European Journal of Cardiovascular Medicine

The bidirectional Glenn (BDG) procedure is a critical component of the staged surgical palliation for patients with single ventricle physiology, serving as an intermediary step before the Fontan operation[1]. The procedure involves the direct anastomosis of the superior vena cava (SVC) to the pulmonary artery (PA), diverting venous blood directly into the pulmonary circulation while reducing the workload on the single functional ventricle. In certain subsets of patients, particularly those with small, restrictive atrial septal defects (ASD), an additional atrial septectomy is required to ensure adequate interatrial mixing, reducing atrial pressure gradients, and optimizing hemodynamics[2]. Conventionally, atrial septectomy is performed via direct atrial incision, which poses risks such as prolonged surgical time, postoperative arrhythmias, and excessive bleeding[3].

Minimally invasive techniques have gained popularity in congenital cardiac surgery to enhance patient recovery and reduce perioperative morbidity. The transvenous surgical atrial septectomy, as described in our case series, presents an innovative approach that eliminates the need for direct atrial incision, instead utilizing the transected SVC as an access route for controlled septal resection. This approach minimizes direct atrial trauma, shortens the cardiopulmonary bypass (CPB) time, and potentially lowers the incidence of arrhythmias while maintaining  Effective surgical outcomes [4] Pathophysiological Considerations.

A restrictive ASD in patients undergoing BD Glenn shunt surgery can lead to significant hemodynamic consequences, including elevated systemic venous pressures, impaired pulmonary circulation, and ventricular volume overload. The inability to relieve these pressures can compromise cardiac function, necessitating an atrial septectomy to facilitate adequate interatrial shunting and preload regulation[5]. The conventional atrial septectomy, performed via atriotomy, requires prolonged aortic cross-clamp time and increases the likelihood of arrhythmic events, owing to surgical manipulation of the atrial myocardium and conduction system[6].

The transvenous approach represents a paradigm shift by leveraging the SVC transection site as a surgical access point for atrial septal resection. By avoiding direct atrial wall disruption, the transvenous technique potentially reduces perioperative bleeding, maintains myocardial integrity, and enables rapid weaning from CPB. Additionally, this approach aligns with the broader movement in congenital heart surgery toward minimally invasive, function-preserving interventions that optimize long-term cardiovascular outcomes[7].

Rationale for This Case Series

While various modifications of the BDG procedure have been described, limited literature exists on transvenous atrial septectomy as a standard adjunct to BD Glenn palliation. Our case series presents six patients with heterogeneous single ventricle pathologies, including tricuspid atresia, transposition of great arteries (TGA) with pulmonary atresia, and hypoplastic left heart syndrome (HLHS), all of whom underwent successful transvenous atrial septectomy. This series aims to evaluate the feasibility, safety, and clinical impact of this technique, focusing on its role in reducing atrial trauma, improving hemodynamics, and streamlining surgical efficiency.

In the following sections, we will outline the surgical methodology, perioperative outcomes, and potential advantages of transvenous atrial septectomy, contributing to the evolving landscape of single ventricle palliation strategies.

Case Series

We report six cases in which the transvenous surgical atrial septectomy technique was performed as an adjunct to the bidirectional Glenn (BDG) procedure. These cases include:

• Three cases of tricuspid atresia
• Two cases of transposition of the great arteries (TGA) with pulmonary atresia
• One case of hypoplastic left heart syndrome (HLHS)

All patients underwent the BDG procedure as part of a staged single-ventricle palliation, with atrial septectomy indicated due to a small restrictive atrial septal defect (ASD). The presence of a restrictive ASD was confirmed preoperatively through echocardiography and cardiac catheterization. The 6 cases are detailed in Table 1

Table 1: Subject Details And The Outcomes

Each patient was operated on through median sternotomy with vertical pericardiotomy. The following surgical steps were performed:

1. Cardiopulmonary bypass (CPB) preparation:
   • Superior vena cava (SVC), inferior vena cava (IVC), innominate vein, main pulmonary artery (MPA), and right pulmonary artery (RPA) were mobilized.
   • Heparinization
   • Cannulation was done over Ascending aorta, SVC-innominate vein junction, and IVC.
   • CPB was initiated after activated clotting time (ACT) reached 480.
2. Transvenous atrial septectomy procedure:
   • Aortic cross-clamp was applied, and the heart was arrested in diastole using antegrade Thomas root cardioplegia and adenosine.
   • The SVC was transected approximately 5 mm from the RA-SVC junction.
   • Transvenous atrial septectomy was performed through the SVC opening.
   • The caudal end of the SVC was oversewn with polypropylene 5-0.
3. Reperfusion and BDG completion:
   • The aortic root was vented, and the heart was de-aired before removing the aortic cross-clamp (mean cross-clamp time:33 minutes).
   • The MPA, LPA, and RPA were snugged, ensuring proper flow.
   • The RPA was opened longitudinally and anastomosed to the cranial end of the transected SVC in an end-to-side fashion.
   • The MPA was ligated, and patients were weaned off CPB.
   • Heparin was reversed using protamine, and decannulation was performed.

