Balance-shaped sternal elevation-assisted uniportal subxiphoid video-assisted thoracoscopic surgery for thymoma with persistent left superior vena cava

Introduction

Uniportal video-assisted thoracoscopic surgery (VATS) via the subxiphoid approach has gained prominence for resection of anterior mediastinal tumors, notably thymomas (1). This route provides an en-face, symmetrical view of the mediastinum, avoids intercostal nerve injury, and is associated with less postoperative pain compared to lateral intercostal approaches (2). However, its widespread adoption is hampered by the inherently confined operating space beneath the sternum, which can restrict instrument maneuverability and obscure visualization of superior and contralateral structures.

Several strategies have been employed to mitigate this limitation. Carbon dioxide (CO₂) insufflation is currently the most widely used method to create an artificial pneumomediastinum. This technique is relatively simple, highly versatile, and well-established in routine clinical practice. It effectively expands the operative field without requiring additional equipment. However, it carries potential risks, including hypercapnia, subcutaneous emphysema, hemodynamic instability due to increased intrathoracic pressure, and, in rare cases, tension pneumomediastinum (3). Direct sternal retraction using hooked instruments improves exposure but poses a non-negligible risk of sternal fracture or chondral separation, potentially increasing postoperative pain (3,4).

Recently, an innovative technique involving percutaneous suspension of the sternum using a balance-shaped retractor system has been introduced (5). By lifting the sternum indirectly through skin and subcutaneous tissue suspension, this method aims to maximize the retrosternal workspace while minimizing direct bony stress. However, like all techniques, it has inherent limitations: it requires dedicated equipment, occupies part of the anterior operative field, and is currently not compatible with robotic-assisted surgery. Additionally, the percutaneous traction maneuver raises theoretical concerns regarding skin injury or local complications at the insertion sites, which warrant careful preventive measures.

The presence of major congenital venous anomalies, such as a persistent left superior vena cava (PLSVC), compounds the technical difficulty of anterior mediastinal dissection. With an incidence of 0.3–0.5% in the general population and higher in those with congenital heart disease, PLSVC necessitates precise identification and protection to prevent catastrophic hemorrhage and ensure adequate venous drainage from the left upper body (6,7). Optimal exposure is paramount in such scenarios. Herein, we present the first documented application of the balance-shaped sternal elevation-assisted uniportal subxiphoid VATS for the resection of a thymoma in a patient with a PLSVC, detailing the technical nuances and perioperative outcomes. We present this article in accordance with the SUPER reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0136/rc).

Preoperative preparations and requirements

A 52-year-old, asymptomatic male was referred for management of an anterior mediastinal mass discovered incidentally on a routine health check-up. Physical examination and routine laboratory tests were unremarkable. The patient’s height was 172 cm, weight 68 kg, and body mass index was 23.0 kg/m². Contrast-enhanced chest computed tomography (CT) with three-dimensional vascular reconstruction revealed a well-circumscribed, lobulated solid mass measuring 6.3 cm × 4.4 cm in the prevascular space of the anterior mediastinum. Critical vascular anatomy was meticulously defined: a normal right superior vena cava (RSVC) draining into the right atrium, and a persistent left superior vena cava (PLSVC) coursing anterior to the left pulmonary hilum and draining into the coronary sinus. The left brachiocephalic vein was congenitally absent. The mass was situated immediately anterior to the aortic arch and proximal great vessels. The closest distance between the tumor capsule and the wall of the PLSVC was measured as 0.8 cm on axial and sagittal reconstructions, with no evidence of frank invasion but likely the presence of loose adhesions (Figure 1).

Figure 1 Preoperative imaging of the thymoma and PLSVC. CT scan showing the anterior mediastinal mass (green arrow), the PLSVC (blue arrow) and the RSVC (yellow arrow). CT, computed tomography; PLSVC, persistent left superior vena cava; RSVC, right superior vena cava.

