Surgical Strategy According to Anatomy in ccTGA

#3 Pulmonary Artery Banding and Double Switch Operation

Background: the deconditioned left ventricle

In ccTGA with intact ventricular septum and no pulmonary stenosis (PS–, VSD–), the morphologic left ventricle (LV) supports only the low-pressure pulmonary circuit once pulmonary vascular resistance falls after birth. Over time, the LV remodels into a thin-walled, compliant, subpulmonary ventricle. Although an arterial switch operation (ASO) is technically straightforward in the absence of RVOTO, this “deconditioned” LV is not capable of sustaining systemic afterload and would fail acutely if moved to the systemic position without preparation.

Anatomic repair is nevertheless attractive because, in multiple observational series, anatomic strategies with a systemic LV provide better survival and freedom from major events than physiologic repair that leaves the morphologic RV systemic.[1,2] In VSD– ccTGA, therefore, the central question is how—and in whom—to safely retrain the LV before undertaking a double switch.

Concept of LV retraining with pulmonary artery banding

Pulmonary artery banding (PAB) is used to increase LV afterload in a controlled fashion. By constricting the main pulmonary artery, the band raises LV systolic pressure toward systemic levels and stimulates hypertrophic remodeling of the LV myocardium. The objective is to create a ventricle with:

• wall thickness and mass appropriate for systemic pressure,
• preserved systolic and diastolic function, and
• no significant distortion of the pulmonary arteries.

Early series of prophylactic PAB in isolated ccTGA showed that banding in infancy can be performed with low perioperative risk, stabilizes or improves systemic tricuspid valve function, and maintains LV preparedness for a later anatomic repair.[3] Subsequent multicenter and single-center studies have refined the approach, emphasizing the importance of age at banding and duration of training.[4]

Practical conduct of PAB in ccTGA

After comprehensive imaging and hemodynamic assessment, a PAB is placed on the main pulmonary artery—usually via median sternotomy, often combined with concurrent repair of associated lesions if present. The band is tightened under pressure and saturation guidance:

• LV systolic pressure is gradually increased toward a target proportion of systemic pressure, typically an LV/RV or LV/systemic ratio of about 0.7–0.9 during the training phase.[4,5]
• Systemic arterial oxygen saturation, RV function, and branch PA flows are monitored to avoid excessive cyanosis, RV failure, or unilateral PA hypoperfusion.

Postoperatively, serial echocardiography and, when indicated, catheterization are used to monitor:

• LV wall thickness, mass, and geometry,
• LV systolic performance under the imposed load,
• the pressure gradient across the band and branch pulmonary arteries.

The training period usually extends over several months. Younger patients tend to show a brisk and balanced hypertrophic response, whereas older children and adolescents may require longer or more intensive training to achieve adequate LV conditioning.[4,6]

Evidence for effectiveness of LV retraining

Multiple cohorts have demonstrated that LV retraining followed by double switch can be accomplished with high success and low mortality:

• In a series of ccTGA patients undergoing PAB followed by double switch, most achieved normal or only mildly depressed LV function at mid-term follow-up, and overall survival after anatomic repair was excellent.[5,7]
• A larger anatomic-repair cohort reported good long-term survival, with PAB used for LV retraining in a substantial subset; outcomes for patients who required retraining were generally favorable but may be slightly less robust than for those whose LV was already systemic-ready.[1,7]

Physiologic data from LV retraining programs show a predictable relationship between LV systolic pressure and LV mass for most patients, indicating an adaptive hypertrophic response to the imposed load.[6] However, a minority demonstrate “excess hypertrophy”—disproportionate mass gain for a given pressure—which may herald diastolic stiffness and requires careful surveillance.[6]

Age at banding appears critical. In one study, patients banded before approximately 2 years of age were more likely to develop an adequately trained LV with preserved function, whereas those banded later had higher rates of residual LV dysfunction or insufficient preparation.[4] These findings support a strategy of early identification and prophylactic or early PAB in anatomically suitable infants with ccTGA and intact septum.

Transition to double switch

Once imaging and hemodynamics confirm that the LV:

• sustains near-systemic pressure at rest,
• has appropriate wall thickness and geometry, and
• maintains satisfactory systolic and diastolic function,

the patient can proceed to an anatomic repair. This usually consists of:

• an atrial switch (Senning or Mustard) to redirect venous return, and
• an arterial switch or Rastelli-type procedure depending on LV outflow tract anatomy.

