OVERCOMING RIGHT-VENTRICULAR FAILURE WITH LEFT-VENTRICULAR ASSIST DEVICES

Background: Right ventricular failure can lead to circulatory collapse while on left ventricular assist device support. By shunting blood fr om the femoral vein to the left ventricular assist device, cardiac out put can be increased, but arterial oxygen saturation will decrease. Me thods: To determine the effects on O-2 delivery, a model was developed on the basis of O-2 uptake in the lungs and whole body O-2 consumptio n. An equation was derived that related cardiac output, pulmonary veno us O-2 saturation, O-2 consumption, and the ratio of shunt-to-systemic blood flow to systemic O-2 delivery, Results: When total cardiac outp ut increases, the shunt will increase systemic O-2 delivery while decr easing arterial O-2 saturation and leaving systemic venous O-2 saturat ion unaltered. When total output does not increase, the shunt will dec rease systemic O-2 delivery, arterial O-2 saturation, and systemic ven ous O-2 saturation. Conclusions: The analysis suggests that measuring systemic venous oxygen saturation may be a useful way to monitor patie nt safety, A decrease in systemic venous O-2 saturation when creating the shunt implies an inadequate increase in cardiac output. J Heart Lu ng Transplant 1997.