Development of heart rate power spectra reveals neonatal peculiarities of cardiorespiratory control

Abstract

Postnatal adaptation should be associated with changes in cardiac rhythmic behavior. To examine the development of heart rate variability, instantaneous heart rate (IHR) and the corresponding breathing signals of 16 healthy infants were analyzed. This was pursued by use of fast Fourier transformation beginning with the 1st day until the 6th mo of life. Power in the low-frequency range (LF, 0.02-0.2 Hz) and high-frequency range (HF, 0.2-1.5 Hz), total power (TP), the quotient LF/HF, and the frequency of the peak in LF and HF (LFF and HFF, respectively) were derived from the IHR spectrum. The peak frequency in HF (RF) was detected in the respiratory spectrum. Power and frequency of IHR rhythms undergo a marked development. TP, LF, and HF are lowest from the end of the 1st mo until the 2nd mo. LF predominates over HF, with LF/HF reaching its peak during 1- to 2-mo period. HF, recording respiratory related rhythms is negatively correlated with the breathing rate (BR). HFF and RF both show an increasing tendency during the 1st mo followed by a decrease down to the 6th mo. However, HFF is lower than RF if BR is high, mainly during the first 2 mo. The distinct changes in BR and its important influence on the IHR spectrum underscore the importance of monitoring respiration as a further measure in the diagnosis of infants. LFF is on average between 0.075 and 0.095 Hz, exhibiting an irregular course with minimum at the 10th, 21st-28th, and 90th day being apparent. The developmental pattern of LFF may by interpreted in terms of the maturation of the nervous system involved in the generation of circulatory rhythms.

High-frequency oscillations of the heart rate during ramp load reflect the human anaerobic threshold

“…In a second step, these intervals were examined with the help of heuristic algorithms regarding their potential technical or physiological origin. The time series were then corrected taking the total duration into consideration (Patzak et al 1996).…”

Ontogeny and control of the heart rate power spectrum in the last third of gestation in fetal sheep

“…In addition, data from preterm and term infants suggest that LF activity still predominates after birth, despite continuous breathing (Clairambault et al 1992;Patzak et al 1996;Regalado et al 2001). While a significant correlation has been reported between respiratory frequency and HF power in preterm and fullterm infants (Patzak et al 1996;Rassi et al 2005), it has also been reported that HF power differs significantly between rapid eye movement and non-rapid eye movement sleep in full-term infants, despite continuous breathing in both states (Clairambault et al 1992). Furthermore, there is evidence that in newborn infants the HF power increases steeply in late gestation (at ∼37-38 weeks; Clairambault et al 1992); together, these data strongly imply that changes in HF power primarily reflect neural maturity and activity rather than a simple link with breathing.…”

Interaction between heart rate variability and respiration in preterm infants

“…We computed the bivariate autoregressive parameters and the noise variances, and also computed the RR and RESP power spectral densities, the RR-RESP coherence, and the RESP to RR (RSA) gain. As reported in the literature [2,4], the standard LF and HF frequency ranges classified for adult HRV analysis do not apply in the infant case. Generally, any frequency above 0.2 Hz has been classified as high frequency in the case of infant HRV.…”

“…There have been reports in the literature about the presence [1,2] as well as absence [3,4] of interaction between heart rate variability (HRV) and respiration (RESP) in preterm infants, known as respiratory sinus arrhythmia (RSA). It has also been reported that heart rate fluctuations may exist at the respiratory frequencies even in the absence of respiration [5].…”