MMCTS
(April 25, 2005). doi:10.1510/mmcts.2004.000836
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Transcervical-subxiphoid-VATS "maximal" thymectomy for myasthenia gravis
Marcin Zieli ski*,
Jaros aw Ku da and
Tomasz Nabiaek
Department of Thoracic Surgery, Pulmonary Hospital, Zakopane, ul. Gadkie 1, 34-500 Zakopane, Poland
* Corresponding author: * Tel.: +48-18-2015045. E-mail: marcinz{at}mp.pl
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Summary
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A maximally extended thymectomy is performed through four incisions: a transverse 5–8 cm incision in the neck, a 4–6 cm subxiphoid incision and two 1 cm incisions for videothoracoscopic ports. The cervical part of the procedure is performed with an open technique, the intrathoracic part of the procedure is performed with the videothoracoscopy assisted (VATS) technique. The whole thymus with the surrounding fatty tissue containing possible ectopic foci of the thymic tissue is removed. The need for sternotomy is avoided while the completeness of the operation is retained.
Key Words: Thymectomy • Videothoracoscopy (VTS) • Videothoracoscopy-assisted (VATS)
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Introduction
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A variety of techniques of thymectomy for myasthenia gravis has been described, utilizing the transsternal, transcervical, videothoracoscopic (VTS) and videothoracoscopy-assisted (VATS) or combined approaches [1,2,3,4,5,6,7]. There is no consensus, however, which of these techniques is the best. The aim of the thymectomy in the treatment of myasthenia gravis is the complete removal of all the thymic tissue, because it is well established that residual thymic tissue left after an incomplete thymectomy often leads to persistence or aggravation of the disease. It was found that the foci of thymic tissue are widely distributed in cervical and mediastinal fat, outside the thymic gland [1,2,8,9,10]. A procedure comprising a removal of the whole thymus along with the surrounding fatty tissue is described as an extended thymectomy. Traditionally, such operation is performed through the complete sternotomy approach, which is an obvious drawback of that procedure, therefore, since September 2000 we have developed an original technique called a "maximal" transcervical-subxiphoid-VATS thymectomy [10]. This procedure, which is intended to be both maximally radical and less invasive than the transsternal approach is described herein.
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Surgical technique
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The procedure can be performed with one- or two-team approach (two teams of surgeons operating simultaneously). In this report one-team approach is described. The operative technique of this procedure is as follows: a patient is positioned supine on the operating table with a roll placed beneath the thoracic spine to elevate the chest and to hyperextend the patient's neck. Under general anaesthesia an endobronchial tube is inserted to conduct selective lung ventilation during the latter part of the procedure. The skin is prepared from the chin to the umbilicus and bilaterally past the posterior axillary line.
Cervical part of the operation: a transverse 5–8 cm incision is made in the neck above the sternal notch (Video 1). The platysma and superficial cervical fascia are divided, the anterior jugular veins are divided and suture-ligated. The upper and lower subplatysmal flaps are developed (Video 2). The strap muscles are split along their median raphe and retracted laterally. The whole thyroid gland is visualized, the middle thyroid veins are secured with clips and divided and the thyroid lobes are mobilized (Video 3). Visualization of the right laryngeal recurrent nerve is started first (Video 4). The carotid sheath of the right common carotid artery is divided with scissors, reaching the clean wall of the artery. The thyroid gland, the trachea and the thymus gland are retracted to the left side with fingers and the right common carotid artery is retracted to the right side. Using blunt dissection with a peanut sponge the right laryngeal recurrent nerve is almost instantly visible. It runs from the point of division of the innominate artery towards the larynx. The deepest fascial layer covering the nerve is preserved, so the nerve is visualized, but not dissected, therefore the risk of injury to the nerve is minimalized.
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Video 1 The cervical incision, division of the platysma and the anterior jugular veins.
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Video 2 The upper subplatysmal flap is dissected and secured with towel clips to the operative dressing. Dissection of the thyroid gland is started.
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Video 3 The right middle thyroid vein is dissected, clipped and divided.
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Video 4 Visualization of the right laryngeal recurrent nerve running between the trachea and the esophagus.
