https://orcid.org/0000-0002-1859-9213
Summary
Transcervical esophagectomy allows for esophagectomy through transcervical access and bypasses the thoracic cavity, thereby eliminating single lung ventilation. A challenging surgical approach demands thorough understanding of the encountered anatomy. This study aims to provide a comprehensive overview of surgical anatomy encountered during the (robot-assisted) minimally invasive transcervical esophagectomy (RACE and MICE).
To assess the surgical anatomy of the lower neck and mediastinum, MR images were made of a body donor after, which it was sliced at 24-μm intervals with a cryomacrotome. Images were made every 3 slices resulting in 3.200 images of which a digital 3D multiplanar reconstruction was made. For macroscopic verification, microscopic slices were made and stained every 5 mm (Mallory-Cason). Schematic drawings were made of the 3D reconstruction to demonstrate the course of essential anatomical structures in the operation field and identify anatomical landmarks.
Surgical anatomy ‘boxes’ of three levels (superior thoracic aperture, upper mediastinum, subcarinal) were created. Four landmarks were identified: (i) the course of the thoracic duct in the mediastinum; (ii) the course of the left recurrent laryngeal nerve; (iii) the crossing of the azygos vein right and dorsal of the esophagus; and (iv) the position of the aortic arch, the pulmonary arteries, and veins.
The presented 3D reconstruction of unmanipulated human anatomy and schematic 3D ‘boxes’ provide a comprehensive overview of the surgical anatomy during the RACE or MICE. Our findings provide a useful tool to aid surgeons in learning the complex anatomy of the mediastinum and the exploration of new surgical approaches such as the RACE or MICE.
INTRODUCTION
Curative treatment of resectable esophageal cancer consists of neoadjuvant therapy followed by esophagectomy.1,2 A transthoracic esophagectomy is considered the standard procedure for an esophagectomy since it allows for a radical mediastinal lymphadenectomy. Due to the complexity and invasiveness of this procedure, a minimally invasive transthoracic esophagectomy is associated with a postoperative complication rate of about 60–80%.3,4 Of these complications, pulmonary complications are observed in one third of cases. Unlike transthoracic esophagectomy, transhiatal esophagectomy avoids single-lung ventilation and is associated with lower rates of postoperative pulmonary complications. However, a transhiatal approach is only applicable to distal esophageal cancer and the mediastinal lymphadenectomy is limited compared to transthoracic esophagectomy since a paratracheal lymphadenectomy cannot be performed.3,5 This might compromise survival.6
A robot-assisted cervical esophagectomy (RACE) is a relatively novel approach that also avoids the transthoracic procedure and thereby the need for single lung ventilation, similarly to the cervical mediastinoscopy.7–13 During a RACE procedure, the esophagus is mobilized in a cranial-caudal direction through transcervical access, which provides a new perspective of the surgical anatomy. This is combined with a transhiatal approach for the distal part of the mediastinal dissection. In contrast with cervical techniques using mediastinoscopy, the surgeon’s view is in 3D. First results are promising with low morbidity and an adequate lymph node yield.7,14–17 The hypothesis is that RACE might achieve lower postoperative pulmonary complications without compromising oncological outcomes such as the lymph node yield and the radicality of resection margins. However, together with a confined workspace that might impede proper exposure and therefore might limit lymphadenectomy, the RACE procedure poses certain anatomical challenges that need to be addressed prior to its clinical introduction. A limited number of previous studies has addressed the anatomy from a cervical viewpoint and a clear method to describe the surgical anatomy during a minimally invasive approach including important landmarks is lacking.14,15,17–19
Therefore, the aim of this study is to provide a comprehensive overview of the unmanipulated surgical anatomy of the minimally invasive transcervical approach for esophagectomies.
