HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Michael A. Savitt Anthony P. Furnary Jeffrey Swanson Hugh L. Gately John R. Handy Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Savitt, M. A. Articles by Handy, J. R. Search for Related Content PubMed PubMed Citation Articles by Savitt, M. A. Articles by Handy, J. R. Related Collections Mediastinum

Ann Thorac Surg 2005;79:450-455
© 2005 The Society of Thoracic Surgeons

---

Original article: General thoracic

Application of Robotic-Assisted Techniques to the Surgical Evaluation and Treatment of the Anterior Mediastinum

Providence St. Vincent Heart and Vascular Institute, Portland, Oregon

Accepted for publication July 14, 2004.

^* Address reprint requests to Dr Savitt, Providence St. Vincent Heart and Vascular Institute, 9155 SW Barnes Rd, Suite 240, Portland, OR97225 (E-mail: msavitt{at}starrwood.com).

	Abstract

Top Abstract Introduction Material and Methods Results Comment References

 
BACKGROUND: We report our initial experience with the application of robotic-assisted technologies to the treatment of diseases of the anterior mediastinum.

METHODS: Between October 2001 and December 2003, 18 consecutive patients with anterior mediastinal masses were referred for diagnosis and treatment. Fifteen patients underwent robotic-assisted surgery with the da Vinci robotic system. A single surgical team performed all operations. Resection was accomplished by either median sternotomy or robotic-assisted techniques.

RESULTS: Fourteen patients underwent successful robotic-assisted thymectomy. One patient underwent robotic-assisted biopsy of a mass that was later determined to be a poorly differentiated carcinoma, 3 patients underwent complete thymectomy by median sternotomy for biopsy-proven extracapsular thymoma, 7 patients had thymoma, and 3 had myasthenia gravis. There were 2 patients each with benign thymic cysts and thymic hyperplasia. Primary thymic carcinoid, thymolipoma, papillary thyroid cancer, and poorly differentiated carcinoma were present in 1 patient each. No conversions, intraoperative complications, or deaths occurred in the 15 patients who underwent robotic-assisted resection. The mean operative time was 96 minutes (range 62 to 132 minutes). The mean robotic time was 48 minutes (range 22 to 76). The median hospital stay was 2 days. All patients are doing well, with a median follow-up of 1 year.

CONCLUSIONS: Robotic-assisted surgery of the anterior mediastinum, and particularly thymectomy, can be performed safely and efficiently. The increased visualization and instrument dexterity afforded by this technology provides an optimal minimally invasive approach to the anterior mediastinum. From this experience we have formulated a comprehensive treatment algorithm for the surgical evaluation and treatment of patients with anterior mediastinal diseases.

	Introduction

Top Abstract Introduction Material and Methods Results Comment References

 
The diagnosis and treatment of benign and malignant diseases of the anterior mediastinum remains a challenge to the thoracic surgeon. Traditional surgical applications to the anterior mediastinum involve both diagnostic and therapeutic procedures. Diagnostic procedures have been used principally for the evaluation of unknown masses of the anterior mediastinum and conformation of suspected hematopoietic malignancies such as lymphoma and Hodgkin's disease. Therapeutic resections have been primarily applied to patients with thymoma, myasthenia gravis, and thymic or bronchogenic cysts [1–4].

Diagnostic surgery of the anterior mediastinum includes mediastinoscopy (anterior and cervical) and thoracoscopy [2, 5–7]. There is little debate that the gold standard for resectional therapy of thymoma, with or without myasthenia gravis, is generally median sternotomy, with thoracoscopy advocated as an alternative for the treatment of known benign cystic diseases [2, 5, 6, 8]. However, debate continues over the optimal resectional approach in patients with isolated myasthenia gravis, with strong advocates for conservative cervical thymectomy, thoracoscopy, and radical transsternal resection [4, 8–17].

