Ann Thorac Surg 2006;81:1507-1509
© 2006 The Society of Thoracic Surgeons
Case report
Chylothorax After Internal Thoracic Artery Harvest
Cliff K. Choong, FRACS,
Carlo Martinez, MD,
Hendrick B. Barner, MD
*
Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, Missouri
Accepted for publication February 15, 2005.
* Address correspondence to Dr Barner, 6125 Clayton Ave, Suite 430, St. Louis, MO 63139 (Email: hendrick.barner{at}tenethealth.com).
 |
Abstract
|
|---|
Chylothorax is a rare complication following coronary artery bypass graft surgery. We report a case of chylothorax that complicated a left internal thoracic artery harvest and review the literature regarding this subject.
|
Introduction
|
|---|
Chylothorax is a rare complication after coronary artery bypass graft surgery. We report a case of chylothorax that complicated a left internal thoracic artery (ITA) harvest and review the literature on this subject.
A 63-year-old man had double coronary bypass using the left ITA and saphenous vein. The ITA was harvested with electrocautery to create a 1.5 to 2.0 cm wide pedicle from the subclavian vein to the bifurcation with the pleura widely open. The chest tube drainage was pink and watery when the tube was removed on postoperative day 2. Over the next 5 days there was a re-accumulation of fluid in the left pleural space. Thoracentesis drained 800 mL of milky appearing fluid suggestive of chyle, which was confirmed on biochemical analysis. A diagnosis of chylothorax due to lymphatic injury was made, and the patient was placed on a low-fat diet. The treatment option of conservative management versus thoracic duct ligation was discussed with the patient. He elected conservative management and was discharged. A week later, the chest roentgenogram revealed 80% opacification of the left hemithorax and thoracentesis drained 1,100 mL of chyle. There was prompt reexpansion of the lung without evidence of fluid loculation. The patient returned at weekly intervals on three more occasions with similar results. At this point he elected to proceed with thoracic duct ligation, which was accomplished through a right thoracotomy. Five mL of methylene blue and 50 mL of cream were placed in the stomach prior to the operation to facilitate identification and ligation of the thoracic duct immediately cephalad to the diaphragm. The procedure was uncomplicated. The patient was discharged on postoperative day 5, and he remained well at 1-year follow-up.
|
Comment
|
|---|
The thoracic duct originates from the cisterna chyli and ascends on the anterior surface of the vertebral body through the aortic hiatus. It lies to the right behind the aorta until the fourth thoracic vertebra where it crosses to the left and continues its ascent behind the aortic arch and then the left subclavian artery. It enters the neck and curves anteriorly across the medial edge of the scalene anticus muscle to descend and join the junction of the jugular and the subclavian veins.
Embryologically, it is a bilateral structure and the pattern described is present about 50% of the time [1]. In addition, an extensive collateral network exists with many lymphaticovenous connections throughout the system so that ligation of the duct does not impair return of chyle to the venous system.
With regard to lymphatic injury during ITA dissection, it is evident that lymphatics of the internal thoracic chain are divided. In addition the left anterior mediastinal lymph node chain, which receives lymphatics from the left lung, crosses the left internal thoracic artery anteriorly near its origin and either joins the thoracic duct or enters the venous confluence directly [2]. Dissection of the mediastinum superiorly at the junction of the ITA pedicle and the subclavian vein may divide these lymphatics, particularly if the internal thoracic vein is divided. Additional length, and the potential for lymphatic injury, is sometimes attained by dissecting the ITA from the inferoposterior surface of the subclavian vein, which exposes the phrenic nerve. It is unlikely that the duct in its usual course would be injured by ITA mobilization, but a variant could be.
Forward flow of chyle is a result of vis a tergo created by chyle entering the lacteals, negative intrathoracic pressure with inspiration, and muscular contraction of the duct wall every 10 to 15 seconds [3]. The volume of chyle varies greatly, up to 2,400 mL in 24 hours. The lymphatic system is populated with valves that normally maintain unidirectional flow despite increases in intrathoracic or systemic venous pressure. Retrograde flow can occur when the valves are defective because of developmental or acquired reasons or if the lymphatic dilates. This could permit leakage of the chyle without injury to the duct and has been visualized in patients with chylothorax after ITA harvest [4, 5]. If the damaged lymphatic enters the venous system directly, then chyle reflux would not occur.
