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© 2002 European Association of Cardio-Thoracic Surgery
Subxiphoid approach for video-assisted thoracoscopic extended thymectomy in treating myasthenia gravis
a Division of Thoracic Surgery, Department of Surgery, Taichung Veterans General Hospital, Taichung, Taiwan, ROC
* Corresponding author. Division of Thoracic Surgery, Department of Surgery, Taichung Veterans General Hospital, 160, Sec 3, Taichung-Kang Rd., Taichung, Taiwan, ROC. Tel.: +886-4-23592525, ext. 5050; fax: +886-4-23599715 Received March 6, 2002; accepted April 9, 2002
Previous experience using the transcervical, left or right thoracic approach for thymectomy, although demonstrating promising efficacy, involves some compromise of the surgical exposure. We performed subxiphoid video-assisted thoracoscopic extended thymectomy (SxVATET) on eight consecutive myasthenic patients. The mean operation time, weights of resected specimen, and thoracic drainage period were 156.9 min (range 120–200 min), 77.5 g (range 40–100 g), and 3.4 days (range 3–4 days), respectively. There were no surgical complications or mortalities, and the cosmesis is satisfying. Our experience demonstrates that SxVATET provides an excellent view of the bilateral pleural cavities. Subsequently, extended thymectomy, resecting ample mediastinal fatty tissue in addition to the thymic glands, can be safely undertaken.
Key Words: Thymectomy; Myasthenia gravis; Thoracoscopy; Subxiphoid
Sternal splitting thymectomy has been the gold standard since Blalock first introduced thymectomy for treatment of myasthenia in 1939 [1]. We had used this approach in performing thymectomy for myasthenia gravis in this institute for the past 20 years. However, with the rise of thoracoscopic surgery we started thoracoscopic thymectomy using a right side approach from 2001. Because it is usually difficult to make a complete mediastinal fatty tissue dissection on the contralateral side, we tried to design a new approach to facilitate extended thymectomy. The idea of a subxiphoid approach originated from the finding of a large potential retrosternal space which we frequently encountered in esophageal reconstruction. Herein, we report our first eight consecutive successful experiences in performing subxiphoid video-assisted thoracoscopic extended thymectomy (SxVATET) in myasthenic patients.
Under general anesthesia with split lung ventilation, the patient was put in a supine position with 90° abduction of bilateral upper extremities. The basic settings are shown in Fig. 1A,B. In brief, a 6 cm semi-curved incision was made just below the xiphoid process, and the anterior rectal sheath was detached from its insertion to the xiphoid process and the bilateral lowest rib cartilages. After excision of the xiphoid process, the retrosternal space was created by finger dissection for introduction of the Kent retractor so as to lift the sternum, facilitating the thoracoscopic and instrumental manipulation. Additional thoracic port sites (1 cm each) were created at the bilateral anterior axillary line in the 6th intercostal space to introduce a 0° 10 mm side-armed thoracoscope with a 5 mm working channel (Stryker Endoscopy, Santa Clara, CA). Further dissection of the anterior mediastinal fatty tissue can be achieved under direct thoracoscopic guide using an endoscopic hook dissector or the suction tip. Split ventilation of the contralateral lung was undertaken when either side of the pleural cavity was entered. The surgeon starts the operation from the right side by opening the pleurae widely. The fat pad in the pericardio-phrenic sinus was dissected as much as possible using electrocautery, either through the subxiphoid wound or thoracic port. By moving the direction of dissection cephalically, all of the mediastinal fat tissues anterior to the phrenic nerve were elevated from the pericardium. Along this avascular plan of dissection, the thymic lobe was also separated from the underlying ascending aorta. The thoracoscope introducing port can be switched between the lateral chest port and the subxiphoid incision according to the location of dissection. With meticulous dissection, the conjunction of the brachiocephalic vein and superior vena cava was identified; the gland was pulled to the left side by ring forceps, facilitating separation of the gland from its underlying brachiocephalic vein. The course of the brachiocephalic vein was traced to expose all the thymic veins. Usually, two to three thymic veins will be encountered and divided between endoscopic clips. The upper pole of the thymic gland was delivered from the neck by a combination of blunt dissection and traction. Basically, the left side pleural cavity was treated in a similar manner. Finally, the totally freed thymic gland and its accompanying mediastinal fatty tissues can be brought out en bloc easily from the subxiphoid incision. A Fr. 20 thoracic tube was put into each side of the pleural cavity through the thoracoscopic port site and secured to the chest wall. The rectal sheath was re-attached, and the subxiphoid incision was closed by subcuticle sutures. Postoperative chest film was taken to make sure no residual pneumothoraces existed. The thoracic catheters were usually removed on the 3rd to 4th postoperative day, and the patients were discharged on the same day.