The introduction of robotic-assisted technologies in the late 1990s provided an improvement in visualization and surgical dexterity over thoracoscopy [18–20]. We had a fair experience with robotic-assisted cardiac and thoracic surgery when a patient was referred with an anterior mediastinal mass. We believed the robotic-assisted technology was applicable in this case. The ease of this first procedure led us to actively seek patients with anterior mediastinal diseases to see if this technology was truly as facilitating as it seemed on that initial case. This is a report of our early experience and preliminary results with the application of robotic-assisted technologies to anterior mediastinal disease.

	Material and Methods

Top Abstract Introduction Material and Methods Results Comment References

 
Patient Characteristics
Between October 2001 and December 2003, 18 consecutive patients with anterior mediastinal disease were referred for diagnosis and treatment. Ten patients were men, 8 were women, and their ages ranged from 23 to 74 years (44 ± 19 years). Fifteen patients underwent robotic-assisted resection with the da Vinci robotic surgical system (Intuitive Surgical, Inc, Sunnyvale, CA). Two patients with biopsy-proven thymoma and convincing preoperative computed tomography (CT) evidence of extracapsular extension of disease [21] were resected with median sternotomy. One patient with biopsy-proven thymoma and questionable preoperative evidence of extracapsular extension underwent an initial right videoscopic evaluation and subsequent resection through a median sternotomy. Thymic disease predominated (16 patients); 6 patients had a thymoma without myasthenia gravis. The clinical and pathologic data on these patients are summarized in Table 1.

The robotic-assisted procedure was performed under general anesthesia with selective single-lung ventilation, and radial artery and central venous catheters. The patient was positioned supine on a beanbag with either the right (13 patients) or left (2 patients) chest elevated 30 degrees, with the ipsilateral shoulder retracted and depressed, the arm internally rotated and elbow flexed at the patient's side (Fig 1). This position allows access to the anterior and midaxillary lines without brachial plexus traction and free motion of thoracoscopic or robotic instrumentation. Laterality was initially determined by the anatomic predominance of the anterior mediastinal mass. The left-sided approach, however, is difficult owing to diminished mediastinal working space secondary to the cardiac mass. The heart impairs the reach of the lower robotic arm into the superior-most anterior mediastinum and visualization of the right phrenic nerve across the midline. Thus, we now favor a right-side approach for all patients.

View larger version (28K): [in this window] [in a new window]   Fig 1. Illustration of the patient position and location of the robotic instrument ports.

In one patient we concluded that a biopsy-proven thymoma was extracapsular and proceeded with thymectomy through a median sternotomy. In the remaining 15 patients, after the initial evaluation, the robotic surgical system was brought up to the table from the patient's left side (13 patients) for right-sided port placement. A 30-degree telescope was used and the robotic instruments were introduced through the third and seventh intercostals space in the anterior axillary line (Fig 1). In young female patients, the camera port can be placed strategically in the submammary fold for improved cosmetics.

Complete thymectomy was then performed in 14 out of the 15 patients. In 1 patient early in our experience, we placed the robotic instruments before obtaining the tissue diagnosis in anticipation of performing a robotic-assisted resection. We then noted a second lesion anterior to the pulmonary artery, and a biopsy specimen was obtained with the robotic instrumentation. A poorly differentiated carcinoma was diagnosed from the frozen section and resection was not performed. In the remaining patients, thymectomy was facilitated by right lung deflation and CO₂ insufflation to a pressure of 10 to 15 mm Hg. The radial arterial and central venous pressures were monitored to ensure adequate hemodynamics during progressive CO₂ insufflation. Maximizing the pressure of insufflation helps create space and facilitates visualization throughout the procedure.

The thymic dissection is begun at the right pericardiophrenic angle and continued up along the right phrenic nerve to the superior vena caval innominate vein junction. The mediastinum is dissected free from the retrosternal area to beyond the left internal mammary artery, extending superiorly until the innominate vein is exposed. The thymus is then retracted rightward, and with rotation of the scope caudally and towards the left chest, the left phrenic nerve can generally be identified. The leftward thymic extent can be dissected in a cephalad manner. If the left phrenic nerve cannot be identified, the left pleural space is entered and the scope passed across the midline into the left chest. The scope then can be used to look down and back while ventilation is temporarily interrupted so that the exact position of the left phrenic nerve may be verified.

