Higher Isoflurane Anesthetic Dose Associated with Higher E Velocity of Mitral Inflow in CABG Patients

Diastolic Dysfunction (DD) is a well-described component of coronary artery disease (CAD), and is common among cardiac surgery patients.Managed care pressures have intensified recent trends of “fast-tracking” coronary artery bypass grafting (CABG) patients, leading to more reliance on volatile anesthetic gases such as isoflurane. However, volatile anesthetics are known to have the side-effect of depressing myocardial function and possible altering diastolic function.The purpose of this study was to make observations among isoflurane anesthetic use and mitral inflow velocities. Methods: Thirtyelective adult CABG patients were studied after the induction of general anesthesia.No patient was having active symptoms or ischemia. The control group consisted of adult elective CABG patients who did not receive isoflurane, instead receiving a higher dose of fentanyl. Patients studied pre cardio-pulmonary bypass in the low dose isoflurane (0.5-0.99%) group did not have statistically significant changes in E or a velocitiescompared to the control group. Patients in the higher dose range of isoflurane group (1-1.6% Isoflurane) showed a statistically significant greater E velocity, compared to the control group.One possible explanation for the increased E velocity seen in our higher isoflurane groups is that the vasodilating effects of the isoflurane reduced afterload and thus increased the E velocity.