Etiology and management of chylothorax following pediatric heart surgery

Etiology and Management of
Chylothorax Following Pediatric Heart
Surgery
Michael Milonakis, M.D., Andrew C. Chatzis, M.D., Nikolaos M. Giannopoulos, M.D.,
Constantinos Contrafouris, M.D., Dimitrios Bobos, M.D., George V. Kirvassilis, M.D.,
and George E. Sarris, M.D.
Department of Pediatric and Congenital Cardiac Surgery, Onassis Cardiac Surgery Center,Athens, Greece ABSTRACT Background: Chylothorax after congenital heart surgery (CHD) is a potentially challenging com-
plication. The purpose of this study was to review our experience with the management of chylothorax
following congenital heart surgery. Methods: Between September 1997 and August 2006, of 1341 pediatric
patients undergoing correction of congenital heart disease in our institution, 18 (1.3%) developed chylotho-
rax postoperatively. Surgical procedures included tetralogy of Fallot repair in 10 patients, ventricular septal
defect closure (one), atrial septal defect with pulmonary stenosis repair (one), Fontan procedure (three),
coarctation of the aorta repair (one), aortopulmonary shunt (one), and ligation of patent ductus arteriosus
in one patient. All patients followed a therapeutic protocol including complete drainage of chyle collection
and controlled nutrition. Somatostatin was used adjunctively in six (33.3%) patients. Surgical intervention
was reserved for persistent lymph leak despite maximal therapy. Following resolution of chylothorax, a
medium-chain triglyceride diet was implemented for six weeks. Results: There were no deaths. Fifteen
patients (83.3%) responded to conservative therapy. Lymph leak ranged from 2.5 to 14.7 mL/kg per day
for 8 to 42 days. Three patients with persistent drainage required thoracotomy with pleurodesis to achieve
resolution, in two of which previously attempted chemical pleurodesis with doxycycline proved ineffective.
Duration of lymph leak in this subgroup ranged from 15 to 47 days with 5.1 to 7.4 mL/kg per day out-
put. Conclusions: Postoperative chylothorax is an infrequent complication of surgery for congenital heart
disease and can occur even after median sternotomy in the absence of pathologically elevated venous
pressure or Fontan circulation. Although hospitalization can be prolonged, conservative therapy is effective
in most cases, while surgical pleurodesis proved successful in the refractory cases. doi: 10.1111/j.1540-
8191.2008.00781.x (J Card Surg 2009;24:369-373)
Postoperative chylothorax in childhood is a poten- nine males and nine females, aged 5 to 68 (median tially serious complication of any thoracic surgical 19.5) months old and with body weight 6 to 18.7 (me- procedure and its management represents a serious dian 9.2) kg, developed chylothorax 1 to 15 days post- challenge. In particular, chylothorax occurring after pe- operatively. Surgical procedures preceding the occur- diatric congenital heart surgery is an uncommon com- rence of lymph leak included tetralogy of Fallot (TOF) plication, occurring in 0.6% to 2% in reported series.1,2 repair in 10 patients, ventricular septal defect (VSD) The intent of our study was to explore the etiology and closure (one), atrial septal defect (ASD) closure with present our experience with the management of this pulmonary stenosis (PS) correction (one), Fontan pro- cedure (three), coarctation of aorta (CoA) repair (one),patent ductus arteriosus (PDA) ligation (one), and place- MATERIALS AND METHODS
ment of a central aortopulmonary (A-P) shunt in a pa-tient with complex CHD (one). Surgical access had The hospital records of all children with a postop- been achieved via median sternotomy in 15 and left erative chylothorax following congenital heart surgery thoracotomy in three patients. Patient characteristics at our institution between September 1997 and Au- and procedures are listed in Table 1. gust 2006 were reviewed. During this period, 1341 Chylothorax was suspected when persistent chest pediatric patients underwent surgery for congenital tube drainage occurred or a pleural effusion developed heart disease (CHD). Of these, 18 patients (1.35%), with the characteristic milky fluid. Microscopic andbiochemical analyses of this fluid revealing a triglyc-eride (TG) level > 1.2 mmol/L and total cell count Address for correspondence: Michael Milonakis, M.D., 356 Sygrou > 1000/μL, predominantly lymphocytes established Ave, 17674 Kallithea, Athens, Greece. Fax: +30210-9493870; e-mail:milonakis@ath.forthnet.gr Patient Characteristics and Procedures
