Conotruncal Rotation #3 — Original Taussig–Bing (NGA Type)

The “Taussig–Bing” label has historically been applied to DORV with transposed great arteries and a subpulmonary VSD (the classic physiology of “TGA with VSD”), as described by Hightower and colleagues. [1] Later morphologic work emphasized that Taussig–Bing is best understood as a spectrum unified by a juxtapu lmonary (subarterial) VSD and malalignment of the infundibular/outlet septal structures, rather than a single fixed great-artery arrangement. [2]

In this module, we deliberately interpret the “original Taussig–Bing” configuration through an NGA (normally related great arteries) reference frame, focusing on how outflow rotation and septal attachment patterns create a characteristic VSD “commitment” and streaming behavior.

1. Core morphologic signature in the NGA frame

In the schematic provided, the posterior great artery remains the aorta and the anterior great artery remains the pulmonary artery, but both show a characteristic lateral “shift” plus a defining infundibular fold (IF) attachment:

Great-artery shift (within the NGA pattern)

Posterior Ao → rightward shift (++)
Anterior PA → leftward shift (+)

Infundibular fold (IF) attachment

The IF anchors to the mitral-side ventriculo-infundibular fold (VIF) (the “left-side VIF” in the diagram).

VSD morphology

The VSD is doubly committed: it extends anteriorly beneath both semilunar valves, creating a shared subarterial “window.”

This “triad” is your one-look pattern-recognition tool: shift vector + IF anchor + VSD commitment.

2. Why IF attachment is the key geometric “switch”

A useful way to read the diagram is to treat the IF/outlet musculature as a hinge that defines whether the subarterial plane is partitioned into “separate” outlets or becomes a common subarterial space:

When the IF attaches to the mitral-side (left) VIF, it tends to become more orthogonal to the interventricular septum (IVS).
That orthogonal re-orientation weakens the usual “capture” of the VSD by a single outflow tract, and instead promotes a shared subarterial defect—the doubly committed VSD.

Practical translation:

This is not simply “a big VSD.” It is a VSD that is strategically positioned in the subarterial plane, such that both outflows are anatomically in play.

3. Putting this into a broader morphologic map (what Elicit highlighted)

The Elicit summary points to a central concept: the insertion/morphology of the outlet (infundibular) septal structures predicts great-artery positioning and the VSD’s subarterial relationship. This is strongly supported by classic specimen-based work:

In 50 DORV specimens, de la Cruz et al. showed that outlet septum insertion determines two major “infundibular interrelationships”:

Anterior/posterior infundibulums (70%): the aorta commonly connects to the posterior infundibulum, and subaortic VSD is frequent (reported as 81.2% among those with aorta connected to the posterior infundibulum). [3]
Side-by-side infundibulums (26%): the pulmonary trunk connects to the medial infundibulum, and subpulmonary VSD is common (reported as 92.3%). [3]

Importantly for this module, doubly committed VSDs were uncommon (reported as 4% in that specimen series). [3]

Take-home: the great-artery relationship alone is not enough; the decisive information is how the outlet/infundibular structures insert and partition the subarterial plane. [3]

4. Terminology primer (aligning the schematic with surgical morphology)

To keep the reading “clean,” it helps to anchor terms to what they do surgically:

Posterior vs anterior great artery: emphasizes A–P stacking (what sits behind vs in front), independent of whether the overall relationship is “normal” or “transposed.”
DORV definition and categorization: DORV is fundamentally defined by the ventriculo-arterial connections; classification then depends on arterial trunk relationship and VSD location/commitment. [4]
Outlet septum / infundibular septal structures: these determine outflow partitioning and strongly influence whether the VSD is effectively “subaortic,” “subpulmonary,” or shared. [5]
Doubly committed VSD: a VSD whose superior margin lies in the subarterial plane beneath both semilunar valves, rather than being committed predominantly to one. [3]

5. Physiologic implication: why this can “behave like” Taussig–Bing physiology

Once the VSD becomes subarterial and doubly committed, physiology becomes highly sensitive to subtle geometry:

