Intercostal thoracoscopic pericardiectomy in left lateral recumbency: A cadaveric study of feasibility, efficiency, and extent of pericardial resection

OBJECTIVE

To describe the feasibility, efficiency, and extent of thoracoscopic pericardiectomy (TP) on a ventilated dog with an intercostal approach in lateral recumbency (ILR), in comparison with the traditional transdiaphragmatic paraxiphoid approach in dorsal recumbency (PDR).

STUDY DESIGN

Randomized experimental study.

ANIMALS

Twenty canine cadavers (n = 10 per group).

METHODS

Thoracoscopic pericardiectomy was performed on mechanically ventilated cadavers to remove the largest pericardial fragment possible using either the ILR or PDR technique. Approach and procedure time were recorded, and surgical extent (cardiac exposure/exteriorization, pericardial fragment area) was assessed. Procedural difficulty and intraoperative visibility were also assessed to evaluate feasibility.

RESULTS

Total surgical time (sum of approach and pericardiectomy time) did not differ between groups, although PDR pericardiectomy took longer (p = .045) by an average of 5.2 min. Exteriorization of the heart from the pericardial sac was achieved for all trials. Pericardial fragments from PDR trials were larger than those of ILR (p = .004), with a mean difference of 23.21 cm2. Cardiac exposure and operative visibility scores were greater for PDR procedures.

CONCLUSION

The ILR approach with bilateral ventilation was a feasible alternative for performing partial pericardiectomies, which did not require more total surgical time when compared with the PDR approach.

CLINICAL SIGNIFICANCE

The ILR approach for TP warrants further evaluation in live dogs as it may hold promise for treating causes of pericardial effusion that do not require subtotal pericardiectomy and improving efficiency when paired with other ILR procedures such as thoracic duct ligation.

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

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.

Triple-combination surgery with thoracic duct ligation, partial pericardiectomy, and cisterna chyli ablation for treatment of canine idiopathic chylothorax

This study aimed to evaluate the outcomes and complications of triple-combination surgery consisting of thoracic duct ligation (TDL), partial pericardiectomy (PPC), and cisterna chyli ablation (CCA) for the treatment of idiopathic chylothorax in dogs. Eleven privately owned dogs with idiopathic chylothorax underwent the triple-combination surgery: TDL and PPC were performed in left recumbency, followed by CCA in dorsal recumbency. Of the 11 dogs, seven were Shiba, two were Afghan hounds, and one each was Borzoi and mixed-breed. TDL and PPC required two intercostal thoracotomies in five dogs, whereas they were performed through a single intercostal incision in the other dogs. None of the dogs showed major intraoperative complications. The median operation time was 190 min (range, 151–234 min). Nine dogs showed no pleural effusion after surgery without medical management. Another dog showed the disappearance of chylous effusion, followed by the pleural accumulation of modified transudate. However, the residual one dog in whom chylothorax did not improve postoperatively died 4 months after the combination surgery. The mortality rate at the conclusion of this study was 9.1%. Although the triple-combination surgery with TDL, PPC, and CCA was complex and required a prolonged operation time, the success rate of resolving chylothorax in our study was comparable to that of open surgery as previously reported. Therefore, this study suggests that such triple-combination surgery can become one of the therapeutic options for the management of canine idiopathic chylothorax.

Thoracoscopic detection of thoracic ducts after ultrasound-guided intrahepatic injection of indocyanine green detected by near-infrared fluorescence and methylene blue in dogs

OBJECTIVE

To describe and compare onset and intensity of thoracic duct (TD) coloration in healthy dogs after intrahepatic injection of either indocyanine green (ICG) visualized by intraoperative near-infrared fluorescence lymphography (NIRFL) or direct thoracoscopic visualization of methylene blue dye (MB).

STUDY DESIGN

Prospective study.

ANIMALS

Healthy adult Beagle dogs (n = 5).

METHODS

All dogs had biochemical panels and complete blood counts preoperatively. Computed tomography lymphography (CTL) was performed prior to a standard 3-port thoracoscopic approach. A mixture of MB and ICG was injected by ultrasound-guided percutaneous injection into right or left-sided hepatic lobes. Data collected included dose of contrast agent (MB vs. ICG), injection site, timing, and quality of operative TD identification. Potential hepatic injury was assessed by repeat laboratory evaluation and abdominal ultrasound 14 days postoperatively.

RESULTS

Preoperative CTL provided a diagnostic study in 5/5 dogs. After intrahepatic injection of combined dyes, NIRFL allowed visualization of TDs in 5/5 dogs, but MB did not result in visible TD coloration in any dog. Intrahepatic injection of ICG achieved successful NIRFL in a median time of 6 minutes and persisted for the 20 minute observation period in all five dogs. All dogs recovered without complication and were subsequently adopted.

CONCLUSION

NIRFL of the TD can be achieved with intraoperative hepatic injection of ICG. Intrahepatic injection of MB did not result in visible TD coloration.

CLINICAL SIGNIFICANCE

Hepatic intra-parenchymal injection is a reliable alternative portal into the TD system for intraoperative visualization of TD anatomy using ICG in dogs.

Canine idiopathic chylothorax: Anatomic characterization of the pre- and postoperative thoracic duct using computed tomography lymphography

Surgical treatment has improved the prognosis of canine idiopathic chylothorax, although a recurrence of the disease occurs occasionally after the procedure. An improved understanding of possible causes for this recurrence would be helpful for prognosis and treatment planning in affected patients. In this retrospective case series study, we described the detailed pre- and postoperative computed tomographic lymphography (CTLG) imaging characteristics for a group of dogs with surgically confirmed idiopathic chylothorax. Preoperative CTLG was performed in 12 of 14 dogs diagnosed with idiopathic chylothorax. Thoracic ducts were present on the right side in 10 dogs, left side in one dog, and bilaterally in one dog. All the 14 dogs received a combination therapy of pericardiectomy and thoracic duct ligation (TDL) by video-assisted thoracoscopic surgery. One week after surgery, a postoperative CTLG was performed, and the thoracic ducts were apparent in seven of 14 dogs. Three dogs had an unchanged course of the thoracic duct, which could have resulted from a missed duct. Four dogs were identified as having a bypass formation: the oblique duct originated at the ligation site and connected to the duct on the other side. Our findings indicated that one of the possible causes for postoperative recurrence of chylothorax in dogs could be "invisible or sleeping" fine ducts that are collapsed and not visible in preoperative CTLG scans. After TDL causes a change in the pressure of lymphatic flow, these fine thoracic ducts may become apparent using postoperative CTLG.

Computed tomographic lymphangiography via intra-metatarsal pad injection is feasible in dogs with chylothorax

Lymphangiography can be useful for preoperative planning in chylothorax. Conventional ultrasound-guided intranodal injection can be difficult in some cases and is dependent upon operator skill. Alternative methods have been proposed to simplify the procedure, but their feasibility has not been sufficiently evaluated in clinical cases. The primary purpose of this multicenter, retrospective, descriptive study was to assess the feasibility and describe the clinical findings of CT lymphangiography by intrametatarsal pad injection in dogs with naturally occurring chylothorax. Twenty dogs were analyzed, and enhancement of thoracic ducts (TDs) was successful in 18 (90%) dogs within 5-14 min after initiating the injection, while successful enhancement of the lymphatic vessels cranial to the popliteal lymph nodes was seen in all dogs within 5 min after injection. The dose with good success to achieve TD enhancement was 1 mL/kg (concentration 350 mg I/kg). Only two dogs had mild discomfort after recovery from general anesthesia. Computed tomography lymphangiography by intrametatarsal pad injection is a feasible, easy, and safe procedure, which could provide adequate TD and cisterna chyli enhancement, identify TD number and cisterna chyli location and structure, and contribute to surgical planning.

Anatomic and volumetric characterization of the cisterna chyli using CT lymphangiography and computer-assisted design software in dogs with idiopathic chylothorax

The objectives of this retrospective, observational study were to characterize the anatomical features of the cisterna chyli (CC) in a cohort of dogs diagnosed with idiopathic chylothorax that underwent CT lymphangiography (CTLa), and to evaluate the feasibility of computer-assisted design (CAD) software to quantify volumetric measurements of the CC. Twenty-three client-owned dogs with idiopathic chylothorax were included. Additionally, CTLa was performed in three canine cadavers to assess the ability of CAD software to accurately acquire volumetric measurements. Injection sites, attenuation values, anatomic location, dimensions, and aortic diameter to CC ratio (Ao:CC) were recorded. Video records of video-assisted thoracic surgery (VATS) thoracic duct ligation (TDL) were reviewed in eight out of 23 dogs to compare operative and CTLa findings. The CC was dorsal and right-sided in 18 out of 23 dogs, located between L1 and L4 in 21 dogs, and extended as far cranially as T11 in two dogs. The median measurements for length, height, and width were 150.0, 5.5, and 13.3 mm, respectively. Median total volume was 1.82 mL. Median volumes to the right and left of the aorta were 1.46 and 0.49 mL, respectively (P = .014). Median total CC volume to body weight ratio (CC:bw) was 0.07 mL/kg. The presence of an intrathoracic CC was observed intraoperatively in six out of eight cases that underwent VATS TDL. Findings supported the use of CTLa and CAD as feasible methods for characterizing the CC in dogs diagnosed with chylothorax. These methods may facilitate interventional planning involving the CC such as embolization.

