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KEY FACTS

Terminology
- Aortic arch elongation with kinking of thoracic aorta distal to origin of left subclavian artery at level of ductus arteriosus
Imaging
- Frontal chest radiograph - Mass-like opacity in left superior mediastinum; may mimic mediastinal mass - Double left aortic arch and reverse 3 sign - No rib notching
- Lateral chest radiograph - Redundant aortic arch buckled forward at isthmus
- Best imaging tool: Contrast-enhanced 3D CT and MR angiography, phase-contrast CMR - Elongated distal aortic arch and proximal descending thoracic aorta with kinking and buckling - Evaluate for complications: Aneurysm formation, subclavian steal syndrome
- Pseudocoarctation of aorta (PCOA) distinguished from coarctation of aorta (COA) by - No hemodynamically significant aortic narrowing by MR or catheter angiography - No collateral arteries or significant poststenotic dilatation - No left ventricular hypertrophy
Top Differential Diagnoses
- Coarctation of aorta
- Aortic aneurysm
- Mediastinal mass
Pathology
- Elongation of distal aortic arch due to abnormal growth of preductal aorta
Diagnostic Checklist
- Sagittal views for CTA and MRA are most useful for demonstrating PCOA

TERMINOLOGY

Abbreviations
- Pseudocoarctation of aorta (PCOA)
Synonyms
- Aortic buckling
- Aortic kinking
- Atypical coarctation
- Nonobstructive coarctation
- Redundant aortic arch
Definitions
- Elongation and kinking of aortic arch and proximal thoracic aorta distal to origin of left subclavian artery (SCA) at level of ductus arteriosus
- Distinguished from coarctation of aorta (COA) by lack of hemodynamically significant stenosis

IMAGING

General Features

Best diagnostic clue

- Kinking and buckling of aorta at level of ductus arteriosus with pressure gradient < 25 mmHg

Location

- Aortic isthmus at site of attachment of ligamentum arteriosum distal to origin of left SCA

Size

- Normal caliber or dilatation > 4 cm, or, occasionally, stenotic at site of aortic buckling

Morphology

- Elongation of distal aortic arch (AA) and proximal descending thoracic aorta (DTA); acute anterior angulation of AA at level of ligamentum arteriosum without significant obstruction

Imaging Recommendations

Best imaging tool
```
- CTA or MRA
```

Protocol advice

- 3D CTA in sagittal orientation with MIP and MPR reconstructions
- 3D high-resolution MRA in sagittal view with MIP and volume rendering
- Time-resolved MRA for evaluation of flow patterns and collateral pathways
- Phase-contrast velocity-encoded sequence for measurement of peak velocities and pressure gradients
- Axial CT/MR useful for confident evaluation of coexisting venous anomaly
- Short-axis images useful for evaluation of coexisting bicuspid valve
- 4D flow MR for flow patterns and quantification

Radiographic Findings
- Frontal chest radiograph - Mediastinal widening, mass-like opacity in left superior mediastinum mimicking mediastinal mass or aneurysm - Double left AA sign - Aorta proximal to kinking appears higher than normal AA - Aorta distal to kinking appears lower than normal with tortuous AA course, producing S-shaped figure - Reverse 3 sign: Outlines medial side of aortic indentation in DTA and E sign in esophagogram - No rib notching
- Lateral chest radiograph - AA is buckled forward at isthmus

CT Findings

NECT

- Elongated and tortuous distal AA and proximal DTA
- Anterior and medial displacement of distal AA
- Kink in posterior and lateral margins of aorta at isthmus

CTA

- Elongated redundant distal AA and proximal DTA with kinking and buckling
- Minimal or no luminal narrowing of distal transverse arch at attachment of ligamentum arteriosum
- High AA extending into left supraclavicular region (children)
- Bicuspid aortic valve may be present
- Aortic aneurysm may be present
- Poststenotic dilatation ± depending on hemodynamic significance
- Abnormal origins of arch arteries; dilatation of brachiocephalic arteries

General - Distinguished from COA based on absent hemodynamically significant aortic narrowing, poststenotic dilatation, collateral arteries, and left ventricular hypertrophy