SxVATET was performed on eight consecutive myasthenic patients. As listed in Table 1, the mean operation time, weights of resected specimens, and thoracic drainage period were 156.9 min (range 120–200 min), 77.5 g (range 40–100 g), and 3.4 days (range 3–4 days), respectively. There were no surgical complications or mortalities, and the cosmesis is satisfying. Fig. 2 shows the completely resected thymus and concomitant ectopic thymoma.
Different approaches for thymectomy have been performed, and each has its own proponents. Even though the transcervical/trans-sternal approach provides the only possible way to perform so-called ‘maximal thymectomy’, a combined cervical incision and sternotomy makes it the most traumatic approach [2]. A less traumatic approach, like transcervical thymectomy, inevitably leads to inadequate lower mediastinal fatty tissue dissection [3]. Thoracoscopic thymectomy through either side of the chest wall provides an excellent view of the operative side [4,5], however, poor endoscopic view of the contralateral side makes it almost impossible to obtain adequate removal of the contralateral side mediastinal fat. A combination of cervicotomy and bilateral thoracoscopic approaches has been used in performing extended thymectomy with acceptable results [6]. Another recent report demonstrated a sternal lifting technique by combined cervical and subxiphoid approaches together with bilateral thoracoscopic approaches in performing thymectomy with promising results [7]. Due to dissatisfaction with the above approaches, we are trying to design a novel subxiphoid approach without additional cervical incision for thymectomy. Using a classical thoracoscopic technique, the bilateral thymic lobes can be equally inspected and dissected. The brachiocephalic vein can be identified at the upper mediastinum easily, and traced to its conjunction with the superior vena cava by meticulous dissection of the thymus and the intervening thymic veins can be divided between endoclips. Our initial thoracic port design was set to the 2nd or 3rd intercostals space in the mid-clavicle line. Even though it is easier to perform dissection of the superior thymic pole form here, the cosmetic result is not satisfying, especially in the female patients. Besides, we need to create additional wounds for placement of the thoracic catheter in the lower chest wall. Hence, we change the thoracic port site down to the 6th intercostal space in the anterior axillary line, which also provides an excellent thoracoscopic view and instrumental manipulations. In the female patients, the skin incision was made on the submammary fold, and the postoperative scar was almost invisible. One latest report from Japan also demonstrates a similar approach with or without concomitant cervical incision with encouraging results [8]. They used traditional endotracheal intubation with bilateral lung ventilation, and accomplished the procedure by introducing the mediastinoscope and other working instruments exclusively through the subxiphoid incision. However, the operation time is much longer than ours even in their latest experience. We believe the operation time can be remarkably shortened by creating an additional port site at the lateral chest wall, which will greatly improve the endoscopic view by concomitant split lung ventilation. Our technique greatly improved the bilateral thoracoscopic view as compared with the other approaches described previously. We believe this is essential for adequate bilateral mediastinal fatty tissue dissection, especially since the surgical plan calls for all the bilateral pericardial fat pads, epiphrenic fat, and the mediastinal fat tissue between the bilateral phrenic nerves to be removed. This approach omits the sternotomy, while extended thymectomy becomes possible due to the bilateral access. All of the possible thymic bearing mediastinal fat tissues can be removed under direct thoracoscopic view, which may subsequently translate into better results. As far as the adequacy of thymectomy is concerned, we believe this can be best reflected by the weight of the resected specimens. Using the SxVATET approach, we had an average specimen weight of 77.5 g, which is heavier than that of the right side thoracoscopic thymectomy we had performed in the same period (mean 39.1 g, range 15–63 g, eight patients). Besides, two of our patients had concomitant thymomas, and both of the tumors were completely removed without additional incisions. Our experiences suggest that small (less than 3 cm in diameter) stage I thymoma can be safely resected by this approach. Furthermore, by avoiding a sternotomy, the patient feels less pain and wound healing is not a big problem. Hypertrophic scarring (or keloid) and the less frequent sternal osteomyelitis can be prevented. We believe this is particularly important to a young female patient, which we often encounter in myasthenia treatment. All of the subxiphoid wounds heal well, and no incisional hernias developed. All of our patients had an uneventful postoperative course. There were no associated morbidities or mortalities. Using a subxiphoid approach, we demonstrate a safe and easy way to perform video-assisted thoracoscopic extended thymectomy without sternotomy with excellent cosmesis. The learning curve of the procedure is short in surgeons who are already well experienced in other thoracoscopic procedures.