At the time of double switch:

• The band is removed and the pulmonary arteries reconstructed.
• The morphologic LV becomes the systemic ventricle, ejecting into the neoaorta.
• The morphologic RV is reassigned to the pulmonary circuit, relieving it of systemic load.

Series of patients managed with this staged approach report excellent early and mid-term results, with a majority in New York Heart Association class I–II and preserved systemic LV function.[5,7]

Limitations, risks, and patient selection

Despite its benefits, PAB-based LV retraining has important limitations:

• Under-training – If the LV is still underprepared at the time of double switch, there is a risk of postoperative low cardiac output and LV failure. Predictors of readiness—combining pressure ratio, wall thickness, and strain imaging—are an active area of investigation.[6]
• Over-training – Excessive band tightness or prolonged high afterload may produce pathologic hypertrophy and diastolic dysfunction, compromising long-term LV performance.[6]
• Pulmonary artery distortion or stenosis at the band site may require patch augmentation during the definitive repair.[3,5]
• Systemic RV function and tricuspid valve status may continue to deteriorate during the training interval, particularly if banding is initiated late. Some data suggest that patients who need LV retraining have slightly worse long-term outcomes than those whose LV was systemic-ready from the outset.[2,7]

Because of these challenges, patient selection is crucial. PAB is generally favored in:

• infants and young children with intact septum, PS–, and preserved systemic RV function
• in whom an anatomic repair is desired but the LV is clearly deconditioned.

In older patients with advanced systemic RV failure, severe tricuspid regurgitation, or significant comorbidities, PAB may be used as a palliative “destination band” to offload the systemic RV rather than as a bridge to double switch, or alternative strategies—including transplantation—may be more appropriate.[2,8]

Key points

• In ccTGA with PS– / VSD–, the subpulmonary LV naturally deconditions and cannot safely assume systemic work without retraining.
• Pulmonary artery banding increases LV afterload, promoting adaptive hypertrophy and preparing the LV for a double switch operation.
• Best results are obtained when banding is performed early in life with careful hemodynamic targets and close imaging surveillance.[3–5]
• Most patients who complete LV retraining proceed to double switch with excellent early and mid-term outcomes, though a subset exhibit abnormal hypertrophy or persistent LV dysfunction.[5–7]
• Thoughtful timing, meticulous band adjustment, and rigorous follow-up are essential to balance the benefits of an anatomic repair against the risks inherent in LV retraining.

References

[1] Murtuza B, Barron DJ, Stumper O, et al. Anatomic repair for congenitally corrected transposition of the great arteries: a single-institution experience. J Thorac Cardiovasc Surg. 2011;142(6):1348-1357.

[2] Jacob KA, Dimagli A, Anzai I, et al. Congenitally corrected transposition of the great arteries: anatomic versus physiologic repair. J Am Coll Cardiol. 2024;83(10):1008-1021.

[3] Metton O, Gaudin R, Ou P, et al. Early prophylactic pulmonary artery banding in isolated congenitally corrected transposition of the great arteries. Eur J Cardiothorac Surg. 2010;38(6):728-734. (PubMed)

[4] Myers PO, Tissot C, Sekarski N, et al. Impact of age and duration of banding on left ventricular training in congenitally corrected transposition of the great arteries. Ann Thorac Surg. 2013;96(2):603-610. (annalsthoracicsurgery.org)

[5] Ibrahimiye AN, Noonan PM, McCracken C, et al. Left ventricular retraining and double switch in patients with congenitally corrected transposition of the great arteries. World J Pediatr Congenit Heart Surg. 2017;8(2):203-209. (PubMed)

[6] Mainwaring RD, Patrick WL, Arunamata A, et al. Left ventricular retraining in corrected transposition: relationship between pressure and mass. J Thorac Cardiovasc Surg. 2020;159(6):2356-2366. (PubMed)

[7] Mac Felmly L, Patrick WL, Lui GK, et al. Surgical outcomes in patients undergoing a double switch operation. Ann Thorac Surg. 2024;117(6):1132-1141. (ScienceDirect)

[8] Cui H, Tobler D, Mah K, et al. Management of congenitally corrected transposition of the great arteries: current state of the art. Circ Cardiovasc Interv. 2021;14(10):e010154. (ahajournals.org)