Resolution, recurrence, and chyle redistribution after thoracic duct ligation with or without pericardiectomy in dogs with naturally occurring idiopathic chylothorax

Abstract

OBJECTIVE To document outcomes of thoracoscopic treatment of idiopathic chylothorax (IC) in dogs with and without constrictive pericardial physiology (CPP) and evaluate patterns of chyle flow redistribution after thoracic duct ligation (TDL). ANIMALS 26 client-owned dogs. PROCEDURES In this prospective cohort study, echocardiography and cardiac catheterization were performed to document CPP in dogs with IC. Thoracoscopic TDL with pericardiectomy was performed if CPP was present (TDL/P group). Dogs without evidence of CPP underwent thoracoscopic TDL alone (TDL group). Dogs underwent preoperative, immediate postoperative, and 3-month postoperative CT lymphangiography studies when possible. Perioperative morbidity, resolution and late recurrence rates, and long-term outcome were recorded. RESULTS 17 dogs underwent TDL, and 9 underwent TDL/P. Twenty-five of 26 (96%) survived the perioperative period. One dog died from ventricular fibrillation during pericardiectomy. Resolution rates for TDL and TDL/P were 94% and 88%, respectively (P = .55), with 1 late recurrence occurring in the TDL group in a median follow-up of 25 months (range, 4 to 60 months). On 3-month postoperative CT lymphangiography studies, ongoing chyle flow past the ligation site was demonstrated in 5 of 17 dogs, of which 1 dog developed recurrence at 13 months postoperatively. In 15 of 17 dogs, chylous redistribution after TDL was principally by retrograde flow to the lumbar lymphatic plexus. CLINICAL RELEVANCE In dogs without evidence of CPP, TDL alone was associated with a very good prognosis for treatment of IC. In the absence of CPP, the additional benefit of pericardiectomy in the treatment of IC is questionable.

Evaluation of thoracic duct ligation and unilateral subphrenic pericardiectomy via a left fourth intercostal approach in normal canine cadavers

“…[1][2][3] This surgery can be performed openly or minimally invasively and has variable success rates, ranging from 60-100% for open, and 85-95% for thoracoscopic TD ligation and pericardiectomy. [1][2][3][4][5][6][7][8][9] Regardless of the technique, TD ligation in dogs has been performed traditionally via a caudal right approach at the eighth-ninth intercostal space despite multiple TD branches at this level. 1,5,6,[8][9][10][11][12] When surgery is performed at a site with multiple branches, there is a risk of persistent chylothorax due to missed collateral vessels that bypass the site of ligation.…”

“…[1][2][3][4][5][6][7][8][9] Regardless of the technique, TD ligation in dogs has been performed traditionally via a caudal right approach at the eighth-ninth intercostal space despite multiple TD branches at this level. 1,5,6,[8][9][10][11][12] When surgery is performed at a site with multiple branches, there is a risk of persistent chylothorax due to missed collateral vessels that bypass the site of ligation. 5,9,13,14 En bloc ligation of tissues adjacent to the TD at this caudal location has been described in canine cadavers and clinical cases as a potential method for incorporating multiple TD branches in the ligation.…”

“…1,5,6,[8][9][10][11][12] When surgery is performed at a site with multiple branches, there is a risk of persistent chylothorax due to missed collateral vessels that bypass the site of ligation. 5,9,13,14 En bloc ligation of tissues adjacent to the TD at this caudal location has been described in canine cadavers and clinical cases as a potential method for incorporating multiple TD branches in the ligation. 8,15,16 Intercostal thoracotomy for en bloc ligation resulted in clinical resolution of chylothorax in 10/12 (83%) of cases.…”

“…Reports on idiopathic chylothorax provide evidence of chyle leakage in the cranial mediastinum, far cranial to the traditional ligation location. 9,13,23,[26][27][28][29][30][31][32] Ligation of the TD at the left fourth intercostal space could therefore provide the same therapeutic effect as caudal ligation, while providing access to a single TD branch.…”

“…However other studies have called the need for pericardiectomy in every case, and its effect on central venous pressure into question. 1,2,4,9 The traditional open approach to treating idiopathic chylothorax has involved two to three incisions in left lateral recumbency: one at the right ninth intercostal space to ligate TD branches; one at the right fifth to sixth intercostal space to perform subphrenic pericardiectomy; and possibly an additional paracostal incision to inject a mesenteric lymph node with methylene blue for TD visualization. 1,2,23,33,34 With a cranial left-sided approach for TD ligation, unilateral subphrenic pericardiectomy could be performed through the same incision, if elected.…”