MR Findings

MRA

- Contrast-enhanced 3D MRA
        - Kinking and buckling of elongated and tortuous distal AA and proximal DTA
        - May be associated with aortic aneurysms due to altered hemodynamics
- Time-resolved MRA
        - May show steal phenomenon in presence of SCA stenosis as reversal of flow in vertebral artery
- Phase-contrast flow MR
        - No elevation of velocity; normal/minimal increased pressure gradient (peak pressure gradient < 25 mmHg) across kink
        - Flow reversal in steal phenomenon
- 4D flow CMR/4D phase-contrast CMR
        - Single 3D acquisition volume with accurate retrospective flow calculation through any plane
        - Quantification of flow volume, retrograde flow/fraction in aorta, peak velocity and gradient at site of maximum kinking
        - 3D flow visualization of highly disrupted flow patterns in tortuous aorta
        - Superior spatial coverage; better at capturing peak velocity of stenotic jet, which is absent in PCOA
        - Elevated wall shear stress (WSS) in PCOA may contribute to aorta dilatation or pseudoaneurysm due to its correlation with blood flow velocity
        - Elevated flow velocity and elevated peak WSS seen in kinked aorta/ PCOA
        - Aneurysm sacs associated with PCOA shows vortex flow during systole with lower peak WSS

General: Distinguished from COA based on absence of hemodynamically significant aortic narrowing, significant poststenotic dilatation, left ventricular hypertrophy, and collateral arteries

Angiographic Findings
- High position of AA
- Reverse 3 sign: Notch in descending aorta at attachment of short ligamentum arteriosum
- Gold standard for accurate pressure gradient measurement before intervention planning or if diagnostic uncertainty

DIFFERENTIAL DIAGNOSIS

Coarctation of Aorta
- Congenital narrowing of aorta at isthmus distal to left SCA origin - Diffuse hypoplasia of AA distal to origin of innominate artery may be associated
- Chest radiograph with rib notching or reverse E or 3 sign from pre- and poststenotic dilatation
- Hemodynamically significant stenosis - Elevated peak pressure gradient > 20 mmHg - Poststenotic aortic dilation - Collateral vessels: Internal mammary, intercostal, parascapular, epigastric arteries - Rib notching on chest XR - Left ventricular hypertrophy
- Both COA and PCOA associated with bicuspid aortic valve
Hypoplastic Aortic Arch
- Mostly in children; commonly seen in patients with COA
- If external diameter of distal arch segment is < 50% of ascending aorta; z-score of 2 or lower, no pressure gradient across narrowed portion
Aortic Aneurysm
- Usually seen in atherosclerotic aorta with calcified intimal plaque
- Saccular or fusiform dilatation with mural thrombus often present within periphery of aneurysm
- Commonly seen in older adult patients; may rupture or result in aortic dissection
Mediastinal Mass
- Mass-like opacity on chest radiograph
- CT and MR angiography can differentiate soft tissue mass from PCOA

PATHOLOGY

General Features

Etiology

- Elongated distal AA and proximal DTA due to failed compression of 3rd-7th dorsal aortic segments causing longer AA that kinks at ductus arteriosum level
- Short taut ligamentum arteriosum or patent ductus arteriosus

Associated abnormalities

- Aberrant SCA; cervical AA; left superior vena cava, left vertebral artery origin from AA, aneurysmal dilatation of SCA
- Aortic stenosis; sinus of Valsalva aneurysm; coarctation of distal descending aorta
- Bicuspid aortic valve; aortic valve incompetence; mitral valve prolapse
- Left-to-right shunts; atrial septal defect; ventricular septal defect; patent ductus arteriosus
- Aortic aneurysm leading to sudden aortic rupture or aortic dissection

Microscopic Features
- Aneurysms associated with PCOA result from cystic medial necrosis rather than atherosclerosis

CLINICAL ISSUES

Presentation

Most common signs/symptoms

- Usually asymptomatic or resistant or difficult to treat hypertension

Other signs/symptoms

- Symptoms related to complications
        - Aneurysm; may be asymptomatic or shortness of breath, hoarseness, and dysphagia due to compression
        - Aneurysm rupture or dissection with chest and back pain, shortness of breath, hypotension and hemothorax
        - Subclavian steal syndrome due to SCA stenosis
                  - Blood pressure discrepancy between upper extremities; dizziness, vertigo, and syncope
- Symptoms related to associated abnormalities; dysphagia from compression of esophagus
- Extreme caution needed while navigating PCOA for endovascular procedure, such as transcatheter aortic valve implantation (TAVI), to prevent aorta perforation

Demographics

Epidemiology

- Very uncommon congenital anomaly occurring in isolation or with other congenital heart diseases

