TGA

Question 1

Define TGA

Answer 1

Transposition of great arteries → ventriculoarterial discordance
* Ao from morphologic RV
* PA from morphologic LV

Question 2

Types of TGA

Answer 2

Complete/simple - D TGA
Congenitally corrected L TGA

Question 3

D TGA: features and situs

Answer 3

• Ventriculoarterial discordance + atrioventricular concordance
  o Situs solitus of atria = RA → RV and LA → LV
  o D-looping of ventricles
  o Anterior rightward Ao (D): subaortic conus

Question 4

D-TGA physiology

Answer 4

• 2 independent circulations in //
  o Systemic venous blood → RA → RV → Ao
  o Pulmonary venous blood → LA → LV → PA
  o Life maintained by 1 or > communication: systemic and pulmonary circulation joined
   ASD → almost all
   VSD → 1/3
   PDA → 2/3

Question 5

Hallmark if PDA present

Answer 5

Reversed differential cyanosis

Question 6

D-TGA Clinical course is determined by

Answer 6

o Associated cardiovascular anomalies
o Anatomic and functional status of pulmonary vascular bed

Question 7

Types of D TGA

Answer 7

o TGA w/ intact IVS
o TGA w/ VSD
o TGA w/ VSD + LVOTO
o TGA w/ VSD + pulmonary vascular obstructive dz

Question 8

Congenitally corrected transposition (L-TGA): features and situs

Answer 8

• Ventriculoarterial + atrioventricular discordance
  o Situs solitus of atria
  o L-looping: LV moves to R side
  o Rare, <1% of congenital heart dz

PV in fibrous continuity w/ MV

Question 9

Physiology L TGA

Answer 9

• Physiology: double discordance physiologically correct the transposition
  o Systemic venous blood → RA → LV → PA
  o Pulmonary venous blood → LA → RV → Ao

Question 10

Consequences of L-TGA

Answer 10

• Morphologic RV supports systemic circulation
  o Pressure overload on RV → CHF later in life
  o RV cannot tolerate systemic pressures because of morphology → structurally weaker
   Intrinsic geometry
   Fiber orientation
   Lower CA flow reserve
   Lower systolic function