ICVTS on-line discussion Author: Prof. Dr. Walter Klepetko, University Hospital Vienna, Cardiothoracic Surgery, Währinger Gürtel 18-20, A-1090 Vienna, Austria Date: 24-July-2002 14:32 Message: This paper reports a very smart method of maximal thymectomy through a minimal invasive approach. The given results, although obtained in a small series of 8 patients only, are promising and suggest that this approach could have the potential to become the preferred method for radical thymectomy. The technique of bilateral transthoracic insertion of instruments together with the subxyphoidal incision seems to offer the necessary visibility to achieve this goal. It would be interesting to hear from the authors about their handling of the anterior mediastinal pleura. Do they only incise it or do they perform a complete resection as well? At present, we are still lacking precise data about the incidence of ectopic thymic documentation in future series would help to elucidate the importance of such a radical resection. Certainly, the results of a larger series together with long-term outcome need to be awaited until a final judgement on this method can be given. However, there is good reason to expect, that this minimal invasive technique will ultimately lead to results, which are at least comparable with those obtained by median sternotomy. Response Author: Dr. Chung-Ping Hsu, Division of Surgical Emergency, Taichung Veterans General Hospital, #160, Sec. 3 Taichung-Kang Rd., Taichung, Taiwan Date: 12-Aug-2002 08:11 Message: Currently, we have increased our experience in performing SxVATET to 11 cases with similar results. As an extended surgery, we excise bilateral anterior mediastinal fat tissues (anterior to the phrenic nerve) together with thymic glands. The described procedure is a technique-demanding one, cooperation between an experienced thoracoscopic surgeon and a well-trained first assistant will make this procedure more comfortable. Author: Dr. Enrico Ruffini, Thoracic Surgery, University of Turin, 3, Via Genova, Turin, Italy Date: 10-Aug-2002 18:23 Message: The authors report on a new approach to resection of thymus gland for Myasthenia Gravis using a subxyphoid approach with video-assisted thoracoscopic equipment. Several concerns arise from the reading of the manuscript, in particular when compared with our standard technique employed in more than 1200 thymectomies, which consists of a 6-cm cervical incision and a sternal splitting using the same skin incision (mean operative time 30 minutes) without opening the pleural cavities, with a mean hospital stay of 2 days: 1) The authors state that their approach provides a more cosmetic result than standard approaches: in fact, they make a 6-cm subxyphoid incision (similar to the standard cervical incision of the transcervical approach) plus two 1- cm incisions for the thoracoscopic ports. This looks far less cosmetic than our transcervical approach. 2) The patients experience, in the postoperative period, two bilateral pleural drainages which, I believe, make his/her postoperative period quite uncomfortable and theoretically at risk for complications. In our technique, we use a mediastinal drainage connected with a Redon system, which is removed the day after the operation. 3) I question the use of an inferior thoracic approach for a disease from an organ which has a cervical location and embryology: I strongly believe that every approach to the thymic gland should include a cervical incision and exploration. 4) I disagree with the use of a thoracoscopic approach in cases of thymomas, although encapsulated. All thymomas should be resected with a sternotomic approach, which only allows for a thorough inspection of the mediastinum. 5) The authors do not indicate the clinical classification of their myasthenic patients. 