Abstract
In order to propose an interpretation of recent experimental findings concerning short-term variability of arterial blood pressure (ABP), heart rate variability (HRV), and their dependence on body posture, we develop a qualitative dynamical model of the short-term cardiovascular variability at respiratory frequency (HF). It shows the respiratory-related blood pressure fluctuations in relation to the respiratory sinus arrhythmia (RSA). Results of the model-based analysis show that the observed phenomena may be interpreted as buffering of the respiratory-related ABP fluctuations by heart rate (HR) fluctuations, i.e., the respiratory sinus arrhythmia. A paradoxical enhancement (PE) of the fluctuations of the ABP in supine position, that was found in experiment, is explained on the ground of the model, as an ineffectiveness of control caused by the prolonged phase shift between the the peak of modulation of the pulmonary flow and the onset of stimulation of the heart. Such phasic changes were indeed observed in some other experimental conditions. Up to now, no other theoretical or physiological explanation of the PE effect exists, whereas further experiments were not performed due to technical problems. Better understanding of the short-term dynamics of blood pressure may improve medical diagnosis in cardiology and diseases which alter the functional state of the autonomous nervous system.Graphical A simple mathematical model of cardiorespiratory dynamics. A novel class of mathematical models of blood pressure dynamics in humans allows to represent respiratory modulation of Arterial Blood Pressure. The model shows how the phase shift in neural control of the heart rate may produce Paradoxic Enhancement of respiratory Blood Pressure fluctuations. Observed in experiment. The model has many options for further development.
Highlights
There are still many mysteries in cardiovascular regulation
The purpose of this paper is to present a modelbased analysis of the possible mechanism underlying the phenomenon of selective buffering, understood as the dependence of the buffering of the arterial blood pressure (ABP)-related variables on the position of the body, and the related paradoxical enhancement of systolic BP fluctuations
The waveform of pa follows the Windkessel principle: i.e., after each flow pulse (“kick”) there is an outflow to the venous compartment, proportional to the pressure gradient pav
Summary
There are still many mysteries in cardiovascular regulation. Providing a solution to them pushes forward the frontier of science, and enables us to formulate new methods of cardiological diagnosis and risk stratification, which results in more efficient patient handling - see [1] and [2] for recent successful examples of such an approach.One of important physiological variables under consideration is the arterial blood pressure (ABP). There are still many mysteries in cardiovascular regulation. Providing a solution to them pushes forward the frontier of science, and enables us to formulate new methods of cardiological diagnosis and risk stratification, which results in more efficient patient handling - see [1] and [2] for recent successful examples of such an approach. One of important physiological variables under consideration is the arterial blood pressure (ABP). Increased variability of ABP is related with increased risk of end-organ damage [3]. It is important to understand the mechanisms that introduce or reduce the instability of ABP. The relation between the heart rate (HR) and the ABP is a subject of intensive experimental and theoretical study
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