Effect of variation in systemic blood flow on plasma TNF-alpha in a pig model with left ventricular assist device

Tumor necrosis factor-alpha (TNF-alpha) release has been implicated in a se psis-like syndrome following cardiopulmonary bypass (CPB). This also may be important in patients who have had a left ventricular assist device (LVAD) implanted. This report investigates the effect of reducing systemic blood flow on hemodynamic response, mixed venous oxygen saturation (Svo(2)), and the release of TNF-alpha. LVADs were implanted in 9 pigs. The aorta was cla mped, and thus the LVAD flow represented the entire systemic blood flow. Pl asma TNF-alpha in the femoral artery (FA) and superior mesenteric vein (SMV ) was measured at baseline and following systemic blood flow changes. Simul taneously, hemodynamic parameters and oxygen saturation in the pulmonary ar tery (Svo(2)) were measured. Following reductions in systemic blood flow, p lasma TNF-alpha increased gradually to a maximum level at a systemic blood now of 20%. There was no significant difference between TNF-alpha levels in the SMV and the FA. There was a significant (p < 0.05) correlation between cardiac index, stroke volume index, and TNF-<alpha>. The Svo(2) decreased significantly (p < 0.05) at a systemic blood flow of 30 and 20%. A rise in TNF-<alpha> occurred when the Svo(2) was less than 75%. The data demonstrat e that a seduction in systemic blood flow causes an increase in plasma TNF- alpha. This can lead to the development of a sepsis-like syndrome in a grou p of patients who already are hemodynamically compromised. While weaning sh ort-term LVAD support, rapid diminution of the cardiac output and the pump flow must be avoided.