Alternative approach to the management of post-operative chylothorax

Abstract

Chylothorax is a rare complication of cardiothoracic surgery which is associated with increased morbidity and mortality. Surgical intervention is necessary in cases refractory to the traditional medical management. However, the increased morbidity and mortality rates of surgical intervention are heralding the growing popularity of percutaneous intervention. We present here a case report of a patient who developed chylothorax, following coronary artery bypass grafting (CABG) who was refractory to medical management. In view of persistent chylothorax, the patient underwent percutaneous intervention and plugging of the chyle leak, which resulted in prompt cessation and resolution of the chylothorax and symptomatic improvement in the patient. Percutaneous intervention such as thoracic duct embolization may be considered a successful alternative to surgical intervention for treatment of chylothorax.

Introduction

Chylothorax is the collection of chylous fluid in the thorax, and is a rare complication associated with increased morbidity and mortality following cardiothoracic surgery, most commonly following coronary artery bypass grafting. Damage to or avulsion of thoracic duct (TD) by electrocautery during left internal thoracic artery (LITA) harvesting leads to chylothorax. Traditional management of chylothorax involves dietary modification, octreotide infusion, and surgical intervention in refractory cases [1]. The very high morbidity and mortality rates of surgical intervention herald the growing popularity of percutaneous radiological intervention for chylothorax [2].

We present here a case of post-operative chylothorax following coronary artery bypass grafting (CABG), refractory to conservative management. An intranodal lymphangiogram and percutaneous coiling and glue embolization of the leak from TD into the pleural cavity resulted in complete resolution of chylothorax.

Case report

A 49-year-old male with insulin-dependent diabetes mellitus and systemic hypertension with recent non-ST elevated myocardial infarction (NSTEMI) was evaluated and found to have double-vessel coronary artery disease. Echocardiography showed a hypokinetic inferior wall with concentric left ventricular hypertrophy (LVH) and a mild left ventricular dysfunction with left ventricular ejection fraction (LVEF) of 49%. Coronary angiography showed a tight stenosis of the proximal left anterior descending (LAD) artery and left circumflex artery (LCx). The right coronary artery (RCA) was non-dominant and normal.

The patient underwent off-pump CABG with two grafts, LITA to LAD, and reversed saphenous vein graft (RSVG) to the obtuse marginal (OM) artery. Intra-operatively there were no signs suggestive of injury to the TD. Immediate post-operative period was uneventful with minimal inotropic supports and extubation within 6 h of surgery. He had a hemoserous fluid drainage in the first post-operative day (POD), which turned turbid and purely chylous after 24 h, from POD2. Fluid biochemistry analysis showed a cholesterol level of 14.9 mg/dl, proteins 1.3 mg/dl, triglycerides 242 mg/dl, and amylase 64 IU/l. The total count was 1450 cells/cumm, with predominant lymphocytosis (L-80%) and presence of mesothelial cells. The results were consistent with chylous drainage.

The patient was placed on conservative management with no fat oral diet (Peptamen, Nestle pharmaceuticals) and injection octreotide (Sun Pharmaceuticals) 100 units subcutaneous 8th hourly. However, the chylous drainage did not respond to these conservative measures even after 13 days post operatively, with daily output of approximately 500 ml of chyle. The patient and his family were advised surgical intervention to manage the chylothorax; however, they were not willing for the same; hence, interventional radiologist opinion was sought and a procedure to plug the leak was considered after obtaining consent from the patient.

Lipidol was injected into an inguinal lymph node and traced to the cisterna chyli, which was then percutaneously cannulated using an ultra-fine catheter (Fig. 1). Multiple leaks in the TD near the subclavian vein were identified with further lipiodol injection (Fig. 2). These leaks were occluded with glue and coil (Fig. 3).

Fig. 1.

Contrast injection of right groin lymphatics and paraspinal lymphatics

Fig. 2.

Contrast leak from thoracic duct into left pleural cavity

Fig. 3.

Coil and glue in the thoracic duct with glue percolating to the leak site

Following the procedure, there was complete cessation of the chylous leak and the chest drains were removed 3 days after the procedure. Follow-up chest X-ray at 1 month was satisfactory with good lung expansion and the patient is symptom free (Fig. 4).

Fig. 4.

Pre- and post procedure chest X-ray. Pre-procedure X-ray showing left pleural effusion with ICD in situ. Post procedure, complete resolution of pleural effusion noted with opacification of the thoracic duct and lymphatics

Discussion

Vesalius, in the sixteenth century, named the TD as vena alba thoracis due to the milky white fluid in it [3]. It is a 38–45-cm-long, 5-mm-wide lymphatic duct that originates at the level of T12 vertebra and ascends until the root of the neck where it joins the systemic veins at the angle of left subclavian vein and left internal jugular vein as a single trunk at the commencement of the brachiocephalic vein. It drains most of the lymphatics in the body, except the right side of torso, upper limb, and head and neck, which drain into the right lymphatic duct [1].

Blalock, in 1936, was the first to describe chylothorax as a possible complication of surgery [3]. Injury to TD and chylothorax have since been described following various cardiothoracic and neck procedures. Although rare, following CABG, chylothorax can occur due to avulsion of small branches of the TD rather than complete disruption, during LITA harvesting using electrocautery [4].

