title: Circadian periodicity of heart rate variability in hospitalized angor patients.
abstract: The relationship between unstable angor (angina) and circadian periodicity of heart rate variability (HRV) was explored in a group of patients hospitalized in a coronary care unit (CCU). Patients were classified as normal (whose symptoms had non-cardiovascular origin, n=8), moderate angor (n=13) and severe angor (n=11). A fourth group of ambulatory healthy volunteers (n=12) was included. Individual 24 h Holter records were analyzed, mean RR and standard deviation of RR (SDNN) being obtained from 1 h-length windows. For frequency domain analysis, 5 min-length windows were employed. The spectral components analyzed were total power (spectral power between 0.01 and 0.5 Hz), low frequency power (LF: power between 0.04 and 0.15 Hz), and high frequency power (HF: power between 0.15 and 0.4 Hz). In addition, LF to HF areas ratio (L/H) was computed. Mesor, amplitude and acrophase for every 24 h rhythm were calculated by cosinor analysis. As compared to ambulatory controls, admission to the CCU diminished amplitude and phase-delayed the circadian oscillation of most HRV parameters, except for SDNN. Moderate angor patients showed decreased amplitude of RR and L/H and augmented amplitude of SDNN when compared to normal hospitalized subjects. A phase delay of about 1.5 h for RR intervals and a phase advance of 3.5-6 h for LFA and SDNN were found in the moderate angor group when compared to normal. Amplitude of 24 h variation of total power decreased in severely angor patients and the circadian oscillation of HF (an indicator of vagal control on the heart) became free running. A phase delay of 2.5 h in SDNN acrophase was found in severely affected patients when compared to moderate. The results indicate that severity of unstable angor correlates with desynchronization of parasympathetic control of heart rate.
authors.affiliation: Instituto de Investigaciones, Médicas Alfredo Lanari, Laboratorio de Neumonología, Combatientes de Malvinas 3150, 1427 Buenos Aires, Argentina. denegri@bigfoot.com
authors.forename: Carlos E
authors.initials: CE
authors.lastname: D'Negri
authors.forename: Liliana
authors.initials: L
authors.lastname: Marelich
authors.forename: Daniel
authors.initials: D
authors.lastname: Vigo
authors.forename: Rafael S
authors.initials: RS
authors.lastname: Acunzo
authors.forename: Luis A
authors.initials: LA
authors.lastname: Girotti
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cardinali
authors.forename: Leonardo Nicola
authors.initials: LN
authors.lastname: Siri
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012727:Sex Characteristics