Efficacy of en bloc thoracic duct ligation in combination with pericardiectomy by video-assisted thoracoscopic surgery for canine idiopathic chylothorax

OBJECTIVE

To compare the outcomes of pericardiectomy performed with conventional clipping thoracic duct ligation (C-TDL) to those with en bloc thoracic duct ligation (EB-TDL) using video-assisted thoracoscopic surgery (VATS) for canine idiopathic chylothorax.

STUDY DESIGN

Retrospective consecutive case series.

ANIMALS

Thirteen client-owned dogs with idiopathic chylothorax.

METHODS

Medical records of dogs treated with pericardiectomy in combination with TDL by VATS without intraoperative contrast were reviewed. Five and seven dogs underwent C-TDL and EB-TDL, respectively, and 11 dogs were evaluated by preoperative and 7- to 10-days-postoperative computed tomography-lymphography (CTLG). No clinical symptoms with absent or minimal pleural effusion was defined as clinical improvement. Long-term remission (LTR) was defined as rapid resolution of pleural effusion and no recurrence for more than 1 year. Anesthesia time, operation time, the duration of hospitalization, and time until pleural effusion resolution were compared.

RESULTS

Clinical improvement was achieved in 91.7% of the cases (C-TDL, 4/5; EB-TDL, 7/7), excluding one case of intraoperative death. The LTR rate was significantly higher with EB-TDL (6/7 [85.7%]) than with C-TDL (1/5 [20%]). Anesthesia time, operation time, and time until pleural effusion resolution were significantly better with EB-TDL than with C-TDL. The rates of thoracic ducts visualization by postoperative CTLG were 100% (5/5) with C-TDL and 42.9% (3/7) with EB-TDL.

CONCLUSION

En bloc TDL was an effective treatment for canine idiopathic chylothorax in this patient population. It compared favorably to C-TDL, although missed branches at the time of surgery may explain the difference between C-TDL and EB-TDL in this small population of cases.

CLINICAL SIGNIFICANCE

En bloc TDL by VATS was an effective minimally invasive treatment for canine idiopathic chylothorax. Computed tomography-lymphography can be used for surgical planning and postoperative evaluation.

Canine and Feline Exudative Pleural Diseases

Exudative pleural diseases are a common cause of respiratory distress and systemic illness in dogs and cats. This article covers the pathophysiology, development, and classification of exudative pleural effusions. The most current diagnostic strategies, causes, imaging findings, and medical or surgical treatment options for select diseases are reviewed in detail.

Outcomes of dogs with recurrent idiopathic pericardial effusion treated with a 3-port right-sided thoracoscopic subtotal pericardiectomy

OBJECTIVE

To describe a 3-port right-sided thoracoscopic subtotal pericardiectomy (TSP) to treat dogs with recurrent idiopathic pericardial effusion (RIPE) and report their long-term survival.

STUDY DESIGN

Retrospective case series.

ANIMALS

Sixteen client-owned dogs.

METHODS

Medical records were searched for dogs with idiopathic pericardial effusion that recurred after 1 or more pericardiocenteses and treated with a 3-port right-sided technique (1 subxiphoid camera port and 2 instrument ports on the right side of the dog). Follow-up consisted of direct examination or communication with referring veterinarians or owners.

RESULTS

Thoracoscopic subtotal pericardiectomy was successfully completed in all dogs, with no surgical complications. The median duration of postoperative follow-up was 191.5 days (range, 5-1345). The median survival time (MST) after surgery was 365 days (range, 5-1345); MST of dogs with a histopathological diagnosis of neoplasia (n = 4) was 76 days, whereas dogs with no evidence of neoplasia had an MST of 367 days (n = 12, P = .14). Recurrent pleural effusion was the ultimate cause of death or reason for euthanasia in 8 of 16 dogs.

CONCLUSION

The technique described here resulted in similar surgical times and outcomes for dogs undergoing TSP for RIPE compared with previous studies. Neoplasia was identified in 4 of 16 dogs.

