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Interrupted/Hypoplastic Aorta 100ba59a-24e8-47b4-b2b2-bbfdc0a21e92
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770e1d77-2287-436e-910b-48232afc7842 Prabhakar Rajiah, MBBS, MD, FACR, FRCR, FACC, FAHA, FSCCT
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e915766e-8102-46e4-a33e-c83f8ae12f29 Harold Goerne, MD
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Cardiac 00b8d951-9dbc-40d4-9499-c8705f77762e 15 01/28/25 Interrupted/Hypoplastic Aorta Cardiac, Diagnosis, Aorta, Interrupted/Hypoplastic Aorta Interrupted/Hypoplastic Aorta | STATdx Interrupted/Hypoplastic Aorta DX true
Cardiac
Diagnosis
Aorta
Interrupted/Hypoplastic Aorta

title: "Interrupted/Hypoplastic Aorta" docid: "100ba59a-24e8-47b4-b2b2-bbfdc0a21e92" authors:

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  • name: "Interrupted/Hypoplastic Aorta" slug: "interruptedhypoplastic-aorta" treeNodeId: null category: "Cardiac" documentVersionId: "00b8d951-9dbc-40d4-9499-c8705f77762e" imageCount: 15 lastUpdated: "01/28/25" pageDescription: "Interrupted/Hypoplastic Aorta" pageKeywords: "Cardiac, Diagnosis, Aorta, Interrupted/Hypoplastic Aorta" pageTitle: "Interrupted/Hypoplastic Aorta | STATdx" enhancedTitle: "Interrupted/Hypoplastic Aorta" type: "DX" references: true breadcrumbs:
  • "Cardiac"
  • "Diagnosis"
  • "Aorta"
  • "Interrupted/Hypoplastic Aorta"

KEY FACTS

  • Terminology

    • Interrupted aortic arch - Complete luminal and anatomic wall discontinuity between ascending aorta and descending aorta
    • Hypoplastic aortic arch - Tubular narrowing without luminal discontinuity

  • Imaging

    • CTA - Best noninvasive modality to assess aortic arch and supraaortic vessels pattern
    • US - 1st-line modality to assess aortic arch abnormalities
    • Best diagnostic clue - Interrupted aortic arch - Blind ends in distal ascending aorta and proximal descending aorta with luminal discontinuity in between - Hypoplastic aortic arch - Tubular narrowing of aortic arch; proximal aortic arch < 60% &/or distal aortic arch < 50% of diameter of ascending aorta

  • Top Differential Diagnoses

    • Coarctation of aorta

  • Pathology

    • Type A (13%) - Interruption distal to left subclavian artery
    • Type B (84%) - Interruption between left common carotid artery and left subclavian artery
    • Type C (3%) - Interruption between brachiocephalic trunk and left common carotid artery

  • Clinical Issues

    • Rare condition - 1% of congenital heart disease

TERMINOLOGY

  • Abbreviations

    • Interrupted aortic arch (IAA)
    • Hypoplastic aortic arch (HAA)

  • Synonyms

    • Atresia of aortic arch

  • Definitions

    • IAA - Complete luminal discontinuity between ascending aorta and descending aorta - Not true interruption, as there is fibrotic continuity between blind ends
    • HAA - Tubular narrowing of aortic arch without luminal discontinuity

IMAGING

  • General Features

    • Best diagnostic clue

      - IAA
        - Blind-ending distal ascending aorta and proximal descending aorta with luminal discontinuity in between
- HAA
        - Tubular narrowing of aortic arch
                  - Proximal arch < 60% &/or distal aortic arch < 50% of diameter of ascending aorta
                  - Transverse aortic arch z-score usually < -3

    • Location

      - Aortic arch: Proximal or distal

    • Size

      - Variable

    • Morphology

      - IAA: Complete anatomic discontinuity between ascending aorta and descending aorta
- HAA: Tubular narrowing of aortic arch

  • CT Findings

    • CTA

      - Interruption: Blind ending ascending and descending aorta without luminal opacification of arch
        - Type, site, and length of interruption
        - Type A: Distal to left subclavian artery
        - Type B: Between left common carotid and subclavian arteries
        - Type C: Between right brachiocephalic and left common carotid arteries
- Hypoplasia: Small caliber of aortic arch
        - Best modality for measuring vessel diameters
- Best noninvasive modality to assess aortic arch and supraaortic vessels pattern
- New-generation scanners provide faster acquisition without sedation or ECG gating
- High-resolution 3D reconstructions provides roadmap for surgery