Recovery of milky fluid from the chest after resumption of oral alimentation is diagnostic of a lymphatic fistula involving the thoracic duct, which can be confirmed by microscopic demonstration of chylomicrons in the fluid. Blood staining of the chyle early after operation may be confusing. Lymphangiography will demonstrate the leak but does little to facilitate surgical repair that requires visual identification with a fat meal [4, 6].
In a review of the English literature, 12 other cases of chylothorax after ITA harvest had been reported (Table 1). The diagnosis was made in the first postoperative week in 7 patients and up to 90 days later in the remaining cases. There was no particular operative circumstance or apparent "risk factor" for this complication. All patients but ours had chest tube placement for drainage. After the diagnosis was established, all patients except 1 received some form of diet modification including a low-fat diet, or a diet with medium chain triglycerides as the allowed fat or total parental nutrition. One patient received somatostatin after 1 week of total parental nutrition with closure of the fistula at the end of the second week. Seven of the patients required no further treatment and the others required thoracotomy with direct suture of the fistula, including a patient who had a clip ligation and another patient who had additional application of fibrin glue. Our patient was treated by duct ligation. In no patient did the thoracic duct itself appear to be involved, and the volume of chyle recovered each day was consistent with this observation. Only 1 of 6 patients presenting after the first postoperative week required thoracotomy. Hospital stay after diagnosis was 11 to 42 days.
Surgical intervention is held for a trial of nonoperative therapy, which includes chest tube drainage and dietary modifications such as a low-fat diet or one with medium-chain triglycerides or total parental nutrition [7]. Somatostatin may further reduce chyle flow [8]. If chyle accumulation persists after 2 to 3 weeks, surgical intervention becomes appropriate. Thoracoscopic identification of the site of chyle leakage after placing fat (milk or cream) in the stomach may allow for direct clipping or suturing or application of fibrin glue. Some have continued to use thoracotomy for direct control of the leak, which is appropriate if there are loculations, empyema, or a peel [4, 5], although it is commonly held that infection is rare because chyle is bacteriostatic, and therefore a peel should not result. Thoracic duct ligation may be more definitive and is easier through the right chest and may be accomplished thoracoscopically. Late presenting chylothorax (after hospital discharge) responds more readily to conservative treatment as the leak volume is smaller and healing is more likely [8].
In summary, chylothorax has occurred after nearly any thoracic intervention at any age and without intervention as a result of congenital lymphatic abnormalities or lymphatic obstruction from disease. Injury to the thoracic duct may drain all or much of the chyle, whereas lesser amounts of chyle may escape when a connecting lymphatic is violated. Internal thoracic artery harvest undoubtedly divides lymph vessels frequently, but never the thoracic duct unless it is aberrant. Chylothorax after ITA harvest is thus rare (one in 3,900 operations in the authors' personal experience) either because the divided lymphatics remain competent or do not join the duct.
|
References
|
|---|
- Kausel HW, Reeve TS, Stein AA, et al. Anatomic and pathologic studies of the thoracic duct J Thorac Surg 1957;34:631.[Medline]
- Riquet M, Le Pimpec Barthes F, Souilamas R, et al. Thoracic duct tributaries from intrathoracic organs Ann Thorac Surg 2002;73:892-899.[Abstract/Free Full Text]
- Robinson CLN. The management of chylothorax Ann Thorac Surg 1985;39:90-95.[Abstract]
- Chaiyaroj S, Mullerworth MH, Tatoulis J. Surgery in the management of chylothorax after coronary artery bypass with left internal mammary artery J Thorac Cardiovasc Surg 1993;106:754-756.[Medline]
- Riquet M, Assouad J, D'Attellis N, et al. Chylothorax and re-expansion pulmonary edema following myocardial re-vascularizationrole of lymph vessel insufficiency. Interact Cardiovasc Thorac Surg 2004;3:423-425.[Abstract/Free Full Text]
- Inderbitzi RGC, Krebs T, Stirnemann P, Althaus U. Treatment of postoperative chylothorax by fibrin glue application under thoracoscopic view with use of local anesthesia J Thorac Cardiovasc Surg 1992;104:209-210.[Medline]
- Lampson RS. Traumatic chylothoraxa review of the literature and report of a case treated by mediastinal ligation of the thoracic duct. J Thorac Surg 1948;17:778-791.[Medline]
- Kelly RF, Shumway SJ. Conservative management of postoperative chylothorax using somatostatin Ann Thorac Surg 2000;69:1945-1947.[Abstract/Free Full Text]
Top
Abstract
Introduction
