tga.pdf
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Transposition of the Great Arteries Preoperative Diagnostic Considerations
John Simpson Evelina Children’s Hospital
London, UK
Euroecho , Copenhagen 2010
Areas to be covered
Definitions
Scope of occurrence of transposition of the great arteries
Echocardiographic findings
Important considerations
Euroecho , Copenhagen 2010
Transposition of the great arteries
The aorta arises predominantly / exclusively from the morphologic right ventricle
The pulmonary artery arises predominantly / exclusively from the morphologic left ventricle
The relationship of the great arteries to each other does not define the condition e.g. aorta anterior
Euroecho , Copenhagen 2010
Morphologies
Transposition of the great arteries may occur in association with a wide range of morphologies
As an example, Pascal et al (2007)
120 consecutive cases of prenatal transposed Gas
56 cases had concordant atrioventricular connection
64 cases had other subarterial morphologies
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Morphologies
Pascal 2007
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“Simple” transposition of the great arteries
Image : www.umich.edu
Differential sats : UL < LL
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Prenatal diagnosis
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Paris Data
Bonnet et al, Circulation, 1999
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“Simple” transposition of the great arteries
Inadequate mixing
Restrictive PFO
Restrictive duct
Has a significant impact on outcome
Image : www.umich.edu
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Cardiac Situs
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Interatrial Communication
Restrictive Unrestrictive
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Balloon Atrial Septostomy
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Four Chamber View
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Subcostal Views of Great Arteries
LV to PA Ao from RV
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Transposition of the Great Arteries
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Parasternal Long Axis
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Parasternal short axis
Ao
PA
Ao
PALR
Ant
Post Both of these examples taken from infants with TGA
The spatial relationship of the great arteries does not define
the lesion
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Suprasternal Views
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Late presentation Once PVR falls postnatally, the LV faces pulmonary vascular resistance
LV involutes
Primary arterial switch impossible
Careful evaluation if presentation beyond 4-6 weeks of age with simple TGA
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Late presentation of TGA
Note septal appearance “Hyperdynamic” LV
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The Coronary Arteries
Key point: Draw a labelled diagram of the coronaries
Coronaries almost invariably from “facing” sinuses
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Coronary arteries
Ao PA
RCA
LAD Anterior
Posterior
LR
Do not be fooled by pericardial folds
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Coronary Arteries
Coronary artery abnormalities are important prognostically
e.g Can an arterial switch operation be performed ?
Identification of :
Intramural
Single coronary artery
particularly important
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Associated Lesions
Ventricular septal defect
AV valve abnormalities
Pulmonary / Subpulmonary Stenosis
Aortic obstruction
Coronary artery abnormalities
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Ventricular Septal Defect
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Ventricular Septal Defect
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Watch for multiple VSDs
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Mitral Valve Abnormalities
RA
LA
LV
RV
MV
Attachments
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Cleft Mitral Valve
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Cleft Mitral Valve
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Subpulmonary Obstruction
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Subpulmonary Obstruction
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Doppler Assessment
Day 1 : Vmax 1.5m/s
Day 10 : Vmax 3.2m/s
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Arch Views in TGA
Aortic arch above ductal arch
Aortic and ductal arches similar plane
Ductal patency may obscure
coarctation of the aorta
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Relative size and relationship of GAs
Ao
PA
PA
Ao Ao
PA
Long Axis Short Axis
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Careful Assessment of Aortic Arch
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Tips and tricks : Transposition Initial assessment
1. Know the upper and lower limb saturations
The upper limbs are most important – brain sats
2. Baby should be on PGE to maintain ductal patency
3. If sats v. low, get senior help early
4. Know the baby’s age !
Rapidly assess main diagnostic points
VA discordance
Mixing status
Atrial mixing
Duct
Ventricular septal defects
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Further assessment
Ventricular septum
VSDs often slit like, take multiple views / 3D
Watch out for multiple VSDs , check the apex !
AV Valves
Do not assume normal AV valve morphology e.g. MV cleft
Careful exclusion of outflow tract obstruction
CF: reassess when PVR falls
Identify “potential” obstruction
Check the aortic arch particularly carefully
Exclusion of coarctation difficult in TGA
Occasionally septostomy + leave off PGE