All patients tolerated the procedure well, and postoperative recovery was uneventful. Postoperative echocardiography confirmed unobstructed atrial flow, and no immediate complications were noted. Fig 1,2

Figure 1: Image showing SVC, IVC, Aorta cannulated with root vent cannula insitu with cross clamp on. SVC opened for ASD visualization. (SVC-Superior Vena Cava, IVC-Inferior vena cava, ASD- Atrial Septal Defect)

Figure 2: Image showing doing atrial septectomy through transvenous approach

The bidirectional Glenn (BDG) procedure is a well-established palliative surgical approach for patients with single-ventricle congenital heart disease, serving as an intermediate step before the Fontan procedure [1]. However, in cases where a restrictive atrial septal defect (ASD) is present, the obstruction to atrial flow can result in increased atrial pressure, pulmonary congestion, and systemic venous hypertension, ultimately compromising cardiac output [2]. Conventionally, atrial septectomy is performed via direct atrial incision, but this approach is associated with increased bleeding risks, prolonged cross-clamp time, and potential postoperative arrhythmias [3]. The transvenous approach described in this case series represents a noval, minimally invasive alternative, effectively circumventing the need for direct atrial incision while maintaining procedural safety and efficacy.

Advantages of the Transvenous Atrial Septectomy Approach

The transvenous technique for atrial septectomy offers several distinct advantages over the traditional method:

1. Avoidance of Direct Atrial Incision – Reducing surgical trauma and associated risks of bleeding and atrial scarring.
2. Reduced Cross-Clamp Time – The mean aortic cross-clamp time was 7.33 minutes, which is significantly lower than conventional atrial septectomy approaches [4].
3. Minimization of Postoperative Arrhythmias – Direct atrial incisions are known to predispose patients to atrial arrhythmias, whereas the transvenous technique avoids direct atrial manipulation, potentially reducing long-term arrhythmic complications [5].
4. Technical Simplicity and Feasibility – The SVC approach provides an adequate surgical window for atrial septectomy without additional incisions, making it a simpler and more reproducible

Comparison with Previous Surgical Approaches

The conventional atrial septectomy technique typically involves a right atrial incision, which can lead to longer operative times, increased intraoperative bleeding, and arrhythmias [6]. Studies have shown that postoperative sinus node dysfunction and atrial arrhythmias occur in up to 30% of cases following traditional atrial septectomy [7]. In contrast, our transvenous approach eliminates direct atrial incision, thereby reducing these risks while maintaining effective atrial decompression.

The off-pump atrial septectomy approach described by Fuchigami et al. has also been proposed for infants with restrictive ASD, but it is typically reserved for non-complex cases and may not be feasible in patients undergoing BDG [8]. Our technique integrates atrial septectomy seamlessly into the BDG procedure, ensuring optimal hemodynamic outcomes while preserving surgical efficiency.

Postoperative Outcomes and Clinical Implications

All six patients in this case series exhibited uneventful postoperative recovery, with no instances of atrial

thrombus formation, residual obstruction, or hemodynamic instability. Postoperative echocardiographic evaluation confirmed adequate atrial decompression, ensuring unobstructed pulmonary venous return and maintaining systemic venous pressures within normal limits. These findings suggest that transvenous atrial septectomy is a viable and effective adjunct in the surgical management of BDG patients with restrictive ASD [9,10].

Limitations and Future Directions

While our findings highlight the efficacy and safety of the transvenous technique, this case series is limited by its small sample size. Larger, multi-institutional studies with longer follow-up periods are required to further evaluate the long-term benefits, arrhythmic burden, and potential refinements to this approach.

In this case series, we have described a noval transvenous approach to atrial septectomy as an adjunct to the Bidirectional Glenn (BDG) procedure in patients with single-ventricle physiology and restrictive atrial septal defects (ASD). This technique eliminates the need for direct atrial incision, thereby reducing the risk of intraoperative bleeding, atrial scarring, and postoperative arrhythmias while ensuring effective atrial decompression.

Our findings demonstrate that transvenous atrial septectomy is a safe, feasible, and technically efficient alternative to conventional atrial septectomy methods. All six patients in this series tolerated the procedure well, with no immediate complications and adequate atrial decompression confirmed postoperatively. The significant advantages of this approach include shorter aortic cross-clamp time, minimal atrial manipulation, and preserved hemodynamic stability.

Despite these promising outcomes, further large-scale studies with long-term follow-up are required to confirm the durability, safety, and broader applicability of this technique. The integration of this minimally invasive approach into routine surgical practice has the potential to enhance outcomes in single-ventricle palliation, optimizing both surgical efficiency and patient safety.

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