Twenty two patients (four men, 18 women, mean age 56 years, range 21 to 88 years) with a history of rheumatic mitral stenosis were studied by cross sectional echocardiography before and after balloon dilatation of the mitral valve. The appearance of the mitral valve on the pre-dilatation echocardiogram was scored for leaflet mobility, leaflet thickening, subvalvar thickening, and calcification....

Inspiratory threshold loading is an important tool in assessing inspiratory muscle function and has been widely used in studies of respiratory mechanics. A simple system was designed to provide a pure and precise inspiratory threshold load. The inspiratory threshold loading system comprises a flow generator attached via a pressure chamber, to the inspiratory port of a Hans-Rudolph valve. By lim...

BACKGROUND Incremental threshold loading (ITL) is a test of inspiratory muscle performance which is usually performed by breathing through a weighted inspiratory plunger, the load on the inspiratory muscles being increased by externally adding weights to the intake valve. This is not a true threshold device and may be inaccurate. This method was compared with a true threshold device consisting ...

Functional mitral regurgitation (MR) is a common finding in patients with global left ventricular (LV) dilatation and dysfunction. In these patients, the mitral leaflets are structurally normal and leaflet coaptation failure results from an imbalance between valve closing forces and valve tethering forces. Impaired LV contractility, global LV dyssynchrony, and reduced mitral annulus systolic co...

A 73-year-old woman was admitted to our hospital for a scheduled percutaneous transcatheter balloon valvuloplasty of a stenotic tricuspid bioprosthesis. The patient had a history consistent with exertional dyspnea, abdominal distension, and edema of the lower extremities resistant to diuretic treatment over the previous few months. Forty-three years prior, she underwent aortic valve replacement...

BACKGROUND Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. METHODS AND RESULTS We report data from 20 consecutive clinical cases in which BVF was successfully performed before or afte...

The prognostic implications of pulmonary hypertension in chronic lung disease, and the difficulty in establishing its severity without cardiac catheterisation, indicate the need for a reliable non-invasive method of assessing the pulmonary artery pressure. It is likely that the time taken by the right ventricle to generate a sufficiently high pressure to open the pulmonary valve will increase p...

There are three forces acting on the valve plate: the force of the escaping air Fv, the force of the steel spring Fs and the pneumatic damping force due to the pressure of the air in the dashpot Fd. Each of these forces varies with distance x. These interact with the valve mass and the pipeline dynamics to produce instability. Perturbations in the pressure travel along the pipe at the sonic vel...

We develop accurate analytical relations for the droplet volume ratio, droplet length during breakup process, and pressure drop of asymmetric T junctions with a valve in each of the branches for producing unequal-sized droplets. An important advantage of this system is that after manufacturing the system, the size of the generated droplets can be changed simply by adjusting the valves. The resu...