The production of acute pericardial effusion: the effects of various degrees of interference with venous blood and lymph drainage from the heart muscle in the dog.

Abstract Obstruction to the venous blood and lymph outflow from the heart muscle leads to the formation of a pericardial effusion originating primarily from the epicardial surface of the heart (the visceral pericardium). The degree of effusion is proportionate to the extent of interference with the venous blood and lymph flow. Pathologic changes found in the myocardium include venous and lymphatic congestion, perivascular and interstitial edema, and early myocardial necrosis. These studies have defined a method of producing an acute pericardial effusion in the dog and clarify certain aspects of the mechanism of formation of pericardial effusions. It is considered likely that all pericardial effusions, irrespective of cause, arise primarily from the epicardial surface (visceral pericardium) of the heart.