  • MR Findings

    • MRA

      - High-resolution images of aorta without radiation; can be performed ± contrast
- Types of interrupted arch
- Shows diameters of each aortic segment and length of HAA
        - Hypoplasia: External diameter of proximal arch, distal arch, or isthmus measuring < 60%, < 50%, or < 40% of that of ascending aorta
        - Transverse aortic arch z-score usually < -3
        - This assumes that ascending aorta diameter is normal
- Dynamic MRA shows multiple vascular phases, providing information about aorta, pulmonary arteries and veins, and systemic venous return pattern with single gadolinium injection
- Associated anomalies can be evaluated

    • MR cine

      - Biventricular function assessment, including ejection fraction, end-diastolic, and end-systolic volumes
- Wall motion abnormalities
- Evaluation of additional intracardiac abnormalities (such as septal defects)

  • Ultrasonographic Findings

    • 1st modality to assess aortic arch abnormalities in children
    • Define true interruption or HAA and type of IAA by looking at pattern of supraaortic trunks
    • Associated patent ductus arteriosus (PDA) - Size, flow, aortic and pulmonary ostial diameters
    • Associated cardiac abnormalities: Atrial septal defect (ASD), ventricular septal defect (VSD), left ventricular outflow tract (LVOT) obstruction, aorticopulmonary window defect

  • Imaging Recommendations

    • Best imaging tool

      - CTA or MRA

    • Protocol advice

      - Newborn and infants: Contrast injection based on body weight
- Bolus tracking position and HU threshold are variable and depend on scanner speed to start acquisition
- Newborn and infants: Acquisition can be started immediately after contrast injection

DIFFERENTIAL DIAGNOSIS

  • Coarctation of Aorta

    • Focal narrowing at aortic isthmus - Same location as type A interruption
    • Usually short segment of luminal narrowing
    • No complete loss of continuity, like interruption - Occasionally, extremely tight stenosis may be seen
    • More pronounced poststenotic dilation - In interruption, arch is smaller caliber, and branch vessels are straighter than normal
    • With advanced cases, distinguishing features may disappear

  • Focal Atresia of Aortic Arch

    • Most common at aortic isthmus, similar to type A interruption
    • Lumen is interrupted, but aortic wall is present
    • Fibrous strand between ascending and descending aorta

PATHOLOGY

  • General Features

    • Etiology

      - Type A
        - Abnormal regression of left 4th aortic arch late in development after left subclavian artery is in position
                  - Reduced blood flow through 4th aortic arch during embryologic phase
                  - Insufficient development of aortic arch with spectrum from coarctation to atresia to IAA
                  - Conal septum not malaligned or deviated; no subaortic stenosis
- Type B
        - High association with chromosome 22q11.2 microdeletion
        - Abnormal regression of left 4th arch, early in development, before cephalad migration of left subclavian artery
        - Malalignment of infundibular septum with muscular septum → LVOT narrowing → decreased growth, hypoplasia, and interruption of arch due to absolute decrease in cardiac output
- Type C
        - Abnormal regression of ventral portion of left 3rd and 4th arches

    • Genetics

      - 50% of patients with IAA have chromosome 22q11.2 deletion
- 42% of patients with DiGeorge syndrome have IAA

    • Associated abnormalities

      - IAA
        - PDA is essential for life in all patients (seen in 97% of cases)
        - VSD in 90% of IAA
        - Other congenital heart abnormalities are present in 98%
                  - Subaortic stenosis
                  - Bicuspid aortic valve
                  - Truncus arteriosus
                  - Aortopulmonary window
                  - Transposition of great arteries
                  - Double-outlet right ventricle
                  - Functional single ventricle
                  - Persistent 5th arch
                  - Anomalous origin of subclavian artery
- HAA
        - ASD
        - VSD
        - PDA

  • Staging, Grading, & Classification

    • Type A (13%) - Interruption distal to left subclavian artery
    • Type B (84%) - Interruption between left common carotid artery and left subclavian artery
    • Type C (3%) - Interruption between right brachiocephalic trunk and left common carotid artery
    • In any of these types, 3 subtypes may be seen depending on origin of right subclavian artery - Subtype 1: Normal subclavian artery origin - Subtype 2: Aberrant right subclavian artery distal to origin of left subclavian artery - Subtype 3: Isolated right subclavian artery originating from right ductus arteriosus

CLINICAL ISSUES

  • Presentation

    • Most common signs/symptoms

      - Differential cyanosis (ductal right-to-left shunt)
        - Type A
                  - Normal saturation in both arms and head, desaturated legs
        - Type B
                  - Normal saturation in right arm and head, desaturated left arm and legs
        - Type C
                  - Normal saturation in right arm and right carotid artery, desaturated left carotid artery, left arm and legs