MATERIAL AND METHODS
Study specimens
One preserved body donor (female, 83 years old) without any signs of previous surgery was used for obtaining MRI, transverse cryomacrotome slicing of the lower neck and mediastinum and subsequent digital multiplanar formatting. The specimen was derived from a body that entered the Department of Anatomy of the University Medical Center Utrecht through a nationwide donation program by written informed consent. Within 24 hours after arrival at the department, the preserved body donor was perfused with 3% formaldehyde through two large cannulas inserted in the femoral artery. After perfusion, the body donor was preserved in a 2% formaldehyde solution for 6 months.
MRI
To aid in orientation anatomical transverse T2-weighted images (reconstructed resolution: 0.52 × 0.52 × 1 mm3) were acquired of the lower neck and mediastinum. A three Tesla scanner was used, equipped with a 16-element phased-array receive coil for thoracic imaging (Ingenia; Philips Medical Systems, Best, The Netherlands).
Sectioning
The preserved body donor was deep-frozen and cut in two blocks of 20 × 16 × 12 cm for the mold of the cryomacrotome (Leica CM3600 XP, Nussloch, Germany). Subsequently, the tissue blocks were frozen in 1% carboxymethylcellulose at minus 25 degrees Celsius. The tissue blocks were sectioned at 24 μm thickness in the transverse plane, and after every third section (72 μm), a digital image was made of the surface of the block (Leica DFC450 C, Wetzlar, Germany) resulting in 3.200 digitized photographs.
Digital reconstruction
The digitized photographs were stacked and by multiplanar reformatting; the remaining other orthogonal planes (sagittal and frontal) were calculated.20 In-house developed software (Enhanced Multiplanar reformatting Along Curves, E-MAC®)21,22 was used to make a 3D reconstruction of the anatomy surrounding the esophagus in various planes (Fig. 1).
Display of initial results of the multiplanar reformatting. Sections in the three standard orthogonal planes (sagittal, frontal and transversal) are combined, in this case of the mediastinum. Orientation of the planes is similar in all photographs. The curved white line is plotted through the long axis of the esophagus which will serve as the center of reconstruction with a circular region of interest. Video 1. The transverse video sequence of real-life unmanipulated mediastinal anatomy is based on the original digital images. It shows the orientation closest to that of the surgeon during the RACE and MICE; thus, the right side on the image is the right side of the body and the left side is on the left. Several added still images highlight the most important structures. Video 2. The video sequence of the frontal plane is a reconstruction made based on the transverse digital images through E-MAC® and contains several stills highlighting anatomical structures. As on traditional imaging, the right side is on the left on the body and the left side is on the right. Video 3. Sagittal video sequence is a reconstruction made based on the transverse digital images through E-MAC® and contains several stills highlighting anatomical structures. The video commences on the left side and runs towards the right. AoA, aortic arch; AV, azygos vein; BCT, brachiocephalic trunk; BCV, brachiocephalic vein; CCA, common carotid artery; EJV, external jugular vein; GCV, great cardiac vein; ICM, intercostal muscles; IMA, internal mammary artery; IMV, internal mammary vein; IPV, inferior pulmonary vein; ITA, inferior thyroid artery; IVC, inferior vena cava; JV, jugular vein; LAD, left anterior descending artery; lMB, left main bronchus; ln*, recurrent laryngeal lymph node; lnn*, recurrent laryngeal lymph nodes, MCV, middle cardiac vein; PA, pulmonary artery; PM, pectoral muscles; RCA, right coronary artery; RLN, recurrent laryngeal nerve; SA, subclavian artery; SCM, sternocleidomastoid muscle; SIV, superior intercostal vein; SPV, superior pulmonary vein; SV, subclavian vein; TCT, thyrocervical trunk; TD, thoracic duct; SVC, superior vena cava; VN, vagus nerve; 2R, right upper paratracheal lymph nodes; 2 L, left upper paratracheal lymph nodes; 4R, right lower paratracheal lymph nodes; 4 L, left lower paratracheal lymph nodes; 5, aorto-pulmonary lymph nodes; 6, anterior mediastinal lymph nodes; 7, subcarinal lymph nodes; 10R, right tracheobronchial lymph nodes; 10 L, left tracheobronchial lymph nodes. Red, oxygen-rich vasculature; dark blue, oxygen-poor vasculature; green, lymphatic duct; yellow, lymph node; lila, nerve; purple, muscle; light blue, airways and lungs; pink, digestive tract; orange/brown, thyroid; black, carotid sheaths and intercarotid fascia; white, bone.