Exposure of the thymic cords is facilitated by the CO₂ insufflation, which helps to create the dissection plane into the neck. Each pole is grasped and dissected in its entirety. The thymic venous tributaries that drain the innominate vein are identified, clipped, and divided. The thymus is then placed in an endoscopic bag and removed through the lower port. With large lesions, and especially thymomas, care must be used when removing the specimen, and occasionally, the port incision has to be extended.

The thymic bed is inspected for homeostasis and completeness of resection. The robotic instrument arms are removed from the surgical field. Rib blocks are placed before lung inflation. If the contralateral pleural space was entered, a small chest tube is placed across the midline, aspirated, and removed. In our series, a chest tube was left postoperatively in 5 patients to drain the operative hemithorax. The port incisions are closed in multiple layers. All patients are extubated in the operating room.

	Results

Top Abstract Introduction Material and Methods Results Comment References

 
No conversions, intraoperative complications, or deaths occurred in the 15 patients who underwent robotic-assisted resection. The mean operative time was 96 minutes (range 62 to 132 minutes), while the mean robotic time was 48 minutes (range 22 to 76 minutes). The median hospital stay was 2 days (range 1 to 4 days). One patient had postoperative paroxysmal atrial fibrillation that returned to sinus rhythm before discharge. All patients are doing well with a median follow-up of 1 year (range 5 to 28 months). The mean operative time in the 3 patients who underwent an extended thymectomy through a median sternotomy was 140 minutes (range 118 to 164). The hospital stay was 4 days (range 3 to 4).

The final pathologic diagnoses in all 18 patients are summarized in Table 1. Fig 2 shows representative CT images of 4 patients, all with different anterior mediastinal disease. Panel A shows a representative CT image of a patient with an encapsulated anterior mediastinal mass. This patient underwent complete robotic-assisted thymectomy for a stage I thymoma. Panel B depicts an encapsulated anterior mediastinal mass treated with complete robotic-assisted thymectomy. This patient had a primary thymic carcinoid tumor. Panels C and D demonstrate large extracapsular masses. The patient in Panel C had known papillary thyroid cancer, and given the low-grade nature of this malignancy, underwent complete robotic-assisted thymectomy. The patient in panel D had a preoperative biopsy-proven thymoma and was treated with median sternotomy.

View larger version (120K): [in this window] [in a new window]   Fig 2. Representative computed tomography images of 4 patients with anterior mediastinal masses. (A) Encapsulated thymoma. (B) Thymic carcinoid. (C) Papillary thyroid cancer. (D) Extracapsular thymoma.

	Comment

Top Abstract Introduction Material and Methods Results Comment References

Debate between advocates of conservative cervical thymectomy and more radical resection for the treatment of isolated myasthenia gravis remains heated. Both groups have demonstrated acceptable long-term clinical results with equivalent perioperative morbidity and mortality [9, 12–15, 22, 23]. The cervical approach is proponed to reduce morbidity in patients with severe myasthenia gravis, an outcome not consistently demonstrated in the literature [9, 12, 14–17]. The only consistently demonstrated benefit of the transcervical approach has been a 1- to 2-day reduction in hospital stay [15]. The reality is that one procedure is chosen over the other simply because of surgeon training and experience.

The application of video-assisted thorascopic surgical (VATS) techniques to the anterior mediastinum was a natural progression of this technology. The advantage of this technology is that it appears to provide a low morbidity, with short hospitalization, while allowing for concomitant diagnosis and resection if indicated [5, 7, 12, 14, 16, 17, 23, 24]. However, in our opinion, the technique is limited for radical thymic resections and should be used only in the removal of benign cystic lesions and normal thymic tissue.