The TD transports about 4 l of chyle daily, so a disruption or blockage of the pathway results in collection of large amounts of lymph in the thorax [1].

Biochemical analysis of pleural fluid is the gold standard in diagnosis of chylothorax with typical findings of chylomicrons (0.5–1 mm size combination of long chain triglycerides and proteins) that are absorbed and transported through lymphatics. Other findings include cholesterol content of < 200 mg/dl and triglycerides > 110 mg/dl. A triglyceride level of < 50 mg/dl rules out chylothorax. Most cases are exudative (low lactate dehydrogenase and high protein). Transudative effusions are seen in about 25% cases, secondary to hepatic or cardiac etiology [5].

Prompt diagnosis and treatment is necessary due to the high morbidity and mortality associated with chylothorax post operatively with mortality reaching up to 50%, if left untreated [5].Conventional management includes medium chain triglyceride diet or nil per oral and starting total parenteral nutrition. Injection octreotide, which is an analogue of somatostatin, has been used successfully. It possibly acts by reducing the gastric, pancreatic, and intestinal secretions and absorption by mild constriction of splanchnic vessels, thereby reducing the chyle flow.

A daily loss of chyle > 1 l for over 5 days or persistent chyle drainage of < 1 l/day on conservative treatment for 2 weeks necessitates surgical intervention either by TD ligation or mass ligation of tissues, if TD is not visualized either in conventional redo-sternotomy or via video-assisted thoracoscopic surgery (VATS) [6–8]. The minimal invasiveness and the ease of identifying the TD make VATS a popular treatment option. Administering high fat substances (cream, ghee) can help in identifying the TD [1]. Complications associated with surgical TD ligation include ongoing chyle leak and development of multiloculated chylothorax along with peri-operative risks of bleeding, pneumonia, and injury to surrounding structures with mortality of approximately 3% [7].

Minimal invasiveness and good safety profile compared to surgical intervention have led to the popularity of interventional radiological procedures in recent times. Thoracic duct embolization (TDE) and thoracic duct disruption (TDD) are the two popular methods [2, 9].

TDE has three major steps: (1) lipoidal lymphangiography, involves direct puncture of inguinal lymph node using a 26-G needle under ultrasonography (USG) guidance and administering lipoidal at the junction of nodal cortex and hilum, which will identify the upper lumbar and cisterna chyli on intermittent fluoroscopy. (2) Thoracic duct access (TDA), a 21-G Chiba needle is advanced into the cisterna chyli and then to the TD. Digital subtraction angiography is performed using water soluble iodinated contrast to identify the leakage points. (3) TDE. After confirmation of the leakage points, the entire TD segment is embolized using a combination of microcoil and N-butyl-2-cyanoacrylate (NBCA) liquid glue plus lipiodol, at a ratio of 1:1.5–1:3 [2, 9].

Studies have shown a success rate of 92.4% at experienced centers using this technique [2]. TDA is the technically most challenging part of this three-step procedure, with possible complications including needle penetration of various abdominal organs particularly gall bladder that could lead to biliary peritonitis, edema of the legs, and diarrhea [10].

TDD involves maceration of cisterna chyli or main retroperitoneal lymphatic channels through multiple needle punctures, reducing the downstream lymphatic flow and exerting pressure over the upstream TD by hematoma formed at the puncture site, allowing the leaks to heal spontaneously. It is used as a bail-out procedure if TDA is technically difficult or prohibited [2].

Despite excellent clinical outcomes, some patients do not respond to TDE and chylothorax persists. A possible explanation to this could be incomplete occlusion of the TD due to insufficient usage or excessive dilution of embolic agents. Existence of collateral channels that continue to leak chylous fluid could also lead to the failure of the procedure [10].

In our case report, failure of conventional dietary modifications and pharmacological intervention to alleviate the chylothorax prompted us to approach a radiological intervention since the patient was not willing for another surgical procedure that could have added to the surgical morbidity and mortality. TDE and plugging of leaks radiologically resulted in prompt cessation of chylothorax and symptomatic improvement in the patient with good lung expansion and no residual pleural effusion post procedure and at follow-up.

Conclusion

Chylothorax is a rare yet important complication of cardiothoracic surgical procedures requiring prompt diagnosis and treatment, due to its high morbidity and mortality. Interventional radiological procedures such as TDE can be considered for successful treatment if conventional treatment fails or as an alternative to surgical intervention. However, further randomized controlled trials would be beneficial in developing treatment guidelines in the presence of a wide array of treatment options.

Author contribution

Anup Holur Srinivasan: writing. Aylliath Gosalakkal Jayakrishnan: conceptualization. Keerthiraj Belle: conceptualization.

Funding

None.

Data Availability

Available with the corresponding author and shall be provided on reasonable request.

Code availability

Not applicable.

Declarations

Ethics committee approval

Not required for case reports as per institutional protocols.

Informed consent

The patient in this study provided written informed consent to participate and for publication.

Conflict of interest

The authors declare no conflict of interests.

Human and animal rights statement

All procedures in this study were performed in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration.