Chylopericardium

Overview
Chylopericardium is defined as a pericardial effusion which consists of chyle. Chyle comes from the lacteals (the lymphatics draining the small intestine) via the thoracic duct. .

Differential Diagnosis

 * Cholesterol pericarditis

Etiology
Chylopericardium refers to a communication between the pericardial sac and the thoracic duct, as a result of trauma, congenital anomalies, or as a complication of open-heart surgery, mediastinal lymphangiomas, lymphangiomatous hamartomas, lymphangiectasis, and obstruction or anomalies of the thoracic duct.

Pathophysiology
Chylopericardium is most often secondary to injury to the thoracic duct. It may also be primary or idiopathic. As result of the leakage of chyle, there can be nutritional and immunologic sequala. In addition, cardiac complications can occur such cardiac tamponade. Because chyle may be a pericardial irritant, constrictive pericarditis may eventually develop.

Diagnosis
Pericardial drainage yields a fluid that is usually milky and opaque in patients with chylopericardium.

Enhanced CT, alone or combined with lymphography, can identify not only the location of the thoracic duct but also its lymphatic connection to the pericardium.

In chylopericardium the cholesterol content can be quite high. However, chylopericardium should not be confused with cholesterol pericarditis. In cholesterol pericarditis the fluid contains cholesterol crystals, foam cells, macrophages and giant cells. The fluid in cholesterol pericarditis is clear, and classically is said to have a glittering "gold paint" appearance.

Treatment
Treatment depends on the aetiology and the amount of chylous accumulation. Chylopericardium after thoracic or cardiac operation without signs of tamponade is preferably treated by pericardiocentesis and diet (medium chain triglycerides). If further production of chylous effusion continues, surgical treatment is mandatory (level of evidence B, class I).

When conservative treatment and pericardiocentesis fail, pericardio-peritoneal shunting by a pericardial window is a reasonable option. Alternatively, when the course of the thoracic duct was precisely identified, its ligation and resection just above the diaphragm is the most effective treatment. In secondary chylopericardium the underlying disease (e.g., mediastinal tumour) should be treated.

Prognosis
Infection, tamponade, or constriction may aggravate the prognosis. The pericardial fluid is sterile, odourless, and opalescent with a milky white appearance and the microscopic finding of fat droplets. The chylous nature of the fluid is confirmed by its alkaline reaction, specific gravity between 1010 and 1021, Sudan III stain for fat, the high concentrations of triglycerides (5 to 50 g/L) and protein (22 to 60 g/L).