VATS right upper posterior segmentectomy with anomalous bronchiand pulmonary vessels: a case report and literature review

Background Anatomic variation may increase the diculty and risk for anatomic segmentectomy. The preoperative three-dimensional computed tomography bronchography and angiography(3D-CTBA) can provide a detailed model of the segmental structure, and contribute to precise and safe segmentectomy. Case presentation We report a case with anomalous bronchi and pulmonary vessels in the right upper posterior segment (RS 2 ), under the guidance of 3D-CTBA, anatomic RS 2 segmentoctomywas performed accurately and safely, the postoperative condition was uneventful. Conclusions This rare case highlights the importance of 3D-CTBA to guild accurate segmentectomy with anatomic variation.


Introduction
With the popularization of chest computed tomography (CT), the discovery of small pulmonary nodules is increasingly common, and it promotes the progress of segmentectomy as well [1,2]. The anatomic structure of the pulmonary segment is sometimes variable, as reported in the previous cases [3][4][5]. The public's attention is now shifting to how to achieve an accurate anatomic segmentectomy. In terms of the successful resection, the development and application of various 3D imaging softwares have given strong technical supports [6]. Preoperative reconstruction of the segment can clearly show the anatomic structure and judge whether there are variations, so as to make an accurate surgical plan. In this case, we reported a 34-year-old female patient who experienced a ground-glass nodule (GGN) at the right upper posterior segment (RS 2 ). The preoperative three-dimensional computed tomography bronchography and angiography (3D-CTBA) displayed multiple anatomic variations. Through the detailed planning of the operation, video-assisted thoracoscopic surgery (VATS) RS 2 segmentectomy was carried out successfully.

Case Presentation
A 34-year-old female was admitted to us with a GGN in RS 2 , discovered by chest CT during health checkup one year ago. A review of CT showed the subpleural GGN was slightly larger than before, with the diameter of 7 mm, and the CT value was − 400HU (  (Fig. 2). With the guidance of 3D-CTBA, VATS anatomic RS 2 segmentectomy and lymph node sampling were conducted accurately (video 1), all anatomic variations were successfully detected during the operation (Fig. 3). The fast-frozen pathology was minimally invasive adenocarcinoma (MIA). The chest radiograph illustrated that the right lung was completely re-dilated, and the incisal margin of the segment displayed no obvious exudation on the 2nd postoperative day (Fig. 4). The drainage tube was removed on the 2nd postoperative day, and the patient was discharged on the 3rd postoperative day. The postoperative pathology revealed MIA with negative surrounding lymph nodes.

Video Description
Intravenous general anesthesia combined with double-lumen endotracheal intubation and contralateral one-lung ventilation were performed. The observation port was made in the 7th intercostal space of the posterior axillary line, and the operation port in the 4th intercostal space of the anterior axillary line. The surgical procedure was as follows: (1) Thoracoscopic exploration revealed a subpleural nodule at the RS 2 ; (2) The parietal pleura was sectioned by harmonic, then the Nos.11 lymph nodes were removed; (3) The V 2 t was dissociated and pulled by silk, the Nos.12 and 13 lymph nodes around the bronchus were completely removed; (4) After ligating the V 2 t, the B 2 was dissected out and transected with a thick tissular (blue cartridge) 45 mm long endostapler (EC45A, JJMC, USA); (5) According to the preoperative 3D-CTBA, the other two veins were judged as the intersegmental veins, so they were all preserved; (6) Due to the posterior segmental artery was very di cult to ligate, we reventilated the right lung with pure oxygen, when the intersegmental plane was clear after about 15 minutes, the segmental hilum was released su ciently to expose the posterior segmental artery, then the artery was ligated safely;(7) The intersegmental plane was divided along the in ation-de ation line using the endostaplers, thus the posterior segment was removed successfully. A sterile glove was made to collect the specimen. No bleeding and air leakage were discovered after the pleural injection of in ation. No. 24 chest drainage tube was placed in the observation port. After the right lung was completely dilated, the incision was sutured. The operative time was about 70 min, and intraoperative blood loss was about 50 ml.

Conclusion
Anatomic segmentectomy for early lung cancer is one of the biggest hotspots in thoracic surgery in recent years. It can not only completely resect the tumor, but also preserve the normal lung tissue to the maximum extent [7]. The distribution of bronchus, artery and vein in pulmonary segment exists variations in some patients. The key to the implementation of this operation is to accurately grasp the anatomical structure of the target segment. The 3D-CTBA can provide a precise anatomical structure, identify the intrasegmental and intersegmental veins from different views [8]. Some complicated pulmonary segmentectomy should be performed under the guidance of 3D-CTBA [9,10].
The e cacy of 3D reconstruction for thoracic surgery has been previously described [11], Kimihiroet al. [12] rst reported the application of 3D-CTBA in VATS segmentectomy. At present, the main softwares for 3D reconstruction of segment include IQQA, DeepInsight, etc [13,14]. All the reconstructive softwares can offer precise anatomical structure of pulmonary segments, but sometimes, it is di cult for surgeons to skillfully use them. In our institution, with the assistance of the radiologists, we adopt the computed tomography pulmonary angiography (CTPA)-based technology to reconstruct the anatomic structure for each patient who undergoing segmentectomy. It shows the precise structure of bronchi, arteries and veins in a natural surgical eld view, and the results are also satisfactory. RS 2 segmentectomy is a common procedure in all kinds of segmental resection, but the anatomic variations may increase the di culty and risk [15]. Xinfeng et al. [16] reported a tracheal bronchus and a variable central vein entering the left atrium dorsal to the right pulmonary artery trunk in a patient underwent VATS RS 2 segmentectomy. Tadashi et al. [17] reported a patient with anatomic variations in bronchi and pulmonary vessels during thoracoscopic RS 2 segmentectomy. However, to the best of our knowledge, bronchial variation associated with variant pulmonary vessels has rarely been reported. The The data used to support the ndings of this study are included within the article.
Authors' contributions JZ was the main surgeon and drafted the manuscript. YZ performed the 3D-CTBA. CY and WM helped care for the patient and draft the manuscript. HL reviewed and modi ed the manuscript. All authors read and approved the nal manuscript. Figure 1 The preoperative computed tomography scanning. A 7-mm ground-glass nodule was identi ed at the posterior segment of the right upper lobe (arrow) , the CT value was -400HU.  The chest radiograph on the 2nd postoperative day. Theincisal margin of the segment displayed no obvious exudation(arrow).

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