The influence of boundary conditions on wall shear stress distribution in patients specific coronary trees.

Patient specific geometrical data on human coronary arteries can be reliably obtained multislice computer tomography (MSCT) imaging. MSCT cannot provide hemodynamic variables, and the outflow through the side branches must be estimated. The impact of two different models to determine flow through the side branches on the wall shear stress (WSS) distribution in patient specific geometries is evaluated.

Why can pulmonary vein stenoses created by radiofrequency catheter ablation worsen during and after follow-up? A potential explanation.

Background: Radiofrequency catheter ablation of excitation foci inside pulmonary veins (PV) generates stenoses that can become quite severe during or after the follow-up period. Since severe PV stenoses have most often disastrous consequences, it would be important to know the underlying mechanism of this temporal evolution. The present study proposes a potential explanation based on mechanical considerations.

Could increased axial wall stress be responsible for the development of atheroma in the proximal segment of myocardial bridges?

Background: A recent model describing the mechanical interaction between a stenosis and the vessel wall has shown that axial wall stress can considerably increase in the region immediately proximal to the stenosis during the (forward) flow phases, so that abnormal biological processes and wall damages are likely to be induced in that region. Our objective was to examine what this model predicts when applied to myocardial bridges.

Method: The model was adapted to the hemodynamic particularities of myocardial bridges and used to estimate by means of a numerical example the cyclic increase in axial wall stress in the vessel segment proximal to the bridge.

Are intramural suction-squeezing effects generated by the variations in radial wall stress during each heart beat the motor of atherosclerosis? A new concept.

In the early sixties, the existence of predilection sites for atherosclerotic lesions inside the arterial circulation led to the concept that low wall shear stress (WSS) was responsible, together with systemic factors like high blood pressure, hypercholesterolemia, or diabetes, for the genesis and progression of atherosclerosis. It was found later that oscillating WSS and high WSS gradients could also be incriminated. Yet, this concept, which is broadly accepted today, fails to explains several facts, for instance that some arteries (e.

An analytical model for the investigation of axial wall forces generated by an arterial stenosis.

The causes of arteriosclerosis are intensively investigated since many decades. While circumferential wall stress has received a lot of attention, axial stress (also called "longitudinal" stress) has been largely neglected, and practically never incriminated. However, it has been suggested in 2003 that moderate and severe arterial stenoses may induce non negligible axial forces cyclically in the vessel segment just proximal to the constriction cone.