Understanding Normally and Abnormally Related Great Arteries


Equations, Apoptosis, Switches, Rotations, and Synergy

Basic Principles

  • 1.

    When the situs (pattern of anatomic organization) of the subarterial infundibulum and the situs of the great arteries are the same (concordant), the great arteries are normally related—solitus normally related, or inversus normally related.

  • 2.

    When the situs of the infundibulum and the situs of the great arteries are different (discordant), the great arteries are abnormally related.

Great Arterial Equations

Equal sign is intended for clarity of understanding. However, morphogenetic movements are typically a range of values not equal to simply one mean or median value.

Normally Related Great Arteries With or Without Associated Malformations

  • 1.

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

    • ↑ ↑

    • GA Inf


Situs of infundibulum (inf) + Situs of great arteries (GA) = Solitus + Solitus , that is , concordant , solitus normal

A.1, Solitus or D-Loop Hearts.

  • 2.

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

    • ↑ ↑

    • GA Inf

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

A.2, Inverted or L-Loop Hearts.

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

A.3, Inverted Tetralogy of Fallot.

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.

A.4, A, B: Absence of Subpulmonary Infundibulum (Formerly Called “Truncus Arteriosus Communis”). B: Absence of the right and left sixth aortic arches results in non-migration of the right pulmonary artery (RPA) branch and the left pulmonary artery (LPA) branch from the aortic sac or common pulmonary artery (CPA), and also results in the main pulmonary artery (MPA) in having no branches.

Correct

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.

A.5, Isolated absence of the aortopulmonary septum is a true example of common aortopulmonary trunk (truncus arteriosus communis). Therefore, truncus arteriosus communis or absence of the common aortopulmonary trunk rarely does exist as an isolated anomaly.

Abnormally Related Great Arteries

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