The opening and closure intervals of heart valves are important factors regarding an optimal blood flow. Using endoscopic video recordings of heart valves, digital kymography can be a method to visualize and to describe the opening and closure intervals. Based on an adequate segmentation of the kymograms, a quantitative description becomes available for the opening and closure characteristics. ...

BACKGROUND The dynamic changes of anterior mitral leaflet (AML) curvature are of primary importance for optimal left ventricular filling and emptying but are incompletely characterized. METHODS AND RESULTS Sixteen radiopaque markers were sutured to the AML in 11 sheep, and 4-dimensional marker coordinates were acquired with biplane videofluoroscopy. A surface subdivision algorithm was applied...

Previous studies of the dynamic geometry of the left ventricle have yielded conflicting results concerning shape changes during the preejection period. Accordingly, left ventricular dimensional changes prior to aortic valve opening in man were analyzed using high-speed biplane cineradiograms exposed in the frontal and lateral projections. In each projection the long axis and three chords perpen...

The in vivo operation of a speaking valve consists of two stages: 1) air passes through the razor-thin slit, the dome opens and the patient can speak; 2) the dome is closed and the patient cannot speak. The valve is thus subject to fatigue, as its service life is made up of a certain number of opening/closing cycles. Two types of valve were investigated: the Staffieri valve and a new valve prot...

BACKGROUND Considerable discrepancies between Doppler and catheter gradients caused by localized gradients and pressure recovery have been reported for normal bileaflet aortic valve prostheses. METHODS AND RESULTS To examine whether this Doppler-catheter gradient relation is affected by prosthetic valve malfunction, a 19-mm CarboMedics aortic valve was simultaneously studied with continuous-w...

BACKGROUND In patients with hypertrophic cardiomyopathy, obstruction to left ventricular outflow is produced by systolic anterior motion of the mitral valve. In many of these patients, the mitral leaflets are elongated and increased in overall size. Mitral valve size may be responsible, in part, for the presence and magnitude of the outflow gradient and the pattern of systolic anterior motion o...

We present a three-dimensional computer simulation of the dynamics of a vein valve. In particular, we couple the solid mechanics of the vein wall and valve leaflets with the fluid dynamics of the blood flow in the valve. Our model captures the unidirectional nature of blood flow in vein valves; blood is allowed to flow proximally back to the heart, while retrograde blood flow is prohibited thro...

an s-curve to describe the gradual transition between exhaust pressure and intake or inlet pressure. The start of compression, which marks the end of the intake process, does not necessarily occur at the same time as the close of the intake valve (IVC). The intake valve closes after bottom center (BC) while the volume in the cylinder is decreasing. The engine speed determines the point at which...