Surgical technique for subxiphoid-subcostal bilateral thoracoscopic thymectomy: how we do it

Introduction

Minimally invasive thymectomy is well accepted and widely practiced for various indications. The two main approaches for minimally invasive thymectomy are the lateral thoracoscopic [video assisted thoracoscopic surgery (VATS)] approach and the anterior subxiphoid approach. There are several variations within and across these two approaches. Minimally invasive thymectomy techniques have better outcomes compared to a sternotomy in terms of length of stay, blood loss, and recovery time (1,2). However, it is important to critically evaluate the various minimally invasive techniques and ensure that one does not compromise on the surgical principles of a thymectomy, and that the long-term outcomes, remission of myasthenia or thymoma recurrence, are also comparable to trans-sternal thymectomy.

Our approach to thymectomy at the University of Minnesota until 2014 was via a lateral VATS approach. We used right VATS and included a left sided port in most cases for safe and complete dissection along the left phrenic nerve, thus essentially performing a bilateral VATS approach. In our endeavor to avoid bilateral chest incisions while still maintaining the quality of the surgery, we familiarized ourselves with the subxiphoid technique. We initially performed a right VATS approach with a subxiphoid port directed to the left pleural cavity and then eventually transitioned completely to the subxiphoid-subcostal approach, thus avoiding intercostal space incisions.

The proposed benefits of the subxiphoid approach over the transthoracic VATS thymectomy are: supine positioning, single lumen endotracheal intubation, visualization of the entire course of both phrenic nerves, and possibly better pain control. We detail here, our adaptation of the subxiphoid approach to thymectomy which we believe enables us to perform a safe and complete resection. We present this article in accordance with the SUPER reporting checklist (available at https://vats.amegroups.com/article/view/10.21037/vats-23-5/rc).

Preoperative preparations and requirements

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 Helsinki Declaration (as revised in 2013). The images and data used in this project are associated with multiple patients. This project and its data collection were conducted under IRB exemption. The images and videos were obtained from multiple patients and we obtained verbal but not formal written consent given their identity is protected and the images do not show patient identifiers.

Patient selection

We use the subxiphoid bilateral subcostal thoracoscopic technique for all patients that need a thymectomy for any indication. We consider previous sternotomy and radiological evidence of invasion into major vasculature as contraindications to this approach and prefer a sternotomy in these patients. Informed consent is always obtained from the patient and/or their legal decision maker prior to every operation and details the risks and benefits of this approach as well as of alternative approaches.

Anesthetic considerations

We use a single lumen tube and ventilate both lungs with low tidal volumes and low positive end expiratory pressure (PEEP) for the duration of the procedure. The anterior approach and the use of CO₂ insufflation negate the need for single lung ventilation. We routinely insert a large bore intravenous catheter in the lower extremity (usually the saphenous vein) for emergent intravenous (IV) access in case of injury to the superior vena cava or innominate vein.

Step-by-step description

We position the patient supine with arms abducted and a footboard with the bed flexed at the waist. With this position and with reverse Trendelenburg, we are able to work upwards in the mediastinum (Figure 1).

Figure 1 The patient is positioned supine, arms abducted and with the bed flexed at the waist.

Port placement

We use a 15 mm subxiphoid port as our initial access. A small incision is made in the subxiphoid area with sharp dissection down to the rectus muscle. We then bluntly dissect in the retrosternal space to create a tunnel to access the right pleural space and introduce the first port. After confirming entry into the pleural space with the camera, we insert 2 lateral subxiphoid ports (Figure 2). We do this by identifying a spot about 5–6 cm lateral to the central subxiphoid port and then inserting a 5 mm port into the mediastinum guided by the finger through the central port space (Figure 3). We then use a 45-degree camera to visualize the insertion of the lateral subcostal ports along the anterior axillary line. A 5 mm port is tunneled under the costal margin, skiving above the diaphragm to enter the pleural space (Figure 4).

