A number of methods for constructing bounding volume hierarchies and point-based octrees on the GPU are based on the idea of ordering primitives along a space-filling curve. A major shortcoming with these methods is that they construct levels of the tree sequentially, which limits the amount of parallelism that they can achieve. We present a novel approach that improves scalability by construct...

The linear dimensions of the ventricle of an in situ perfused trout heart were measured with an ultrasound scanner. Using a pyramidal model, linear dimensions taken from real-time, two-dimensional, echotomographic images of the ventricle were used to calculate ventricular end-diastolic and end-systolic volumes and, by the difference between them, stroke volumes for various filling and output pr...

OBJECTIVES To examine relationships between severity of echocardiography (echo) -evidenced diastolic dysfunction (DD) and volumetric filling by automated processing of routine cine cardiovascular magnetic resonance (CMR). BACKGROUND Cine-CMR provides high-resolution assessment of left ventricular (LV) chamber volumes. Automated segmentation (LV-METRIC) yields LV filling curves by segmenting a...

To test the hypothesis that the effects of positive end-expiratory airway pressure (PEEP) on intracavitary left ventricular end-diastolic pressure (LVEDP) depend on the ventricular filling conditions under which PEEP is applied, the effects of PEEP on pressure in and around the left ventricle were determined before and after stepwise expansion of intravascular blood volume in 10 closed-chest do...

Symptoms of intravascular volume overload and increased cardiac filling pressures in the systemic and pulmonary venous circulations are among the most common complaints in patients with chronic heart failure (CHF). The clinical utility of physical examination for estimation of intravascular volume status in patients with CHF is limited due to poor specificity and sensitivity of most signs of co...

Methods 31 patients (20.6 ± 10.3 years) underwent an MRI examination before and after (20 ± 18 months) pulmonary valve replacement or reconstruction (PVR) for the volume overload of the RV. For segmental analysis of the RV, a custom made analysis software was developed. The method provides an automatic contour detection algorithm for the determination of the RV blood volume and enables the user...

BACKGROUND Transmitral Doppler flow indices are used to evaluate diastolic function. Recently, velocities measured by Doppler tissue imaging have been used as an index of left ventricular relaxation. OBJECTIVE To determine whether Doppler tissue velocities are influenced by alterations in preload. METHODS Left ventricular preload was altered in 17 patients (all men, mean (SD) age, 49 (8) ye...

A large atrial contribution to left ventricular (LV) filling (%A) in patients with LV hypertrophy has been assumed by some to indicate abnormal LV compliance. We tested this assumption by examining the influence of short- and long-term changes in load on compliance and filling dynamics using nitroprusside to decrease load in 11 patients with severe aortic stenosis (AS) and ergonovine to increas...

Background: Transmitral Doppler flow indices are used to evaluate diastolic function. Recently, velocities measured by Doppler tissue imaging have been used as an index of left ventricular relaxation. Objective: To determine whether Doppler tissue velocities are influenced by alterations in preload. Methods: Left ventricular preload was altered in 17 patients (all men, mean (SD) age, 49 (8) yea...

We studied the effects of the right ventricle (RV) and pericardium on left ventricular (LV) diastolic pressure-volume (P-V) relations in the normothermic isolated blood-perfused dog heart. Studies were performed at a constant heart rate (atrial pacing at 120 beats/min) with a coronary perfusion pressure of 100 mm Hg. LV volume was directly controlled by an intraventricular balloon, whereas RV f...