A 7-year-old female spayed 14-kilogram mixed breed dog was presented to HOPE Veterinary Specialists for a surgical consult after a recent diagnosis of a right auricular mass. She initially presented to her local emergency clinic for an acute episode of lethargy, pale mucous membranes and increased respiratory effort. Radiographs at that time showed a characteristic “globoid” heart shape and a focal thoracic ultrasound revealed pericardial effusion causing cardiac tamponade. Pericardiocentesis was performed, she was evaluated the following morning by a cardiologist and an echocardiogram revealed a 3 x 4 cm right auricular mass. Bloodwork showed mild hypoalbuminemia but no evidence of anemia. Cytology of the pericardial fluid was consistent with hemorrhage and no neoplastic cells were noted. Pericardiocentesis was required three additional times over the next few days.
Based on the presentation, echocardiogram findings, and repeated hemorrhagic pericardial effusion, cardiac hemangiosarcoma was suspected. She was transferred to a referral center at which time she was hospitalized and received a dose of Doxorubicin. After discharge from the referral center, the owners presented to HOPE for discussion of surgical options. The treatment for the tamponade component of this disease has historically been repeated pericardiocentesis or a pericardial window/subtotal pericardiectomy via thoracotomy in combination with adjuvant chemotherapy. However, due to the poor prognosis with cardiac hemangiosarcoma, many owners are reluctant to pursue surgical intervention because of the invasiveness and postoperative morbidity of a thoracotomy.
Instead of an open thoracotomy, the owners were offered minimally invasive thoracoscopy and after a discussion about the prognosis and the options for treatment, they elected to proceed with the procedure. In this procedure, three small incisions are made in the thorax to allow placement of ports for passage of a rigid endoscope and thoracoscopic instruments. Through this approach, the pericardium is able to be grasped, elevated and resected to create a pericardial window. The goal is to allow the pericardial effusion to drain into the pleural cavity thereby avoiding cardiac tamponade in the future. A sample of pericardium can also be obtained for biopsy.
A: Pericardium grasped and elevated.
B: Mild amount of pericardial effusion visible.
Figure 2: Portion of pericardial window completed.
D: Thoracostomy tube.
Video 1: Pericardial window
Because of the small size of the incisions, local blocks with bupivacaine were used at each of the sites to provide multimodal analgesia. The patient recovered well from anesthesia and within two hours of surgery was able to stand and go for a walk outside. She was maintained on intravenous doses of methadone overnight, her chest tube was removed the following day, and she was transitioned off intravenous narcotics at that time.
Although it is relatively new in veterinary medicine, thoracoscopy has been used in humans for over 100 years. It was initially used for lysis of pleural adhesions due to tuberculosis and in the 1990’s, started to be used to perform video-assisted procedures1. In veterinary medicine, this approach is currently used for a variety of thoracic procedures including pericardial window, subtotal pericardiectomy, lung lobectomy, and to obtain pleural, mediastinal or lung biopsies2,3,4. There are several disadvantages to thoracoscopy including the initial cost of the equipment and steep learning curve. However, there are numerous advantages including decreased postoperative pain, a faster return to activity and a decreased hospital stay which results in a lower cost for the client. Additionally, the small incision size allows us to provide local anesthetic blocks at the incision sites which results in a decreased need for intravenous opioids. Especially in cases where the surgical treatment is palliative, the advantages of thoracoscopy make it a good choice for our patients.
While cardiac tumors in dogs are uncommon in comparison to other tumors, hemangiosarcoma is the most common type of cardiac neoplasia in dogs. The initial presentation is often for signs related to acute cardiac tamponade including lethargy, pale mucous membranes, and collapse. These patients may be anemic however the anemia may not be as profound as it is in cases of splenic hemangiosarcoma because the amount of hemorrhage needed to cause cardiac tamponade is relatively small. Thoracic radiographs show a globoid cardiac silhouette and identification of the mass is achieved via echocardiography. Although it can occur in any region of the heart, the right auricle is the most common location.
Treatment options for this disease are limited. Mass excision, pericardial window, subtotal pericardiectomy and chemotherapy have all been reported and all of these are intended to be palliative as there is no effective long-term treatment for hemangiosarcoma.
Due to the aggressive nature of the disease (the median survival time is often reported as 3-4 months) and reported presence of distant metastasis in up to 75% of cases of cardiac HSA5, owners are often reluctant to pursue open thoracotomy for mass excision, subtotal pericardiectomy or pericardial window. These owners often decline surgery because of the concern of prolonged postoperative morbidity during the relatively short expected survival time. A recent retrospective study6 evaluated the effectiveness of Doxorubicin alone in the treatment of cardiac hemangiosarcoma and found a median survival time of 116 days compared to 42 days for dogs that were not treated with chemotherapy. Based on these results, this appears to be an appropriate option for patients who do not have recurrent episodes of cardiac tamponade. However, for patients with recurrent tamponade, short term treatment of the pericardial effusion is necessary through repeated pericardiocentesis or a pericardial window. With the introduction of thoracoscopy, we are now able to provide a long-term solution to eliminate recurrent tamponade with minimal postoperative morbidity. In the future, the combination of minimally invasive thoracoscopy and adjuvant chemotherapy may provide a more effective approach for the palliative treatment of this disease than previously available.
Submitted by: Brian Bretz, DVM, DACVS
2.Skinner OT, et al. Pericardioscopic Imaging Findings in Cadaveric Dogs: Comparison of an Apical Pericardial Window and Sub-phrenic Pericardectomy. Vet Surg 2014; 43(1):45-51. https://www.ncbi.nlm.nih.gov/pubmed/?term=Pericardioscopic+Imaging+Findings+in+Cadaveric+Dogs%3A+Comparison+of+an+Apical+Pericardial
3.García F, et al. Examination of the Thoracic Cavity and Lung Lobectomy by Means of Thoracoscopy in Dogs. Can Vet J. 1998; 39(5):285-91. https://www.ncbi.nlm.nih.gov/pubmed/?term=Examination+of+the+Thoracic+Cavity+and+Lung+Lobectomy+by+Means+of+Thoracoscopy+in+Dogs
4.Atencia S, et al. Thoracoscopic Pericardial Window for Management of Pericardial Effusion in 15 dogs. J Small Animal Prac. 2013; 54(11):564-9. https://www.ncbi.nlm.nih.gov/pubmed/?term=Thoracoscopic+Pericardial+Window+for%E2%80%89Management+of+Pericardial+Effusion+in+15+dogs
5.Yamamoto S, et al. Epidemiological, Clinical and Pathological Features of Primary Cardiac Hemangiosarcoma in Dogs: A Review of 51 Cases. Journal of Veterinary Medical Science 2013; 75(11):1433–1441. https://www.ncbi.nlm.nih.gov/pubmed/?term=Epidemiological%2C+Clinical+and+Pathological+Features+of+Primary+Cardiac+Hemangiosarcoma+in+Dogs
6.Mullin CM, et al. Doxorubicin Chemotherapy for Presumptive Cardiac Hemangiosarcoma in Dogs. Veterinary and Comparative Oncology 2014; Dec 18. https://www.ncbi.nlm.nih.gov/pubmed/?term=Doxorubicin+Chemotherapy+for+Presumptive+Cardiac+Hemangiosarcoma+in+Dogs