular graft, particularly malpositionedAbnormal interface of aorta and fistulizing entityAdhesions and loss of normal fat planePeriaortic foci of gasAbnormal walls of fistulizing entityTethered or thickened walls of adjacent structureAbnormal surrounding environmentPerigraft fluid collectionFree hemorrhage or hemorrhage into adjacent organ—for example, pulmonary hemorrhage in cases of aortobronchial fistula

Vu et al., Radiographics, 2009. Tagowski et al. Radiol Res Pract. 2014. Sipe et al., Emerg Radiol,2017.

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IMAGING FEATURESExample of a Direct Imaging Feature

Example of an Indirect Imaging Feature

A

B

History of aortic and mitral valve replacements in 68-year-old woman. Oblique (left) and axial (right) CT angiograms demonstrate a fistula (arrow) between the

aortic root and left atrium

.

Progressive abdominal pain for 1 week and sudden hematemesis after AAA repair in 61-year-old man. Axial (left) and sagittal (right) CT angiograms show

perigraft phlegmon (arrow, left image) with foci of air (arrows, right image).

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Case of a 55-year-old man with a history of prior coronary artery bypass graft who presented with chest pain. A, B, Axial (A) and coronal (B) CT angiograms demonstrate a type A dissection (arrows in A and B) extending into the aortic root. C, As seen on the sagittal CT angiogram, the dissection resulted in a fistula (arrow) between the noncoronary sinus and right atrium.

B

C

A

Case 1

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Valve endocarditis, paravalvular abscessAortic aneurysm, pseudoaneurysm, dissection

Direct visualization of fistula

Congestive heart failure

New continuous murmur

AORTOATRIAL FISTULA

Fierro et al., Cardiol Rev, 2018.

Features

Imaging

Clinical

Features

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Case 2

A

B

Case of a 7-year-old patient with a history of double-outlet right ventricle and subpulmonary ventricular septal defect after arterial switch procedure with the LeCompte maneuver and ventricular septal defect closure. Patient underwent balloon dilation of the left pulmonary artery for neopulmonary stenosis. At follow-up, a new continuous murmur was noted.

A,

Doppler echocardiogram shows continuous antegrade flow with systolic accentuation within the aortopulmonary fistula.

B,

Cardiac catheterization angiogram shows

a fistula (red arrow) between the ascending aorta (blue arrow) and left pulmonary artery (green arrow)

. C (click to play), Video of the cardiac catheterization demonstrates a fistula between the ascending aorta and left pulmonary artery.

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High oxygen saturation in the pulmonary artery and oxygen step-up between the right atrium and the pulmonary artery at catheterizationDirect contrast material extravasation from aorta into pulmonary artery

Pseudoaneurysm formation

Congestive heart failure

Acute pulmonary edema

New continuous murmur

AORTOPULMONARY FISTULA

Features

Imaging

Clinical

Features

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Case of 61-year-old man with hemoptysis, a history of heart transplantation, and left ventricular assist device placement. A, Axial CT image shows a pseudoaneurysm of the descending thoracic aorta at the anastomosis site (red arrow) and the thrombosed outflow remnant graft (blue arrow). B, C, Angiograms show aortic graft stent placement, with extravasation of contrast material seen (arrows in C),

representing an underlying communication. D, Axial CT image shows an endoblocker (arrow) placed in the left mainstem bronchus for treatment.

A

B

C

D

Case 3

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AORTOBRONCHIAL FISTULA

Dyspnea

Hemoptysis

Bronchial or airway tract leading to aorta

Extravasation of intravenous contrast medium into airway

Parenchymal hemorrhage

Picichè et al. Ann Thorac Surg, 2003

Clinical

Features

Features

Imaging

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Case 4

A

B

Case of 70-year-old man with prolonged tracheostomy for laryngeal cancer who presented with acute bright red hematemesis. Axial CT angiograms show loss of the outline of the aneurysmal aortic arch medial wall, with a

nipple-like outpouching (arrows) tethered to the esophagus and adjacent focus of air.

The fistula was surgically confirmed.

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AORTOESOPHAGEAL FISTULA

Midchest pain, dysphagia

Hematemesis

Exsanguination after symptom-free period

Tract between esophagus and aorta

Extravasation of intravenous contrast medium into esophagus

Extravasation of oral contrast medium from esophageal lumen into aorta

Mediastinal hemorrhage

Chiari triad

Kieffer et al., Ann Surg,2003.

