[Deterministic-chaotic and spectral-functional analysis of heart rate and respiratory movements]. / Deterministisch-chaotische und Leistungsspektralanalyse von Herzfrequenz- und Atembewegungen.

After an introduction into the analysis of periodical-linear and deterministic- chaotic characteristics of heart rate fluctuations and respiratory movements their physiological background and clinical aspects are debated. Using the example of own results at the mature rabbit and new-born pig different relations of periodical-linear and deterministic-chaotic characteristics in dependence on the experimental status and neurovegetative blockades are demonstrated. From the data assignments of these characteristics are derived.

Deterministic--chaotic and periodic properties of heart rate and arterial pressure fluctuations and their mediation in piglets.

OBJECTIVE: Only the simultaneous analysis of periodic and nonlinear properties of heart rate fluctuations (HRF) can describe completely this complex physiological process. Up to now there is, apart from a study of our own, no systematic and correlative investigation using both parameter groups, also not in early development. Thus, we tried to describe in this manner these properties of HRF, the corresponding mean arterial pressure fluctuations (MAPF) and respiratory movements (RM) and their mutual relations in neonatal pig. METHODS: In 6 term newborn piglets, periodic properties of HRF, RM, and MAPF were analyzed by spectral and coherence analysis, and deterministic-chaotic properties by calculation of correlation dimension (CD), Lyapunov exponent (LE), and construction of phase space plots. The assumption of deterministic chaotic components was supported by Theiler's test for nonlinearity, by always positive leading LEs, and by the results of a nonlinear deterministic model. These analyses were done in sleep states, general anaesthesia, hypoxic hypoxia, in ventilated state, and during cholinergic and additional beta-adrenergic blockade. RESULTS: In all experimental states, HRF and MAPF have periodic and nonlinear, very probably deterministic-chaotic properties, but in different relations. In anaesthetized piglets, periodic properties of HRF and MAPF dominate. In hypoxia the decreasing LE and CD of HRF and CD of MAPF were connected with increasing MAPF power density. Cholinergic blockade caused a decreased overall HRF and MAPF power and a decreasing LE and CD, but beta-adrenergic blockade decreased a small part of power density of both in 0.02-0.08 Hz only. The results of CD, LE, Theiler's test and the low dimensional deterministic model data suggested mainly deterministic-chaotic properties in the nonlinear part of HRF and MAPF. CONCLUSIONS: Already in neonatal piglets, both periodic and nonlinear, very probably deterministic chaotic properties of HRF and MAPF exist which change both during hypoxia and cholinergic blockade. They are partly cholinergically and--to a small extent--also beta-adrenergically mediated. The decrease of nonlinear complexity of HRF and MAPF during hypoxia suggests characteristic pathological change even in early development.

Relations between parameters of spectral power densities and deterministic chaos of heart-rate variability.

To evaluate whether or not heart-rate variations (HRV) have both periodic and deterministic-chaotic properties in conscious and anaesthetized states, HRV of 9 rabbits were analysed by power spectral analysis and methods of deterministic chaos. In order to correlate these properties with the physiological structure of HRV, cholinergic and beta-adrenergic blockades and medullar transections were done. A predominant deterministic-chaotic structure of HRV with high fractal correlation dimension (CD) during conscious state changes to a more periodic structure and lower CD during general anaesthesia. The main periodic and deterministic-chaotic components of HRV are vagally mediated because of their strong reduction by cholinergic blockade, but not by beta-adrenergic blockade or medullar transection.

Heart rate fluctuations of lower frequencies than the respiratoryrhythm but caused by it.

In conscious adult rabbits, "classical" respiratory sinus arrhythmia does not occur because the respiratory frequency (RF) always exceeds half the heart rate (HR). However, slow HR fluctuations, not synchronous with the respiratory rhythm but affected by it, occur systematically. We have shown that these can be calculated by using aliasing rules. During general anaesthesia, when the RF decreases so that respiratory frequency is less than half the heart rate, classical respiratory sinus arrhythmia occurs and can be greatly reduced by vagal blockade. The slow HR fluctuations which are not synchronous with the respiratory rhythms, but are affected by it are mainly vagally mediated, because vagal blockade virtually eliminates them.

Forms of physiological aliasing within the heart rate fluctuations by higher frequent respiratory movements.

In adult conscious rabbits, the respiratory frequency (RF) is almost always higher than half the heart rate (HR) Thus, no "classical" respiratory sinus arrhythmia occurred. But now, slow HR fluctuations, which were not synchronous to the respiratory rhythm but effected by it, occurred systematically. By cholinergic blockade, these slow HR fluctuations could be essentially reduced but not completely abolished. Up to now, this phenomenon was not be taken into account in the analysis of HR fluctuations. Thus misinterpretations are inevitable. During general anaesthesia, the RF decrease up to 2 RF < HR, and now classical respiratory sinus arrhythmia occurred which also could be essentially reduced but not completely abolished by vagal blockade. The possibilities of calculation of such slow HR fluctuations were shown, as those during 1/2 HR < RF < 3/2 HR and RF > 3/2 HR.