Superior thoracic aperture (Box 1). (A) An overview of the unmanipulated anatomy at the level of the superior thoracic aperture is shown in a digital image (B) with highlighted anatomical structures. The crossing of the thoracic duct from dorsal to ventral in a sagittal plane, can be seen in the left dissection plane, where the subclavian artery changes its orientation from perpendicular to parallel to the esophagus. (C) The first box corresponds to the superior thoracic aperture and shows a 3D overview of this anatomical region depicting an ‘anatomical box’ in which only the most important anatomical structures are shown in each of the surgical dissection planes during the first phase of the RACE and MICE. CCA, common carotid artery; ITA, inferior thyroid artery; IJV, internal vein; ln(n), lymph nodes(s); ln(n)*, recurrent laryngeal nerve lymph node(s); SA, subclavian artery; SCM, sternocleidomastoid muscle; TD, thoracic duct; TCT, thyrocervical trunk; RLN, recurrent laryngeal nerve; VN, vagus nerve; gray line, intercarotid or alar fascia and carotid sheaths.
Histology
To confirm macroscopic findings, histologic sections were obtained at 5 mm intervals. Adhesive tape (3 M Glass Cloth Tape 365) was affixed to the frozen sample, and a section of 24 μm was cut that remained attached to the tape. Mallory-Cason and silver nitrate staining was performed to improve contrast of these on-tape sections.23
Surgical anatomy boxes
Using the digital reconstruction of the mediastinum and current anatomical literature, schematic drawings depicted as 3D ‘boxes’ were created, highlighting the most important structures encountered during the minimally invasive transcervical esophagectomy from a surgeon’s perspective and their relations to each other. Focusing on landmarks and danger zones, an overview of the surgical anatomy of each step in the procedure was developed. To create a comprehensive overview, the following four anatomical regions were distinguished: the lower neck, the superior thoracic aperture, the upper mediastinum and the region below the carina. The latter three regions were each depicted in the 3D boxes. The descriptions of the surgical anatomy are structured from dorsal to left, to right and lastly to ventral, according to the stepwise surgical mobilization of the esophagus. The focus is put on: (i) the course of the thoracic duct in the mediastinum; (ii) the course of the left recurrent laryngeal nerve; (iii) the crossing of the azygos vein right and dorsal of the esophagus; and (iv) the position of the aortic arch, the pulmonary arteries and veins.
RESULTS
Anatomical landmarks, and danger zones and surgical planes are identified based on the digital reconstruction of the mediastinum. Video 1 shows a transverse video sequence in cranial-caudal direction, depicting the unmanipulated anatomy that is encountered during the RACE from the lower neck to the diaphragm following the line of the esophagus. In Videos 2 and 3, the frontal and sagittal reconstructions are provided. Relevant anatomical structures are highlighted in the stills included in the videos.
Lower neck
Starting the procedure, the esophagus is approached from the left ventral side with an incision along the caudal third of the medial border of the left sternocleidomastoid muscle and medially of the omohyoid muscle. The left carotid sheath is found medially of the incision and laterally of the strap muscles. Approaching the dorsal left lateral side of the esophagus, the intercarotid (or alar) fascia, running between the two common carotid arteries passing the esophagus dorsally, is reached to form the dorsal plane of this dissection. By using this plane, distance is kept from the left recurrent laryngeal nerve (RLN), situated slightly ventral from the dissection plane.
Superior thoracic aperture (Box 1)
The first box (Fig. 2) depicts the transition from the lower neck to the thorax. Once the intercarotid fascia is reached dorsomedial to the incision, the surgical planes will continue to follow the course of the esophagus from cranial to caudal.
At the level of the superior thoracic aperture, the dorsal dissection plane is formed by the prevertebral fascia, which covers the vertebrae ventrally, just dorsal of the intercarotid fascia. During dissection, the prevertebral fascia and vertebrae can act as a guide in cranial-caudal direction. When the level of the subclavian veins and arteries is reached, the thoracic duct changes its orientation. The general anatomical course of the thoracic duct, running from caudal to cranial, is from cisterna chyli, just below the level of the diaphragm, toward the left venous angle where it drains into the left subclavian vein, passing on the left side of the esophagus. From a cranial perspective, this is seen as the thoracic duct running from ventral to dorsal in a sagittal plane as it moves in caudal direction, moving away from the left venous angle. From then onwards, it lies on the dorsal left side of the esophagus, between the intercarotid fascia ventrally and the prevertebral fascia dorsally. During this crossing, it shortly lies to the left of the left lateral surgical plane as can be seen in Figure 2. At this same level, the subclavian arteries begin to divert from running in a transverse plane to running in a frontal plane towards the aortic arch by which they become part of the lateral dissection planes. As the superior thoracic aperture is reached, the mediastinal pleura of both lungs become part of the lateral planes. The ventral surgical plane is formed by the pars membranacea of the trachea until the carina is reached. Right and left of the trachea are the danger zones in which the RLNs are found, in the tracheoesophageal groove in close relation to the RLN lymph nodes in the compartment surrounding it (Fig. 2). Outside of the surgical field during the RACE and MICE, the right RLN branches of the right vagus nerve and loops underneath the right subclavian artery. Next, the right recurrent laryngeal nerve runs in cranial direction towards the thyroid passing through the right tracheoesophageal groove, thus making part of the ventral dissection plane. Similarly, in caudal direction the right vagus nerve runs through the right tracheoesophageal groove. Also outside the surgical field, the right subclavian artery then moves to ventral as it joins the left common carotid artery into the brachiocephalic trunk after which it moves toward the aortic arch crossing the ventral side of the trachea in a frontal plane (Fig. 3).
Upper mediastinum (Box 2)
The most important structures in the region of the upper mediastinum are depicted schematically in the second box, seen in Figure 4.
Dorsally, the prevertebral fascia remains to form the dissection border, with intermittently dorsal to it the intercostal arteries and veins. Also forming part of the dorsal dissection plane, the thoracic duct is found on the left dorsal side of the esophagus. On the left lateral side, the subclavian artery and the left mediastinal pleura form the left dissection plane until the aortic arch is reached. The lower paratracheal and anterior mediastinal lymph nodes (stations 4RL and station 6, respectively) are found at this level (Fig. 5). In case of lymph node dissection in the aortopulmonary window (station 5), another danger zone is reached and care must be taken of the left RLN looping around the aortic arch after it branches of the vagus nerve, which mostly takes place outside of the surgeon’s view (Fig. 4C). The aortic arch, however, can be seen clearly. More caudally, the mediastinal pleura and briefly the azygos vein form the right dissection plane. As the aortic arch is seen in the left dissection plane and ventrally the carina is approached, the azygos vein drains into the superior vena cava, crossing over the right main bronchus in a sagittal plane thus briefly forming the border of the right dissection plane with directly behind it the mediastinal pleura. Continuing caudally, the azygos vein passes the esophagus in a frontal plane, from the right to the left dorsal side (Fig. 5). Here, it joins the course of the thoracic duct in the para-aortic compartment. Once the azygos vein reaches this compartment, the dorsal dissection plane remains unchanged until the diaphragm is reached. Ventral to the ventral dissection plane, the left RLN runs in the left tracheoesophageal groove (Fig. 3). As can be seen in Figure 3, the upper paratracheal lymph nodes (station 2RL) would be extremely challenging if not anatomically impossible to reach for resection through a transcervical approach with current robotic instruments without damaging vascular structures or the left RLN and right vagus nerve.
Upper mediastinum above the aortic arch. The right subclavian artery has moved forward as it joined the left common carotid artery into the brachiocephalic trunk. Next, it will move toward the aortic arch, crossing the ventral side of the trachea in a frontal plane. Behind the right dissection plane lie the right vagus nerve and mediastinal pleura. AoA, aortic arch; BCV, brachiocephalic vein; BCT, brachiocephalic trunk; ln, lymph node; ln*, recurrent laryngeal nerve lymph node; RLN, recurrent laryngeal nerve; SA, subclavian artery; TD, thoracic duct; VN, vagus nerve; 2R, 2 L, right and left upper tracheal lymph nodes.
Upper mediastinum (Box 2). (A) An overview of the unmanipulated anatomy in a transversal plane at the level of aortic arch and slightly above the draining of the azygos vein into the superior vena cava, is shown in a digital image. (B) The second landmark, the draining of the azygos vein into the superior vena cava, at the level of the lower part of the aortic arch is shown in a digital image with highlighted anatomical structures. (C) The second box provides a 3D overview of the upper mediastinal region in which it is clearly seen how the azygos vein moves from dorsal to ventral in a sagittal plane, coursing over the right main bronchus. Cranial to this the right bronchial artery branches off the aortic arch and moves towards the right lung, passing the esophagus dorsally and the azygos vein laterally. At the level of the carina, the azygos vein then moves from the right to the left dorsal side of the esophagus. Further important structures in the dissection planes of the upper mediastinum are shown, such as the left recurrent laryngeal nerve looping around the aortic arch as it branches of the vagus nerve. AoA, aortic arch; SVC, superior vena cava; AV, azygos vein; ln*, recurrent laryngeal nerve lymph node; lPA, left pulmonary artery; RBA, right bronchial artery, RLN, recurrent laryngeal nerve; TD, thoracic duct; VN, vagus nerve; 2R, 2 L, right and left upper tracheal lymph nodes; 5, aorto-pulmonary lymph nodes; 6, anterior mediastinal lymph nodes; 7, subcarinal lymph nodes.
Frontal view of the carina and azygos vein. (A) As the carina is approached, the azygos vein branches of the superior vena cava, crossing over the right main bronchus in a sagittal plane thus forming the border of the right dissection plane with directly behind it the mediastinal pleura. (B) Continuing caudally, the azygos vein passes the esophagus in a frontal plane, from the right to the left dorsal side. Here, it joins the course of the thoracic duct in the para-aortic compartment, dorsal to the aortopleural and aorto-esophageal ligament and ventral to the prevertebral fascia. AV, azygos vein; ICM, intercostal muscle; ln(n), lymph node(s); lPA. left pulmonary artery; rPA, right pulmonary artery; SPV, superior pulmonary vein; SIV, superior intercostal vein; 4R, 4 L, right and left lower tracheal lymph nodes; 6, anterior mediastinal lymph nodes; 7, subcarinal lymph nodes.
Subcarinal mediastinum (Box 3) The region below the carina contains the third landmark and pitfall, namely the subcarinal lymph nodes (station 7) located just dorsal of the pulmonary trunk and more caudally the pulmonary veins, as seen on (A) the digital 3D reconstruction. The area on the right shows the right lateral dissection plane, the area on the top shows the ventral dissection plane and the area below the dorsal dissection plane. (B) The digital image highlights the most important anatomical structures at this level. (C) The third box shows a 3D perspective of the final part of the cervical part of the dissection during the RACE as well as the above discussed subcarinal lymph nodes and their proximity to the great vasculature. AV, azygos vein; IVC, inferior vena cava; LA, left atrium; lMB, left main bronchus; ln(n), lymph node(s); lPV, left pulmonary vein; RBA, right bronchial artery; rMB, right main bronchus; rPA, right pulmonary artery; rPV, right pulmonary vein; SVC, superior vena cava; TD, thoracic duct; VN, vagus nerve; 4R, 4 L, right and left lower tracheal lymph nodes; 7, subcarinal lymph nodes; green line, dissection plane.