ClinicalFeatures

Features

Imaging

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AORTOESOPHAGEAL FISTULA

A

B

B

C

Case of a patient with aortic dissection (not shown) complicated by

rupture with contrast medium extravasation anteriorly (red arrow in

A

)

forming a

mediastinal hematoma (blue arrow in A and B) indenting the left atrium, as seen on these axial CT images. C, Axial CT image after aortic stent-graft repair and esophageal stent placement demonstrates an esophageal leak and probable aortoesophageal fistula outlined by extravasated oral contrast medium extending to the aortic stent (arrow).

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AORTOESOPHAGEAL FISTULA

A

B

C

D

E

Case of a 65-year-old man with known esophageal cancer who presented with hematemesis and respiratory distress.

A–C,

Axial

(A)

and sagittal (B and C) CT angiograms show an outpouching from the aortic wall and intravenous contrast medium extravasation into the esophagus (arrows). D, E, Axial CT angiograms show hemorrhage (arrow) in the esophagus and stomach.

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Bonus: ABERRANT RIGHT SUBCLAVIAN ARTERY–ESOPHAGEAL FISTULA

A

B

F

C

D

E

Case of a 42-year-old woman with esophageal cancer who presented with massive hematemesis.

A, B,

Axial

(A) and sagittal (B) CT angiograms show an aberrant right subclavian artery (ARSA)

(arrow) adjacent to the concentric esophageal wall thickening. C, ARSA angiogram reveals a

pseudoaneurysm (arrow) in the proximal segment. D, E, Digital subtraction angiograms reveal an

ARSA-esophageal fistula with active contrast medium extravasation into the esophagus (arrow).

F, Check ARSA angiogram reveals no opacification of the pseudoaneurysm following closure of the tract.

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Case 5

A

B

C

Case of a 72-year-old man with prior

abdominal aortic aneurysm

repair who presented with acute-onset severe midabdominal pain, gastrointestinal bleeding, and syncope.

A

–C,

CT angiograms of the abdomen and pelvis show extravasation of arterial contrast medium into the duodenum and proximal jejunum (blue arrow), confirming the clinical suspicion for aortoenteric fistula to the third portion of the duodenum (red arrow in A). The patient underwent urgent repair with explantation of the aortobi-iliac graft and repair with a cadaveric aortic homograft and aortoduodenal fistula repair.

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Gastrointestinal bleedingAbdominal or back pain

Pulsatile abdominal massSepsis, shock

AORTOENTERIC FISTULA

Tract between the bowel and aorta

Extravasation of intravenous contrast medium into the bowel

Extravasation of oral contrast medium from the bowel into the aorta

Bowel wall thickening or tethering

Retroperitoneal hemorrhage

Xiromeritis et al.,Int Surg, 2011. Vu et al.,Radiographics, 2009.

Cooper triad

ClinicalFeatures

Features

Imaging

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AORTOENTERIC FISTULA

A

C

B

Case of a 48-year-old man with a history of aortobifemoral bypass surgery who presented with right lower extremity gangrene due to a thrombosed endograft.

A–C,

Axial

CT images after amputation show

ascending (probably infected) thrombosis (blue arrow in B) up to the aortic graft, with intraarterial contrast medium (red arrow) extending beyond the aorta that is concerning for an aortoduodenal fistula. The patient then reported having low-grade gastrointestinal bleeding for several weeks. During surgery, a large defect involving >50% of the circumference of the fourth portion of the duodenum was found.

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AORTOENTERIC FISTULA

A

B

C

D

E

F

Case of a 30-year-old man with a metastatic nonseminomatous germ cell tumor who presented with hematemesis, melena, hematochezia, and a palpable abdominal mass.

A, B,

Axial

(A)

and coronal

(B)

maximum intensity projection

(MIP) CT images show a

large

aortocaval lymph node extending from the aortic bifurcation to the duodenum (arrows),

with infiltration into the duodenum and blood supplied by the inferior and superior mesenteric arteries.

C,

Coronal

angiogram shows

the inferior mesenteric artery (arrow) subsequently coiled

. One month later, the patient demonstrated massive hematemesis and melena.

D

–

F, Axial CT (D), c

oronal MIP CT angiogram

(E),

and

coronal digital subtraction angiogram

(F)

show

periaortic soft tissue and fluid (yellow arrows in

D

and

E

)

and an aortic pseudoaneurysm (green arrow in

E

and

F

)

just above the bifurcation communicating with the small bowel

.

The fistula was confirmed

when contrast medium extravasation into the bowel loops (purple arrow in

F

) was seen at digital subtraction angiography.

