Figure 7-4 Histograms depicting the slope (M_W , top panel) and length intercept (L_W , middle panel) of the regional preload recruitable stroke work relationship and the time constant for isovolumic relaxation (τ, bottom panel) in the conscious state before (C, red bar) and after pacing (P) and during 1.1, 1.4, and 1.7 MAC (minimal alveolar concentrations) for isoflurane (light gray bars) and halothane (dark gray bars). a, Significantly (P < .05) different from P; b, significantly (P < .05) different from 1.1 MAC; c, significantly (P < .05) different from the corresponding isoflurane value. (Adapted from Pagel PS, Lowe D, Hettrick DA, et al: Isoflurane, but not halothane, improves indices of diastolic performance in dogs with rapid ventricular, pacing-induced cardiomyopathy. Anesthesiology 85:644–654, 1996.)