Surgical Strategy According to Anatomy in ccTGA
#2 Atrial Switch and Arterial Switch Operation (Double Switch)
Rationale for anatomic repair
In ccTGA without significant pulmonary stenosis, the morphologic right ventricle (systemic RV) supports the systemic circulation from birth. Natural-history studies show a high incidence of systemic RV failure, progressive tricuspid regurgitation, and heart failure by mid-adulthood, especially in patients with associated lesions [1]. These concerns have driven interest in anatomic repair, in which an atrial switch (Senning or Mustard) is combined with an arterial switch operation (ASO) to place the morphologic left ventricle (LV) in the systemic position and return the morphologic RV to the pulmonary circuit.
The central question is whether the subpulmonary LV is adequately prepared to sustain systemic pressure. Thus, LV pressure and remodeling state are the key determinants when planning a double switch.
Scenario: ccTGA without pulmonary stenosis (PS–)
When there is no pulmonary stenosis, pulmonary vascular resistance is low and, in the absence of a VSD, the LV experiences only pulmonary pressures. Surgical strategy then diverges according to the presence or absence of a VSD and the current LV loading conditions.
1. High LVP with VSD (+): elective double switch
In patients with a large VSD, LV and RV pressures are essentially equal (LVP ≈ RVP). The LV is chronically “pressure-trained” to systemic levels because it ejects into both the pulmonary artery and, via the VSD, into the aorta.
Hemodynamics and morphology
- LV wall thickness and mass are preserved, and systolic function is usually satisfactory on echocardiography or MRI.
- Catheterization typically confirms a systemic-level LV pressure with a Qp/Qs close to 1 if pulmonary stenosis is absent.
Strategic implications
- These patients form the ideal substrate for anatomic repair: the LV is already prepared, and the systemic RV can be unloaded before severe dysfunction or tricuspid regurgitation develops.
- An elective double switch (Senning + ASO) can therefore be planned once the child has reached an appropriate size and associated lesions (e.g., VSD anatomy, coronary pattern, arch anomalies) are fully delineated [2–3].
- If pulmonary overcirculation is a concern before definitive repair, a pulmonary artery band (PAB) may be used, primarily to control pulmonary blood flow and protect the pulmonary vasculature rather than to train the LV.
Series of anatomic repairs—including Senning/ASO and variants—report excellent early results in such prepared LVs, with early survival around 94% and intermediate survival above 90%, along with improvement in tricuspid regurgitation and systemic RV size after unloading [2–3].
2. High LVP without VSD (VSD–): early double switch before LV deconditions
In ccTGA without a VSD, the LV initially experiences near-systemic pressures in the neonatal period while pulmonary vascular resistance is still high. As pulmonary resistance falls, the LV transitions to a true subpulmonary ventricle and gradually remodels to a thin-walled, low-pressure chamber.
Hemodynamic evolution
- In early infancy, LVP may remain relatively high, and the LV mass index and geometry are still compatible with systemic work.
- Over time, if no intervention is undertaken, LV pressure and wall thickness decline; the LV may no longer be able to support systemic circulation without a period of retraining.
Strategic implications
- If an anatomic repair is the chosen long-term strategy, timing is critical. A primary double switch during the “window” when LVP is still high allows the LV to be moved into the systemic position without prior training.
- Once LVP has fallen and the LV has clearly deconditioned, a PAB-based LV training protocol is usually required before anatomic repair, or the team may instead favor physiologic repair or transplant pathways depending on age, RV function, and comorbidities.
Pulmonary artery banding can successfully retrain a deconditioned LV, but it is not benign. Data from Quinn et al. show that morphologic LVs requiring PAB before double switch have a higher risk of late LV dysfunction, even though early outcomes are comparable to those of patients whose LVs were already prepared [4]. Similarly, Myers et al. demonstrated that timing of banding and repair matters: LV dysfunction after anatomic repair occurred in 4 of 6 patients banded after 2 years of age versus none of 12 banded before 2 years, and in 4 of 7 patients repaired after 3 years versus none repaired earlier [5]. These findings support early referral for LV training when needed and reinforce the value of a primary double switch in infancy before the LV deconditions.
Practical framework for ccTGA without PS
Putting the above pathways together:
- ccTGA, PS–, VSD (+)
- LV is chronically pressure-loaded and generally suitable for systemic work.
- Plan elective Senning + ASO once patient size, coronary anatomy, and associated lesions permit.
- Consider PAB only to limit pulmonary overcirculation.
- ccTGA, PS–, VSD (–)
- LV initially sees high pressure but will decondition as PVR falls.
- For anatomic repair, aim for a primary double switch in early infancy while LVP and LV mass are still adequate.
- If the LV is already deconditioned, PAB-based LV retraining can be used, ideally started before age 2 years, with anatomic repair completed before 3 years to minimize the risk of late LV dysfunction [5]. Patients requiring prolonged or intensive training should be counseled about the higher risk of LV dysfunction and need for lifelong surveillance [4–5].
Conceptual summary
In ccTGA without pulmonary stenosis, the decision to pursue atrial + arterial switch revolves around LV preparedness and timing:
- A naturally trained LV (typically with a large VSD) allows flexible, elective double switch with excellent early and intermediate outcomes [2–3].
- An untrained LV without VSD offers only a limited early window for primary double switch; beyond this, PAB-based LV training becomes necessary and carries a measurable risk of late LV dysfunction [4–5].
Using this framework, the surgical team can align the complexity and timing of anatomic repair with each patient’s anatomy and ventricular conditioning, maximizing the chance of a durable systemic LV while pre-empting failure of the systemic RV.
References
[1] Graham TP Jr, Bernard YD, Mellen BG, et al. Long-term outcome in congenitally corrected transposition of the great arteries: a multi-institutional study. J Am Coll Cardiol. 2000;36(1):255–261. (academia.edu)
[2] Devaney EJ, Charpie JR, Ohye RG, Bove EL. Combined arterial switch and Senning operation for congenitally corrected transposition of the great arteries: patient selection and intermediate results. J Thorac Cardiovasc Surg. 2003;125(3):500–507. (annalsthoracicsurgery.org)
[3] Gaies MG, Goldberg CS, Ohye RG, et al. Early and intermediate outcome after anatomic repair of congenitally corrected transposition of the great arteries. Ann Thorac Surg. 2009;88(6):1952–1960. (annalsthoracicsurgery.org)
[4] Quinn DW, McGuirk SP, Mehta C, et al. The morphologic left ventricle that requires training by means of pulmonary artery banding before the double-switch procedure for congenitally corrected transposition of the great arteries is at risk of late dysfunction. J Thorac Cardiovasc Surg. 2008;135(5):1137–1144.e1–2. (PubMed)
[5] Myers PO, del Nido PJ, Geva T, et al. Impact of age and duration of banding on left ventricular preparation before anatomic repair for congenitally corrected transposition of the great arteries. Ann Thorac Surg. 2013;96(2):603–610. (PubMed)