Click on image to view larger version.

Figure 4 Serial changes in low-frequency (LF) component of RR variability (0.04–0.14 Hz). Two groups could be definitely identified by the study design. In seven patients, the LF component began to rise within 1 min after balloon inflation and reached a peak at about 80 s (closed squares). In contrast, there were no appreciable changes in spectral components of RR interval variability in the remaining seven patients (open circles). Following LF augmentation, high-frequency (HF) component (0.15 Hz) began to increase in the middle to late phase of coronary occlusion, but the changes did not reach statistical significance. Consequently, the ratio of LF to HF component rose to be significantly greater in the LF augmentation group than the no LF augmentation group. Data are expressed as mean ± standard error of percent changes from the control value. *p < 0.05 vs. baseline value, #p < 0.05 vs. open circles at the corresponding time.