Step-by-step description

• Patient positioning and anesthesia: the patient was placed in a supine position under general anesthesia with single-lumen endotracheal intubation. Both arms were tucked at the sides. Standard monitoring was established.
• Establishment of the percutaneous balance-shaped sternal suspension system (Figure 2).
  

  Figure 2 The balance-shaped sternal elevation technique. Schematic diagram illustrating the principle: creation of a subcutaneous tunnel and assembly of the device (left), the effect of percutaneous suspension (middle), and the expanded retrosternal space after sternal elevation (right).

Tunnel creation

Two transverse skin incisions, each approximately 0.5 cm in length, were made at the suprasternal notch and the lower third of the sternal body. The distance between these incisions was slightly less than the total length of the sternum. Blunt dissection was performed through these incisions to create a subcutaneous tunnel anterior to the sternum. A subcutaneous plane, rather than a submuscular plane, was deliberately chosen to avoid entering the muscle compartment, thereby reducing tissue trauma and bleeding while still effectively distributing the lifting forces. The specially designed balance-shaped sternal retractor was then introduced through the caudal incision, advanced cephalad within this tunnel, and securely anchored to a pre-assembled external lifting frame.

Preventive measures against skin injury: Care was taken to ensure that the subcutaneous tunnel was created at an adequate depth (close to the surface of the sternum) to distribute traction forces evenly. The skin incisions were protected with small gauze pads during traction to minimize pressure points.

Surgical access

A 5-cm vertical midline incision was made inferior to the xiphoid process to establish the primary surgical port for entry into the thoracic cavity.

Key steps for sternal elevation

Under continuous thoracoscopic guidance via a 10-mm 30° scope introduced through the subxiphoid port, the external suspension frame was gradually elevated. This maneuver uniformly lifted the presternal soft tissues, resulting in an indirect, non-contact elevation of the sternum itself, which substantially expanded the retrosternal operative space and optimized the surgical field exposure.

Key operative steps

Upon entering the anterior mediastinum, careful identification and preservation of bilateral phrenic nerves, the RSVC, and the PLSVC were performed first. After reconfirming the resectable relationship between the PLSVC and the tumor, a modular dissection proceeded in the following sequence (Figure 3).

• Anterior plane (retrosternal): dissection proceeded cephalad along the posterior sternal surface to the level of the inferior thyroid veins, separating the retrosternal space from the anterior mediastinal contents. This allowed the mediastinal tissues to fall away posteriorly by gravity, further augmenting the operative space.
• Lateral planes (pleural): using the anterior borders of the phrenic nerves as landmarks, both mediastinal pleura were incised sequentially from caudal to cranial and from right to left. The pericardium on both sides, the RSVC, and the PLSVC were meticulously dissected and mobilized, completing the lateral exposure.
• Posterior plane (prepericardial): adhering closely to the anterior surface of the pericardium, dissection continued cranially to free critical structures including the aortic arch and its branches, the trachea, and the thymic veins, thereby separating the anterior mediastinum from the pericardium.

Figure 3 Intraoperative identification and relationship with the vascular anomaly. (Left) The thymoma (green arrows) adjacent to the persistent left superior vena cava (blue arrows) before resection. (Right) View of the anterior mediastinum after tumor removal, showing the preserved PLSVC (blue arrows). PLSVC, persistent left superior vena cava.

Following the dissection along these four planes (anterior, bilateral lateral, and posterior), the planes were united at the thoracic inlet. The thymoma along with the anterior mediastinal fat was completely resected en bloc, accompanied by lymph node dissection (Figure 3). Throughout the dissection, the significantly enlarged surgical field, afforded by the sternal elevation, allowed for excellent visualization of all major anterior mediastinal vessels, minimizing the risk of inadvertent injury.

