Transposition of the Great Arteries Flashcards
Concordance in normal heart?
- AV (atrioventricular) concordance: LA to LV; RA to RV
- VA (ventricular arterial) concordance: LV to aorta; RV to PA
Key abnormalities in complete transposition of the great arteries (d-TGA)?
- Transposed Ao and PA
- PDA
- Great arteries are transposed so there is VA discordance: LV to PA; RV to aorta
Characteristics of d-TGA?
- PA arises from morphological LV and aorta arises from morphological RV
- Communication between atria via PFO and/or communication between aorta and PA via PDA
How does d-TGA occur?
- Occurs when coco-truncal septum fails to grow in its normal spiral course and instead runs straight down
- As a result, aorta is anterior and rightward and arises from RV
- PA is posterior and leftward arising from LV
d-TGA: Circulatory Pathway
- Deoxygenated blood from IVC and SVC enters RA and flows to RV –> aorta –> systemic circulation
- Oxygenated blood returning from pulmonary veins –> LA –> LV –> PA to lungs
- 2 circulations, systemic and pulmonary, are in parallel rather than in series
- In order to survive, communication between atria via PFO and/or communication between aorta and PA via PDA must also exist
d-TGA: Associated lesions?
- VSD
- Pulmonary outflow tract obstruction
- CoAo
- Aortic arch hypoplasia
- Variations in coronary artery origin and course
d-TGA: Associated syndromes?
- DiGeorge Syndrome
- Down Syndrome
- Goldenhar Syndrome
How is d-TGA diagnosed?
- Diagnosed in PLAX by demonstrating side-by-side parallel alignment of aorta seen anteriorly and PA seen posteriorly
- From PSAX, both great vessels are seen in their short axis wth aorta seen anterior to PA
- Normal sausage or circle appearance of great arteries is absent from PSAX
Palliative procedures in d-TGA?
Palliative procedures such as balloon septostomy may be performed in infants with TGA when PFO inadequate and when PDA has closed, or in anticipation of ductal closure
Echo in balloon septostomy?
- Commonly performed under echo guidance
- Used to ensure inflated balloon is within LA and not across MV prior to jerking balloon back across IAS
- Aim to increase size of PFO or to create a small ASD
Echo Post Balloon Septostomy?
Assess efficiency of septostomy; look at size of hole in IAS and degree of shunting through this defect
Options of surgical repair in d-TGA?
- Atrial switch (Mustard and Senning)
- Arterial switch (Jatene)
What is the Atrial Switch operation?
- At atrial level, vena canal flow is baffled to a systemic venous atrium (SVA), across MV, to LV and ejected to PA
- Pulmonary venous flow is baffled to a pulmonary venous atrium (PVA), across TV to RV and ejected to aorta
- As a result, circulation is corrected
Circulation post atrial switch operation?
- Vana cava –> SVA –> MV –> LV –> PA –> lungs
- Pulmonary veins –> PVA –> TV –> RV –> aorta –> systemic circulation
Role of echo post atrial switch?
- Intra-atrial channel potency
- RV and LV size and systolic function
- TR severity
- PASP (LVSP from MR)