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 ± 0^b

-

-

-

-

-

-

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