Direct effects of volatile anesthetics on cardiac function

The volatile anesthetics are a class of general anesthetic drugs used by the perfusionist during cardiopulmonary bypass (CPB). These agents are used in low doses in combination with other anesthetics to produce complete anesthesia. During CPB, these agents are capable of safely anesthetizing the paitent. It is well understood that these anesthetics act at the level of the central nervous system. However the intent of this study was to define the effects of isoflurane and sevoflurane on left ventricular function. C57BL/6 female mice were anesthetized with either isoflurane or sevoflurane at concentrations ranging from 0.5 to 5%. The cardiac function was assessed with transthoracic echocardiography (TTE). Sevoflurane caused a reduction of left ventricular function at lower concentrations compared with isoflurane. At concentrations of 2% and greater, sevoflurane significantly reduced cardiac output, ejection fraction, fractional shortening, and increased end-diastolic and end-systolic volumes. Isoflurane-induced reduction of left ventricular function was much less in magnitude when compared with sevoflurane. These data underscore the importance of using lower concentrations of volatile anesthetics during CPB especially during periods of cardiac recovery after aortic cross-clamp removal.