Correlations between Electrolytes Levels and Heart Rate Variability in Apparently Healthy Subjects

Context: Previous studies correlating electrolytes levels with heart rate variability (HRV) were conducted exclusively in diseased patients and fail to demonstrate significant correlations, except for a few. Whether absence of significant correlations is physiological or hidden by the associated pathologies is uncertain. Aim: To evaluate the effects of electrolytes concentrations on heart rate variability in apparently healthy subjects. Setting and Design: It was a cross-sectional case-control laboratory-based study. Patients and Methods: The study involved twenty-two apparently healthy males and twenty-three females. Sodium, potassium, calcium, magnesium, hemoglobin and random blood glucose levels, weight, height, blood pressures and HRV were measured according to the standards. Possible confounding factors were introduced as a covariate when correlating electrolytes concentrations with HRV indices using partial correlations. Results: The study involved 23(51.1%) females and 22(48.9%) males. The ages of studied subjects range between 20 – 40 years (Mean (M) ± Standard deviation (SD) = 25.24±4.79 years). M±SD of the body mass indices = 24.74±6.13 Kg/m, the mean arterial blood pressures = 90.17±9.78 mmHg, Hemoglobin concentrations =13.00±2.48 g/dl, random blood glucose concentrations = 95.69±16.70 mg/dl. There were no significant correlations between sodium, potassium and calcium concentrations and studied short-term HRV indices. In contrast, there is a significant negative correlation between magnesium concentrations and sympathovagal balance (correlation coefficient (CC) = 0.376, P = 0.020. Conclusion: Sympathetic modulations on heart rate tend to override parasympathetic modulations as magnesium concentration decreases. Otherwise, there were no significant correlations between sodium, potassium and calcium concentrations and HRV indices.