title: Heritability of ambulatory heart rate variability.
abstract: BACKGROUND
  Reduced heart rate variability (HRV) is a prognostic factor for cardiac disease and cardiac mortality. Understanding the sources of individual differences in HRV may increase its diagnostic use and provide new angles for preventive therapy. To date, the contribution of genetic and environmental factors to the variance in HRV has not been investigated during prolonged periods of ambulatory monitoring in a naturalistic setting.
  
  
  RESULTS
  In 772 healthy twins and singleton siblings, ambulatory ECG was recorded during 24 hours. Two time domain measures of HRV were used: the standard deviations of all normal-to-normal intervals across 5-minute segments (SDNN index) and the root mean square of successive differences between adjacent normal RR intervals (RMSSD). Multivariate genetic analyses across 4 periods of day (morning, afternoon, evening, night) yielded significant estimates for genetic contribution to the mean ambulatory SDNN index (ranging from 35% to 47%) and the mean ambulatory RMSSD (ranging from 40% to 48%).
  
  
  CONCLUSIONS
  Ambulatory HRV measures are highly heritable traits that can be used to support genetic association and linkage studies in their search for genetic variation influencing cardiovascular disease risk.
authors.affiliation: Vrije Universiteit, Amsterdam, The Netherlands. hm.kupper@psy.vu.nl
authors.forename: Nina H M
authors.initials: NH
authors.lastname: Kupper
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.forename: Mireille
authors.initials: M
authors.lastname: van den Berg
authors.forename: Dolf
authors.initials: D
authors.lastname: de Boer
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Posthuma
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: Eco J C
authors.initials: EJ
authors.lastname: de Geus
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006339:Heart Rate / Q000235:genetics*; D006801:Humans; D008297:Male; D035781:Siblings; D014429:Twins, Dizygotic / Q000235:genetics / Q000502:physiology; D014430:Twins, Monozygotic / Q000235:genetics / Q000502:physiology