B

figure 1-9 (continued) B, Right anterior view. Note the basically segmental nature of distribution. Reproduced, by permission of Mayo Foundation for Medical Education and Research, from Salassa JR et al.16

Aorta figure 1-9 (continued) B, Right anterior view. Note the basically segmental nature of distribution. Reproduced, by permission of Mayo Foundation for Medical Education and Research, from Salassa JR et al.16

Salassa and colleagues identified from three to seven principal tracheal arteries along the entire length of the lateral tissue pedicles.16 Just lateral to the tracheoesophageal groove, the primary vessels divide into tracheal and esophageal branches (Figure 1-11). The tracheal branches pass directly to the tracheal wall,

figure 1-10 Principal patterns of bronchial artery supply to the trachea and bronchi. Frequency of occurrence is noted. These patterns account for over 92% of variations. Not shown in these diagrams are the proximal branch of the superior bronchial artery which courses anteriorly over the left main bronchus to carina (see Figure 1-9A) and the middle bronchial branch passing beneath the left main bronchus to carinal anastomosis (see Figure 1-9B). Adapted from Cauldwell EW et al.17

branching up and down over the width of several rings. These fine branches in turn connect with the branches of the next segmental vessels above and below. These vessels form a somewhat irregular but generally complete series of fine longitudinal anastomoses on the wall of the trachea.

From the vessels that reach the trachea, transverse intercartilaginous arteries extend deeply into the tracheal wall and anastomose with those from the opposite side at the midline (see Figure 1-11). These vessels branch into the submucosa. Smaller intercartilaginous branches point posteriorly and terminate in the membranous tracheal wall. The posterior membranous wall of the trachea is also supplied by secondary small branches from the primary esophageal vessels branching from the tracheoesophageal arteries. Well-developed longitudinal anastomoses are also present. The tracheal cartilages receive nourishment from the submucosal plexus only. The submucosal plexus of both the mucosa overlying the cartilages and that overlying the membranous wall interconnect and are important in supplying the membranous wall.

Although a large part of the length of the trachea can usually be circumferentially dissected without necrosis if the trachea remains intact (and with it the vertical longitudinal vessels), circumferential dissec-

Coronal section of tracheal wall...

Anterior transverse intercartilaginous artery

Trachea

Lateral longitudinal anastomosis

Anterior transverse intercartilaginous artery

Primary tracheal artery

Pattern of microvasculature of mucosa

Tracheoesophageal artery

Primary esophageal artery

Secondary tracheal— twig to posterior wall

Primary tracheal artery

Pattern of microvasculature of mucosa

Tracheoesophageal artery

Primary esophageal artery

Muscular posterior

Esophagus wal1 of trachea

Secondary tracheal— twig to posterior wall figure 1-11 Microscopic blood supply of the trachea. See text. Reproduced, by permission of Mayo Foundation for Medical Education and Research, from Salassa JR et al.16

tion of an excessively long segment of trachea above or below a point of tracheal division can lead to devas-cularization. Necrosis may follow. No absolute distances acceptable for toleration of circumferential dissection have been experimentally determined since the intimate blood supply of the trachea varies with species. Clinical experience, however, dictates the wisdom of minimizing circumferential dissection of trachea that is to remain in the patient, with a goal of dissecting free no more than 1 or 2 cm of trachea above or below an anastomotic line. Mediastinal lymph node dissection for tracheal tumors should be limited to lymph nodes immediately adjacent to the segment to be resected, in order to avoid contributing to devas-cularization. Surgical caution applies to the very rare situation where circumferential tracheal resection may seem to be desirable during concomitant esophagectomy. Tracheal necrosis may well follow because the tracheoesophageal arteries are interrupted by esophagectomy.18

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