Postoperative considerations and tasks

The total operative time was 58 minutes with an estimated blood loss of 5 mL. No chest tube was placed postoperatively. A follow-up chest radiograph showed no significant effusion or pneumothorax. Postoperative pain was minimal [Visual Analog Scale (VAS) score of 1]. The skin incision sites were examined on postoperative day 1 and 3; no erythema, ischemia, or infection was observed. The patient recovered without complications and was discharged on postoperative day 3.

Pathological examination confirmed a World Health Organization (WHO) type AB thymoma with a maximum diameter of 6.0 cm. All surgical margins were tumor-free, and all sampled lymph nodes were reactive (Figure 4).

Figure 4 Gross pathological specimen. The resected thymoma, measuring 6.0 cm × 5.0 cm × 5.0 cm, exhibits a lobulated, firm, tan-white cut surface. Histopathological examination confirmed a World Health Organization type AB thymoma.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Tips and Pearls

Preoperative contrast-enhanced CT with three-dimensional vascular reconstruction is essential when thymoma is associated with major venous anomalies. In patients with PLSVC, the course of the anomalous vein, its drainage pattern, the presence or absence of the left brachiocephalic vein, and the distance between the tumor and the venous wall should be carefully assessed before surgery.

The balance-shaped suspension system should be prepared and checked before incision. The presternal tunnel should be created at an adequate depth close to the sternum to allow even distribution of traction force. The use of gauze padding at the skin entry sites and gradual elevation of the external frame may help reduce focal pressure and skin ischemia. Sternal elevation should be performed under continuous thoracoscopic visualization. Excessive traction is unnecessary; the traction force should be increased gradually and maintained at the minimum level required for adequate exposure. The skin entry sites should be inspected both intraoperatively and postoperatively.

For tumor dissection, early identification of the bilateral phrenic nerves, RSVC, and PLSVC is recommended before mobilizing the thymoma. A structured dissection sequence—retrosternal anterior plane, bilateral pleural planes, and posterior prepericardial plane—helps maintain orientation and reduces the risk of inadvertent vascular injury. When the tumor is close to the PLSVC, blunt and sharp dissection should be performed along the tumor capsule while preserving the venous wall.

Discussion

VATS via the subxiphoid approach has become a well-established minimally invasive technique for resecting anterior mediastinal tumors, largely owing to its direct midline visualization and reduced postoperative pain compared to intercostal approaches (8,9). Nonetheless, a fundamental constraint of this method is the limited operative space beneath the sternum, which can compromise exposure, particularly in cases involving complex anatomical variations such as a PLSVC (10). The presence of a PLSVC—a congenital venous anomaly with an estimated prevalence of 0.3% to 0.5%—adds considerable complexity to mediastinal dissection, elevating the risk of inadvertent vascular injury during thymectomy (6,7,11).

Comparison with CO₂ insufflation

Currently, CO₂ insufflation is the most widely adopted method for expanding the operative field in subxiphoid VATS, given its simplicity, versatility, and well-established safety profile (3). Its advantages are well-recognized: it is simple to implement, requires no additional specialized equipment, is applicable to both VATS and robotic-assisted procedures, and provides a relatively bloodless field by compressing small vessels. However, CO₂ insufflation is not without limitations. Increased intrathoracic pressure can lead to hemodynamic compromise, particularly in patients with limited cardiac reserve. Hypercapnia and acidosis may occur, requiring careful ventilation management. Subcutaneous emphysema, though usually benign, can extend to the face and neck, causing patient discomfort. In rare instances, tension pneumomediastinum or venous air embolism have been reported (3). In patients who poorly tolerate hemodynamic changes or when insufflation is technically challenging, mechanical sternal elevation may be a valuable complementary option.

In contrast, the balance-shaped sternal elevation technique provides mechanical expansion of the retrosternal space independent of intrathoracic pressure (5). This may be particularly advantageous in patients who cannot tolerate the hemodynamic effects of positive-pressure pneumomediastinum. Additionally, by physically lifting the sternum, this technique creates a more stable and sustained operative field compared to CO₂ insufflation, which can be compromised by air leakage or fluctuations in pressure. A similar percutaneous suspension approach was recently described for thymic carcinoma resection, supporting the feasibility of such sternal elevation strategies. In the present case, the sternal elevation increased the retrosternal space from 3.5 cm to 8.2 cm (a 135% increase), providing exceptional visualization of both the RSVC and PLSVC and enabling safe dissection around these critical structures (4,12).

