As the ventricle contracts in systole, there is longitudinal shortening ( negative strain ), circumferential shortening ( negative strain ) and transmural ( wall ) thickening ( positive strain ).
12.
Transmural deformation has also been called " radial ", but this is unfortunate as in ultrasound in general the term radial describes " in the direction of the ultrasound beam " ).
13.
In principle Speckle tracking is available for deformation measurement in all directions, however, due to the limitation of lateral resolution in apical images, measuring circumferential and transmural deformation needs parasternal cross sectional views.
14.
The large negative intra-thoracic pressure increases the pressure across the wall of the left ventricle ( increased transmural pressure, equivalent to [ pressure within ventricle ]-[ pressure outside of ventricle ] ).
15.
Additionally, having a smaller preload reduces the ventricular transmural pressure ( pressure exerted on the walls of the heart ), which decreases the compression of heart arteries to allow more blood to flow through the heart.
16.
It is unclear if syrinx fluid originates from bulk movement of cerebrospinal fluid into the spinal cord, from bulk transmural movement of blood fluids through the spinal vasculature into the syrinx, or from a combination of both.
17.
transmural pressure ( P ) and cavitary radius ( r ) and inversely proportionate to wall thickness ( W ) : In response to the pressure overload left ventricular wall thickness markedly increases while the cavitary radius remains relatively unchanged.
18.
However, transmural pressure across the wall of the blood vessels increases down this zone due to gravity . consequently the vessels wall are more stretched so the caliber of the vessels increases causing an increase in flow due to lower resistance.
19.
The tube law, the relation between transmural pressure P-Pexternal ( where p is the internal pressure ) and alpha, for a long thin-walled tube can be approximated by thin-shell theory for an axially uniform elastic ring
20.
"' Compliance "'is the ability of a hollow organ ( vessel ) to distend and increase volume with increasing transmural pressure or the tendency of a hollow organ to resist recoil toward its original dimensions on application of a distending or compressing force.
