BACKGROUND The effective aortic regurgitant orifice area varies with aortic pressure in animal models of acute aortic regurgitation. The purpose of this study was to determine whether the aortic regurgitant orifice area changes during diastole in patients with chronic aortic regurgitation. METHODS AND RESULTS Two-dimensional and Doppler echocardiography were performed immediately before and a...

The sizeof the compensating orifice in the slipper of hydrostatic units has an important influence on the volumetric, mechanical, and overall efficiencies. A simple model was derived to predict the changes in efficiencies caused byfirst reducing and then blanking the orifice. Testing in a hydrostatic unit was performed to measure the effects of the slipper orifice design on efficiency. Comparis...

BACKGROUND AND AIM OF THE STUDY In patients with aortic stenosis (AS), it has been reported that the transvalvular pressure gradients (APs) may be reduced or even abolished in the presence of concomitant arterial hypertension, but the mechanisms underlying this phenomenon remain unclear. The study aim was to: (i) examine the relationship between systemic arterial hemodynamics and the peak-to-pe...

The definition of air resistance is nonuniform when analyzing the bearing capacity, stiffness, and stability an orifice throttling aerostatic restrictor. In this study, a capillary tube similar to inlet section restrictor used as research object, Bernoulli equation under adiabatic conditions established. Through experiment, pressure temperature outlet flow through are measured. Based on definit...

The present work involves measurements to examine the effects of initial conditions on aerodynamic and acoustic characteristics of a Jet at M=0.8 by changing the orientation of sharp edged orifice plate. A thick plate with chamfered orifice presented divergent and convergent openings when it was flipped over. The centerline velocity was found to decay more rapidly for divergent orifice and that...

The present work involves measurements to examine the effects of initial conditions on aerodynamic and acoustic characteristics of a Jet at M=0.8 by changing the orientation of sharp edged orifice plate. A thick plate with chamfered orifice presented divergent and convergent openings when it was flipped over. The centerline velocity was found to decay more rapidly for divergent orifice and that...

BACKGROUND Precise knowledge of left atrial appendage (LAA) orifice size is crucial for correct sizing of LAA closure devices. The aim of the present study was to determine the performance of real-time 3D transesophageal echocardiography (RT3DTEE) for LAA orifice size assessment, compared with 2D transesophageal echocardiography (2DTEE), and to investigate the impact of atrial fibrillation (AF)...

In low flow states, underestimation errors occur when the Gorlin formula is used to calculate valve area. A model of valvular stenosis designed to examine changes in the hydraulic discharge coefficient (Cd) and coefficient of orifice contraction (Cc) may explain these errors. Unsteady flow was examined in a pulsatile pump model and in a dog model. Valve areas were calculated from pressure and f...

Background Precise knowledge of left atrial appendage (LAA) orifice size is crucial for correct sizing of LAA closure devices. Aim of the present study was to determine the performance of real-time three-dimensional transesophageal echocardiography (RT3DTEE) for LAA orifice size assessment, compared to twodimensional transesophageal echocardiography (2DTEE), and to investigate the impact of atr...

AIMS Pulsed Doppler measurement of left atrial appendage (LAA) emptying velocity, a marker of left atrium contractile function, has been shown to predict success of cardioversion, thrombo-embolic risk, and maintenance of sinus rhythm after cardioversion and pulmonary vein isolation. However, in the published literature, emptying velocity measurement location is not uniform, and no standard curr...