CLINICAL SIGNIFICANCE

Thoracoscopic subtotal pericardiectomy can be readily performed with only 2 instrument ports, both on the same side of the dog, and without 1-lung ventilation. Recurrent pleural effusion led to the death of half of the dogs in this series.

Hybrid single-port laparoscopic cisterna chyli ablation for the adjunct treatment of chylothorax disease in dogs

OBJECTIVE

To describe a hybrid, single-port, minimally invasive cisterna chyli ablation (CCA) technique in clinical cases of canine idiopathic chylothorax and evaluate this technique as a method for mesenteric lymphangiography (ML) in canine cadavers and clinical cases of idiopathic chylothorax.

STUDY DESIGN

Cadaveric and retrospective study.

ANIMALS

Six canine cadavers and 14 client-owned dogs with naturally occurring idiopathic chylothorax.

METHODS

Both cadaveric and clinically affected dogs were placed in sternal recumbency. A wound retractor device (WRD) and a single-port device were placed in the abdominal flank 2-3 cm caudal to the 13th rib. Mesenteric lymphangiography was evaluated by using indocyanine green (ICG) in 6 canine cadavers. Single-port laparoscopic CCA was performed in all clinical cases with idiopathic chylothorax.

RESULTS

Successful ML was completed by using ICG in all 6 canine cadavers. A right- or left-sided single-port laparoscopic CCA was successfully performed in 14 dogs with naturally occurring idiopathic chylothorax. Mesenteric lymphangiography was successfully performed through the WRD in 11 of these cases. No intraoperative complications were reported. Three dogs developed severe chyloabdomen postoperatively, with 1 dog requiring multiple abdominocenteses.

CONCLUSION

Direct ML and single-port laparoscopic CCA was performed through a WRD in dogs positioned in sternal recumbency. Although minimal operative complications were noted, postoperative chyloabdomen was reported.

CLINICAL SIGNIFICANCE

This hybrid single-port laparoscopic technique performed in sternal recumbency allows both a CCA and an intraoperative ML through the same incision. This procedure may be combined with thoracoscopic thoracic duct ligation and pericardectomy for the treatment of idiopathic chylothorax in dogs.

Thoracic duct lymphography by subcutaneous contrast agent injection in a dog with chylothorax

A 4-year-old male Japanese Shiba Inu presented with recurrent chylothorax. The thoracic duct was successfully imaged using computed tomography after the injection of an iodine contrast agent into the subcutaneous tissue surrounding the anus. The thoracic duct was successfully ligated and pericardectomy performed via an open thoracotomy. Pleural effusion improved but relapsed a week after the surgery. A second lymphography revealed a collateral thoracic duct that was not detected during the first lymphography. The collateral duct was ligated and chylothorax was resolved after the second surgery. The lymphography applied in this study was minimally-invasive and easily provided images of the thoracic duct in a dog with chylothorax.

Complications and Conversion from Endoscopic to Open Surgery

Endoscopic surgery is a rapidly expanding modality of diagnosis and treatment of small animal patients. The development of skills, equipment, and minimally invasive means of correcting complications may be of great importance in decreasing the incidence of conversion from endoscopic to open surgery; however, conversion to an open approach should never be seen as a failure. Conversion should be considered at any time that it is of the greatest benefit for the patient. This concept is important enough to warrant discussion with the owner before surgery and acceptance of the need to convert without further consultation during the procedure.

Pleural Space Disease

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Abnormalities within the pleural space may include pleural effusion, pneumothorax, or space-occupying soft tissue structures (diaphragmatic hernia, neoplasia).

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A diagnostic thoracocentesis may also prove therapeutic in severely affected patients.

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Fluid analysis and cytologic evaluation should always be performed on aspirates from a patient with newly diagnosed pleural effusion of unconfirmed etiology.

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Aerobic and anaerobic culture and susceptibility testing of suppurative effusions are imperative.

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Comparison of pleural fluid and serum triglyceride levels and cholesterol concentrations are necessary to confirm the diagnosis of chylothorax.

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Clinical evidence of cardiovascular shock often precedes dyspnea in patients with hemothorax.

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Tension pneumothorax, regardless of its origin, rapidly may be fatal. Immediate drainage via thoracocentesis or thoracostomy tube placement is required before taking thoracic radiographs.

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Clinical signs of a traumatic diaphragmatic hernia may be delayed; however, early detection and correction are important because perioperative outcome is worse in chronically affected patients.

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Tools such as ultrasonography, computed tomography (CT), and thoracoscopy are becoming increasingly available to aid in the diagnostic evaluation and treatment of pleural space disease.