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Visualization of the left laryngeal recurrent nerve: the carotid sheath of the left common carotid artery is divided with scissors, the same as on the right side (Video 5). The left common carotid artery is retracted to the left side and the trachea is retracted with the fingers to the right side. Using blunt dissection with the peanut sponge, both from the medial and the lateral side of the left upper pole of the thymus gland, the left laryngeal nerve is easily shown, running parallel to the trachea in the trachea-esophageal groove. The fatty tissue containing the right superior pole of the thymus is separated from the lower poles of the thyroid gland with inferior thyroid veins divided and suture-ligated (Video 6). The thymus with the surrounding fat is then separated from the right side of the trachea with preservation of the right laryngeal recurrent nerve (Video 7). The left upper pole of the thymus is separated from the thyroid gland and from the trachea (Video 8). The specimen containing the thymus is separated from the left carotid artery and the innominate artery (Video 9). At this point a sternal retractor connected to the firm frame with a traction mechanism is inserted under the manubrium of the sternum to elevate it several centimeters to provide improved access to the anterior mediastinum (Video 10). The lower thyroid veins (1–4) and the thymic veins (1–4) are dissected, clipped and divided close to the left innominate vein which is dissected from the mediastinal structures (Videos 11, 12, 13 and 14). The fatty tissue from the area called "the aorta-caval groove" is removed. The boundaries of this space are the division of the innominate artery and the aorta (medially), the trachea (posteriorly) and the right innominate vein and the right mediastinal pleura (laterally) and the right main bronchus, the azygos vein and the superior vena cava (inferiorly) (Videos 15 and 16). The left internal thoracic vein and the accessory hemiazygos vein are dissected, secured with clips or sutures and divided in order to gain wider access to the aorta-pulmonary window (Video 17). The next step is the visualization of the left phrenic nerve which runs very close to the left internal thoracic vein and the left vagus nerve which runs laterally to the left common carotid artery (Video 18). With blunt dissection using a peanut sponge, the fatty tissue contained in the aorta-pulmonary window is dissected from these nerves, the aorta and the left mediastinal pleura (Video 19). At the bottom of the aorta-pulmonary window the left pulmonary artery is visualized. In difficult cases the dissection of the aorta-pulmonary window is completed at a later stage of the operation with a videothoracoscopic camera inserted inside the chest. The dissection proceeds caudally, below the left innominate vein and the specimen is separated from the pericardium at a distance of several centimeters (Videos 20 and 21).
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Video 5 Visualization of the left laryngeal recurrent nerve.
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Video 6 Separation of the upper poles of the thymus from the thyroid gland.
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Video 7 Separation of the right upper pole of the thymus from the trachea.
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Video 8 Separation of the left upper pole of the thymus from the thyroid and the trachea.
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Video 9 Separation of the specimen containing the thymus from the left carotid artery and the innominate artery.
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Video 10 Elevation of the sternum.
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Video 11 Closure with clips and division of the lower thyroid vein.
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Video 12 Dissection of the thymic veins and the left innominate vein.
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Video 13 Dissection of the thymic veins and the left innominate vein (continued).
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Video 14 The thymic veins are dissected and secured with vascular clips and divided.
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Video 15 Dissection of the aorta-caval groove.
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Video 16 Dissection of the aorta-caval groove (continued).
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Video 17 Dissection of the accessory hemiazygos vein. The left internal thoracic vein is divided and suture-ligated.
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Video 18 Visualization of the left phrenic nerve.
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Video 19 Visualization of the aorta-pulmonary window.
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Video 20 Dissection of the specimen from the pericardium.
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Video 21 Dissection of the specimen from the pericardium (continued).
