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We assessed the variability of the series resulting from the subtraction of the RR intervals from the pulse intervals (PI-RR) and examined how it was affected by two maneuvers that modify the cardiac autonomic status. The RR, PI, PI-RR and respiratory series of 20 healthy subjects were computed during three 5-min conditions: supine, standing and exercise. High frequency (HF) and low frequency (LF)...
Our aims were to assess: 1) the variability of the systolic and diastolic periods, estimated by the electromechanical interval measured from the R wave to the systolic peak of the pressure wave (RPre), and the interval from this peak to the next R wave (PreR), respectively; 2) the effect of two maneuvers on the variability of these periods. ECG, arterial pressure and respiration were recorded from...
Spectral components of cardiovascular oscillations are related to complex autonomic control mechanisms. Since these oscillations are non-stationary, time-frequency (T-F) analysis has been used in studying cardiovascular oscillations such as variabilities of heart rate and blood pressure; however, few studies have extended the T-F analysis to other cardiovascular signals such as pulse transit time...
This paper first describes the AM-FM demodulation of an arterial pressure signal. Although it is known to be efficient on signals modulated by breathing, we demonstrate that in case of lack of respiratory modulation (real or simulated central sleep apnea), the AM-FM algorithm doesn't perform well in heart rate extraction. We introduce then a new algorithm based on singular spectrum analysis eigen...
This paper examines the effect of water ingestion on the cardiovascular system, utilizing advanced fluctuation analysis. The ingestion of water has been known to significantly raise the blood pressure in subjects with autonomic disorders, resulting in the effect of preventing syncope occurrences. For precise characterization of the effect of water ingestion, head-up tilt experiments at 80 degrees...
Estimation of the baroreflex gain has become an important tool in clinical practice in order to assess cardiac autonomic system control. Spectral analysis and sequence analysis techniques based on the spontaneous variability of systolic arterial pressure and heart period have been proposed to evaluate the baroreflex gain. These analyses can be significantly altered by the presence of nonstationarities...
Atrial fibrillation (AF) is a common arrhythmia characterized by desynchronization of atrial electrical activity causing a consequent irregular ventricular response. Blood pressure (BP) fluctuates in a complex mode composed of both short-term and long-term variability. In AF, the beat-to-beat variation of BP is increased because of variations in filling time and in contractility. However, a few studies...
Cardiac autonomic control was studied in a group of five young hyperinsulinaemic, insulin resistant, Zucker fatty rats (ZFR) compared with a control group of five young Zucker lean rats (ZLR). Power spectrum analysis (PSA) of heart rate variability (HRV) was performed with autoregressive (AR) models. All rats were anaesthetised with sodium pentobarbital. Mean insulinaemia and glycaemia levels were...
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