Small changes in outlet septal/IF orientation can alter which ventricle preferentially supplies each great artery.
This helps explain why Taussig–Bing–type anatomies are often discussed as “TGA-like” physiology in practice, even though the morphologic substrate is best read from the infundibular relationships and VSD commitment. [2,3]

6. Surgical meaning: why precise anatomic mapping matters

Modern repair strategy for Taussig–Bing/DORV variants is tailored to:

VSD relationship (subaortic vs subpulmonary vs doubly committed)
Great-artery relationship
Outlet septal/infundibular geometry
Coronary pattern and arch obstruction (when present)

This “anatomy-first” planning principle is emphasized in management reviews and surgical series. [6,7]

Two surgical anatomy points that connect directly back to your schematic:

Infundibular septum displacement changes the feasibility of intraventricular routing and may shift strategy toward arterial switch + VSD closure versus alternative pathways in selected morphologies. [8]
Clinical series of arterial switch + VSD closure for Taussig–Bing/DORV with subpulmonary VSD demonstrate that outcomes are strongly influenced by coronary anatomy and associated lesions, reinforcing the need for a precise preoperative anatomic map. [7,9,10]

7. One-look summary (what you want the reader to remember)

Vector logic: posterior Ao shifts right (++), anterior PA shifts left (+) in this NGA-based Taussig–Bing framing.
Hinge logic: the IF attachment to the mitral-side VIF is the rotational clue that helps explain the outflow partition.
Defining lesion: the VSD is doubly committed—a shared subarterial window beneath both great arteries.
Clinical translation: Taussig–Bing is best approached as a morphologic spectrum where infundibular/outlet relationships drive both physiology and operative strategy. [2,3]

References

[1] Hightower BM, Barcia A, Bargeron LM Jr, Kirklin JW. Double-outlet right ventricle with transposed great arteries and subpulmonary ventricular septal defect. The Taussig-Bing malformation. Circulation. 1969;39(5 Suppl 1):I207-13.

[2] Stellin G, Zuberbuhler JR, Anderson RH, Siewers RD. The surgical anatomy of the Taussig-Bing malformation. J Thorac Cardiovasc Surg. 1987;93(4):560-569.

[3] de la Cruz MV, Cayré R, Arista-Salado Martinez O, Sadowinski S, Serrano A. The infundibular interrelationships and the ventriculoarterial connection in double outlet right ventricle. Clinical and surgical implications. Int J Cardiol. 1992;35(2):153-164.

[4] Anderson RH, Becker AE, Wilcox BR, Macartney FJ, Wilkinson JL. Surgical anatomy of double-outlet right ventricle--a reappraisal. Am J Cardiol. 1983;52(5):555-559.

[5] Capuani A, Uemura H, Ho SY, Anderson RH. Anatomic spectrum of abnormal ventriculoarterial connections: surgical implications. Ann Thorac Surg. 1995;59(2):352-360.

[6] Cetta F, Boston US, Dearani JA, Hagler DJ. Double outlet right ventricle: opinions regarding management. Curr Treat Options Cardiovasc Med. 2005;7(5):385-390.

[7] Kurosawa H, Van Mierop LH. Surgical anatomy of the infundibular septum in transposition of the great arteries with ventricular septal defect. J Thorac Cardiovasc Surg. 1986;91(1):123-132.

[8] Masuda M, Kado H, Shiokawa Y, Fukae K, Kanegae Y, Kawachi Y, Morita S, Yasui H. Clinical results of arterial switch operation for double-outlet right ventricle with subpulmonary VSD. Eur J Cardiothorac Surg. 1999;15(3):283-288.

[9] Griselli M, McGuirk SP, Ko CS, Clarke AJB, Barron DJ, Brawn WJ. Arterial switch operation in patients with Taussig-Bing anomaly--influence of staged repair and coronary anatomy on outcome. Eur J Cardiothorac Surg. 2007;31(2):229-235.

[10] Rodefeld MD, Ruzmetov M, Vijay P, Fiore AC, Turrentine MW, Brown JW. Surgical results of arterial switch operation for Taussig-Bing anomaly: is position of the great arteries a risk factor? Ann Thorac Surg. 2007;83(4):1451-1457.