Ligation of the thoracic duct is found in any patient with a traumatic or iatrogenic chylothorax who has not responded to a brief trial of conservative management such as a low-fat diet, medium-chain triglycerides, total parenteral nutrition or octreotide.
Spontaneous chylothorax which is generally linked with mediastinal diseases such as lymphoma are not often amenable to such therapy. Both open and thoracoscopic approaches to duct ligation are feasible in most patients.
Chylothorax following minimally invasive pulmonary surgery is easily managed by VATS thoracic duct ligation. Chylothorax following minimally invasive esophagectomy either with a combined trans-thoracic trans-abdominal approach or a completely trans-abdominal approach is also an indication for thoracoscopic ligation of the duct.
In contrast, chylopericardium is managed by pericardial drainage and ligation of the duct, both of which can be performed thoracoscopically. An unusual situation is presented by patients who have a thoracic duct cyst they will require ligation of the duct during excision of the cyst.
In patients who had a recent thoracotomy (within 7-10 days) there is no advantage in performing thoracoscopy to ligate the duct. The thoracotomy should be reopened if ligation of the duct is required, particularly if the thoracotomy has been performed on the right.
Thoracoscopic ligation of the thoracic duct may still be appropriate if the thoracotomy which resulted in the chylothorax was performed on the left side.
Operative Steps For Thoracoscopy Ligation Thoracic Duct
General anesthesia with single lung ventilation is required and the duct is always approached through the right chest due to its constant position in the lower right chest.
The patient is placed in a left lateral decubitus position, rolled forward, and flexed to allow increased exposure of the posterior mediastinum.
The thoracoscope is placed in the seventh intercostal space along the line of the anterior superior iliac spine and the working incision (5cm) is placed in the fifth or sixth intercostal space in the anterior axillary line.
The soft tissues of the chest wall are kept open with a Weitlaner retractor and the intercostal incision is made longer than the skin incision. This makes it possible to introduce two or three instruments through this incision and allows suction to be applied within the chest without causing re-expansion of the lung.
A third incision is made at the level of the dome of the diaphragm after visualizing the desired space thoracoscopically. This incision is placed along the mid-axillary line.
A 30-degree scope is used to visualize the chest and a tonsil sponge introduced through the incision over the diaphragm is used to retract the diaphragm inferiorly.
Simultaneously, the posteroinferior edge of the lower lobe is grasped with a ring clamp introduced through the working incision and retracted superiorly and posteriorly to display the inferior pulmonary ligament, which is then divided with cautery.
Care must be taken as the inferior pulmonary vein is approached and it is preferable to use scissors to mobilize this part of the ligament.
Gentle blunt dissection with a tonsil sponge is helpful in completing the dissection and allowing the inferior pulmonary vein to be identified.
This dissection is then continued either sharply or with cautery, superiorly for a distance, opening the mediastinal pleura posterior to the hilum until the bronchus intermedius is reached.
This allows the lung to be retracted anteriorly with a tonsil sponge or fan retractor which increases the exposure to the posterior mediastinum. Rolling the operating table forward further facilitates this exposure.
The posterior mediastinal pleura between the azygous vein and the chest wall are initially opened and the vein is mobilized. This allows the vein to be retracted without avulsion of intercostal venous tributaries.
The mediastinal pleura between the azygous vein and the esophagus are opened longitudinally with cautery or scissors. This is done at a point inferior to the level of the inferior pulmonary vein, as at this level the duct is most often solitary and has not duplicated, which may occur at a higher level.
The esophagus is retracted anteriorly using a ring clamp or sponge stick and the dissection continued bluntly towards the aorta using a peanut dissector. Venous tributaries from the azygos vein and arteries from the aorta to the esophagus can be clipped with a 5mm clip applier and divided sharply. Alternatively, they can be divided with a harmonic scalpel.
Exploration of this area bluntly will reveal the thoracic duct as a thin tubular structure with occasional peristalsis. Once a sufficient length of duct is isolated it is doubly clipped using 5 or 10mm clips depending on the size of the duct and is divided.
Transection with a linear cutting stapler with a vascular load (30mm length, 2.0mm staple height) works just as well. The stapler or clip applier can be introduced through the working incision or the incision used for retraction of the diaphragm.
If an adequate length of the duct can be isolated, a portion can be excised and sent for frozen section to confirm its identity.
If the duct is not directly identified, all fatty and lymphatic tissue anterior to the azygous vein, posterior to the esophagus, and between the aorta and right parietal pleura is divided between endoclips, intracorporeally placed ligatures, or with a linear cutting stapler with a vascular load.
Since these are the anatomic bounds of where the thoracic duct is located, these maneuvers can successfully ligate the duct without directly identifying it.
The divided ends of the duct are examined for the lymphatic leak which, if present, can be re-clipped or stapled. The application of fibrin glue as a further sealant is a useful adjunct to the ligation, and a mechanical pleurodesis using abrasion of the parietal pleura with a sponge or Bovie scratch pad may decrease the chance of a recurrent chylothorax.