EFFECTS OF HALOTHANE AND ISOFLURANE ON LEFT-VENTRICULAR DIASTOLIC FUNCTION DURING SURGICAL STRESS IN PATIENTS WITH CORONARY-ARTERY DISEASE

Background: The effects of inhalation anesthetics on left ventricular (LV) systolic function are well documented, while the effects of these agents on LV diastolic function have mainly been evaluated in animal studies, with conflicting results. Methods: We investigated the effect s of halothane and isoflurane, when used to control the stress respons e to sternotomy in 33 patients with coronary artery disease (CAD). LV early diastolic relaxation and end-diastolic stiffness were evaluated from mitral Doppler flow profiles, transesophageal two-dimensional ech ocardiography, and central hemodynamic measurements. Measurements were performed a) after induction of anesthesia, b) after volume loading, c) prior to surgery and d) during surgery, 10 min after introduction o f the inhalation anesthetic. The effects of the anesthetics on Doppler indices reflecting early diastolic relaxation, and on the left ventri cular end-diastolic pressure-area (LVED P/A) relationship, were studie d. Results: When data obtained during surgical stress were compared to the control situation, we found an increase in the LV filling pressur es in both groups, while only the isoflurane group showed an increase in heart rate. An increase in end-systolic LV area and decreased fract ional area change was present in the halothane group, while an increas e in LV end-diastolic area, and similar changes in the mitral Doppler indices (decreases of deceleration rate and time of early diastolic fi lling), indicating an impairment of early diastolic relaxation, was pr esent in both groups. Isoflurane induced a displacement of the LVED P/ A relationship leftwards from the baseline LVED P/A curve. Conclusion: Both halothane and isoflurane impair early diastolic relaxation in pa tients with CAD, when used to control intraoperative surgical stress. In contrast to halothane, isoflurane induced a change in the LVED P/A relationship, suggestive of an increased LVED stiffness.