Robotic-assisted technologies were developed to extend minimally invasive techniques. In cardiothoracic surgery, robotics have been primarily applied to cardiac surgery, focusing on mitral valve repair, atrial fibrillation ablation, placement of left ventricular bipolar pacing leads, and atrial septal defect repair [18–20]. Little has been reported on its application in general thoracic surgery [11].

We have had an extensive experience with this technology, and the current platform appears to be best suited for application to anatomic regions that are difficult to access with VATS techniques. These include the heart, thorax, and pelvis. The improved dexterity in areas with a limited and finite space appears to be quite enabling. The advent of this technology has led to the understanding that working space is at a premium, especially in anatomic areas where insufflation alone is inadequate, such as the anterior mediastinum.

Thorascopy is limited by the shear fact that the arms don't articulate, which makes it difficult to operate around corners in a fixed three-dimensional space. In robotic-assisted surgery, a three-dimensional image is obtained, mimicking the natural surgical field with the added advantage of optical magnification. Robotic-assisted technology introduces several improvements over standard endoscopy: (1) the high-resolution, real-time video image can be magnified to obtain the best possible view of the operative site; (2) the surgical endowrist can articulate and rotate 360 degrees, improving maneuvering around organs and vessels; and (3) hand tremors are filtered, allowing greater technical precision.

We have now done robotic-assisted surgical procedures on more than 70 patients at our institution, and the easiest and quickest robotic setup is for thoracic cases. The robotic setup is done by a single member of our operative team and takes 20 minutes before anesthetic induction; while robotic positioning and port placement takes about 5 minutes of operative time. After our initial learning curve, the total operative time required to perform a robotic-assisted thymectomy is less then 2 hours, and is now faster then our open cases and significantly faster then the VATS approach.

A key difference in our operative time is that for the VATS technique we use a harmonic scalpel, while for the robotic-assisted technique we use a simple unipolar cautery to perform the dissection. This highlights one of the many advantages of the robotic-assisted technique, articulation. In the VATS technique it is very difficult to operate around corners, to the left side of the pericardium, and into the neck with a simple nonarticulating cautery or harmonic device. With the added dexterity (articulation) of the robotic instruments, this is very easily accomplished and greatly reduces operative times.

The elimination of the harmonic scalpel and the reduction in operative times has made the cost between these two techniques (robotic-assisted and VATS) virtually equivalent at our institution. We generally use only two robotic instruments when we do these cases, a simple grasper and a robotic unipolar cautery, which cost about $200 to $250 for each procedure. The yearly service fee for maintenance of the robotic system is about $200 a procedure (depending on case load). These costs amount to an additional cost of $600 to 1000 per case but are offset by eliminating the harmonic scalpel and reducing the overall operative time.

In the absence of convincing data demonstrating the superiority of one approach over another, the choice of surgical approach comes down to balancing the theoretic benefit of removing the maximal quantity of thymic tissue with minimal invasive and cosmetic consequences. Most anterior mediastinal disease involves the thymus. In our series, 16 of the 18 patients had primary thymic pathology. Only 3 patients had myasthenia gravis, and none of these patients had a thymoma. In our experience, most patients who present for surgical treatment of anterior mediastinal disease require a complete thymectomy. Given the equivalent morbidity and mortality of the various surgical approaches, it makes no sense that patients with isolated myasthenia gravis should undergo any procedure that does not assure complete removal of all possible thymic tissue.

All patients with anterior mediastinal disease should be treated in a similar fashion and with a similar goal to remove as much thymus as can be accomplished safely. The advent of robotic-assisted technologies has provided a tool that should allow this goal to be accomplished with comparable morbidity and mortality to previous surgical approaches, with the added benefit of a reduction in hospital stay and cosmetics as seen with the so called less invasive techniques.