Figure 2 A 15 mm subxiphoid port is used as initial access into the pleural space followed by two lateral subxiphoid ports. Left: a 15 mm subxiphoid port is used as initial access into the pleural space (number 1 represents the location). Right: two lateral subxiphoid ports are placed subsequently (numbers 2 and 3 represent the locations). AAL, anterior axillary line; MCL, midclavicular line.

Figure 3 Port placement. (A) External view of the lateral subxiphoid port placement. (B) Intrathoracic view of the laterally placed subxiphoid port.

Figure 4 Numbers 4 and 5 represent the locations of the 5 mm lateral subcostal ports that are placed along the anterior axillary line. AAL, anterior axillary line; MCL, midclavicular line.

Operative steps (Video 1)

Our first step is to dissect the pericardiophrenic fat inferiorly (Figure 5). Once the thymic fat is separated off the diaphragm, we proceed to dissect the thymus off the phrenic nerve. We use sharp dissection with scissors and clipping for hemostasis along the phrenic nerve to minimize the potential for energy injury from an energy device. With camera hopping between the most lateral ports we are able to get excellent visualization of both the right and left nerves as we carry out this dissection (Figures 5,6). On the left side, the pericardiophrenic fat is dissected and pulled over to give a clear view of the phrenic nerve. The thymic tissue is then separated off the retro-sternum anteriorly and the pericardium posteriorly. The innominate vein is visualized superiorly and the thymus is dissected off the innominate vein. We always dissect the cervical thymic horns completely. For this dissection, we place the camera in one of the more central ports and we are able to carry out the dissection of the horns until their most cephalad attachment (Figure 7). Once the thymus is completely dissected, a specimen bag is introduced through the subxiphoid port and the specimen is extracted. We insert a small bore drain through one of the 5 mm subxiphoid ports into the mediastinum and across both pleural spaces. This tube is removed on postoperative day 1.

Figure 5 The cardiophrenic fat and right phrenic nerve are visualized in this view of the right chest.

Figure 6 The left phrenic nerve is visualized during sharp dissection.

Figure 7 The innominate vein is skeletonized and the thymic horns are clearly visible.

Postoperative considerations and tasks

Postoperatively, patients should be monitored using continuous pulse oximetry and cardiac telemetry. A postoperative chest X-ray should be obtained in the recovery unit to evaluate positioning of the drain, assess lung expansion, and evaluate the diaphragm. Postoperative complications include bleeding, respiratory insufficiency and/or failure, and phrenic nerve injury. Bleeding immediately during and after surgery should raise suspicion for possible internal mammary artery injuries, cardiac injury, or innominate vein injury. Postoperative dyspnea and respiratory failure raise concern for phrenic nerve and diaphragmatic injury in addition to atelectasis and pneumothorax. For patients undergoing thymectomy for myasthenia gravis, interdisciplinary collaboration with neurology should drive resumption of relevant medications.

Tips and pearls

• Positioning with reverse Trendelenburg and flexion at the hip allows the camera to be angled easily to visualize the superior extent of the thymus.
• Visualization of the pericardiophrenic angles can be challenging. Moving the camera to the most lateral ports and changing to a 45-degree camera is helpful.
• We recommend sharp dissection along the phrenic nerve using clips for the vascular fatty tissue and using scissors to minimize the risk of thermal injury.
• Once the inferior cardiophrenic fat is dissected, pulling the fat over to the right side exposes the entire extent of the left phrenic nerve. This maneuver is especially useful in patients with a higher body mass index (BMI) and bulky mediastinal fat.
• During placement of the lateral subcostal ports, it is essential to stay right under the costal margin and enter just above the insertion of the diaphragm with 5 mm ports. At the end of the procedure, we place the subxiphoid port into the peritoneum and inspect the upper quadrants to ensure there was no visceral injury.

Discussion

In the last decade, minimally invasive thymectomy has been generally accepted as a non-inferior and less morbid approach to thymectomy compared to the transsternal approach (3,4). The minimally invasive subxiphoid approach to thymectomy was first described by Kido in 1999 (5). Since then, several authors have reported variations of the subxiphoid technique with the main principle being access to an anterior mediastinal structure from an anterior rather than lateral approach (6).

