The association between blood metal concentrations and heart rate variability: a cross-sectional study

Objectives: Analysis of heart rate variability (HRV) is useful for measuring cardiovascular autonomic function. The effects of blood metals on cardiovascular autonomic function have not been studied extensively. The objective of the present study was to determine the association between the concentrations of blood metals, including toxic and essential trace elements, and cardiovascular autonomic function, based on HRV, in subjects without clinical cardiovascular diseases. Methods: The subjects were public officials and their family members (n = 331) in a district of Seoul, Republic of Korea. Age, height, weight, smoking habits, medical history, blood pressure, electrocardiogram (ECG) recording, and chest X-ray were assessed by means of a self-administered questionnaire and medical examination. Blood metal concentrations (blood Pb, As, and Cd; serum Al, Co, Cu, and Zn) were measured by inductively coupled plasma-mass spectrometry. HRV parameters (low frequency, LF; high frequency, HF; total power spectrum, TPS) were measured with LRR-03 and MemCalc software (GMS, Japan). Results: The concentrations of each of the blood metals were almost within normal ranges. Age and heart rate were negatively associated with LF, HF, and TPS (P< 0.01). Whole-blood Cd concentrations were negatively associated with LF (P< 0.01) and HF (P< 0.05). Serum Zn concentrations were positively associated with LF and TPS (P< 0.01). Conclusion: Our study suggests that levels of blood metals even within normal ranges may affect heart rate variability.