Chylothorax results from the leakage of chyle from the thoracic duct or one of its lymphatic branches into the pleural space. Common causes include neoplasm and iatrogenic injury. Life-threatening metabolic derangements may occur if chylothorax is not recognized and treated promptly. Numerous maneuvers can be undertaken as part of a conservative approach to treating chylothorax, but surgical intervention is usually the most effective method of achieving definitive results.
The thoracic duct was first described in humans by Veslingus in 1634. The first successful thoracic duct ligation was performed by Lampson in 1948 for a traumatic chylothorax.1 Before this time, chylothorax was treated conservatively and associated with a mortality rate of almost 50%. An accurate understanding of the anatomic course of the thoracic duct and common sites of variant anatomy can help to minimize iatrogenic chylothorax and ensure successful surgical intervention through direct repair or mass ligation.
The thoracic duct is a continuation of the cisterna chyli as it passes from the abdomen into the thorax (Fig. 113-1). There are many variations in the course and number of divisions of the thoracic duct. In most individuals, the thoracic duct starts at the cisterna chyli and enters the chest through the aortic hiatus, coursing behind the esophagus between the aorta and azygos vein. The duct runs cephalad in the right hemithorax along the spinal column. At the level of the fifth or sixth thoracic vertebra, the duct crosses to the left hemithorax and continues cephalad along the left side of the esophagus into the superior mediastinum behind the aortic arch and posterior to the left subclavian artery. The duct terminates at the angle formed by the left internal jugular and left subclavian veins, where it drains into the venous system. Of surgical importance is the consistency in location and paucity of branching of the thoracic duct between the cisterna chyli and the level of the eighth vertebral body in the lower right hemithorax.
The thoracic duct is the primary lymph vessel that carries the lipid products of digestion (fatty chyle) and lymph from the intestines to the left subclavian vein. In the thorax, the duct begins at the level of the cisterna chyli, a lymph sac that lies just below the diaphragm and aortic hiatus, when present. The duct ascends through the right chest, crosses over to the left chest at the fifth or sixth thoracic vertebra, and empties at the angle formed by the left internal jugular and left subclavian veins. This is known as the lymphaticovenous junction (inset A), and there is a one-way valve at the termination of the thoracic duct. The anatomy may vary. Some common sites of variation are shown in insets B and C.
Chyle is a milky fluid that consists primarily of proteins, triglycerides, and lymphocytes. Under normal conditions, the thoracic ...