Table 2

Time-domain indexes of heart rate variability before and at various intervals after coronary artery bypass grafting
Variable
 Group
 Preoperative
 After surgery






3 days
 6 days
 15 days
 30 days
 60 days
 90 days
Mean R–R (ms)
 CABG
 903 ± 40
 761 ± 45*
 781 ± 42*
 790 ± 36*
 802 ± 26*
 801 ± 36
 802 ± 35

CAD
 856 ± 49
 -
 -
 -
 842 ± 38
 816 ± 33
 835 ± 47

Healthy
 860 ± 36
 -
 -
 -
 -
 -
 -
SDNN (ms)
 CABG
 35 ± 3
 16 ± 2*
 16 ± 2*
 19 ± 2*
 25 ± 2*
 32 ± 3
 27 ± 3

CAD
 31 ± 4
 -
 -
 -
 29 ± 3
 30 ± 3
 31 ± 2

Healthy
 42 ± 5†
 -
 -
 -
 -
 -
 -
SDANN (ms)
 CABG
 16 ± 3
 6 ± 1*
 6 ± 1*
 9 ± 1*
 15 ± 3
 18 ± 3
 14 ± 2

CAD
 21 ± 4
 -
 -
 -
 19 ± 3
 20 ± 3
 20 ± 3

Healthy
 39 ± 7†
 -
 -
 -
 -
 -
 -
RMSSD (ms)
 CABG
 24 ± 4
 10 ± 2*
 10 ± 1*
 12 ± 1*
 19 ± 4
 21 ± 3
 19 ± 2

CAD
 22 ± 3
 -
 -
 -
 18 ± 3
 19 ± 2
 20 ± 4

Healthy
 27 ± 3
 -
 -
 -
 -
 -
 -
pNN50 (%)
 CABG
 8 ± 0
 3 ± 0*
 3 ± 0*
 3 ± 0*
 4 ± 0*
 7 ± 0
 6 ± 0

CAD
 4 ± 0
 -
 -
 -
 3 ± 0
 4 ± 0
 3 ± 0

Healthy
 11 ± 0b
 -
 -
 -
 -
 -
 -

Values are means ± SEM. *P < 0.05 versus CABG preoperative value; †P < 0.05 versus CABG and CAD. CABG, patients who underwent coronary artery bypass grafting; CAD, patients with coronary artery disease who did not undergo surgery; healthy, control subjects without CAD; pNN50, percentage number of pairs of adjacent R–R intervals differing by more than 50 ms; RMSSD, square root of the mean of squares of differences between adjacent R–R intervals; SDANN, standard deviation of the averages of the R–R intervals calculated in 5-minute segments; SDNN, standard deviation of all R–R intervals.

Soares et al. Critical Care 2005 9:R124   doi:10.1186/cc3042