Heart rate variability: for real doctors. Translation from the Russian version of the book, published at Kharkiv, 2010, 131 p.
The basics and practice of the clinical use of the technology of heart rate variability are outlined for doctors of all specialties and students of medical faculties of universities.
9. Regulation in the disease
Some pathological conditions
Fetus and newborns. The main criteria for assessing the condition of the fetus and newborn are the density of the spectrum and the frequency, which corresponds to the maximum density in the high-frequency region of the spectrum. In newborns, the average HR is 108, supraventricular extrasystoles are more common, and the average hourly HRV is low, which indicates the immaturity of the autonomic regulation link. Long-term HRV is affected by body behavior and movements, and during REM sleep, breathing rhythm and variations in oxygen concentration in the blood. In the healthy development of newborns, slow sleep is distinguished from fast RR by large RR intervals, high spectrum power of the HF component, and low power of the spectrum of the LF component. Respiratory arrhythmia (HF) is about 30% of HRV. Low HRV of the fetus should alert the doctor. It predetermines respiratory and cardiovascular disorders with an increased risk of sudden death.
After the release of newborns from the state of severe respiratory and cardiovascular insufficiency, HRV noticeably increases, and its temporal parameters increase by 2-3 times, the settings of the frequency domain – by 8 times, and neuronal network indicators – by 20 times. HR does not noticeably change. HRV usually stabilizes in 4-5 days. In the premature in the first 3 days, the power of the spectrum of the LF component of HRV increases, which can be explained by the predominance of sympathetic tone before birth. In the “calm” state of “immature” (23.5 weeks) fruits, the HRV power at all frequencies from 0.2 to 1.0 Hz is 2 times greater than that of the “mature” (39.75 weeks), which demonstrates the formation and maturation ANS. At frequencies below 0.1 Hz, both groups show a low correlation between the spectral density and frequency. The altered sympathetic and parasympathetic control of the heart rhythm in stunted newborns may be due to a more active metabolism. In are reactive full-term disorders of the central nervous system, there are signs of previous asphyxia without any particular deviations of HRV, whereas, in reactive ones, prolonged tachycardia, a drop in HRV and a slower rhythm occur. The effects of gestational and postnatal age on HRV in premature infants during the first seven days of life manifested by a decrease in the power of its long-term component. HRV also decreases with brain lesions caused by intraventricular hemorrhage, asphyxiation, or sedative therapy. In the last trimester of pregnancy, insulin-induced hypoglycemia causes an increase in fetal movements and a decrease in HRV. In a healthy pregnancy, hypoglycemia is rare, but for mothers with diabetes, the risk of severe hypoglycemia episodes ranges from 19% to 40%.