Advertisement

Thoracoscopic Thymectomy

      Our experience with video-assisted thoracoscopic (VATS) thymectomy began in the late 1990s. This has evolved from our larger VATS experience with a wide array of other thoracic procedures. We are primarily utilizing the thoracoscopic approach in those patients with myasthenia gravis. Although there are a number of approaches (the classic transsternal approach, transcervical approach, subxiphoid approach, and the combined transcervical-transsternal maximum thymectomy), we are almost exclusively performing this operation via VATS at the University of Minnesota Medical Center with excellent results. We have also performed a number of these operations with the DaVinci robot following the same technical steps. The details of our thoracoscopic approach are described in this article.

      Operative Technique

      Following induction of general anesthesia and intubation with a double-lumen endotracheal tube, the patient is positioned in the partial left lateral decubitus position angled with a bump under the right side (Fig. 1A and B). An important consideration during positioning is that we maintain access to the left chest by keeping the left inframammary fold exposed. The patient is then prepped and draped and the left lung is selectively ventilated. Ports are planned for the right VATS portion of the procedure with our recent preference to place 3 ports on the right side (10 mm) (Fig. 2).
      Figure thumbnail gr1
      Figure 1Patient positioning in the partial left lateral decubitus position. (A) View from left side of patient. (B) View from right side of patient. Note the 30° angle with a bump under the right side.
      Figure thumbnail gr2
      Figure 2Port placement on the right chest wall.
      The 30° thoracoscopic camera is introduced and the entire hemithorax is evaluated. CO2 insufflation at a pressure of 10 mm Hg is used as an adjunct to rapidly achieve right lung collapse. The right phrenic nerve is identified and preserved during the dissection. The mobilization of the thymus is begun by incising the mediastinal pleura anterior to the phrenic nerve with hook electrocautery (Fig. 3). Dissection of the thymus gland and the associated soft tissue begins at the right inferior pole at the level of the diaphragm and it can be nicely dissected off the pericardium moving superiorly (Fig. 4). The thymus is also completely mobilized medially by dividing the mediastinal pleura anteriorly along the length of the internal mammary artery/vein at the level of the sternum. The dissection is continued superiorly, freeing it from the innominate vein. The numerous vein branches are dissected and controlled by endoclips (Fig. 5). Gentle traction on the gland aids in exposure and control of these vein branches. Both superior poles of the thymus are dissected and liberated under direct vision (Fig. 6). Exposure of the superior poles is best achieved with gentle downward traction on the thymus and careful dissection with the use of countertraction directed superiorly to liberate the poles. During this dissection, the CO2 insufflation that we routinely use also aids with this dissection. The arterial branches in this region from the internal mammary are identified and clipped. The thymus is then retracted toward the right side and the dissection is completed anteriorly across the chest to expose the left side of the thymus (Fig. 7).
      Figure thumbnail gr3
      Figure 3Mobilization of the thymus is begun by incising the mediastinal pleura anterior to the right phrenic nerve with hook electrocautery. IMA = internal mammary artery; IMV = internal mammary vein; n. = nerve.
      Figure thumbnail gr4
      Figure 4Dissection of the thymus gland and the associated soft tissue begins at the right inferior pole at the level of the diaphragm. The thymus can be easily dissected off of the pericardium moving superiorly. SVC = superior vena cava.
      Figure thumbnail gr5
      Figure 5Demonstration of the use of endoclips to control the numerous vein branches as they are encountered. RIMA = right internal mammary artery; RIMV = right internal mammary vein.
      Figure thumbnail gr6
      Figure 6Both superior poles of the thymus are dissected and liberated under direct vision. Exposure of the superior poles is best achieved with gentle downward traction on the thymus and careful use of countertraction. The CO2 insufflation used throughout the dissection also significantly aids with this portion of the procedure.
      Figure thumbnail gr7
      Figure 7The thymus is then retracted to the right side and dissection is completed across the chest to expose the left side of the thymus.
      Next, a 5-mm scope and separate camera and video setup are prepared for left VATS. During this portion of the procedure, the right lung is ventilated. We then make a 5-mm port incision below in the inframammary crease on the left side and insert the 5-mm 30° thoracoscope to observe the left phrenic nerve and ensure that our dissection is carried all the way over to it without injury (Fig. 8). This ensures complete resection of the thymus and all accompanying fat. The specimen (Fig. 9) is removed in an EndoCatch bag through 1 of the 10-mm port sites (right chest). The mediastinum is then inspected for removal of any additional remaining fatty mediastinal tissue. The superior vena cava and brachiocephalic vein should be completely skeletonized at this point (Fig. 10). Hemostasis is assured and one 19-French Blake drain is placed through a port incision to drain the chest. The wounds are then closed in layers with absorbable suture after visually ensuring lung re-expansion.
      Figure thumbnail gr8
      Figure 8Positioning of the VATS port sites for the left-sided approach to visualize the thymus from the left chest. This setup ensures complete resection of the thymus and all accompanying fat, which, importantly, minimizes the chance of left phrenic nerve injury.
      Figure thumbnail gr9
      Figure 9Representative thymic specimen obtained.
      Figure thumbnail gr10
      Figure 10Final view of the mediastinum with completely skeletonized SVC and brachiocephalic vein. SVC = superior vena cava; v. = vein.

