Correlations among time and frequency measures of heart rate variability recorded by use of a Holter monitor in overtly healthy Doberman pinschers with and without echocardiographic evidence of dilated cardiomyopathy.
OBJECTIVE
To determine correlations between time-domain and frequency-domain variables of heart rate variability (HRV) derived from 24-hour recordings obtained by use of an ambulatory electrocardiographic recorder (Holter monitor).


METHODS
59 overtly healthy Doberman Pinschers (41 without echocardiographic evidence of cardiomyopathy and 18 with precongestive heart failure attributable to cardiomyopathy).


METHODS
The HRV was analyzed from 24-hour recordings. Variables were calculated from the entire 24-hour recording as well as 4 user-selected time epochs. Comparisons were made for total power to SD of normal beat-to-normal-beat (NN) intervals (SDNN), ultra-low frequency power to SD of the means of NN intervals, low-frequency power and very-low-frequency power to mean of the SD of NN intervals, and high-frequency (HF) power to the root mean square successive difference of NN intervals (RMSSD) and percentage of NN intervals that varied from the previous NN interval by > 50 milliseconds (PNN50).


RESULTS
58 of 66 (88%) comparisons revealed significant values, indicating that relationships between variables were not random (r > 0.7 in 41 of 66 [62%)) comparisons). Strong correlations (r > 0.8) were found between the square root of total power and SDNN and between HF power and RMSSD.


CONCLUSIONS
Time-domain surrogates for variables of frequency-domain analysis variables that correlated in the dogs reported here are the same ones that reportedly correlate in humans. When 24-hour recordings obtained by use of a Holter monitor are used to calculate HRV, SDNN and total power as well as RMSSD and HF power are interchangeable.
Calvert
C A
CA
Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Wall
T M
TM
D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology / Q000662:veterinary*; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D015716:Electrocardiography, Ambulatory / Q000662:veterinary; D006339:Heart Rate / Q000502:physiology*; D018709:Statistics, Nonparametric; D013997:Time Factors