Subcarinal mediastinum (Box 3)
Figure 6 shows the third and last box depicting the region below the carina, the most caudal part of the dissection of the RACE and MICE.
Until the level of the diaphragm, the dorsal dissection plane is formed by the prevertebral fascia with the vertebrae behind it. The left border is formed by the left mediastinal pleura and the descending aorta with the aorto-esophageal ligament. The right border is still formed by the right mediastinal pleura and intermittently the intercostal arteries and veins. As the carina is reached, the subcarinal lymph nodes (station 7) can be identified in the ventral dissection field. As this station is removed, care should be taken not to dissect too far ventrally into the danger zone where the right pulmonary artery, running from its origin towards the hilum of the right lung, and the left pulmonary vein running towards the left atrium, are located. Caudal to that the pericardium of the left atrium, then the right atrium and finally on the right the inferior vena cava form the ventral border of the dissection field. The level of the left atrium is usually the rendezvous point for the transcervical dissection to meet the transhiatal dissection.
Continuing towards the diaphragm, the dissection planes remain mostly unchanged. The middle and lower paraesophageal lymph nodes (stations 8 M and 8 L) are found surrounding the esophagus. As the esophageal hiatus is reached, the esophagus moves to ventral as well as the structures dorsal to it. Finally, the thoracic duct and azygos vein are found dorsally, the cardia of the stomach on the left, the liver on the right and the caudal part of the heart on the ventrally.
DISCUSSION
This study provides a detailed, comprehensive overview of the surgical anatomy of the lower neck and the mediastinum as it is encountered during a minimally invasive transcervical approach. The digital reconstruction of the cryomacrotome slices and the surgical anatomy boxes provide insight into the landmarks and danger zones that should be considered during this new surgical approach for esophageal cancer.
Previous studies have described the RACE procedure based on cadaveric dissections14,15,17–19 and clinical experience7,9,16 in an attempt to clarify the complex anatomy and surgical landmarks and danger zones that are encountered during this procedure. However, the authors felt that more detail on the surgical anatomy including important landmarks was required prior to broader clinical application. In this study, the digital reconstructions and the video sequences enabled the creation of a unique 3D overview by using the concept of surgical anatomy boxes. This provides a comprehensible overview of the complex anatomy of this region for upper gastrointestinal and thoracic surgeons who are interested in implementing this new approach. Profound anatomical knowledge of the procedure can guide physicians in the clinical decision-making for optimal patient selection for this technique, taking into consideration variables such as patient comorbidities as well as tumor type, location, size, and lymph node involvement.
The anatomy of the dissection planes in the cervical approach was carefully assessed. Structures that cross the dissection planes and can thus be transected are the left inferior thyroid artery in the lower neck and the aorto-esophageal ligament below the aortic arch. The left RLN to inferior thyroid artery relationship is most frequently dorsal (35.7%). However, a ventral relationship (6.5%) or an RLN running between two branches of the inferior thyroid artery can also be found.24 Ventrally, in the lower neck, it has been proposed to use the visceral fascia of the trachea and esophagus to shift the RLNs from the tracheoesophageal groove25–27 towards the tracheal compartment by detaching it from the esophagus and moving it away from the surgical field to avoid damage to the RLNs.18
Creating an anatomical understanding in a specimen without disturbing any structures can only be achieved using digital data. To visualize the mediastinum, several modalities are used.28,29 However, the accuracy is limited and may hinder the interpretation of anatomy encountered during minimally invasive surgery. Furthermore, it is known that due to partial volume effect the identification of nerves in proximity to muscles is challenging.20,30 In this study, important peripheral nerves such as the vagus nerves and RLNs could be identified over the largest part of their course. Another important aspect of this study is the creation of an anatomical understanding through a new perspective; in this case, a cranial-caudal as opposed to lateral perspective of the mediastinum, thus considering the surgical field as created by a transcervical approach. Through digital data, structures can be viewed from any angle, which enables the exploration of anatomy following surgical planes. By using photographs of unmanipulated anatomy—for which sectioning is considered the gold standard20,31–33—surgeons can visualize the surgical route with the changing topography of structures and possible pitfalls they will encounter in a comprehensive manner.