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The subxiphoid part of the operation: a transverse 4–6 cm incision is made above the xiphoid process. The subcutaneous tissue is cut and the medial parts of the rectus muscles are cut near the insertions to the costal arches. The xiphoid process is divided transversely and left without removal (Video 22). The selective left lung ventilation is started resulting in the collapse of the right lung. The anterior mediastinum is opened from below the sternum. A second sternal retractor connected to the traction frame (the same one which is used for traction of the manubrium) is placed under the sternum, which is elevated to facilitate access to the anterior mediastinum from below. A 10-mm thoracoscopic port is inserted into the right pleural cavity in the 6th intercostal space in the anterior axillary line (Video 23). The right epiphrenic fat pad is dissected from the diaphragm with a sharp dissection (Videos 24 and 25). The right mediastinal pleura is cut near the sternal surface up to the level of the right internal thoracic vein which is left intact (Video 26). The right epiphrenic fat pad and the prepericardial fat containing the thymus gland are dissected from the pericardium with a sharp dissection (Video 27). The right phrenic nerve is a margin of dissection. Any vessels lying close to the phrenic nerve are closed with clips (Videos 28 and 29). Dissection of the thymus from the pericardium covering the ascending aorta is proceeded upwards (Videos 30, 31 and 32). The left mediastinal pleura is cut below the sternum and the left pleural cavity is opened from the right approach (Video 33). At this moment the thymus is attached to the pericardium only with its left lower pole. Ventilation of the right lung is resumed and the left lung is collapsed. A 10-mm thoracoscopic port is inserted into the left pleural cavity, as on the right side. The operating table is rotated on the right side with elevation of the left side which lowers the mediastinum, improving access to the left pleural cavity. Under the control of the VTS camera the left prepericardial fat is dissected from the pericardium above the level of the previously divided left internal thoracic vein with preservation of the left phrenic nerve (Video 34). The left lower pole of the thymus is separated from the pericardium and the specimen is removed. The operative field is finally searched for any retained foci of the adipose or thymic tissue (Videos 35, 36, 37 and 38). Hemostasis is checked, VTS ports are removed and the chest tubes are inserted into both pleural cavities through the incisions made for insertion of the ports. Ventilation of both lungs is resumed. The cervical and subxiphoid incisions are closed in the standard manner.
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Video 22 Subxiphoid incision.
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Video 23 Insertion of the VTS port to the right pleural cavity.
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Video 24 Dissection of the right epiphrenic fat pad.
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Video 25 Dissection of the right epiphrenic fat pad (continued).
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Video 26 Separation of the specimen from the sternum.
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Video 27 Dissection of the specimen from the pericardium.
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Video 28 Dissection of the specimen from the right phrenic nerve.
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Video 29 Dissection of the specimen from the right phrenic nerve (continued).
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Video 30 Dissection of the thymus from the pericardium covering the ascending aorta.
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Video 31 Dissection of the thymus from the pericardium covering the ascending aorta (continued).
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Video 32 Dissection of the thymus from the pericardium covering the ascending aorta (continued).
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Video 33 Opening of the left mediastinal pleura.
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Video 34 Dissection of the specimen from the left part of the pericardium and the left phrenic nerve.
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Video 35 View of the region of the aorta-pulmonary window.
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Video 36 View of the operative field from the right VTS port after removal of the specimen.
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Video 37 View of the operative field from the left VTS port after removal of the specimen.
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Video 38 View of the operative field from the subxiphoid incision after removal of the specimen.
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Results
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In the series of 150 consecutive patients operated on since September 2000 there was no mortality and 14.0% morbidity (Table 1). There was no conversion to sternotomy due to technical reasons in any case. In two patients conversion to sternotomy was necessary because of intraoperative diagnosis of unsuspected thymoma. Ectopic foci of the thymic tissue were found in 70% of patients, the foci were most prevalent in the perithymic and aorta-pulmonary window regions (about 30% for each location). The complete remisssion rates of myasthenic symptoms are 25% after one year, 37.5% after two years and 40% after three years follow-up for this technique of thymectomy (Graph 1). The complete rates achieved with use of various techniques of thymectomy are shown in Table 2.
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Table 1 Complications in 150 patients with myasthenia gravis operated on with transcervical-subxiphoid-VATS "maximal" thymectomy
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Graph 1 The complete remisssion rates of myasthenic symptoms after 1-, 2-, and 3-year follow-up after transcervical-subxiphoid-VATS "maximal" thymectomy.
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References
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Summary
Introduction