Natural History & Prognosis
- Typically asymptomatic - Aneurysmal dilatation may develop; may result in rupture or dissection - Necessitates annual surveillance of thoracic aorta for early diagnosis and intervention of aortic aneurysm
Treatment
- Conservative management in asymptomatic and mildly symptomatic patients
- Surgical treatment for complications - Aneurysm formation - Open repair: Artificial or biologic grafts - Closed repair: Endovascular stent graft - Aortic dissection - Stanford type A: Surgery due to involvement of ascending aorta - Stanford type B: Medical control of hypertension is standard; surgery or endovascular stenting in complicated cases - Subclavian steal syndrome - Angioplasty/stenting of SCA - Common carotid artery-to-SCA bypass, innominate artery-to-SCA bypass, or axillary artery-to-axillary artery bypass

DIAGNOSTIC CHECKLIST

Image Interpretation Pearls
- Sagittal views for CTA and MRA are most useful for demonstrating PCOA - 3D CTA with MIP and MPR reconstructions - 3D MRA with MIP and volume rendering
- No hemodynamically significant aortic narrowing, poststenotic dilatation, left ventricular hypertrophy, or collateral arteries - Allows differentiation from COA

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References

Selected References

Differential diagnosis

Narrowed Aorta

DDX:763503a4-a7b8-4aff-8846-3dfbe312125c

Cases

{'cases': [{'authors': [{'key': None, 'value': None}, {'key': 'd06dfcc4-4b3a-4c2a-b6ae-6ac081d23b98', 'value': 'Jonathan Hero Chung, MD'}, {'key': '3d1e4c57-c1cf-4c89-b0f0-5d82b29a31e1', 'value': 'Suhny Abbara, MD, FACR, MSCCT, FNASCI'}], 'caseVersionId': '46419090-2276-43b0-af99-f8af72b59c4c', 'description': 'Sagittal oblique VR image from contrast enhanced CTA (#1) shows a redundant morphology of the aortic arch with kinking and mild narrowing (arrows) of the proximal descending aorta at the level of the ligamentum arteriosum, highly suggestive of pseudocoarctation. No enlarged collateral bronchial, intercostal, or internal mammary arteries are present, which suggests that the aortic narrowing is not hemodynamically significant. Short axis view of the aortic valve during diastole (#2) demonstrates an aortic bicuspid morphology (arrows). The right and left cusps are fused, resulting in the larger size of the anterior fused cusp (curved arrow); a small raphe (open arrow) is present. Bicuspid aortic valves are commonly associated with aortic coarctation; however, bicuspid aortic valves have also been described in the setting of pseudocoarctation. Coronal oblique MIP image (#3) shows dilation (open arrows) of the ascending aorta. \n\nComment: Bicuspid aortic valves are associated with ascending aortic aneurysms and dissection, even in the absence of significant aortic stenosis.', 'history': 'Patient with history of congential heart defect.', 'imagePoolId': '9aeb1d4b-6c4a-45a1-9416-30d6f8237358', 'name': 'Bicuspid aortic valve', 'teachingPoint': None}], 'caseType': 'typical', 'name': 'TYPICAL'}

Images

Selected Images

Coronal oblique graphic in a patient with pseudocoarctation of the aorta (PCOA) demonstrates an elongated, kinked, and buckled aortic arch distal to the origin of left subclavian artery at the level of the ductus arteriosus.

Sagittal oblique volume-rendered CTA shows kinking and mild narrowing of the proximal descending aorta at the level of the ligamentum arteriosum, consistent with pseudocoarctation. No enlarged collateral bronchial, intercostal, or internal mammary arteries are present.

Posteroanterior chest radiograph shows a prominent and high-riding aortic arch . The normal heart size and absence of rib notching due to collateral vessels distinguish PCOA from coarctation of the aorta (COA).

Lateral chest radiograph in the same patient demonstrates forward buckling of the aortic arch at the isthmus. The aorta is enlarged proximal to the narrowed segment .

PA radiograph with bone subtraction (left) in a 67-year-old man shows abnormal elongation of the proximal descending thoracic aorta (DTA) , which can be visualized in coronal 3D volume-rendered image (right).

Lateral radiograph shows elongation and superior extension of the aortic arch , which then courses inferiorly with kinking before taking its normal course . These findings are highly suggestive of pseudocoarctation.

MIP (left) and volume-rendered (right) images in the same patient show aortic PCOA with elongation and superior extension of the proximal DTA , which then extends inferiorly with kinking before taking its normal course .