The management of anterior mediastinal diseases remains controversial. Advocates of surgical intervention emphasize the possibility of potential growth and malignancy [3, 25, 26]. Nonsurgeons are often concerned about surgical trauma, advocating percutaneous aspiration or mediastinoscopy of mediastinal cysts, for example [27]. Robotic-assisted technologies provide a less invasive surgical approach with access to every part of the anterior mediastinum.

Based on this experience, we now approach all patients with anterior mediastinal disease in a similar fashion. Our current treatment algorithm is summarized in Figure 3. We advocate an initial minimally invasive surgical approach for all patients with anterior mediastinal masses to provide histologic diagnosis, alleviate symptoms, and prevent the development of associated complications. Robotic-assisted techniques, in our opinion, are the superior choice for minimally invasive resections except in the instance of extracapsular thymoma, which is a contraindication to this approach owing to its propensity to seed the pleural spaces [2, 6].

View larger version (18K): [in this window] [in a new window]   Fig 3. Treatment algorithm for anterior mediastinal pathology. Low-grade malignancy includes papillary and follicular thyroid cancer, carcinoid, and germ cell neoplasms. *Obvious extra-capsular extension on preoperative computed tomography scan with biopsy proven thymoma may proceed directly to median sternotomy with extended thymectomy. **VATS biopsy may be forgone in patients with preoperatively confirmed pathologic diagnosis. (VATS = video-assisted thoracic surgery.)

	References

Top Abstract Introduction Material and Methods Results Comment References

 

