Diagnosis and Minimal Invasive Therapy of Pericardial Effusion in Dogs

Pericardial effusion (PE) is the most common pericardial disease in the dog but an uncommon cardiovascular disease. The etiology in 90% is neoplasia or idiopathic PE. PE occurs primarily in older large breed dogs. There seems to be a breed predisposition for Golden Retriever, German Shepherd dogs and St. Bernhard with Golden Retrievers over-represented in dogs with idiopathic PE. PE causes cardiac tamponade with decreased ventricular filling and cardiac output which can lead to right hart failure and cardiogenic shock. The diagnosis can be established with the help of clinical signs, physical examination, radiology, electrocardiography and echocardiography, considered as the “gold standard”. The first therapy is pericardiocentesis. The diagnostic value of pericardial fluid examination is limited. Cytology of the fluid can not distinguish between idiopathic and most neoplastic, but in cases of infectious pericarditis or lymphosarcoma it can be diagnostic. 

Surgery

In cases of idiopathic PE pericardiocentesis can be the only treatment in 33- 50% of affected dogs but in malignant effusion relapse can be expected in 100%. In case of relapse surgical management with subtotal or partial pericardectomy is advised. Pericardectomy is considered to be curative in recurrent idiopathic PE and to be palliative in malignant PE. Thoracotomy is the conventional method of performing this procedure, which is associated with marked morbidity and mortality combined with prolonged hospitalization.  Recently less invasive procedures as percutaneous balloon pericardiotomy or thoracoscopic partial pericardectomy has been described. Percutaneous balloon pericardiotomy is effective but less investigations are done, the procedure needs fluoroscopic guidance and no biopsy is collected. Thoracoscopic partial pericardectomy offers the advantage of a minimal invasive surgical treatment with examination of the thorax, performing the pericardectomy and gaining biopsy material. 
Thoracoscopic partial pericardectomy can be done with lateral approach and exclusion of the ipsilateral lung, but this includes a risk for shunting, reduced gas exchange and is not recommended in compromised animals. In the technique described here the procedure can be performed in dorsal recumbency without lung exclusion but mechanically ventilated. The first trocar has to be inserted transdiaphragmal paraxyphoid on the left side. The trocar stays open to create an controlled open pneumothorax. Under thoracoscopic control 2 separate instrumental portals at each side of the chest were introduced after determination of the optimal position. The pericardial sac has to be held with a endograsper and can be opened with a endoscissor. A window from about 4x5 cm should be cut out of the pericard using the endoscissor or bipolar cauterization. The piece of pericardium was should be removed through one of the instrumental portals. If only this procedure was done without damaging the lungs a chest tube is not necessary. Closure of the portal insertions should be performed in a routine manner. The thorax has to be evacuated by thoracocentesis until negative pressure is obtained.
Thoracoscopic pericardectomy with transdiaphragmatic paraxyphoid approach offers several advantages over pericardectomy by thoracotomy including less postoperative pain, morbidity and mortality, faster recovery, shorter hospitalization length and improved cosmetic appearance. It can be performed without pulmonary exclusion and the associated risks. [...]