Inflammatory Activation after Experimental Cardiac Tamponade

Background/Purpose: Cardiac tamponadeis a medical emergencysituation associated with a high rate of life-threatening complications, even after immediate interventions. Our aim was to characterize the acute inflammatory consequences of this event in a clinically relevant large animal model. Methods: Cardiac tamponadewas induced for 60 min in anesthetized, ventilated and thoracotomized minipigs by intrapericardial fluid administration, the mean arterial pressure (MAP) being maintained in the interval of 40-45 mm Hg (n = 8). A further group (n = 7) served as sham-operated control. The global macrohemodynamics, including the right- and left-heart end-diastolic volumes(RHEDV and LHEDV), the pulmonary vascular resistance index (PVRI) and the superior mesenteric artery(SMA) flow, were monitored for 240 min, and the intestinal microcirculatory changes ( pCO2gap) were evaluated by indirect tonometry. Blood samples were taken for the determination of cardiac troponin Tand vasoactive inflammatory mediators, including histamine, nitrite/nitrate, big-endothelin, superoxide and high-mobility groupbox protein-1 levels in association with intestinal leukocyte and complement activation. Results: The cardiac tamponadeinduced significant decreases in MAP, cardiac output, LHEDV and SMA flow, while the PVRI and the pCO2gap increased significantly. After the removal of fluid from the pericardial sac, the MAP and the LHEDV were decreased, while the PVRI and the pCO2gap remained elevated when compared with those in the sham-operated group. In the posttamponade period, the abrupt release of inflammatory mediators was accompanied by a significant splanchnicleukocyte accumulation and complement activation. Conclusions: The macrocirculatory and splanchnicmicrocirculatory disturbances were accompanied by a significant proinflammatory reaction; endothelin and the complement systemmay be significant components of the inflammatory cascade that is activated in this porcine model of pericardial tamponade.