Thoracic duct embolisation

Thoracic duct embolisation (TDE) is a safe, efficacious treatment for chylothorax ¹. Chylothoraces with a low drain output (<1L/day) are traditionally managed conservatively with dietary change, whilst high output (>1L/d) are managed with surgical thoracic duct (TD) ligation ².

Thoracic duct embolisation was developed as a minimally-invasive alternative to thoracic duct ligation. However, recent research demonstrates that thoracic duct embolisation has better outcomes than conservative management or surgery for the treatment of chylothorax. As such, TDE is increasingly used as a first line intervention in chylothorax ¹.

Experience and research pertaining to this procedure are limited, with the largest case series involving 109 patients. Further research is needed to clearly define the place of thoracic duct embolisation in the management of chylothorax. There have also been a few published case studies of other techniques, such as retrograde or direct catheterisation of the thoracic duct or CT guidance ⁸. These techniques offer hope to the relatively high proportion of patients who fail TD catheterisation.

Indications

• high-output (>1L/day) traumatic chylothorax or low output that has failed conservative/surgical management ³
• non-traumatic chylothorax not caused by lymphatic malformation ⁵

Contraindications

• absolute: uncorrectable coagulopathy
• relative
  • pregnancy
  • prior severe anaphylactic reaction to iodinated contrast media ⁵

Procedure

• intranodal lymphangiography ^5,6
  • an alternative to the technically challenging and laborious traditional pedal lymphangiographic technique
  • US guidance is used to directly access the hilum of an inguinal lymph node with a 25 G spinal needle
  • injection of an oil-based contrast agent (e.g. Lipiodol) at a rate of 1 to 2 mL per 5 minutes, up to 6 mL, which should achieve appropriate opacification of the abdominal and pelvic lymphatics
• thoracic duct embolisation ⁵
  • when the target duct is confirmed, a 21-22 G x 15 to 20 cm needle is used for transabdominal access under fluoroscopy, regardless of intervening abdominal structures
  • after double wall penetration is achieved, a stiff 0.018 guidewire is used to access the duct
  • a 3 Fr 65 cm microcatheter is then advanced over the wire into the TD, after which the guidewire may be removed
  • contrast is then injected to define the source of the leak and TD anatomy
  • the TD or its branches are then embolised proximally to the leak with a combination of coils and glue

Outcomes

• traumatic chylothorax
  • the overall intent-to-treat success rate is ~70% in the largest series of 109 patients; this relates directly to the ability to catheterise the thoracic duct with successful catheterisation increases the probability of clinical success to 90% ³
• non-traumatic chylothorax: the overall intent-to-treat success rate is ~50% in the largest series of 34 patients; this relates directly to the cause of the leak ⁴

Complications

• acute: misembolisation of the portal veins (rare) ⁷
• chronic ⁷
  • protein-losing enteropathy and chylous ascites, manifesting as chronic diarrhoea (~5%)
  • chronic leg swelling (~5%)
  • both (~2%)