title: Low-level lead exposure, metabolic syndrome, and heart rate variability: the VA Normative Aging Study.
abstract: BACKGROUND
  Altered heart rate variability (HRV), a marker of poor cardiac autonomic function, has been associated with sudden cardiac death and heart failure.
  
  
  OBJECTIVE
  We examined the association of low-level lead exposure measured in bone by K-X-ray fluorescence with alterations in HRV, and whether metabolic syndrome (MetS) or its individual components modify those associations.
  
  
  METHODS
  HRV measures [power in high-frequency (HFnorm) and low-frequency (LFnorm) in normalized units, and LF/HF] were taken among 413 elderly men from the Normative Aging Study. MetS was defined as subjects having three or more of the following criteria: abdominal obesity, hypertriglyceridemia, low high-density lipoprotein, high blood pressure, and high fasting glucose.
  
  
  RESULTS
  Of the subjects, 32% were identified as having MetS. Inverse but nonstatistically significant associations of both tibia and patella lead levels with HFnorm and nonstatistically significant positive relations with LFnorm and LF/HF were found in the entire cohort. There was a graded, statistically significant reduction in HFnorm and increases in LFnorm and LF/HF in association with an increase in patella lead as the number of metabolic abnormalities increased. We also observed that higher patella lead was consistently associated with lower HFnorm and higher LFnorm and LF/HF among subjects with MetS or its individual components. No statistically significant interaction between MetS and tibia lead was observed.
  
  
  CONCLUSIONS
  The results suggest that elderly men with MetS were more susceptible to autonomic dysfunction in association with chronic lead exposure as measured in patella. The modification by MetS is consistent with a role for oxidative stress in lead toxicity on the cardiovascular system.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA. sungkyun@umich.edu
authors.forename: Sung Kyun
authors.initials: SK
authors.lastname: Park
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Marc
authors.initials: M
authors.lastname: Weisskopf
authors.forename: David
authors.initials: D
authors.lastname: Sparrow
authors.forename: Pantel S
authors.initials: PS
authors.lastname: Vokonas
authors.forename: Robert O
authors.initials: RO
authors.lastname: Wright
authors.forename: Brent
authors.initials: B
authors.lastname: Coull
authors.forename: Huiling
authors.initials: H
authors.lastname: Nie
authors.forename: Howard
authors.initials: H
authors.lastname: Hu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D004781:Environmental Exposure / Q000009:adverse effects; D004785:Environmental Pollutants / Q000633:toxicity*; D006331:Heart Diseases / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007854:Lead / Q000633:toxicity*; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology / Q000503:physiopathology*; D008875:Middle Aged; D018384:Oxidative Stress; D010329:Patella / Q000737:chemistry; D014481:United States; D014493:United States Department of Veterans Affairs; D014728:Veterans
chemical_list: D004785:Environmental Pollutants; D007854:Lead