CONICET | Buscador de Institutos y Recursos Humanos

The relationship between unstable angor and circadian periodicity of heart rate variability (HRV) was explored in a group of patients hospitalized in the coronary care unit (CCU). Patients were classified as normal (symptoms with 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 24h Holter records were analyzed, mean RR and standard deviation of RR (SDNN) being obtained from 1h-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 ratio (L/H) was calculated. The results were analyzed by cosinor analysis to obtain the mesor, the oscillation amplitude and the acrophase for every 24h rhythm. As compared to ambulatory controls, admission to the CCU diminished amplitude and phase-delayed the circadian oscillation of most HRV parameters, except for SDNN in normal subjects. 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 1.5h 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 subjects. As compared to moderate angor patients, amplitude of 24 h variation of total power decreased in severely affected patients and the circadian oscillation of HF (an indicator of vagal control on the heart) became free running. A phase delay of 2.5h in SDNN acrophase was found in severe angor patients when compared to moderate angor. The results indicate that severity of unstable angor correlates with desynchronization of parasympathetic control of heart rate.

enviar mensaje