OBJECTIVE: Tachycardia is a clinical feature of Machado-Joseph disease (MJD), and it may be attributable to cardiac autonomic dysfunction. We investigated heart rate variability in MJD patients to reveal heart rate dysregulation in MJD. METHODS: Power spectral analysis of successive R-R intervals (300 beats) was performed in 10 genetically diagnosed MJD patients and 10 healthy control subjects to obtain frequency-domain measures, including high- (HF; 0.15-0.4 Hz) and low frequency power (LF; 0.04-0.15 Hz) and the ratio of LF to HF (LF/HF) of heart rate variability. In addition, the coefficient of R-R intervals (CV(R-R)) was calculated as a time-domain measure. RESULTS: HF in the MJD patients (26.2+/-25.3 ms(2)) was lower than that in the controls (82.1+/-82.6 ms(2), p=0.004). LF was also lower in the MJD patients (70.6+/-69.4 ms(2)) than in the controls (106.9+/-81.3 ms(2); p=0.029). There was no significant difference in LF/HF or CV(R-R) between the groups. CONCLUSION: HF, which is modulated by parasympathetic vagal activity, was low in our MJD patients. The reduced parasympathetic activity may be a cause of tachycardia in MJD patients. 2009 Elsevier B.V. All rights reserved.
OBJECTIVE:Tachycardia is a clinical feature of Machado-Joseph disease (MJD), and it may be attributable to cardiac autonomic dysfunction. We investigated heart rate variability in MJDpatients to reveal heart rate dysregulation in MJD. METHODS: Power spectral analysis of successive R-R intervals (300 beats) was performed in 10 genetically diagnosed MJDpatients and 10 healthy control subjects to obtain frequency-domain measures, including high- (HF; 0.15-0.4 Hz) and low frequency power (LF; 0.04-0.15 Hz) and the ratio of LF to HF (LF/HF) of heart rate variability. In addition, the coefficient of R-R intervals (CV(R-R)) was calculated as a time-domain measure. RESULTS: HF in the MJDpatients (26.2+/-25.3 ms(2)) was lower than that in the controls (82.1+/-82.6 ms(2), p=0.004). LF was also lower in the MJDpatients (70.6+/-69.4 ms(2)) than in the controls (106.9+/-81.3 ms(2); p=0.029). There was no significant difference in LF/HF or CV(R-R) between the groups. CONCLUSION: HF, which is modulated by parasympathetic vagal activity, was low in our MJDpatients. The reduced parasympathetic activity may be a cause of tachycardia in MJDpatients. 2009 Elsevier B.V. All rights reserved.