Heart rate variability in severe aortic stenosis.
OBJECTIVE
Autonomic dysfunction may be a risk factor for the generation of arrhythmias and sudden death in patients with severe aortic stenosis; thus, patients with this condition were studied to assess cardiac autonomic function.


METHODS
Twelve patients (five males, seven females; mean age 63 +/- 13 years) with severe symptomatic aortic stenosis before and after aortic valve replacement, were compared with a control group matched by age and sex. In the study group, mean fractional shortening was 36.5 +/- 5% and maximal aortic gradient 94.7 +/- 12 mmHg, assessed echocardiographically. Autonomic dysfunction was evaluated by following heart rate variability in both time and frequency domains. Spectral analysis was assessed at very low frequency (VLF: 0.017-0.05 Hz), low frequency (LF: 0.05-0.15 Hz) and high frequency (HF: 0.15-0.50 Hz). Heart rate variability was analyzed during three intervals, between 6:00-8:00 am (morning), 14:00-16:00 (afternoon) and 02:00-04:00 (night), and re-evaluated at 8-10 months after aortic valve replacement.


RESULTS
Compared with controls, patients with aortic stenosis presented a significantly lower heart rate variability in the morning and afternoon, analyzed either by time or frequency domain: 50 +/- 22 versus 132 +/- 52 ms (p < 0.05); VLF 5.0 +/- 1.5 versus 7.9 +/- 1.4 ln (ms)2 (p < 0.05); LF 4.9 +/- 1.7 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05); HF 5.3 +/- 1.4 versus 7.5 +/- 1.8 ln (ms)2 (p < 0.05). Results at night showed a similar tendency, but were not statistically significantly different. At 8-10 months after aortic valve replacement, heart rate variability was increased significantly during the morning, from 50 +/- 22 to 79.5 +/- 22 ms (p < 0.05); VLF from 5.0 +/- 1.5 to 6.7 +/- 0.8 ln (ms)2 (p < 0.05); LF from 4.9 +/- 1.7 to 6.2 +/- 1.3 ln (ms)2 (p < 0.05). HF values tended to increase, though not significantly so. During the remainder of the day there was also a non-statistically significant increment in all values of heart rate variability.


CONCLUSIONS
The study results suggest that patients with severe symptomatic aortic stenosis present with autonomic dysfunction that tends to normalize within the first year of valve replacement.
Vukasovic
J L
JL
Hospital Salvador, University of Chile, Santiago de Chile, Chile.
Florenzano
F
F
Adriazola
P
P
Escobar
E
E
D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D001341:Autonomic Nervous System / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000294:innervation / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D014463:Ultrasonography