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Shiozaki et al. Mini-invasive Surg 2020;4:50 I http://dx.doi.org/10.20517/2574-1225.2020.31 Page 7 of 9

Figure 7. Pitfall around the azygos vein. At the lower mediastinal level, the azygos vein (blue arrow) is locates on the left side (A); at the
middle mediastinal level, the position of the azygos vein (blue arrow) gradually changes to the right side (B); the arch of the azygos vein
(blue arrow) flows into the superior vena cava at the cranial side of the right main bronchus (C); in right main bronchus lymph node (red
circle) dissection, these lymph nodes are resected from the right main bronchus (red arrow). At this point, there is the risk of damage to
the arch of the azygos vein (blue arrow) (D); to avoid damage, it is important to identify the arch of the azygos vein (blue dotted lines)
at the dorsal side of the right main bronchus prior to right main bronchus lymph node dissection (E)

cranial side of the right main bronchus [Figure 7C]. In our procedure for right main bronchus lymph node
dissection, after the ventral and caudal sides were separated, these lymph nodes were resected from the
right main bronchus. At this point, there was a risk of damage to the arch of the azygos vein [Figure 7D].
To avoid this, it was important to identify the arch of the azygos vein at the dorsal side of the right main
bronchus prior to right main bronchus lymph node dissection [Figure 7E]. We also avoided damaging the
membranous portion of the right main bronchus at this point.

DISCUSSION
Recent advances in the development of surgical devices and the standardization of operative procedures
have resolved the conventional limitations associated with transmediastinal esophagectomy, such as
difficulties maintaining a surgical field and operability. We previously reported the significance of
transmediastinal radical esophagectomy as a minimally invasive surgery [10-13,16] . This procedure initially
reduced the incidence of postoperative respiratory complications because neither thoracotomy nor two-
lung ventilation is performed. The total operative time may have been decreased because a change in
position during surgery was not necessary in this approach. We previously compared the treatment
outcomes of 84 patients with esophageal cancer who underwent mediastinal lymph node dissection
by the laparoscopic transhiatal approach with those of 75 patients who underwent dissection by right
[11]
thoracotomy . The total operative time was significantly shorter in patients treated with the laparoscopic
[11]
transhiatal approach (332.4 ± 106.2 min) than in those treated with right thoracotomy (435.7 ± 98.0 min) .
Furthermore, a magnified view of the deep mediastinal space using a mediastinoscope decreased the total