Linear and non-linear assessment of heart rate variability in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) is characterised by the failure of the autonomic control of breathing and is defined as a multi-system disorder with symptoms of diffuse autonomic nervous system dysfunction. The present study, considering the heart rate variability (HRV) parameters as expression of cardiac autonomic nervous system activity, reports higher heart rate (HR) levels and reduced HRV, at rest in supine position, in CCHS patient in comparison with controls. The CCHS subject presented lower values of HF spectral component and SD1 Poincaré plot parameter, indicating a decrease of vagal cardiac influence.

Linear and non-linear parameters of heart rate variability during static and dynamic exercise in a high-performance dinghy sailor.

The analysis of heart rate variability (HRV) is recognized as a powerful non-invasive tool to evaluate the influence of autonomic nervous system on the heart and the heart-brain interaction. It is well-known that relatively high HRV is correlated to health condition while low HRV corresponds to cardiovascular disease or could be caused by mental stress, depression or exercise. In order to investigate heart-brain interaction we compare linear and non linear parameters calculated from HRV signals recorded in the same subject at similar heart rate (HR) values, during two different conditions, i.

Computer aided data acquisition and analysis of acetlycholinesterase velocity sedimentation profiles.

Acetylcholinesterase (AChE) is an enzyme that appears in several molecular forms. Individual AChE molecular forms can be isolated and identified on the basis of their velocity sedimentation profiles. We have improved an existing method for analyzing AChE sedimentation profiles with a computer aided data acquisition and analysis system.

Pressure sensitivity of flow oscillations in postocclusive reactive skin hyperemia.

Skin blood flow was monitored using a laser-Doppler (LD) flowmeter in 21 healthy volunteers after an occlusion of the digital arteries. The peripheral vascular bed was exposed to occlusion ischemia of varying duration (1, 4, or 8 min) and to a change in digital arterial pressure produced by different positions of the arm above heart level to characterize the pattern of LD flow oscillations in postocclusive reactive hyperemia (PRH) and to elucidate the relevance of metabolic and myogenic mechanisms in governing its fundamental frequency. The descending part of the hyperemic flow was characterized by the appearance of conspicuous periodic oscillations with a mean fundamental frequency of 7.

The voltage-clamp apparatus assisted by a 'current pump'.

A current pump is described, which is attached to the last stage of the 2-microelectrode voltage-clamp apparatus. Thus a voltage-to-current conversion independent of the impedance of the current microelectrode is obtained. In this way it is possible to pass relatively large currents through the current microelectrode and in the same time to have a stable negative feed-back system.

Further observations on modelling of the cardiovascular function in the electrical model.

In 1976 the fourth type of the electrical model of the cardiovascular function was constructed, showing formal and electronic changes: inverting system, hysteresis comparator (for the valve function), simulation of the insufficiency and the stenosis of the valves. The analog values were established but they are not yet definitive. The important values are: pressure 100 mm Hg = 100mV; flow 100 ml/sec = 137 microA.

Dynamic characteristics of the thorax connected with the heart action.

We determined the indices of local vibrations (resonance frequency, damping coefficient, stiffness constant, extinction time) and transfer function H(s) . 10(-6) for three somatotypes and three respiratory positions on 88 points of the thorax. The examinees were males (age 21 years).