Heart rate variability and ambulatory blood pressure monitoring in young patients with hypertrophic cardiomyopathy.
BACKGROUND
Sudden cardiac death commonly occurs in young patients with hypertrophic cardiomyopathy (HCM); however, their heart rate variability (HRV) and blood pressure (BP) response to daily life activities is not well known.


RESULTS
HRV and ambulatory BP monitoring were performed in 20 patients (age range: 7-21 years) and 57 age-matched healthy volunteers (age range: 10-22 years). Time domain variables and spectral data were obtained at hourly intervals throughout the day. To determine the BP response to daily life activities, the ratios of the mean BP and pulse pressure in the morning, afternoon, and night to those during sleeping were calculated. The association between the BP level and HRV was also evaluated. The HCM patients showed significantly increased sympathovagal imbalance and decreased parasympathetic activity in the early morning, around noon, and in the early evening. This abnormality was independent of cardiac symptoms. Symptomatic patients showed a significantly lower systolic BP response in the morning, and a higher incidence of dissociation between sympathetic activity and BP response than asymptomatic patients.


CONCLUSIONS
An abnormal BP response in the presence of impaired HRV appears to be predictive for cardiac events in young patients with HCM.
Department of Pediatrics, Graduate School of Medical and Dental Sciences, Kagoshima University, Japan.
Sadamitsu
S
Yanagi
Masao
M
Yoshinaga
Hitoshi
H
Horigome
Yuji
Y
Tanaka
Naoki
N
Fusazaki
Yuji
Y
Matsuoka
Atsushi
A
Shimago
Toshiro
T
Fukushige
Taisuke
T
Eguchi
Koichi
K
Tokuda
Junichiro
J
Nishi
Yukiharu
Y
Kono
Yuichi
Y
Nomura
Koichiro
K
Miyata
Yoshifumi
Y
Kawano
D000293:Adolescent; D000328:Adult; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology*; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results