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



Situsofinfundibulum (inf)+Situsofgreatarteries(GA)=Solitus+Solitus,thatis,concordant,solitusnormal



A.1


Solitus or D-Loop Hearts.

Reproduced with permission from Van Praagh R, Van Praagh S. Isolated ventricular inversion: A consideration of the morphogenesis, definition, and diagnosis of nontransposed and transposed great arteries. Am J Cardiol. 1966;17:395-406.






  • 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.

Reproduced with permission from Van Praagh R, Van Praagh S. Isolated ventricular inversion: A consideration of the morphogenesis, definition, and diagnosis of nontransposed and transposed great arteries. Am J Cardiol. 1966;17:395-406.




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.

Reproduced with permission from Van Praagh R, Van Praagh S. Isolated ventricular inversion: A consideration of the morphogenesis, definition, and diagnosis of nontransposed and transposed great arteries. Am J Cardiol. 1966;17:395-406.




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.

Reproduced with permission from Vizcaino A, Campbell J, Litovsky S, Van Praagh R. Single origin of right and left pulmonary artery branches from ascending aorta with nonbranching main pulmonary artery: Relevance to a new understanding of truncus arteriosus. Pediatr Cardiol . 2002;23:230.






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.

Reproduced with permission from Vizcaino A, Campbell J, Litovsky S, Van Praagh R. Single origin of right and left pulmonary artery branches from ascending aorta with nonbranching main pulmonary artery: Relevance to a new understanding of truncus arteriosus. Pediatr Cardiol. 2002;23:230.




Abnormally Related Great Arteries


D-Transposition of the Great Arteries




  • 9.

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




    • ↑ ↑


      GA Inf




Infundibular situs is situs inversus, the same as in Equation 2 of situs inversus totalis.







    • Infundibular situs = Inversus



    • Great arterial situs = solitus, abnormal



    • Infundibuloarterial situs analysis = inversus + solitus, discordant, abnormal




Typical D-TGA is isolated infundibular inversion.


A.6


D-Transposition of the Great Arteries.

Reproduced with permission from Van Praagh R, Van Praagh S. Isolated ventricular inversion: A consideration of the morphogenesis, definition, and diagnosis of nontransposed and transposed great arteries. Am J Cardiol. 1966;17:395-406.




L-Transposition of the Great Arteries




  • 10.

    TGA {S,L, L } = 0R + 4L




    • ↑ ↑



    • GA Inf




Infundibular situs = Solitus normal, the same as in Equation 1.







    • The great arterial situs = inverted.



    • I-A situs analysis = Solitus + Inversus.



    • Conclusion: Discordant , that is, abnormal



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Aug 8, 2022 | Posted by in CARDIOLOGY | Comments Off on Understanding Normally and Abnormally Related Great Arteries

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