Thoracoscopic anterior segmentectomy of the right upper lobe (S³)

S³ segmentectomy can be indicated for solitary metastases, cT1a non-small cell lung carcinomas and ground glass opacities (Figure 1). At first sight, it looks as a challenging procedure as the anatomy of vascular elements is complex, the segment is comprised between S¹ and the middle lobe and, in addition, the minor fissure is most often fused. A sufficient exposure of the bronchial trifurcation must be achieved. Creating a tunnel between S³ and the middle lobe greatly eases dissection of the vessels.

Figure 1 cT1aN0 ground glass opacity of the right upper lobe anterior segment.

Anatomical landmarks

Bronchi

B³ is the anterior branch of the upper bronchus. In 14% of the cases, it is independent from the apicoposterior truncus (B¹⁺²), and in 40% of the cases it is a branch of a trifurcation B1-B2-B3 (1). It is usually easily recognized by its anterior direction, while B¹ and B² have a cephalad direction. Lymph nodes are frequently found at the origin of B³. Even for benign conditions, removal of these nodes is required for an optimal disclosure of the B³ root.

Arteries

A³ is the lowermost branch of the truncus anterior. In 48% of the cases, S³ receives its 2 branches (A^3a and A^3b) from the truncus anterior (TA). In the other cases, there is also an ascending A³ artery from the arterial truncus intermedius (TI) which raises close to the ascending A² and is recognized from its anterior direction (Figure 2).

Figure 2 Modelisation of the arterial supply to S³. Note the presence of an ascending A³ raising from the arterial intermediate truncus.

Veins

Variations of the venous pattern are numerous (2). There are two types of veins: (I) a large V³ that is the lowermost branch of the central vein and (II) 1 or 2 small ascending veins branching from the central vein that are easily recognized as they come directly from the anterior segment (Figure 3).

Figure 3 Modelisation of the venous drainage and of the bronchi of S3.

Technique

We used a fissure-based technique and multiple ports access, as described by our team (3) and by others (4). The anterior portion of the major fissure, between S³ and the middle lobe is usually fused, or even inexistent. First opening of this fissure is the key for an easy vascular dissection. When incomplete, the fissure can be opened by a tunnel technique, as follows:

The fissure is opened at the junction of the transverse and oblique fissures as for an apicoposterior segmentectomy. Once Asc.A²—and Asc.A³ if present—is identified, the edge of the middle lobe is lifted up and a path is created with a blunt tip dissector and/or an endo-peanut, keeping close to the vessels (Figure 4). The course is pursued in an anterior direction (Figure 5). The upper and middle lobes are then retracted backward to expose the upper vein in a usual manner, so that the middle lobe vein and V³ are clearly seen. In a second step, the hilum is exposed and a path is done with a dissector between the venous branches and an endo-peanut permits dissection in a posterior direction. The instrument is gently manoeuvred and pushed so that it meets up with the already dissected posterior opening of the fissure. A curved tip 60 mm endostapler can then be inserted in the tunnel and fired. The middle lobe and S³ are now separated, giving access to the vessels. Figure 6 illustrates a rather straightforward case with a thin and short fissure (Figure 6) and Figure 7 demonstrates a more difficult case with a thick and long fissure (Figure 7).

Figure 4 Creation of a tunnel between S³ and the middle lobe. Borders are V³ and V⁴⁺⁵. ML, middle lobe; RLL, right lower lobe.

Figure 5 Completion of the tunnel. Arrow indicates the anterior mediastinum. ML, middle lobe.

Figure 6 Creating a tunnel for separation of S³ from the middle lobe in a patient with a thin minor fissure (5). Available online: http://www.asvide.com/article/view/26799

Figure 7 Creating a tunnel for separation of S³ from the middle lobe in a patient with a thick minor fissure (6). Available online: http://www.asvide.com/article/view/26801

Control of the B³ bronchus requires a large exposure of the upper lobe bronchus so that a sufficient retraction of the segmental bronchi can be exerted. The posterior aspect of the fissure is opened as for an upper lobectomy, in order to expose the ascending A² (Asc.A²) and the bronchus (Figure 8). Once these two elements have been dissected, both are looped (Figure 9). The upper lobe bronchus is then retracted backward and the Asc.A² forward, thus exposing B³. Lymph nodes are frequently present at the origin of B³ (Figure 10) (1,3). They are dissected and removed (Figure 11). If the patient is operated on for a malignant disease, these nodes are sent for frozen section. If positive, the procedure should be transformed into a lobectomy (8). B³ is dissected, taped and then stapled (Figures 12,13). In some patients, even after an extensive dissection, the space is very limited and does not permit passage of a stapler, even with a curved tip. In these cases, B³ must be cut with a scalpel blade and its stump sutured (Figures 14,15).

Figure 8 Opening of the posterior part of the major fissure for better exposure of the segmental bronchi (7). Available online: http://www.asvide.com/article/view/26802

Figure 9 Exposure of B³ thanks to retraction of the upper lobe bronchus and of the ascending A². CV, central vein; ML, middle lobe.

Figure 10 Lymph nodes at the origin of B³. LN, lymph nodes; RUL-B, right upper lobe bronchus.

Figure 11 Origin of B³ after clearance of lymph nodes.

Figure 12 Backward retraction of B³.

Figure 13 Dissection and stapling B³ (9). Available online: http://www.asvide.com/article/view/26805

Figure 14 Example of impossible stapling of the origin of B³ due to lack of space. Manual suturing of B³ stump. B³s, stump of B³.

Figure 15 Manual division of B³ because of insufficient room for stapling (10). Available online: http://www.asvide.com/article/view/26806

The large central vein runs in an anteroposterior direction. The two most anterior tributaries, V^3a and V^3b, drain S³. These are clipped and dissection of the central vein and V³ is pursued (Figure 16).

Figure 16 Dissection and control of A³ (11). Available online: http://www.asvide.com/article/view/26807

Dissection of the veins helps exposing A³ artery whose 2 branches are dissected (Figure 17) and then clipped or stapled (Figure 16).

Figure 17 Exposure of A³. CV, central vein; ML, middle lobe; V³s, stump of V³.

As the fissure has already been opened at the beginning of the procedure, S³ is now fully mobile and the intersegmental plane S²–S³ can be divided, according to the predetermined demarcation line, whatever the method used. We favor near-infrared imaging with systemic injection of indocyanine green (12). The stump of B³ is gently pushed away using blunt dissection, so that it cannot be caught into the staple line. A large clamp is applied on the intersegmental plane to compress the parenchyma and ease application of the stapler (Figures 18,19). The viability of the remaining segments 1 and 2 is checked by reventilation (Figure 20).

Figure 18 Compression of the intersegmental plane before stapling. CV, central vein; V2t, transversal V2; B³s, stump of B³; A³s, stump of A³.

Figure 19 Delineation of the intersegmental plane using systemic injection of indocyanine green under near-infrared imaging and division of the plane (13). Available online: http://www.asvide.com/article/view/26808

Figure 20 Reventilation of segments 1 and 2 (14). Available online: http://www.asvide.com/article/view/26809

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Alessandro Brunelli) for the series “Uncommon Segmentectomies” published in Journal of Visualized Surgery. The article has undergone external peer review.

Conflicts of Interest: The series “Uncommon Segmentectomies” was commissioned by the editorial office without any funding or sponsorship. DG is consultant for an instrument manufacturer (Delacroix Chevalier). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this manuscript and any accompanying images.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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