PCOA in an asymptomatic 72-year-old woman shows elongation and kinking of the proximal DTA. There was no gradient across the lesion on phase-contrast MR. The aorta is aneurysmal distal to PCOA, measuring 3.5 cm.

Sagittal 3D volume-rendered CTA in a patient with PCOA demonstrates kinking and mild narrowing of the proximal descending aorta at the level of the ligamentum arteriosum.

Axial CECT in a patient with PCOA shows marked kinking and buckling of the aortic arch . No enlarged collateral bronchial, intercostal, or internal mammary arteries are identified.

Additional Images

Axial PC MR obtained just distal to the pseudocoarctation shows an absence of increased flow velocity. Note that the bright signal in the ascending aorta indicates flow in the cephalad direction , and the dark signal in the descending aorta indicates caudal flow .

Sagittal thin MIP contrast-enhanced MRA shows a very elongated and abnormal aortic arch with areas of aneurysmal dilatation of aortic arch proximal to and narrowing (PCOA). Note the abnormal origin of the left common carotid artery from the pseudocoarctation

Coronal CTA shows a dilated and elongated right aortic arch , which is irregular and peripherally calcified. Note that there is extension of the aortic arch into the right lower neck , PCOA and presence of an aberrant left subclavian artery .

Sagittal 3D volume-rendered CTA in the same patient shows an abnormally dilated and buckled aorta and the origins of the innominate and left subclavian arteries. (Courtesy S. Tanju, MD.)

Coronal oblique thin MIP contrast-enhanced MRA shows aneurysmal dilatation of the aortic arch , which extends to the supraclavicular space and narrowing of distal aortic arch . Also note the stretching of the supraaortic arteries.

Axial CTA in the same patient shows a dilated right aortic arch and a high-grade stenosis of the origin of the aberrant left subclavian artery . (Courtesy S. Tanju, MD.)

Sagittal reformatted black-blood MR shows narrowing of the thoracic aorta distal to the left subclavian artery . Phase-contrast flow quantification (not shown) revealed normal peak velocity and gradient across the narrowed segment, indicating PCOA.

Axial black-blood MR demonstrates size discrepancy between the ascending aorta and the proximal DTA at isthmus . Note the lack of collateral vessels consistent with PCOA.

Sagittal reformatted CECT shows kinking of distal aortic arch with narrowing of the aortic isthmus just distal to the left subclavian artery . Note severe aortic valve calcifications in this patient with associated aortic valve stenosis .Abnormalities commonly associated with PCOA include aortic stenosis, bicuspid aortic valve, and left-to-right shunts.

3D volume-rendered CTA in a patient with PCOA shows narrowing of the aortic arch and dilatation of the aorta proximal to the narrowed segment . Note the diminished size of the DTA distal to the site of narrowing.

3D volume-rendered CTA in the same patient demonstrates marked kinking and tortuosity of the aortic arch . The lack of poststenotic dilatation and absence of collateral vessels are consistent with PCOA.

Axial CECT in a patient with PCOA demonstrates kinking and buckling of the aortic arch, which is elongated and tortuous . Note the notch in the distal transverse aortic arch at the attachment of the ligamentum arteriosum.

Axial CECT in a patient with PCOA shows dilatation of the aorta proximal to the narrowed segment and diminished size of the DTA distal to the narrowed segment . Note the lack of collateral vessels in the mediastinum.

34 KiB Raw Blame History

KEY FACTS

Terminology

Imaging

Top Differential Diagnoses

Pathology

Diagnostic Checklist

TERMINOLOGY

Abbreviations

Synonyms

Definitions

IMAGING

General Features

Best diagnostic clue

Location

Size

Morphology

Imaging Recommendations

Best imaging tool

Protocol advice

Radiographic Findings

CT Findings

NECT

CTA

MR Findings

MRA

Angiographic Findings

DIFFERENTIAL DIAGNOSIS

Hypoplastic Aortic Arch

Aortic Aneurysm

Mediastinal Mass

PATHOLOGY

General Features

Etiology

Associated abnormalities

Microscopic Features

CLINICAL ISSUES

Presentation

Most common signs/symptoms

Other signs/symptoms

Demographics

Epidemiology

Natural History & Prognosis

Treatment

DIAGNOSTIC CHECKLIST

Image Interpretation Pearls

References

Selected References

Differential diagnosis

Narrowed Aorta

Cases

Images

Selected Images

Additional Images

34 KiB

Raw Blame History