Strengths of this study are the use of techniques in which tissue was not manipulated, in the histology sections as well as the macroscopic digital reconstruction. Hereby, artificial layers that can be created by dissection or during surgery were prevented. The use of MRI and on-tape sections in addition to the digital images and reconstructions provided further orientation possibilities, especially aiding in the identification of nerves. To our knowledge, this study resulted in the only video sequence of a full and unmanipulated mediastinum of one and the same specimen in the three orthogonal planes as well as a reconstruction along the esophagus. Furthermore, the use of schematic surgical anatomy boxes to depict only the most important structures in 3D creates a visually comprehensive tool, which can be a useful surgical roadmap for upper gastrointestinal and cardiothoracic surgeons as well as anatomists. It can also be used for educational or research purposes. Integration with real-time artificial intelligence technology in robotic consoles can further improve the surgical navigation of the RACE.34 Despite having analyzed a limited number of specimens, findings were confirmed by three investigators thereby warranting the correctness of the observations. Nevertheless, the video sequences only show the anatomy of one individual and do not account for anatomical variations.
Limitations include that only one specimen was used for the video sequences. Especially, the upper mediastinum can be subject to anatomical variation. However, histological slides of two further specimens from earlier studies at this laboratory35 and digital reconstructions of two superior mediastina36 were available for reference. The provided 3D reconstruction in this study offers a valuable overview of the surgical anatomy encountered during a minimally invasive transcervical approach. To create a better understanding of the mediastinal anatomy from a cervical perspective, future studies could focus on identifying, which anatomical variations are relevant to the RACE and MICE and could potentially be added to the presented surgical boxes. Examples given in this study are the left inferior thyroid artery and the RLNs. Structures of interest could be the thoracic duct, azygos vein and right bronchial artery.37–39 Cadaveric studies in which the minimally invasive transcervical approach is performed should be used to assess optimal anatomical approaches, focusing on lymph node yield and possible pitfalls such as damage to the RLNs or vagus nerves.
The concept of schematic surgical anatomy boxes creates a visual, comprehensive roadmap for surgeons. For the RACE and MICE, four landmarks and danger zones are identified: (i) the course of the thoracic duct in the mediastinum, (ii) the course of the left recurrent laryngeal nerve, (iii) the crossing of the azygos vein right and dorsally of the esophagus, and (iv) the position of the aortic arch, the pulmonary arteries and veins. Knowledge gained from this study increases the understanding of peri-esophageal anatomic relations and aids surgical planning, especially in the context of the RACE and MICE. Moreover, the material can be used to train upper gastrointestinal and thoracic surgeons and to create sectional anatomy atlases and 3D models.
CONTRIBUTIONS
Conception and design: all authors; provision of study materials or patients: RLAW Bleys; collection and assembly of data: ICLJ Filz von Reiterdank; data analysis and interpretation: all authors; manuscript writing: ICLJ Filz von Reiterdank, IL Defize, EM de Groot, JP Ruurda, R van Hillegersberg, RLAW Bleys; final approval of manuscript: all authors.
Disclosures
P.P.G, J.P.R., and R.v H. are proctors for Intuitive Surgical Inc, Sunnyvale, CA. P.P.G. is a member of the advisory board of Medicaroid Europe GmbH, Düsseldorf, Germany. H.S. is a senior director at the Department of Surgical Applications Engineering, Intuitive Surgical, Sunnyvale CA, USA The authors declare that there is no conflict of interests or sources of funding for this work.
ACKNOWLEDGMENTS
We thank Marco Rondhuis for his assistance in the logistics regarding storing and processing the body donor used for this study. We thank Claire Mackaaij and Suzanne Verlinde-Schellekens for their invaluable and extensive work in cutting and staining the tissue sections. We thank Annelot Krediet for her help in using the E-MAC® software. We thank Mariëlle Phillipens for her assistance in making the MR images of the body donor used for this study.
