Effects of sevoflurane increments on left ventricular systolic long-axis performance during sevoflurane–remifentanil anesthesia for cardiovascular surgery

Background: The direct impact of sevoflurane on intraoperative left ventricular (LV) systolic performance during cardiac surgery has not been fully elucidated. Peak systolic tissue Doppler velocities of the lateral mitral annulus (S′) have been used to evaluate LV systolic long-axis performance. We hypothesized that incremental sevoflurane concentration (1.0–3.0 inspired-vol%) would dose-dependently reduce S′ in patients undergoing cardiac surgery due to mitral or aortic insufficiency. Methods: In 20 patients undergoing cardiac surgery in sevoflurane–remifentanil anesthesia, we analyzed intraoperative S′ values which were determined after 10 min exposure to sevoflurane at 1.0, 2.0, and 3.0 inspired-vol% (T1, T2, and T3, respectively) with a fixed remifentanil dose (1.0 μg/kg/min) using transesophageal echocardiography. Results: Linear mixed-effect modeling demonstrated dose-dependent declines in S′ according to the end-tidal sevoflurane concentration increments (C_{ET-sevoflurane}, p < 0.001): the mean value of S′ reduction for each 1.0 vol%-increment of C_{ET-sevoflurane} was 1.7 cm/s (95 % confidence interval 1.4–2.1 cm/s). Medians of S′ at T1, T2, and T3 (9.6, 8.9, and 7.5 cm/s, respectively) also exhibited significant declines (by 6.6, 15.6, and 21.2 % for T1 vs. T2, T2 vs. T3, and T1 vs. T3, p < 0.001, =0.002, and <0.001 in Friedman pairwise comparisons, respectively). Conclusions: Administering sevoflurane as a part of a sevoflurane–remifentanil anesthesia regimen appears to dose-dependently reduce S′, indicating LV systolic performance, in patients undergoing cardiac surgery. Further studies may be required to evaluate the clinical implications of these findings.