We started performing subxiphoid-subcostal thoracoscopic thymectomy in 2014 and transitioned to this approach completely in 2016. Our previous experience with subxiphoid thoracoscopic lung resections (7) gave us the technical advantage to successfully adopt this approach. We have performed 45 subxiphoid-subcostal thymectomies since then and have recently published our results showing comparable outcomes between our own group of patients undergoing subxiphoid versus transthoracic minimally invasive thymectomy for various indications (8). We found that there was no significant difference in perioperative outcomes such as blood loss, operative time, length of stay or 30-day complication rate between the two groups. These conclusions are similar to other studies comparing the two minimally invasive approaches (9-12). The largest thymoma we resected in the subxiphoid group was 10.5 cm. In the subxiphoid group, we had two conversions to sternotomy; one emergent conversion for bleeding and one elective conversion for difficult dissection of an aorto-pulmonary window lymph node. This conversion rate is also comparable to other published subxiphoid and transthoracic series (2,13-15). To date we have had no phrenic nerve injuries. On follow up (median 10 months; range, 2–24 months), we have had no incidence of diaphragm hernia.

Irrespective of the approach, the primary goal of a thymectomy is to remove the thymus gland completely. Visualizing and protecting the phrenic nerves without compromising on the extent of thymectomy is critical. With our technique we are able to clearly visualize and safely dissect from nerve to nerve and from diaphragm to the cervical horns. Thus, the extent of the thymectomy tends to be closer to the maximal thymectomy described by Sonett and Jaretzki (16), although we do not routinely remove the fat lateral to the phrenic nerve or the aorto-pulmonary window fat. The uniqueness of our approach is the addition of the 2 lateral subcostal ports. This allows for camera hopping between the lateral ports for excellent visualization of both nerves from the inferior cardiophrenic fat all the way up to the thoracic inlet. Subxiphoid thymectomy in obese patients can be challenging; the lateral ports and CO₂ insufflation facilitate dissection even in morbidly obese patients. The median BMI of patients in the subxiphoid group in our series was 30 (range, 26–32) kg/m².

There are several acceptable approaches to performing a thymectomy while adhering to the core principles of a complete resection and safe operation. We believe that our approach has been successful in this regard. We have also recently performed the procedure robotically with similar port placement. We will continue to track our results in a database as we grow our experience with the subxiphoid and subcostal thoracoscopic approach.

Conclusions

Minimally invasive thymectomy is commonly performed using a transthoracic thoracoscopic approach.

The subxiphoid-subcostal approach is another minimally invasive technique that is beginning to gain traction as a safe and acceptable alternative to the traditional transthoracic approach with the advantages of minimizing intercostal neuropathy, allowing for visualization of the entirety of bilateral phrenic nerves, and decreasing the need for single lung ventilation. By describing our surgical technique and our pearls and pitfalls in this article, we are hopeful that our approach to thymectomy is reproducible by other surgeons and will facilitate commentary within the surgical community regarding the various approaches to thymectomy.

Acknowledgments

We would like to thank the University of Minnesota Department of Surgery for their continued support of the Thoracic Surgery Department and our mission to provide high quality care for our patients.

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editors (Carlos Galvez Munoz and Paula A. Ugalde Figueroa) for the series “Advanced Uniportal VATS” published in Video-Assisted Thoracic Surgery. The article has undergone external peer review.

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://vats.amegroups.com/article/view/10.21037/vats-23-5/rc

Peer Review File: Available at https://vats.amegroups.eom/article/view/10.21037/vats-23-5/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://vats.amegroups.com/article/view/10.21037/vats-23-5/coif). The series “Advanced Uniportal VATS” was commissioned by the editorial office without any funding or sponsorship. The authors have no other 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 Helsinki Declaration (as revised in 2013). The images and data used in this project are associated with multiple patients. This project and its data collection were conducted under IRB exemption. The images and videos were obtained from multiple patients and we obtained verbal but not formal written consent given their identity is protected and the images do not show patient identifiers.

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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