Understanding Normally and Abnormally Related Great Arteries

Normally Related Great Arteries With or Without Associated Malformations

• 1.

  SNRGA {S,D, S } = 0R + 4L

  • ↑ ↑

  • GA Inf

• 2.

  INRGA {I,L, I } = 4R + 0L

  • ↑ ↑

  • GA Inf

  • Situs of inf + Situs of GA = Inversus + Inversus, that is, concordant, inversus normal

Tetralogy of Fallot

• 3.

  TOF {S,D, S } = 0R + 3L (TOF, mild/moderate PS)

• 4.

  TOF {S,D, S } = 0R + 2L (TOF, severe PS)

• 5.

  TOF {S,D, S } = 0R + 1L (TOF, P Atresia)

  • ↑ ↑

  • GA Inf

Situs of inf + GA

Situs of the infundibulum is of the solitus normal type, except that the subpulmonary infundibulum is hypoplastic: mildly (3L), moderately (2L), or severely (1L). The situs of the great arteries is solitus normal. Hence, the sum of the infundibular situs and the great arterial situs is Solitus + Solitus, that is, concordant, and therefore solitus normal .

Tetralogy of Fallot may also be regarded as the Monology of Stensen. First described by Niels Stensen, the Dane of parotid duct fame, in 1671, all four of these anomalies are now thought to be sequelae of subpulmonary infundibular hypoplasia: pulmonary outflow tract obstruction, subaortic ventricular septal defect (VSD), aortic overriding (subnormal semilunar dextral rotation), and postnatal right ventricular hypertrophy.

Inverted or L-Loop Hearts

Absence of Subpulmonary Infundibulum (Formerly Called “Truncus Arteriosus Communis”)

• 6.

  AOSPI {S,D ,-} = 0R + (-L) + APW (“TAC” type A1)

• 7.

  AOSPI {S,D ,-} = 0R + (-L) - PV - MPA (“TAC” type A2)

  • TOF does not have absence of subpulmonary infundibulum.

  • AOSPI + TOF are closely associated anomalies.

Understanding of Truncus Arteriosus Communis

In “truncus arteriosus communis” type A2 – with right pulmonary artery (RPA) and left pulmonary artery (LPA) from the aortic sac, the main pulmonary artery (MPA) is absent ( Fig. A.4a ). Without an MPA, “TAC” is impossible.

However, rarely it is possible to have isolated absence of the Ao – PA septum ( Fig. A.5 ).

• 8.

  AOAPS {S,D,S} = 0R + 4L – APS

Absence of the aortopulmonary septum (AOAPS), as an isolated anomaly, appears to be very rare.