Two-year responses of heart rate and heart rate variability to first occupational lead exposure

Abstract

Objective: Because of the falling lead exposure, the literature relating autonomous nervous function to blood lead has limited relevance. Design and method: In the longitudinal Study for Promotion of Health in Recycling Lead (URL: https://www.clinicaltrials.gov; Unique identifi er: NCT02243904), we recorded the 2-year responses of heart rate, heart rate variability (Cardiax, International Medical Equipment Developing, Budapest, Hungary), and median nerve conduction velocity (Brevio, NeuMed, West Trenton, NJ), a routine test in occupational medicine, to fi rst lead exposure in 195 newly hired workers (91.3% men; mean age, 27.8 years). High-and low-frequency heart rate variability power and orthostatic heart rate variability responses were derived from 5-minute eletrocar-diograms in the supine and standing positions by Fourier transform and autoregres-sion. Blood lead was determined by inductively coupled plasma mass spectrometry. Results: From baseline to follow-up, blood lead increased from 4.22 to 14.1 ug/dL and supine/standing HR from 63.6/75.5 to 67.1/78.8 beats per minute. In analyses stratifi ed by fourths of blood lead changes, trends in heart rate and Fourier/autore-gressive heart rate variability did not reveal a dose-response curve (0.074< = P< = 0.98). In multivariable-adjusted mixed models, heart rate, Fourier/autoregressive heart rate variability, and nerve conduction velocity changes were unrelated to blood lead except for a weak inverse association between supine heart rate and blood lead changes (-0.55%; P = 0.029). The expected associations between heart rate variability and heart rate changes were preserved with no differences at base-line/follow-up. Analyses ichotomised by baseline median blood lead or cumulative blood lead index (4.30 ug/dL or 32.1 ug/dL × year) suggested an heart rate variability increase versus decrease in the low versus high baseline exposure group. Conclusions: Thus, a > 3-fold blood lead increment did not affect autonomous neural function as captured by heart rate variability. CARDIOVASCULAR RISK AND SUBCLINICAL VASCULAR ORGAN DAMAGE IN PATIENTS WITH AND WITHOUT HYPERTENSION Objective: Assessment of subclinical organ damage and sex differences in car-diovascular risk stratifi cation in patients with or without hypertension. Design and method: We divided 100 patients in two groups: HT+: patients with arterial hypertension (25 women and 25 men); HT-: patients without arterial hy-pertension (25 women and 25 men). The average age of them [yrs]: 56 and 53 (*p < 0,05). Ankle-brachial index (ABI), pulse wave velocity (PWV) and carotid intima-media thickness (IMT) were evaluated. We assessed cardiovascular risk according to: SCORE and Framingham scales. Statistical calculations were performed in PQStat 1.6. For comparison of variables we used the t-test for unrelated samples. To perform the correlation we used Spearman's rank correlation RS. Results: We revealed following results in both groups: HT+ and HT-respectively [*for p< = 0,05; **for p < 0,001; NS-negligible statistically]. In the group with hypertension women were characterized by a lower IMT and PWV than men. The cardiovascular risk according to risk SCORE and Framing-ham scales in men was signifi cantly higher than in women in both groups. In female with hypertension, there was a signifi cant negative correlation between ABI and IMT. In male without hypertension, there was a signifi cant negative correlation between ABI and IMT. Conclusions: 1. There was no difference in values of: ABI, PWV and IMT between the sexes in normotensive patients. 2. Women with hypertension were characterized by a lower IMT and PWV. 3. There were signifi cant negative correlation between ABI and IMT in female and male groups.