    • Other signs/symptoms

      - When ductus arteriosus begins to close, neonate develops signs of hypoperfusion and cardiogenic shock
- Death usually occurs 4-10 days after closure of ductus arteriosus
        - By 1 month, 76% of untreated infants are dead; by 1 year, > 90% are dead

  • Demographics

    • Age

      - Neonates

    • Sex

      - Male patients: 59%
- Female patients: 41%

    • Epidemiology

      - Rare condition
        - 1% of congenital heart disease
- 2/100,000 live births

  • Natural History & Prognosis

    • When untreated and ductus arteriosus closes, distal hypoperfusion leads to renal failure, lactic acidosis, and eventually death in few days

  • Treatment

    • Surgical correction is only treatment; goal is to establish continuity in aortic arch
    • Prostaglandin E₁ is given to maintain patency of ductus arteriosus until neonate is stable for surgical correction

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References

Selected References

  1. Evans WN et al: Prenatal diagnosis of hypoplastic aortic arch without intracardiac malformations: the nevada experience. J Card Surg. 37(11):3705-10, 2022
  2. LaPar DJ et al: Surgical considerations in interrupted aortic arch. Semin Cardiothorac Vasc Anesth. 22(3):278-84, 2018
  3. Hanneman K et al: Congenital variants and anomalies of the aortic arch. Radiographics. 37(1):32-51, 2017
  4. Goudar SP et al: Echocardiography of coarctation of the aorta, aortic arch hypoplasia, and arch interruption: strategies for evaluation of the aortic arch. Cardiol Young. 26(8):1553-62, 2016
  5. Roubertie F et al: Aortopulmonary window and the interrupted aortic arch: midterm results with use of the single-patch technique. Ann Thorac Surg. 99(1):186-91, 2015
  6. Ramos-Duran L et al: Developmental aortic arch anomalies in infants and children assessed with CT angiography. AJR Am J Roentgenol. 198(5):W466-74, 2012
  7. Hellinger JC et al: Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT. Radiol Clin North Am. 49(5):969-96, 2011
  8. Frank L et al: Cardiovascular MR imaging of conotruncal anomalies. Radiographics. 30(4):1069-94, 2010
  9. Kimura-Hayama ET et al: Uncommon congenital and acquired aortic diseases: role of multidetector CT angiography. Radiographics. 30(1):79-98, 2010
  10. Dillman JR et al: Interrupted aortic arch: spectrum of MRI findings. AJR Am J Roentgenol. 190(6):1467-74, 2008
  11. Yang DH et al: Multislice CT angiography of interrupted aortic arch. Pediatr Radiol. 38(1):89-100, 2008
  12. Loffredo CA et al: Interrupted aortic arch: an epidemiologic study. Teratology. 61(5):368-75, 2000
  13. Kaulitz R et al: Echocardiographic assessment of interrupted aortic arch. Cardiol Young. 9(6):562-71, 1999
  14. Reardon MJ et al: Interrupted aortic arch: brief review and summary of an eighteen-year experience. Tex Heart Inst J. 11(3):250-9, 1984
  15. CELORIA GC et al: Congenital absence of the aortic arch. Am Heart J. 58:407-13, 1959

Images

Selected Images

Posterior oblique CTA cinematic rendering shows type B interrupted aortic arch with an aberrant right subclavian artery . Also note the collateral vessel with right carotid artery . Left carotid artery and left subclavian artery (LSA) are also shown. Posterior oblique CTA cinematic rendering shows type B interrupted aortic arch with an aberrant right subclavian artery . Also note the collateral vessel with right carotid artery . Left carotid artery and left subclavian artery (LSA) are also shown.

Posterior oblique CTA cinematic rendering shows type B interrupted aortic arch with an aberrant right subclavian artery . Also note the collateral vessel with right carotid artery . Left carotid artery and left subclavian artery (LSA) are also shown. Posterior oblique CTA cinematic rendering shows type B interrupted aortic arch with an aberrant right subclavian artery . Also note the collateral vessel with right carotid artery . Left carotid artery and left subclavian artery (LSA) are also shown.

Anterosuperior oblique CTA cinematic rendering shows type B interrupted aortic arch (IAA) with aberrant right subclavian artery . Patent ductus arteriosus (PDA) provides blood flow to both subclavian arteries and the distal descending aorta (DA). Anterosuperior oblique CTA cinematic rendering shows type B interrupted aortic arch (IAA) with aberrant right subclavian artery . Patent ductus arteriosus (PDA) provides blood flow to both subclavian arteries and the distal descending aorta (DA).