Safety considerations and preventive measures

The percutaneous nature of this technique raises legitimate concerns regarding potential skin injury or local complications at the insertion sites. Potential complications, including subcutaneous hematoma, wound infection, and skin necrosis, should be carefully monitored. In this case, several preventive measures were implemented: (I) subcutaneous tunnels were created at an adequate depth (close to the surface of the sternum) to distribute traction forces; (II) traction force was applied gradually and maintained at the minimum level required for adequate exposure; (III) the skin incision sites were inspected intraoperatively and postoperatively for signs of ischemia. Strict aseptic technique and postoperative wound care were employed, and no such events were observed. With these precautions, no skin complications occurred. However, we acknowledge that this is a single case, and the safety profile of this technique requires further evaluation in larger series.

Limitations and applicability

We recognize that the balance-shaped sternal elevation technique has inherent limitations that may restrict its widespread adoption. First, it requires dedicated equipment that may not be available in all centers. This currently restricts the technique to a limited number of facilities, and wider dissemination will depend on device simplification and commercial availability. Second, the external traction system occupies part of the anterior operative field, which could potentially interfere with instrument manipulation, although this was not problematic in our experience. Third, the technique is currently not compatible with robotic-assisted surgery, as the robotic arms would conflict with the external suspension frame. Fourth, the creation of subcutaneous tunnels adds an additional step to the procedure, though it required less than 5 minutes in this case. Furthermore, patient body habitus may affect the ease of setup and the extent of retrosternal space expansion, with obese individuals potentially requiring longer preparation time. Finally, while the technique provides excellent exposure in the midline, its effectiveness for accessing far lateral structures (e.g., posterior mediastinum) may be limited.

Comparison with direct sternal retraction

Compared to direct sternal retraction, the balance-shaped elevation technique offers theoretical advantages in reducing skeletal complications (Table 1). By applying force indirectly through subcutaneous tissues rather than directly to bone, the risk of sternal fracture or chondral separation is minimized (4,12). Additionally, postoperative pain may be reduced, as the periosteum and bone are not subjected to traction. In this case, the patient reported minimal pain (VAS 1), consistent with this hypothesis. However, comparative studies are needed to confirm these potential benefits.

Study limitations

As a single case report, there are inherent limitations in this study. The findings may not be generalizable to all patients or all anterior mediastinal tumors. The technique was performed by experienced thoracic surgeons at a high-volume center; its reproducibility in other settings remains to be demonstrated. Long-term oncological outcomes, including recurrence rates, are not yet available. Prospective studies with larger cohorts and longer follow-up are necessary to comprehensively evaluate the efficacy, safety, and broader applicability of this innovative approach.

Conclusions

This case demonstrates that balance-shaped sternal elevation-assisted uniportal subxiphoid VATS can provide satisfactory exposure for resecting an anterior mediastinal tumor accompanied by a PLSVC. While there are inherent limitations with this technique—including the need for dedicated equipment, incompatibility with robotic surgery, and theoretical concerns regarding skin complications—it may serve as a valuable adjunct in anatomically complex cases where conventional methods prove inadequate. With appropriate preventive measures, the procedure appears safe and feasible. Further studies are warranted to define its optimal indications and compare its outcomes with established techniques.

Acknowledgments

The authors thank the patient for providing consent for this publication. We also acknowledge the surgical and nursing teams of the Department of Thoracic Surgery, West China Hospital. The authors also acknowledge the use of DeepSeek for language editing and writing assistance during the preparation of this manuscript.

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0136/rc

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0136/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2026-1-0136/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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