Grzegorz Graff

Relationship between heart rate variability, blood pressure and arterial wall properties during air and oxygen breathing in healthy subjects.

Previous studies reported that normobaric hyperoxia influences heart rate, arterial pressure, cardiac output and systemic vascular resistance, but the mechanisms underlying these changes are still not fully understood. Several factors are considered including degeneration of endothelium-derived nitric oxide by reactive oxygen species, the impact of oxygen-free radicals on tissues and alterations of autonomic nervous system function. Recently, new devices for the detailed non-invasive assessment of large and small arteries have been developed. Therefore, the aim of our study was to assess heart rate variability (HRV) as a potential indicator of autonomic balance and its relation to blood pressure and vascular properties during medical air (MAB) and 100% oxygen breathing (OXB) in healthy volunteers. In 12 healthy subjects we assessed heart rate and blood pressure variability, baroreflex sensitivity, respiratory frequency, common carotid artery diameter and its wall distensibility, as well as changes in the digital artery pulse waveform, stroke index and systemic vascular resistance during MAB and OXB. Mean and systolic blood pressure have increased significantly while digital pulse amplitude and carotid artery diameter were significantly lower during hyperoxia. Heart rate variability measures did not differ during MAB and OXB. However, the correlations between spectral HRV components and those hemodynamic parameters which have changed due to hyperoxia varied substantially during MAB (correlated significantly) and OXB (no significant correlations were noted). Our findings suggest that autonomic nervous system might not be the main mediator of the cardiovascular changes during 100% oxygen breathing in healthy subjects. It seems that the direct vascular responses are initial consequences of hyperoxia and other cardiovascular parameter alterations are secondary to them.

Minimal number of periodic points for C 1 self-maps of compact simply-connected manifolds

Abstract Let ƒ be a self-map of a smooth compact connected and simply-connected manifold of dimension m ≥ 3, r a fixed natural number. In this paper we define a topological invariant which is the best lower bound for the number of r-periodic points for all C 1 maps homotopic to ƒ. In case m = 3 we give the formula for and calculate it for self-maps of S 2 × I.

Fixed point indices of iterations of planar homeomorphisms

Let

Entropy Measures in the Assessment of Heart Rate Variability in Patients with Cardiodepressive Vasovagal Syncope

f

Electrophysiological features in patients with sinus node dysfunction and vasovagal syncope

be a local planar homeomorphism with an isolated fixed point at

Minimal number of periodic points for smooth self-maps of two-holed 3-dimensional closed ball

0

Computing algebraic transfer entropy and coupling directions via transcripts

. We study the form of the sequence

On the growth of the number of periodic points for smooth self-maps of a compact manifold

\{\ind(f^n,0)\}_{n\not=0},

General form of fixed point indices of an iterated C 1 map and infiniteness of minimal periods

where

Periodicity of a sequence of local fixed point indices of iterations

\ind(f,0)