1. Burkell CC, Cross JM, Kent HP, Nanson EM. Mass lesions of the mediastinum. Curr Probl Surg 1969:2–57..
2. Conkle DM, Adkins Jr RB. Primary malignant tumors of the mediastinum Ann Thorac Surg 1972;14(5):533-567.[Medline]
3. Wick MR, Scheithauer BW, Weiland LH, Bernatz PE. Primary thymic carcinomas Am J Surg Pathol 1982;6(7):613-630.[Medline]
4. Davis Jr RD, Oldham Jr HN, Sabiston Jr DC. Primary cysts and neoplasms of the mediastinum: recent changes in clinical presentation, methods of diagnosis, management, and results Ann Thorac Surg 1987;44(3):229-237.[Abstract]
5. Kern JA, Daniel TM, Tribble CG, Silen ML, Rodgers BM. Thoracoscopic diagnosis and treatment of mediastinal masses Ann Thorac Surg 1993;56(1):92-96.[Abstract]
6. Verley JM, Hollmann KH. ThymomaA comparative study of clinical stages, histologic features, and survival in 200 cases. Cancer 1985;55(5):1074-1086.[Medline]
7. Yim AP. Video-assisted thoracoscopic management of anterior mediastinal massesPreliminary experience and results. Surg Endosc 1995;9(11):1184-1188.[Medline]
8. Jaretzki 3rd A, Barohn RJ, Ernstoff RM, et al. Myasthenia gravis: recommendations for clinical research standards Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of AmericaAnn Thorac Surg 2000;70(1):327-334.
9. Jaretzki 3rd A, Penn AS, Younger DS. "Maximal" thymectomy for myasthenia gravisResults. J Thorac Cardiovasc Surg 1988;95(5):747-757.[Abstract]
10. Jaretzki 3rd A, Bethea M, Wolff M, et al. A rational approach to total thymectomy in the treatment of myasthenia gravis Ann Thorac Surg 1977;24(2):120-130.[Abstract]
11. Ashton Jr RC, McGinnis KM, Connery CP, Swistel DG, Ewing DR, DeRose Jr JJ. Totally endoscopic robotic thymectomy for myasthenia gravis Ann Thorac Surg 2003;75(2):569-571.[Abstract/Free Full Text]
12. Jaretzki 3rd A. Video-assisted thoracoscopic extended thymectomy and extended transsternal thymectomy in non-thymomatous myasthenia gravis patients J Neurol Sci 2004;217(2):233-234; author reply 235–6..[Medline]
13. Pego-Fernandes PM, de Campos JR, Jatene FB, Marchiori P, Suso FV, de Oliveira SA. Thymectomy by partial sternotomy for the treatment of myasthenia gravis Ann Thorac Surg 2002;74(1):204-208.[Abstract/Free Full Text]
14. Savcenko M, Wendt GK, Prince SL, Mack MJ. Video-assisted thymectomy for myasthenia gravis: an update of a single institution experience Eur J Cardiothorac Surg 2002;22(6):978-983.[Abstract/Free Full Text]
15. Shrager JB, Deeb ME, Mick R, et al. Transcervical thymectomy for myasthenia gravis achieves results comparable to thymectomy by sternotomy Ann Thorac Surg 2002;74(2):320-326; discussion 326–7..[Abstract/Free Full Text]
16. Wright GM, Barnett S, Clarke CP. Video-assisted thoracoscopic thymectomy for myasthenia gravis Intern Med J 2002;32(8):367-371.[Medline]
17. Yim AP, Kay RL, Ho JK. Video-assisted thoracoscopic thymectomy for myasthenia gravis Chest 1995;108(5):1440-1443.[Abstract/Free Full Text]
18. Autschbach R, Onnasch JF, Falk V, et al. The Leipzig experience with robotic valve surgery J Card Surg 2000;15(1):82-87.[Medline]
19. Falk V, Diegler A, Walther T, Autschbach R, Mohr FW. Developments in robotic cardiac surgery Curr Opin Cardiol 2000;15(6):378-378.[Medline]
20. Mohr FW, Falk V, Diegeler A, et al. Computer-enhanced "robotic" cardiac surgery: experience in 148 patients J Thorac Cardiovasc Surg 2001;121(5):842-853.[Abstract/Free Full Text]
21. Rendina EA, Venuta F, Ceroni L, et al. Computed tomographic staging of anterior mediastinal neoplasms Thorax 1988;43(6):441-445.[Abstract/Free Full Text]
22. Kirschner PA. Reoperation for thymoma: report of 23 cases Ann Thorac Surg 1990;49(4):550-554; discussion 55.[Abstract]
23. Popescu I, Tomulescu V, Ion V, Tulbure D. Thymectomy by thoracoscopic approach in myasthenia gravis Surg Endosc 2002;16(4):679-684.[Medline]
24. Hazelrigg SR, Landreneau RJ, Mack MJ, Acuff TE. Thoracoscopic resection of mediastinal cysts Ann Thorac Surg 1993;56(3):659-660.[Abstract]
25. Takeda S, Miyoshi S, Minami M, Ohta M, Masaoka A, Matsuda H. Clinical spectrum of mediastinal cysts Chest 2003;124(1):125-132.[Abstract/Free Full Text]
26. Wick MR, Carney JA, Bernatz PE, Brown LR. Primary mediastinal carcinoid tumors Am J Surg Pathol 1982;6(3):195-205.[Medline]
27. Ponn RB. Simple mediastinal cysts: resect them all? Chest 2003;124(1):4-6.[Free Full Text]

This article has been cited by other articles:

				F. Augustin, T. Schmid, M. Sieb, P. Lucciarini, and J. Bodner Video-Assisted Thoracoscopic Surgery versus Robotic-Assisted Thoracoscopic Surgery Thymectomy Ann. Thorac. Surg., February 1, 2008; 85(2): S768 - S771. [Full Text] [PDF]

				F. Rea, G. Marulli, L. Bortolotti, P. Feltracco, A. Zuin, and F. Sartori Experience With the "Da Vinci" Robotic System for Thymectomy in Patients With Myasthenia Gravis: Report of 33 Cases Ann. Thorac. Surg., February 1, 2006; 81(2): 455 - 459. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Michael A. Savitt Anthony P. Furnary Jeffrey Swanson Hugh L. Gately John R. Handy Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Savitt, M. A. Articles by Handy, J. R. Search for Related Content PubMed PubMed Citation Articles by Savitt, M. A. Articles by Handy, J. R. Related Collections Mediastinum