6) I do not think that myasthenic patients, who are at risk of developing a postoperative respiratory insufficiency, may benefit from a 3-hour operation with one-lung ventilation anaesthesia: I maintain that the shortest operative time compatible with the most radical resection should be performed; further, and if possible, one-lung ventilation anaesthesia is to be avoided because of the risk of postoperative respiratory complications. Response Author: Dr. Chung-Ping Hsu, Division of Surgical Emergency, Taichung Veterans General Hospital, #160, Sec. 3 Taichung-Kang Rd., Taichung, Taiwan Date: 12-Aug-2002 08:11 Message: In addition to perform an extended thymectomy, our approach also avoids sternotomy which is always more painful and sometimes leads to osteomyelitis or dehiscence. Thymus even though originated from the neck, only the upper poles are located at the neck. We do not believe an extended thymectomy can be adequately performed by a transcervical approach without opening of the pleurae. If we are not performing the so called "maximal thymectomy" as Dr. Jaretzki suggested, more or less, we all have the chance to leave some ectopic thymic tissues in the mediastinum and neck. However, we believe the best way for measuring the adequacy of thymectomy is closely related to the weight of thymic tissue and the accompany mediastinal fatty tissues that you resected. I also believe an adequate procedure is more important than a faster procedure. Have you measured the weight of your resected specimens? Author: Dr. Tomasz Grodzki, Thoracic Surgery, Regional Hospital for Lung Diseases, Sokolowskiego 11, Szczecin Zdunowo, Poland Date: 10-Aug-2002 19:02 Message: I'd like to congratulate the promising results. Our role as surgeons in myasthenia gravis is usually limited to surgical procedure ordered by a neurologist. The most important thing for the patient is completeness of thymectomy and good long term results. Good cosmetic effect seems to be the second major expectation. Extended thymectomy can be performed by different approaches but should always be complete. If we are talking about videothoracoscopic procedures I can’t see the advantage of the described approach over simultaneous bilateral videothoracoscopies which provide an excellent view of both sides from the apex to the diaphragm. I agree with the authors that double lumen intubation facilitates the procedure significantly. As to subxiphoid incision I have two technical questions: did it happen to open the peritoneum accidentally Did the long term follow-up reveal any cases of wound hernia? Response Author: Dr. Chung-Ping Hsu, Division of Surgical Emergency, Taichung Veterans General Hospital, #160, Sec. 3 Taichung-Kang Rd., Taichung, Taiwan Date: 12-Aug-2002 08:11 Message: We don’t have experience in accidental entrance of the peritoneal cavity. We also don’t have any case of postoperative incisional hernia. I do agree a bilateral thoracoscopic approach makes extended thymectomy possible. However, our approach may be less painful due to omission of extra thoracic port sites. Author: Dr. Marcello Migliore, Department of Surgery, Sect. General Thoracic Surgery, University of Catania, Ospedale Tomaselli, Via Passo Gravina 187, Catania, Italy Date: 10-Aug-2002 19:27 Message: This new technique is a modification of previous published methods, and represents the result of recent advances in endoscopic techniques that have facilitated less invasive approaches to thymectomy. This thoracoscopic technique for myasthenia gravis allows to perform thymectomy from both sides avoiding the disadvantages of performing operations from the left or right side of the chest. The technique requires one-lung ventilation. What is the policy in cases of pleural adhesion, pulmonary insufficiency, or previous operations in the chest? Have the authors found difficulties to resect ectopic thymus tissue in the aorto pulmonary window? Although video assisted thymectomy is becoming the most common approach for treatment of myasthenia gravis, the effectiveness still must be proved by means of a larger series of patients and a longer follow-up. Response Author: Dr. Chung-Ping Hsu, Division of Surgical Emergency, Taichung Veterans General Hospital, #160, Sec. 3 Taichung-Kang Rd., Taichung, Taiwan Date: 12-Aug-2002 08:11 Message: Our procedure is not suitable for patients with severe pleural adhesions or patients who can not tolerate one lung ventilation. Because we set our dissection line anterior to the phrenic nerve, the A-P window was not routinelydissected. PII: S1569929302000038
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Abstract
1. Introduction
