[Appraisal of the state of the autonomic nervous system in hypertrophic cardiomyopathy by the analysis of heart rate variability].
BACKGROUND
The analysis of heart rate variability has been accepted as a non-invasive method to evaluate the influence of the autonomic nervous system over the heart. Although heart rate variability has been used during the last decade in several illnesses the studies in hypertrophic cardiomyopathy are scarce.


OBJECTIVE
We report the activity of the autonomic nervous system in patients with hypertrophic cardiomyopathy using the analysis of heart rate variability.


METHODS
Heart rate variability was evaluate by the analyzing 24-h ambulatory electrocardiograms (Holter) in 20 patients with hypertrophic cardiomyopathy and in 15 controls. This method has been used to measure heart rate variability. Spectral analysis of the frequencies were calculated using fast Fourier transformation. Spectral heart rate variability was computed as high (0.15 to 0.40 Hz) low (0.04 to 0.15 Hz) and total (0.01 to 1.0 Hz). We compared the relation between low/high frequency as an index of the sympathetic/parasympathetic balance. All data are expressed as mean value +/- SD. The unpaired Student t-test was used. A two tailed p valued < 0.05 was considered statistically significant.


RESULTS
There were no differences in the mean heart rates among the patients with hypertrophic cardiomyopathy and normal subjects (mean +/- SD: 71 +/- 9 versus 74 +/- 11 beats/minute; p = NS) while there was a significant decline in total spectral (mean +/- SD: 7.14 +/- 1.1 versus 7.57 +/- 0.6 ln [ms2]; p = 0.02) and high (mean +/- SD: 5.22 +/- 0.8 versus 5.63 +/- 1.3 ln [ms2]; p = 0.04) as well as in low spectral frequency of heart rate variability (mean +/- SD: 22 +/- 0.8 versus 5.63 +/- 1.3 ln [ms2]; p = 0.04) in patients with hypertrophic cardiomyopathy. There were no differences in the low/high frequency component ratio in these patients (mean +/- SD: 1.1 +/- 0.1 versus 1.2 +/- 0.1 ln [ms2]; p = NS).


CONCLUSIONS
These facts suggest that the patients with hypertrophic cardiomyopathy have an alteration in the autonomic nervous system: sympathetic (low spectral frequencies) and parasympathetic activity (high spectral frequencies), although this does not reflect an imbalance between sympathetic and parasympathetic activities (relation of low to high spectral frequencies).
Arribas Jiménez
A
A
Servicio de Cardiología, Hospital Universitario, Salamanca.
Martín Luengo
C
C
Sáez Jiménez
A
A
Nieto Ballestero
F
F
Diego Domínguez
M
M
Moríñigo Muñoz
J L
JL
Luis Sánchez Fernández
P
P
Pabón Osuna
P
P
Rodríguez Collado
J
J
D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D015716:Electrocardiography, Ambulatory; D005583:Fourier Analysis; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology
Aproximación al conocimiento del estado del sistema nervioso autónomo en la miocardiopatía hipertrófica mediante el análisis de la variabilidad de la frecuencia cardíaca.