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AORTOENTERIC FISTULAA

B

Case of a 39-year-old woman with an aortoduodenal fistula. Axial CT angiograms demonstrate

loss of fat planes between the aorta and duodenum and contrast medium extravasation beyond the aortic lumen into the duodenum (arrow in

A

).

B,

Contrast medium within the bowel loops only (arrow)

is seen during the delayed phase. This case also illustrates the utility of multiphasic imaging in patients with these fistulas.

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Case 6Case of a 58-year-old man who became hypotensive at workup for suspected renal colic. Coronal (A) and axial (B)

CT angiograms demonstrate a saccular infrarenal aortic aneurysm (red arrows in

A), with a chronic dissection flap (blue arrow in

B)

and fistulization with the inferior vena cava (green arrow). The patient underwent aortobi-iliac bypass surgery with polyester graft placement and fistula repair.

A

B

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AORTOCAVAL FISTULA

Low back pain

Pulsatile abdominal mass

Hematuria

Congestive heart failure

Tract between inferior vena cava (IVC) and aorta

Simultaneous enhancement of IVC and aorta

Retroperitoneal hematoma

Dilated IVC and pelvic veins

Brewster et al., J Vasc Surg, 1991.

Features

Imaging

Clinical

Features

Slide27

AORTOCAVAL FISTULA

B

C

A

Case of a 60-year-old man who underwent imaging for bacteremic sepsis. Axial (

A

and

B

) and sagittal

(C)

CT images show phlegmonous extension of infection into the aorta (arrows in A) and early dense opacification of the inferior vena cava that matches the opacification of the aorta (arrow in B

), suggesting aortocaval fistulization secondary to adjacent L3-L4 diskitis-osteomyelitis (arrows in C). 

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BONUS: ILIAC-URETERAL FISTULA

A

B

C

D

A,

Coronal maximum intensity projection image shows a

left ureteral stent very closely abutting the left iliac artery graft (arrow).

B,

Axial CT image shows air and hemorrhage (arrows) in the urinary bladder that are concerning for fistula. Although the lack of intravenous contrast material limits the evaluation, suspicion for a fistula was raised on the basis of ancillary imaging findings. C, D, The left arterioureteral fistula was then confirmed at aortography when a direct communication between the left iliac artery and ureter (arrow in C) was identified, with contrast medium draining into the ipsilateral ureter and urinary bladder (D, video [click to play]).

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BONUS: TRAUMATIC ILIAC ARTERY–VEIN FISTULA

Case of a 21-year-old man with a history of a gunshot wound to the abdomen.

A

–

C, Axial CT angiograms show a fistula (arrows in B and C) between the iliac arteries and veins.

A

B

C

Slide30

BONUS: TRAUMATIC ILIAC ARTERY-VEIN FISTULA

Case of a 39-year-old man with new-onset “stabbing” back pain.

A, B,

Sagittal

(A) and axial (B) CT images show a diagnosed traumatic left common iliac artery–to–common iliac vein (CIV) fistula, secondary to a retained fractured knife blade from a trauma that occurred 12 years prior. C, D, As seen on these CT images, the protracted development can be inferred from the massive aneurysmal dilatation of the CIV and extensive transpelvic and lumbar venous collateralization. The patient was successfully managed with endovascular repair and exclusion of the fistula, and coil placement in the left hypogastric artery.

A

B

C

D

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PITFALLS IN IMAGING: THORACIC AORTANormal VariantsAortic nippleAortic spindleDuctus diverticulumKommerell diverticulum

Familiarity with appearance and typical locations of normal variants

Absence of ancillary imaging features of fistula

A

B

C

D

E

F

A–C,

Normal appearance of an aortic nipple. Coronal

(A)

and axial

(B

and

C)

CT images show a

tiny beaking at the lateral aortic contour (arrow in

A

and

B

),

which corresponds to the origin of the third intercostal artery from the

aorta

(arrow in

C

).

D,

Normal appearance of an aortic spindle.

Sagittal maximum intensity projection (MIP) image shows a

smooth bulge of the descending aorta just distal to the isthmus (arrow).

E,

Normal appearance of a ductus diverticulum.

Sagittal MIP image shows

a smooth outpouching (arrow) at the level of the isthmus where the ligamentum arteriosum attaches;

this is also a common site of trauma.

F,

Normal appearance of Kommerell diverticulum. Coronal MIP image shows a diverticulum arising from the

proximal descending aorta, giving rise to the right subclavian artery (arrow).

