Poor fidelity invasive arterial blood pressure (IABP) traces are a frequent practical problem. It is common practice to describe any such trace as being 'damped'; the resonance behaviour of IABP measurement systems having been extensively described in the literature. However, as poor quality arterial blood pressure signals are seen even with optimal pressure transduction circuits, this cannot b...

We present a novel analysis of arterial pulse wave propagation that combines traditional wave intensity analysis with identification of Windkessel pressures to account for the effect on the pressure waveform of peripheral wave reflections. Using haemodynamic data measured in vivo in the rabbit or generated numerically in models of human compliant vessels, we show that traditional wave intensity...

BACKGROUND Atherosclerosis begins in the arterial wall, with endothelial dysfunction accompanied by functional and structural changes that influence arterial stiffness. Pulse contour analysis provides an assessment of compliance or elasticity of the large conduit arteries (C(1)) and small microcirculatory arteries (C(2)). In this study, the predictive value of reduced elasticity of these arteri...

This study combines experimental and modeling approaches in order to investigate the temporal dynamics of the human brain at rest. The dynamics of the neuronal activity is modeled with FitzHugh-Nagumo oscillators and the blood-oxygen-level-dependent (BOLD) time series is inferred via the Balloon-Windkessel hemodynamic model. The simulations are based on structural connections that are derived f...

Patient-specific one-dimensional (1D) blood flow modeling requires estimating model parameters from available clinical data, ideally acquired noninvasively. The larger the number of arterial segments in a distributed 1D model, the greater the number of input parameters that need to be estimated. We investigated the effect of a reduction in the number of arterial segments in a given distributed ...

We present preliminary data of the vascular hemodynamics in a novel, anatomically shaped ascending aortic graft in comparison to non-operated individuals by use of 3D magnetic resonance (MR) flow measurements. We examined a 72-year-old male patient after Tiron David I valve sparing aortic root reconstruction and replacement of the ascending aorta (AAo) with an anatomically curved prosthesis. Re...

Recently, it was shown that proportional relationships exist between systolic, diastolic and mean pulmonary artery pressure (P(sys), P(dia) and P(mean)) and that they are maintained under various conditions in both health and disease. An arterial-ventricular interaction model was used to study the contribution of model parameters to the ratios P(sys)/P(mean), and P(dia)/P(mean). The heart was m...

Our aim was to use early magnetic resonance imaging (MRI) to investigate the causes of cognitive decline in elderly people with mild cognitive impairment (MCI). Baseline structural and flow quantification MR sequences, and clinical and neuropsychological follow-up for at least two years, were performed on 62 elderly subjects with MCI. Of these subjects, 17 progressed to dementia, and 15 of thes...

BACKGROUND Altitude and gravity changes during aeromedical evacuations induce exacerbated cardiovascular responses in unstable patients. Non-invasive cardiac output monitoring is difficult to perform in this environment with limited access to the patient. We evaluated the feasibility and accuracy of stroke volume estimation by finger photoplethysmography (SVp) in hypergravity. METHODS Finger ...

Pulmonary artery (PA) impedance provides detailed information on right ventricular (RV) afterload in pulmonary hypertension (PH). This study aimed to examine PA impedance in a rat model of monocrotaline-induced PH (MCT-PH) and to develop an experimental system for in vivo loading of pathological PA impedance on the RV of normal rats. PA impedance was quantified in normal (n= 10) and MCT-PH rats...