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Arquivos Brasileiros de Cardiologia
Print version ISSN 0066-782X
FREGONEZI, Guilherme et al. Heart rate variability in Myotonic Dystrophy type 1 patients. Arq. Bras. Cardiol. [online]. 2012, vol.98, n.4, pp. 353-361. Epub Mar 08, 2012. ISSN 0066-782X. http://dx.doi.org/10.1590/S0066-782X2012005000021.
BACKGROUND: Cardiac involvement is common in myotonic dystrophy (MD) patients. Heart rate variability (HRV) is a simple and reliable technique that can be useful for studying the influence of the autonomic nervous system on the heart. OBJECTIVE: Study heart rate variability in patients with type 1 MD. METHODS: We studied HRV during 5-minute recordings in MD patients and in a healthy control group. We analyzed frequency domains (LF and HF) in normalized units (nu) and sympathovagal balance, in the sitting and supine position. RESULTS: Seventeen patients (10 men and 7 women) and seventeen matched healthy individuals (10 men and 7 women) were studied. Sympathetic and parasympathetic modulations of the heart increased in male MD patients from supine to sitting position in 19% of LFnu and the LF/HF ratio rose by 42.3%. In the sitting position, male MD patients exhibited significantly higher sympathovagal balances in 50.9% compared to healthy control individuals. HRV was influenced by both gender and disease. Gender influenced LFnu in the supine position while the LF/HF ratio and HFnu were affected in both positions. Post hoc analyses showed that gender significantly impacts MD patients and healthy individuals in different ways (p < 0.01). The low frequency domain in the sitting position (LFnu) was significantly influenced by the disease. CONCLUSION: The results of this study suggest that the sympathetic drive in middle-aged male MD patients who are not severely impaired and present moderate disease duration seems to be greater than in healthy matched individuals.
Keywords : Heart rate; myotonic dystrophy; spectrum analysis; autonomic nervous system.