      Discussion

      Since the first major report advocating thymectomy for myasthenia gravis, median sternotomy has been the gold standard approach for thymic resection. Recently, thoracic surgeons have explored less invasive approaches to thymic resection.
      • Hazelrigg S.R.
      Thoracoscopic or video-assisted (VATS) thymectomy.
      • Shrager J.B.
      Extended transcervical thymectomy: The ultimate minimally invasive approach.
      • Daniel V.C.
      • Wright C.D.
      Extended transsternal thymectomy.
      • Mack M.J.
      Video-assisted thoracoscopy thymectomy for myasthenia gravis.
      The identical radical thymectomy can be safely performed thoracoscopically for patients with myasthenia gravis. Patients can usually be discharged within 1 to 2 days with a cosmetically pleasing result when compared with thymectomy performed via other approaches (ie, sternotomy).
      • Mack M.J.
      • Landreneau R.J.
      • Yim A.P.
      • et al.
      Results of video-assisted thymectomy in patients with myasthenia gravis.
      • Yim A.P.
      • Kay R.L.
      • Ho J.K.
      Video-assisted thoracoscopic thymectomy for myasthenia gravis.
      This procedure also lends itself to an excellent application for the DaVinci robot. Although we have not employed the harmonic scalpel in our approach, it has successfully been utilized.
      • Soon J.L.
      • Agasthian T.
      Harmonic scalpel in video-assisted thoracoscopic thymic resections.
      Importantly, our thoracoscopic approach described here, involving bilateral VATS, provides confidence in complete resection of all thymic tissue.
      Complications from thoracoscopic thymectomy are similar to those seen from alternative approaches, and, although infrequent, include the following: bleeding, wound infection, hypocalcemia, pneumothorax, surgical emphysema, intercostal neuralgia, and phrenic nerve palsy.
      • Ng C.S.
      • Wan I.Y.
      • Yim A.P.
      Video-assisted thoracic surgery thymectomy: The better approach.
      • Shiono H.
      • Kadota Y.
      • Hayashi A.
      • et al.
      Comparison of outcomes after extended thymectomy for myasthenia gravis: Bilateral thoracoscopic approach versus sternotomy.
      Management of such complications is straightforward and includes source control/antibiotics for infections and tube thoracostomy for pneumothoraces; treatment of neuralgia/nerve palsies is patient-dependent and directed at symptom control. Re-exploration for bleeding is an exceedingly rare occurrence.
      Utilization of the thoracoscopic approach for resection of thymoma remains more controversial. VATS resection is quite feasible for small tumors (<3 cm), and we advocate the same approach for such tumors. A strict precaution of no handling or disruption of the tumor must be taken. We favor more traditional approaches for larger tumors to ensure complete and aggressive resection of tumor along with the avoidance of drop metastases during the operation.
      • Ng C.S.
      • Wan I.Y.
      • Yim A.P.
      Video-assisted thoracic surgery thymectomy: The better approach.
      • Shiono H.
      • Kadota Y.
      • Hayashi A.
      • et al.
      Comparison of outcomes after extended thymectomy for myasthenia gravis: Bilateral thoracoscopic approach versus sternotomy.
      • Yim A.P.
      • Kay R.L.
      • Izzat M.B.
      • et al.
      Video-assisted thoracoscopic thymectomy for myasthenia gravis.

      References

        • Hazelrigg S.R.
        Thoracoscopic or video-assisted (VATS) thymectomy.
        Op Tech Thorac Cardiovasc Surg. 2004; 9: 184-192
        • Shrager J.B.
        Extended transcervical thymectomy: The ultimate minimally invasive approach.
        Ann Thorac Surg. 2010; 89: S2128-S2134
        • Daniel V.C.
        • Wright C.D.
        Extended transsternal thymectomy.
        Thorac Surg Clin. 2010; 20: 245-252
        • Mack M.J.
        Video-assisted thoracoscopy thymectomy for myasthenia gravis.
        Chest Surg Clin North Am. 2001; 11 (xi-xii): 389-405
        • Mack M.J.
        • Landreneau R.J.
        • Yim A.P.
        • et al.
        Results of video-assisted thymectomy in patients with myasthenia gravis.
        J Thorac Cardiovasc Surg. 1996; 112 (discussion 1359-1360): 1352-1359
        • Yim A.P.
        • Kay R.L.
        • Ho J.K.
        Video-assisted thoracoscopic thymectomy for myasthenia gravis.
        Chest. 1995; 108: 1440-1443
        • Soon J.L.
        • Agasthian T.
        Harmonic scalpel in video-assisted thoracoscopic thymic resections.
        Asian Cardiovasc Thorac Ann. 2008; 16: 366-369
        • Ng C.S.
        • Wan I.Y.
        • Yim A.P.
        Video-assisted thoracic surgery thymectomy: The better approach.
        Ann Thorac Surg. 2010; 89: S2135-S2141
        • Shiono H.
        • Kadota Y.
        • Hayashi A.
        • et al.
        Comparison of outcomes after extended thymectomy for myasthenia gravis: Bilateral thoracoscopic approach versus sternotomy.
        Surg Laparosc Endosc Percutan Tech. 2009; 19: 424-427
        • Yim A.P.
        • Kay R.L.
        • Izzat M.B.
        • et al.
        Video-assisted thoracoscopic thymectomy for myasthenia gravis.
        Semin Thorac Cardiovasc Surg. 1999; 11: 65-73