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Slings

Vascular Rings - Slings

1. Complete Rings

A. Double Aortic Arch
3) Balanced
B. Left ligamentum
1) Retroesophageal L subclavian
2) Mirror image branching

2. Incomplete Rings

A. Innominate artery compression syndrome
B. Pulmonary artery sling (RPA off LPA behind trachea)

3. Clinical Symptoms

A. Present in first 6 months
B. Respiratory distress, stridor, cough, dysphagia
C. Early presentation in double arch
D. Apnea - innominate artery tracheal compression

4. Diagnostic Studies

A. Chest x-ray - arch location, tracheal compression
B. Barium swallow - posterior indentation
1) Sling - anterior indentation
C. MRI - definitive study
D. Bronchoscopy - innominate artery/pulmonary sling

5. Operation Double Aortic Arch

A. Left thoracotomy
B. Divide ligamentum
C. Divide and oversew lesser of 2 arches
D. Divide adhesive bands

6. Operation Right Arch/Left Ligamentum

A. Left thoracotomy
B. Divide ligamentum
C. Kommerell's diverticulum to chest wall

7. Operation Innominate Artery Compression - Suspension

A. Right thoracotomy
B. Resect thymus
C. Suspend innominate artery to sternum
D. Post-operative bronchoscopy optional

8. Operation Innominate Artery Compression - Re-implantation

A. Optional operation
B. Moves origin so IA does not cross trachea

9. Operation Pulmonary Artery Sling

A. Median sternotomy
B. Cardiopulmonary bypass
C. Reimplant LPA into main PA
D. LPA anterior to trachea
E. Tracheoplasty for complete rings

10. Results Pulmonary Artery Sling

A. Op mortality < 0% rings/IA compression
B. Op mortality 10-20% PA sling
C. Permanent relief of symptoms >90%
D. Patency of PA sling >90%
E. Tracheoplasty long-term results unknown

11. Summary

A. High suspicion based on symptoms
B. Chest x-ray, MRI, Barium esophagram
C. Operative approach based on anatomy
D. Symptoms relieved in 90%

EXTENDED OUTLINE

1. Classification

A. Double Aortic Arch
B. Right Arch with left ligament
C. Left Arch with arch vessel anomalies
D. PA sling

2. Embryology

A. Complete Ring
1) Double Aortic Arch (DAA)
a) Right dominant (70%), Left dominant (20%), and balanced (10%)
b) persistence of R 4th arch
c) R CCA & SCA off the R arch
d) L CCA & SCA off the L arch
e) R arch is usually dominant and travels posteriorly to the esophagus to join the descending aorta
2) Right Arch with left ligament
a) persistence of R arch with involution of the L between the L CCA & the L SCA
b) Retroesophageal L SCA (65%), or mirror image branching (35%)
c) Kommerrell's diverticulum may be present at the base of the SCA
B. Incomplete Ring
1) L Arch with aberrant R SCA
a) secondary to regression of the R arch between the R CCA & R SCA
b) aberrant R SCA deforms the esophagus posteriorly
c) most common arch anomaly (incidence of 0.5%), but is not a complete vascular ring
2) L Arch with aberrant innominate
a) leftward and posterior displacement of the innominate on the arch
b) anterior compression of the trachea
3) PA Sling
a) L lung captures the arterial supply from the R 6th arch instead of the L 6th arch
b) origin of the L PA off the R PA
c) courses between the trachea and the esophagus causing anterior compression of the esophagus
d) associated with tracheobronchial malacia and complete tracheal rings
e) associated with intracardiac defects

3. Presentation

A. symptoms secondary to compressive effects of on the trachea and the esophagus
B. occasional stridor, brassy cough, misdiagnosed asthma, frequent URI's
C. dysphagia less common and presents as infant progresses from liquids to solids
D. with innominate artery compression 1/2 have apneic spells

4. Diagnosis

A. CXR - diagnosis a R arch
B. Barium swallow - indentation of the esophagus
1) DAA or R arch with L ligamentum have a deep posterior indentation
2) R arch with aberrant L SCA has an oblique posterior indentation
C. Angiogram - rarely needed
D. Bronchoscopy/Bronchography - especially needed with PA sling
E. MRI/CT - very good at defining anatomy
1) " 4 artery sign" - 2 SCA's and 2 CCA encircling the trachea
2) disadvantage of not visualizing nonvascular structures

5. Treatment

A. General
1) all symptomatic patients ASAP
2) Asymptomatic patients
a) complete ring - elective repair
b) incomplete ring - follow clinically
B. Double Arch
1) Left posteriolateral thoracotomy
2) divide the smaller of the two arches
a) usually between the CCA and the SCA
3) ligate the duct and fibrous tissue being careful of the recurrent laryngeal nerve
C. R Arch with L Ligamentum
1) Left posteriolateral thoracotomy
2) Divide the ligament
3) Kommorrell's diverticulum, pex or resect
D. L Arch with aberrant R SCA
1) most are truly asymptomatic
2) Symptoms
a) ligate R SCA in small children
b) reimplant in most others
E. L Arch with aberrant innominate
1) suspend the arch to the posterior sternum
2) reimplant the innominate to the right and anterior on the arch
F. PA Sling
1) median sternotomy
2) address tracheomalacia the primary repair or pericardial patch
3) reimplant L PA on to the main PA

4. Results

A. up to 1/2 have abnormal flow on formal pulmonary testing at one year despite been asymptomatic
B. noisy breathing may take awhile to resolve
C. successful 95% of the time
D. minimal morbidity except with PA Sling