F. Helderman

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Wall shear stress (WSS), the frictional force between blood and endothelium, is an important determinant of vascular function. It is generally assumed that WSS remains constant at a reference value of 15 dyn/cm(2). In a study of small rodents, we realized that this assumption could not be valid. This review presents an overview of recent studies in large(More)
PURPOSE To evaluate if early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension (PAH). MATERIALS AND METHODS Fifty-five patients with suspected pulmonary hypertension (PH) underwent right-sided heart catheterization and retrospectively ECG-gated MR phase-contrast velocity quantification in the main(More)
RATIONALE Pulmonary hypertension (PH) is characterized by increased arterial load requiring more right ventricular (RV) hydraulic power to sustain adequate forward blood flow. Power can be separated into a mean and oscillatory part. The former is associated with mean and the latter with pulsatile blood flow and pressure. Because mean power provides for net(More)
BACKGROUND Atherosclerosis is considered an inflammatory disease. Recent studies provided evidence for a predominant upstream location of plaque inflammation. The present study introduces a novel technique that evaluates the underlying mechanism of this spatial organization. METHODS AND RESULTS In hypercholesterolemic rabbits, atherosclerosis of the(More)
BACKGROUND Pulmonary artery (PA) dilatation is one of the consequences of pulmonary arterial hypertension (PAH) and is used for noninvasive detection. However, it is unclear how the size of the PA behaves over time and whether it is related to pressure changes. The aim of this study was to evaluate PA size during follow-up in treated patients with PAH and(More)
Atherosclerotic lesions preferentially localize near side branches or curved vessels. During the last few decades, research has been shown that low or low and oscillating shear stress is associated with plaque location. Despite ample evidence, the precise mechanism is unknown. This is mainly because of a lack of appropriate animal models. We describe two(More)
PURPOSE OF REVIEW This review describes evidence that shear stress acts through modulation of inflammation and by that process affects atherogenesis and plaque composition. RECENT FINDINGS In low shear stress regions antiatherogenic transcription factors are downregulated and pro-atherogenic transcription factors are upregulated. Consequently,(More)
Aneurysms of the abdominal aorta enlarge until rupture occurs. We assume that this is the result of remodelling to restore wall stress. We developed a numerical model to predict aneurysm expansion based on this assumption. In addition, we obtained aneurysm geometry of 11 patients from computed tomography angiographic images to obtain patient specific(More)
PURPOSE To assess pulmonary artery (PA) size, flow variables, and wall shear stress (WSS) in patients after Fontan operation at a young age. MATERIALS AND METHODS Flow in the branch PA was obtained with phase contrast velocity-encoded cardiovascular magnetic resonance imaging in 14 patients before and after low-dose dobutamine stress (7.5 microg/kg/min)(More)