Duration
Diagnosis/
Patients (Month) Operation
(mL/kg/Day) Somatostatin Doxycyclin Surgery
Comments
All patients were treated conservatively, initially, the course of the thoracic duct. The etiology of lymph with complete pleural drainage of the chyle collection leak in these patients is unclear but may involve in- and either enteral low-fat diet or, in most cases, to- jury to small lymphatic vessels around the ascending tal parenteral nutrition (TPN). A somatostatin analogue aorta, the superior vena cava, or the pulmonary artery was used adjunctively in six patients (33.3%). At- trunk and its branches, which may require extensive tempted chemical pleurodesis with doxycycline via dissection for cannulation or repair. Variations in lym- chest tube was unsuccessful in two patients. Surgical phatic pathways and the presence of accessory or mi- intervention was reserved for persistent lymph leak de- nor lymphatic channels in the mediastinum may render spite maximum medical treatment and was necessary them vulnerable to inadvertent trauma during these in three patients. All patients continued on medium- procedures, resulting in chylous effusion without in- chain triglyceride (MCT) diet for a total of six weeks terference of the main thoracic duct. Chylopericardium following resolution of chylothorax and on low-fat diet has been reported as a rare complication after opera- tions for congenital heart disease.3 Isolated chyloperi-cardium is difficult to diagnose and may be mistaken forpostpericardiotomy syndrome. This raises the question whether the pleural effusions seen in our sternotomy There were no deaths. Fifteen patients (83.3%) re- cases are in fact pericardial collections draining through sponded to conservative therapy. The median duration an opening in the pleura in one of the hemithoraces and of lymph leak in these patients was 16 days (range 8 to presenting as chylothoraces. It should be mentioned 42), and the median lymph leak 5.6 (range 2.5 to 14.7) that we routinely open both pleurae (drained separately mL/kg per day. In two out of three patents with per- to prevent postoperatively fluid collection). It is of in- sistent drainage, chemical pleurodesis with doxycyclin terest that in two of our patients, the presentation of via chest tube proved ineffective. The median duration chylothorax in the right hemithorax coincided with the of lymph leak in this medically refractory subgroup was development of a mild pericardial effusion. 24 (range 24 to 47) days with median output 7.4 (range Chylothorax can also occur after obstruction in the 5 to 8.7) mL/kg per day. These patients underwent tho- superior vena cava without anatomic injury of lymph racotomy, lymphatic ligation, and abrasion pleurodesis channels. Blalock et al. proved experimentally that oc- resulting in postoperative resolution of chylothorax. clusion of the superior vena cava (SVC) can producechylothorax.4,5 Therefore, certain cardiovascular pro-cedures like the Fontan operation are more prone to CONCLUSION
this complication due to the expected increase in SVC Injury to the main thoracic duct or its branches is pressure. However, no sign of increased central ve- possible after virtually any procedure performed near nous pressure was noted in our group of patients, and its route, typically during aortic procedures performed only three of the 40 patients (7.5%) who underwent in the left hemithorax. However, most of our patients a Fontan procedure during the same period developed (83.3%) who developed chylothorax had undergone postoperative chylothorax, this complication occurring a sternotomy, and surgical manipulation remote from despite a low Fontan pressure (∼12 mmHg). Continue MCT diet for 6 weeks Remove drain when output <1ml/kg/day Figure 1. Protocol for postoperative chylothorax treatment.
