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1.
Physiol Meas ; 39(6): 065002, 2018 06 19.
Article in English | MEDLINE | ID: mdl-29767628

ABSTRACT

OBJECTIVE: Ventricular arrhythmias in Brugada syndrome (BS) mainly occur at rest, especially during nighttime, suggesting that parasympathetic activity at night may play an important role in the arrhythmogenesis of the disease. This study examined and compared the autonomic function of symptomatic and asymptomatic BS patients overnight. APPROACH: We analyzed various heart rate variability (HRV) and heart rate complexity (HRC) markers in a clinical series including 87 BS patients, where 23 were symptomatic. MAIN RESULTS: Statistically significant differences were found in markers MIRR, SDNN, SDANN, [Formula: see text] and SampEn, suggesting that symptomatic patients may be related to lower heart rate variability and complexity values, as well as to greater circadian fluctuations overnight. SIGNIFICANCE: The results provide further evidence for the role of autonomic imbalance in the pathophysiology of BS, highlighting the relevance of nighttime analysis to the unmasking of significant ANS changes. Based on these outcomes, the role of HRV and HRC assessment at night could be a step forward towards the understanding of BS and the risk for the occurrence of symptoms in these patients, with a potential future impact on therapeutic strategies.


Subject(s)
Asymptomatic Diseases , Brugada Syndrome/physiopathology , Heart Rate , Female , Humans , Male , Middle Aged , Signal-To-Noise Ratio , Time Factors
2.
Physiol Meas ; 38(2): 387-396, 2017 02.
Article in English | MEDLINE | ID: mdl-28134132

ABSTRACT

Symptoms such as ventricular arrhythmias in Brugada syndrome (BS) typically occur at rest, especially during sleep, suggesting that the autonomic nervous system (ANS) function may be relevant in the arrhythmogenesis of the disease. The aim of this work was to assess the ANS response captured by nonlinear heart rate variability (HRV) measures in 69 patients diagnosed with BS, who underwent a standardized physical stress test. Heart rate complexity (HRC) was evaluated by the power-law scaling analysis (ß slope) during rest, exercise, recovery and rest post-recovery, in order to discriminate between symptomatic and asymptomatic BS patients. Symptomatic patients showed a significant reduction in HRC in comparison to asymptomatic subjects, after exertion (p = 0.015); during the whole recovery period (p = 0.023), and in particular within the passive recovery phase (p = 0.025), as well as during rest post-recovery (p = 0.022). Based on these results, symptoms could be associated with a lower ANS complexity during the stress test stages where parasympathetic activity is predominant. Therefore, the proposed HRV indicators could be of help in the risk stratification of asymptomatic patients.


Subject(s)
Brugada Syndrome/physiopathology , Exercise Test , Heart Rate , Adult , Aged , Asymptomatic Diseases , Autonomic Nervous System/physiopathology , Brugada Syndrome/diagnosis , Female , Heart/physiopathology , Humans , Male , Middle Aged , Signal Processing, Computer-Assisted , Young Adult
3.
JRSM Short Rep ; 1(6): 48, 2010 Nov 02.
Article in English | MEDLINE | ID: mdl-21234111
4.
J Chromatogr ; 409: 61-9, 1987 Nov 13.
Article in English | MEDLINE | ID: mdl-2826514

ABSTRACT

A high-performance liquid chromatographic (HPLC) support was prepared, based on silica beads coated with a beta-cyclodextrin-containing polymer, which allows the elution of solutes in order of their affinity for beta-cyclodextrin. Binding constants were determined from the retention data for drugs eluted with pure buffer on the new support and good agreement was observed with results obtained by the Hummel and Dreyer method, previously used in HPLC studies of drug-protein interactions.


Subject(s)
Cyclodextrins/analysis , Dextrins/analysis , Pharmaceutical Preparations/analysis , Starch/analysis , beta-Cyclodextrins , Chromatography, High Pressure Liquid , Indicators and Reagents , Isomerism , Polymers/analysis , Silicon Dioxide
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