Spectral analysis of heart rate variability in dogs with mild mitral regurgitation.
OBJECTIVE
To assess autonomic function in dogs with mild mitral regurgitation (MR) that did not have clinical signs of the condition.


METHODS
6 healthy adult Beagles.


METHODS
Mild MR was experimentally induced. A 24-hour ambulatory ECG was recorded before and after induction of MR. Heart rate variability was analyzed in frequency domains by use of the ambulatory ECG. Low-frequency (LF) and high-frequency (HF) power were calculated by integrating over their frequency intervals, and the ratio of LF to HF was also calculated. Measurements of frequency domains were analyzed for 4 time periods (midnight to 6 AM, 6 AM to noon, noon to 6 PM, and 6 PM to midnight).


RESULTS
Dogs with experimentally induced MR were classified as International Small Animal Cardiac Health Council class Ia. The HF power of dogs with MR was significantly decreased between 6 AM and noon. The ratio of LF to HF in dogs with MR was significantly increased for the periods between midnight and 6 AM, 6 AM and noon, and noon and 6 PM.


CONCLUSIONS
Compensatory response through autonomic modulation was observed in dogs with mild MR that did not have abnormalities, except for cardiac murmur, during clinical examination. This result suggests that treatment during the early stages of mild MR may be beneficial. Additional studies are necessary to determine whether such treatment will delay the onset of congestive heart failure and prolong survival in dogs affected with mild MR.
Fujii
Yoko
Y
Department of Surgery I, Azabu University, School of Veterinary Medicine, Fuchinobe, Sagamihara-shi, Kanagawa-ken, 229-8501, Japan.
Wakao
Yoshito
Y
D000818:Animals; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D008297:Male; D008944:Mitral Valve Insufficiency / Q000503:physiopathology* / Q000662:veterinary*