Lymphatic dysplasia with spontaneous chylothorax analyses of the pleural effusion should show triglyc- is also a feature of Noonan and Turner syndromes.6,7 erides > 1.2 mmol/L and cell count > 1000 cell/μL with One of our patients who developed chylothorax after a predominance of lymphocytes.9,10 Because dietary ASD closure had Noonan’s syndrome. fat in neonates and infants either consists mainly of The morbidity of chylothorax is potentially severe, as triglycerides, or is metabolized to them during diges- large losses of fluids, proteins, lipids, and white blood tion, the presence of cholesterol cannot be expected. cells can cause dehydration, nutritional deficiency, and Therefore, it is best to measure triglyceride levels in a immunologic dysfunction. Nonetheless, intrapleural in- fections are rare, possibly due to the bacteriostatic na- Upon diagnosis, aggressive medical therapy should ture of the chylous fluid.8 Accurate diagnosis and early be commenced immediately.12-14 Our therapeutic pro- treatment are important for achieving a favorable out- tocol (Fig. 1) involves an initial approach with complete come and, therefore, the development of a pleural effu- evacuation of pleural effusion to obtain good lung ex- sion after a thoracic procedure should always raise the pansion. In addition, no or low-fat enteral diet is estab- suspicion of possible chylothorax. Diagnosis is based lished. It has been shown that long-chain fatty acids of on examination of the effusion. Chyle is a lymphatic 12 or more carbon atoms undergo a second esterifi- fluid enriched with fat absorbed by intestinal cells and cation and enter the lymph as chylomicrons, whereas transported via the thoracic duct into the circulation. medium-chain fatty acids pass directly into the por- The fluid has a milky appearance when chylomicrons tal system coupled to albumin.15 This has led to the are present, while during starvation it appears clear adoption of a medium-chain triglyceride diet as nutri- with a light yellow tint. Microscopic and biochemical tional support for patients with chylothorax. When oral diet is not successful, oral intake is forbidden and total anatomy, often lead to failure of this approach, result- parenteral nutrition (TPN) infusion instituted. This con- ing in continuous chylous effusion with the associated servative approach was effective in 15 (83.3%) of our morbidity.2 Our preferred surgical strategy is to per- patients, although a lengthy hospitalization was neces- form a thoracotomy on the affected side aiming to sary. The time limit for conservative treatment is three identify and control the specific lymphatics involved, to four weeks as most of our patients responded fa- if possible with the aid of preoperative cream adminis- vorably to medical therapy within that time frame. Con- tration. In addition, abrasion pleurodesis completes the servative treatment should not be thought to be free procedure. This approach was successful in the three of complications. Parenteral nutrition itself may engen- patients, one of who had a lymphatic leak associated der several problems related to infection, thrombosis, with an operation around the descending thoracic aorta or cholestasis.16 However, we have not encountered such problems in our small series of patients. Our data confirm that postoperative chylothorax fol- There is scarce clinical evidence that somatostatin lowing surgery for congenital heart surgery is rare and may be helpful in affecting the rate and amount of tho- in some instances may be connected to chyloperi- racic chyle leak.17 Somatostatin reduces gastric, pan- cardium. Nonoperative management can be success- creatic, and intestinal secretion.18-20 The inhibition of ful in the majority of cases.23 Somatostatin may play serotonin and other gastrointestinal peptides also ap- an adjunctive role in some patients, while doxycycline pears to reduce intestinal absorption and decrease hep- chemical pleurodesis seems entirely ineffective. Sur- atic venous pressure gradient and splachnic blood flow. gical intervention can be reserved for the minority of This influence on the hemodynamics of splachnic circu- patients who fail to respond to medical treatment and it lation (increased splachnic arteriolar resistance) and in- is successful. Overall appropriate therapy of this com- testinal motility (decreased gastrointestinal blood flow) plication may be lengthy but can prevent significant may be reflected in a reduction of chyle output.21 In six of our patients (33.3%), a somatostatin analoguewas added as an adjunct to the initial conservative REFERENCES
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