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PITFALLS IN IMAGING: ABDOMINAL AORTARetroperitoneal fibrosis (RPF)Lymphadenopathy (LAD)Inflammatory rind in other causes of aortitis, Erdheim-Chester

B

A

Lack of periaortic gas

RPF – can also be seen in other sites—eg, periureter; entire soft-tissue plaque may enhance variably

LAD – increases distance between spine and aorta; also likely in other sites

A,

Axial CT image shows a soft-tissue periaortic rind

(arrow)

that slightly increases the distance between the aorta and spine

, probably owing to LAD. B, Axial CT image shows the rind (arrows) to be smooth and symmetric, probably owing to RPF.Vu et al., Radiographics, 2009.

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PITFALLS IN IMAGING: TECHNICALObtain echocardiographically gated study or check for other evidence of motion such as blurred margins.Absence of ancillary imaging features of fistulaAvoid using positive oral contrast medium.Perform noncontrast and arterial phase imaging with a delayed sequence in patients with prior interventions to check for endoleaks.

Cardiac motion

Oral contrast medium obscuring intravenous contrast medium extravasation

Lack of adequate phases

A

B

Case of a 64-year-old man for whom there is clinical concern for a fistula.

A,

Arterial phase CT image shows a

hyperattenuating focus in the small bowel (arrow) that is

concerning for intravenous contrast medium extravasation into the bowel. B, However, the noncontrast CT image shows a similar focus in the small bowel (arrow), which is probably due to ingested content.

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PITFALLS IN IMAGING: POSTOPERATIVEVu et al., Radiographics, 2009. Green et al., Radiology: Cardiothoracic Imaging 2019. Tagowski et al. Radiol Res Pract. 2014. >3 months post-op

Perigraft soft tissue, fluid, or hematoma

Perigraft air

>6 to 7 weeks

post-op

Infection or fistula

Direct signs of fistula—eg,

intravenous contrast medium leakage into periaortic space or adjacent organ, or

graft migration

Expected postoperative changes ?Fistula

Indirect signs of fistula—eg, focal wall thickening or tethering of adjacent organ, or disrupted aortic plaqueNonequiv-ocalFistula more likelyConsider scintigraphy for infectionInfection ?Fistula?Blood cultures & inflammatory lab markers are less reliable and nonspecific:Up to 47% of blood cultures are negative.White blood cell count and/or C-reactive protein can be elevated in all three cases.Clinical Dilemma:VsVs

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- 761.9

-326

-169

A

B

Hemostatic agents

Bioabsorbable sponge or gauze can have air pockets that mimic fistula.

Clues:

Higher attenuation than pure air (-104 to -458 HU)

Similar-sized air pockets or lattice distributionUnchanged distribution across studiesNo air-fluid level or enhancementUsually resolve in 7-14 days (seen for up to 38 days)Refer to operative notesHyperattenuating graft materialFelt pledgets can mimic contrast medium extravasation or a pseudoaneurysm. Clues:Seen on noncontrast images Typical location and configurationRefer to operative notesGreen et al., Radiology: Cardiothoracic Imaging 2019. Hanneman et al., Radiographics, 2015. Sandrasegaran et al. AJR, 2005.A, Axial CT image after ascending aorta pseudoaneurysm repair shows linearly arranged, fairly uniform-sized periaortic hypoattenuating foci that are higher in attenuation than air. B, Axial CT image 17 days later shows the foci are completely resolved.Normal appearance of graft material, with hyperattenuating curvilinear felt pledget (arrow) along the aortic wall abutting the pulmonary artery

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INFECTION OR FISTULA?Case of a 69-year-old woman with an abdominal aortic aneurysm who presented with acute abdominal pain. Axial (A) and coronal (B)

CT images show an expanding infrarenal aortic aneurysm (red arrows), with tiny foci of air (blue arrow in

B) within the aneurysm sac. No obvious signs of a fistula were seen, making it unclear whether this was a fistula or infection.

A

B

Slide37

INFECTION OR FISTULA?Case of a 67-year-old man who underwent endovascular repair 4 years ago and presented with acute abdominal pain. A, B, Coronal (A)

and sagittal (B) CT images show an expanding infrarenal aortic aneurysm (red arrows) with

tiny foci of air (blue arrows). It was unclear whether this was simply an infection or there was an underlying fistula. C, Tagged 111In white blood cell scan shows

increased uptake in the perigraft region (arrows), consistent with infection. The patient underwent excisional debridement of the aorta with implantation of antibiotic beads and staged graft explantation

.

