In-cylinder exhaust gas recirculation (EGR) stratification, generally achieved by supplying EGR asymmetrically into intake ports on a four-valve diesel engine, is sensitive to trapped exhaust gas in the intake manifold and intake ports that is caused by the continuous supply of EGR during the valve-close periods of the intake valves. The subject of this study is to evaluate the distribution of ...

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...

Since April 1969, frame-mounted three-cusp fascia lata and pericardial valves have been used in over 200 patients for heart valve replacement. Six autologous fascia lata valves have been removed from the mitral position because of regurgitation produced by shrinkage of one or two cusps. To elucidate the cause and mechanism of graft failure the opening characteristics of fascia lata and Silastic...

Twenty-seven patients with complete right bundle-branch block as the only abnormal finding were studied using high speed M-mode echocardiography to determine the effect of the electrical delay on the mechanical events of right ventricular systole. Pulmonary valve opening (PVOm) was delayed in all cases. In some the delay was mainly between mitral valve closure (MVC) and tricuspid valve closure ...

Electrical Impedance Tomography (EIT) is a non-invasive and low-cost functional imaging technique that measures thoracic impedance. Until now, it was primarily used to reveal respirationrelated changes in the lungs. However, recent work has shown the feasibility of using this technology to monitor hemodynamic parameters. In particular, mean arterial blood pressure can be estimated via EIT, give...

Regional abnormalities of left ventricular function are frequently determined from superimposed cavity outlines at end-diastole and end-systole. The timing of end-diastole is standardised with respect to the electrocardiogram, but that of end-systole is undefined, and frequently determined by simple inspection. To examine the effect of variation in the timing of the end-systolic frame on appare...

Disc excursion and opening and closing velocities of prosthetic disc valves can be measured accurately by diagnostic echocardiography. The ultrasound beam is projected along the longitudinal axis of the valve and the echoes arising from the struts, disc, and suture ring are displayed on the oscilloscope. Twenty-four patients with normally functioning mitral Beall valves of various sizes and thr...

The aortic valve echogram was recorded in open chest dogs simultaneously with aortic flow, acceleration of flow, aortic and left ventricular pressures, and intracardiac phonocardiograms. Comparison of echographic with hemodynamic data showed the following: The aortic valve started its opening with the onset of flow, at the same point that left ventricular pressure exceeded aortic pressure. Comp...

The speed of closure of the mitral valve during diastole, as recorded by ultrasonocardiography, is reduced in patients with mitral stenosis. A pattern of movement similar to that of severe mitral stenosis is seen in recordingsfrom patients with normally functioning mitral Starr-Edwards prostheses. Simultaneous ultrasound recordings of ball and cage movements show that the prosthetic valve remai...