Sagittal oblique MIP CTA shows a hypoplastic aortic arch and PDA . Sagittal oblique MIP CTA shows a hypoplastic aortic arch and PDA .

Sagittal oblique CTA cinematic rendering in the same patient shows a hypoplastic aortic arch and PDA . CT is the best noninvasive imaging modality to assess aortic arch and supraaortic vessel patterns as well as to measure vessel diameters. Sagittal oblique CTA cinematic rendering in the same patient shows a hypoplastic aortic arch and PDA . CT is the best noninvasive imaging modality to assess aortic arch and supraaortic vessel patterns as well as to measure vessel diameters.

Anterosuperior oblique CTA cinematic rendering shows type B IAA. The brachiocephalic trunk (BCT) and left carotid artery originate from the proximal aorta. The LSA originates from the ductal arch. Anterosuperior oblique CTA cinematic rendering shows type B IAA. The brachiocephalic trunk (BCT) and left carotid artery originate from the proximal aorta. The LSA originates from the ductal arch.

Sagittal oblique MIP CTA shows type B IAA . The BCT and left common carotid artery (LCC) originate from the proximal aorta. The LSA originates from the ductal arch. Sagittal oblique MIP CTA shows type B IAA . The BCT and left common carotid artery (LCC) originate from the proximal aorta. The LSA originates from the ductal arch.

CTA cinematic rendering demonstrates type B IAA. The LSA originates from the DA . The BCT and LCC originate from the proximal ascending aorta (AA). The PDA provides blood flow to both the LSA and DA. CTA cinematic rendering demonstrates type B IAA. The LSA originates from the DA . The BCT and LCC originate from the proximal ascending aorta (AA). The PDA provides blood flow to both the LSA and DA.

Sagittal oblique CTA cinematic rendering shows a hypoplastic distal aortic arch involving the isthmus and proximal DA . Sagittal oblique CTA cinematic rendering shows a hypoplastic distal aortic arch involving the isthmus and proximal DA .

Neonate with type A IAA shows AA terminating as the BCT , LCC , and LSA (left). Notice the AP window defect between the AA and main pulmonary artery (MPA) . A PDA supplies the DA . PA branches are visible. Neonate with type A IAA shows AA terminating as the BCT , LCC , and LSA (left). Notice the AP window defect between the AA and main pulmonary artery (MPA) . A PDA supplies the DA . PA branches are visible.

Coronal (left) and sagittal (right) images in a neonate with type B IAA show the AA terminating as the BCT and LCC . The LSA and DA are supplied by a PDA . PA branches arise from the MPA. (Courtesy S. Kligerman, MD.) Coronal (left) and sagittal (right) images in a neonate with type B IAA show the AA terminating as the BCT and LCC . The LSA and DA are supplied by a PDA . PA branches arise from the MPA. (Courtesy S. Kligerman, MD.)

Additional Images

CTA cinematic rendering demonstrates a hypoplastic aortic arch with severe coarctation . Note the decreased diameter of the aortic arch due to hypoplasia. CTA cinematic rendering demonstrates a hypoplastic aortic arch with severe coarctation . Note the decreased diameter of the aortic arch due to hypoplasia.

Sagittal oblique MIP CTA in the same patient demonstrates decreased diameter of the aortic arch due to a hypoplastic aortic arch and associated severe aortic coarctation . Sagittal oblique MIP CTA in the same patient demonstrates decreased diameter of the aortic arch due to a hypoplastic aortic arch and associated severe aortic coarctation .

Coronal (left) and sagittal (right) oblique images in a 1-day-old with type B IAA show a hypoplastic ascending aorta terminating as the right common carotid and left common carotid arteries. The PDA supplies the descending thoracic aorta (DTA) . A portion of the LSA is seen from the DTA. Coronal (left) and sagittal (right) oblique images in a 1-day-old with type B IAA show a hypoplastic ascending aorta terminating as the right common carotid and left common carotid arteries. The PDA supplies the descending thoracic aorta (DTA) . A portion of the LSA is seen from the DTA.

Coronal image in the same patient shows that an aberrant right subclavian artery arises from the DTA distal to the LSA , making this a type B IAA, subtype 2. Coronal image in the same patient shows that an aberrant right subclavian artery arises from the DTA distal to the LSA , making this a type B IAA, subtype 2.

3D image in a neonate with type B IAA shows the ascending aorta terminating as the right BCT and LCC . The PDA supplies the descending thoracic aorta and LSA . (Courtesy S. Kligerman, MD.) 3D image in a neonate with type B IAA shows the ascending aorta terminating as the right BCT and LCC . The PDA supplies the descending thoracic aorta and LSA . (Courtesy S. Kligerman, MD.)

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