Slide38

PRINCIPLES OF MANAGEMENTAortic fistulas can have extremely grim outcomes. Accurate and prompt diagnosis and treatment are crucial for patient survival. Open surgical repair is usually the treatment of choice. Repair may need to be staged, as there is usually concomitant infection and tissue friability.Primary closure with use of sutures, a patch device, ligation of the tract, or a combination of these techniques, with graft reconstruction of the aorta. Endovascular repairs are becoming increasingly more common for noninfected fistulas.Device closure, embolization coils, stents or balloons, and even cyanoacrylate can be used. Picichè et al. Ann Thorac Surg, 2003. Kieffer et al., Ann Surg,2003. Jainandunsing et al., J Thorac Dis, 2019.

Slide39

TEACHING POINTSIncreased incidence of aortic fistulas approximately parallels the increased use of endovascular aortic repair (EVAR) and aortic valvular replacements. Timely diagnosis is key to patient survival. Aortic fistulas are like “ticking time bombs” that can acutely decompensate after a single sentinel or herald bleed. Multidetector CT angiography is the modality of choice. Subtle and indirect imaging signs are often the only clues. Adjunctive use of scintigraphic techniques to identify infection or slow-to-intermittent bleeding can be very helpful.Differentiation of fistulas from postoperative change is a common dilemma.

Perigraft air, or fluid or soft-tissue thickening

occurring more than 1.5 or 3.0 months, respectively, after surgery should be further evaluated at workup for possible infection or fistula.

Slide40

References Dua A, Kuy S, Lee CJ, et al. Epidemiology of aortic aneurysm repair in the United States from 2000 to 2010. J Vascular Surgery 2014;59:1512-1517. Picichè M, De Paulis R, Fabbri A, et al. Postoperative aortic fistulas into the airways: etiology, pathogenesis, presentation, diagnosis, and management. Ann Thorac Surg 2003;75:1998-2006.3. Fierro EA, Sikachi RR, Agrawal A, Verma I, Ojrzanowski M, Sahni S. Aorto-atrial fistulas: a contemporary review. Cardiol Rev 2018;26:137-144.4. Anguera I, Miro JM, Vilacosta I, et al. Aorto-cavitary fistulous tract formation in infective endocarditis:

clinical and echocardiographic features of 76 cases and risk factors for mortality. European Heart J 2004;26:288-297.

5. Chiesa R, Melissano G, Marone EM, Marrocco-Trischitta MM, Kahlberg A.

Aorto-oesophageal and aortobronchial fistulae following thoracic endovascular aortic repair: a national survey. Eur J Vasc Endovasc Surg 2010;39:273-279.

6. Kieffer E, Chiche L, Gomes D. Aortoesophageal fistula: value of in situ aortic allograft replacement. Ann Surg 2003;238:283-290.

7. Xiromeritis K, Dalainas I, Stamatakos M, Filis K. Aortoenteric fistulae: present-day management. Int Surg 2011;96:266-273.

8. Brewster DC, Cambria RP, Moncure AC, et al. Aortocaval and iliac arteriovenous fistulas: recognition and treatment. Journal of Vascular Surgery 1991;13:253-265.

9. Leigh-Smith S, Smith RC. Aorto caval fistula: the "bursting heart syndrome." J Accid Emerg Med 2000;17:223-225.

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References, continued10. Vu QD, Menias CO, Bhalla S, Peterson C, Wang LL, Balfe DM. Aortoenteric fistulas: CT features and potential mimics. RadioGraphics 2009;29:197-209.11. Tagowski M, Vieweg H, Wissgott C, Andresen R. Aortoenteric fistula as a complication of open reconstruction and endovascular repair of abdominal aorta. Radiol Res Pract 2014:383159.12. Wells ML, Hansel SL, Bruining DH, et al. CT for evaluation of acute gastrointestinal bleeding. RadioGraphics 2018;38:1089-1107.13. Love C, Palestro CJ.

Radionuclide imaging of infection. J Nucl Med Technol 2004;32:47-57.

14. Lebenatus A, Salehi Ravesh M. Aortocaval fistula at 4D flow MRI: visualization and quantification of vascular flow. Radiology 2018;289:617.

15. Ananthasubramaniam K. Clinical and echocardiographic features of aorto-atrial fistulas

. Cardiovasc Ultrasound 2005;3:1.16. Sipe A, McWilliams SR, Saling L, Raptis C, Mellnick V, Bhalla S. The red connection: a review of aortic and arterial fistulae with an emphasis on CT findings.

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