title: Variability of R-R, P wave-to-R wave, and R wave-to-T wave intervals.
abstract: We analyzed the effect of changing posture from supine to standing on the variability of R-R, P-R, and R-T intervals in 10 healthy volunteers using power spectral analysis. An electrocardiogram and respiratory trace were recorded before and after posture change. Variability in the P-R and R-T intervals was much less than in the R-R interval and demonstrated a lower-frequency (LF)-to-high-frequency (HF) ratio. Changing from a supine to a standing position showed no change in indexes of vagal influence on the P-R and R-T variability, in contrast to the well-documented decrease in the indexes of vagal influence on the R-R variability (HF power decreased from 2.33 to 0.41 ms2, P = 0.003; amplitude of the respiration-to-heart rate impulse response decreased from 31.6 to 14.4 ms.ml-1.s-1, P = 0.03; and LF/HF increased from 1.96 to 5.22, P = 0.005). We concluded from this study that the effects of standing were an observed reduction in vagal influence on the heart rate variability of the R-R interval and maintenance of lung volume-related vagal modulation of the P-R and R-T intervals.
authors.affiliation: Department of Anaesthetics, Waikato Hospital, New Zealand.
authors.forename: J
authors.initials: J
authors.lastname: Forester
authors.forename: H
authors.initials: H
authors.lastname: Bo
authors.forename: J W
authors.initials: JW
authors.lastname: Sleigh
authors.forename: J D
authors.initials: JD
authors.lastname: Henderson
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000502:physiology; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D015233:Models, Statistical; D011187:Posture; D015203:Reproducibility of Results; D012119:Respiration / Q000502:physiology*; D012849:Sinoatrial Node / Q000502:physiology; D016683:Supine Position; D013564:Sympathetic Nervous System / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology*