Intrapericardial cyst causing cardiac tamponade in a cat

A two-year-old cat with episodic dyspnea was diagnosed with an intrapericardial cyst via two-dimensional echocardiography. The cyst directly compressed the right ventricle, resulting in cardiac tamponade. Centesis of the cyst was performed to reduce tamponade prior to surgery. At surgery, a large, fluid-filled cystic structure was found within the pericardium. The cystic structure was continuous with a pedicle of liver that passed through a small peritoneopericardial diaphragmatic hernia. Surgical resolution was achieved by median sternotomy, midline pericardotomy, resection of the cyst, and diaphragmatic herniorrhaphy.