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Table 3 Heart rate variability in infants with bronchiolitis, by etiology.

From: Altered cardiac rhythm in infants with bronchiolitis and respiratory syncytial virus infection

Variable Admission 28 ± 3 days after admission
  RSV-positive
(n = 34)
RSV-negative
(n = 35)
RSV-positive
(n = 34)
RSV-negative
(n = 35)
Sinoatrial block, No. (%) 26 (76.5)°^ 1 (2.9) 0 (0.0) 0 (0.0)
Sinoatrial block 1-2 sec., No. (%) 21 (61.8)°^ 1 (2.9) 0 (0.0) 0 (0.0)
Sinoatrial block > 2 sec., No. (%) 5 (14.7)*" 0 (0.0) 0 (0.0) 0 (0.0)
More than 3 sinoatrial blocks, No. (%) 25 (96.2)°^ 0 (0.0) 0 (0.0) 0 (0.0)
Mean heart rate, bpm ± SD 139.23 ± 15.7*" 116.65 ± 15.9 119.37 ± 19.6 112.06 ± 10.1
Maximum heart rate, mean bpm ± SD 204.29 ± 20.6*" 173.30 ± 28.8 179.49 ± 21.8 170.10 ± 21.3
Minimum heart rate, mean bpm ± SD 49.62 ± 17.1 45.61 ± 26.10 49.31 ± 19.45 48.44 ± 20.14
SDNN (ms), mean ± SD 58.34 ± 26.37 54.61 ± 24.11 56.46 ± 22.21 55.39 ± 22.68
SDANN (ms), mean ± SD 49.61 ± 28.75 45.57 ± 25.70 47.66 ± 25.55 46.91 ± 26.96
ASDNN (ms), mean ± SD 37.11 ± 17.20 33.33 ± 13.70 35.64 ± 18.52 34.39 ± 16.31
rMSSD (ms), mean ± SD 20.31 ± 19.55 19.30 ± 16.99 19.25 ± 19.43 19.77 ± 19.03
PNN50, mean % ± SD 4.21 ± 7.2 2.93 ± 4.5 3.33 ± 5.3 3.22 ± 4.9
LF (ms2), mean ± SD 636.13 ± 306.7*" 369.48 ± 276.7 373.49 ± 269.73 369.55 ± 288.76
LF (nu), mean ± SD 33.93 ± 6.8*" 24.91 ± 5.6 25.01 ± 5.9 24.99 ± 6.1
HF (ms2), mean ± SD 271.06 ± 573.5 106.09 ± 152.5 143.9 ± 155.5 176.73 ± 169.6
HF (nu), mean ± SD 7.10 ± 7.6 6.76 ± 2.8 6.76 ± 4.5 6.85 ± 4.9
LF/HF ratio, mean ± SD 4.78 ± 1.60*" 3.68 ± 1.48 3.69 ± 1.40 3.64 ± 1.55
  1. SD: standard deviation; bpm: beats per minute; SDNN: standard deviation of all NN intervals; SDANN: standard deviation of the average of NN intervals in all 5-minute segments of the 24-h recording; ASDNN: mean of the standard deviation in all 5-minute segments of the 24-h recording; rMSSD: square root of the mean of the squares of the differences between adjacent NN intervals; pNN50: percentage of differences between adjacent NN intervals of > 50 msec; LF: low-frequency power; HF: high-frequency power; nu: normalised units.
  2. °p < 0.0001 and *p < 0.05 for the comparison between groups (i.e., RSV-positive vs RSV-negative upon admission); ^p < 0.0001 and "p < 0.05 for the comparison within group (i.e., admission vs 28 ± 3 days after admission in the RSV-positive group); no other significant difference between or within-group.