Functional imaging computational fluid dynamics simulations of right ventricular (RV) inflow fields were obtained by comprehensive software using individual animal-specific dynamic imaging data input from three-dimensional (3-D) real-time echocardiography (RT3D) on a CRAY T-90 supercomputer. Chronically instrumented, lightly sedated awake dogs (n = 7) with normal wall motion (NWM) at control and normal or diastolic paradoxical septal motion (PSM) during RV volume overload were investigated. Up to the E-wave peak, instantaneous inflow streamlines extended from the tricuspid orifice to the RV endocardial surface in an expanding fanlike pattern. During the descending limb of the E-wave, large-scale (macroscopic or global) vortical motions ensued within the filling RV chamber. Both at control and during RV volume overload (with or without PSM), blood streams rolled up from regions near the walls toward the base. The extent and strength of the ring vortex surrounding the main stream were reduced with chamber dilatation. A hypothesis is proposed for a facilitatory role of the diastolic vortex for ventricular filling. The filling vortex supports filling by shunting inflow kinetic energy, which would otherwise contribute to an inflow-impeding convective pressure rise between inflow orifice and the large endocardial surface of the expanding chamber, into the rotational kinetic energy of the vortical motion that is destined to be dissipated as heat. The basic information presented should improve application and interpretation of noninvasive (Doppler color flow mapping, velocity-encoded cine magnetic resonance imaging, etc.) diastolic diagnostic studies and lead to improved understanding and recognition of subtle, flow-associated abnormalities in ventricular dilatation and remodeling.

We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts. cardiac image analysis; ventricular function; cardiac fluid dynamics; right ventricle; heart chamber volume QUANTITATIVE ANALYSIS of three-dimensional (3-D) digital cardiac images has become increasingly important given the recent advances in the digital cardiac imaging techniques of 3-D echocardiography, magnetic resonance imaging, computed tomography, and digital fluoroscopy (1,24,26). The growth of these digital imaging techniques is accompanied by an increasing usage of image manipulation tools, providing more elaborate image analysis and measurement and quantitative evaluation and leading to more refined diagnostic accuracy than visual interpretation alone. Moreover, complex mathematical procedures are being used to localize and highlight important changes in cardiac function that cannot be visually detected directly from the original images. With the concurrent development of high-performance computers and analytical software, a functional sort of imaging can now evolve, geared toward the creation of physiological images that are the result of a mathematical simulation derived from a set of images. Such functional imaging will allow visualization and understanding of the evolution of any dynamic process of interest (filling, ejection) within the heart. Accordingly, it should allow better insights into cardiac physiology and pathophysiology and may possibly detect warning signs of diseases not yet overt.This study developed innovative dynamic geometric chamber reconstruction models for use in functional imaging analyses of right ventricular (RV) filling dynamics and physiology. With the use of a new volumetric "prism method," it is first shown that the geometric chamber reconstructions provide accurate and reliable dynamic instantaneous RV chamber geometry ...

By limiting filling, abnormalities of right ventricular (RV) diastolic function may impair systolic function and affect adaptation to disease. To quantify diastolic RV pressure-volume relations and myocardial compliance (MC), a new sigmoidal model was developed. RV micromanometric and sonomicrometric data in alert dogs at control (n ϭ 16) and under surgically induced subacute (2-5 wk) RV pressure overload (n ϭ 6), volume overload (n ϭ 7), and ischemia (n ϭ 6) were analyzed. The conventional exponential model detected no changes from control in the passive filling pressure-volume (Ppf -V) relations. The new sigmoidal model revealed significant quantifiable changes in Ppf -V relations. Maximum RV MC (MCmax), attained during early filling, is reduced from control in pressure overload (P ϭ 0.0016), whereas filling pressure at maximum MC (PMCmax) is increased (P ϭ 0.0001). End-diastolic RV MC increases significantly in volume overload (P ϭ 0.0131), whereas enddiastolic pressure is unchanged. In ischemia, MCmax is decreased (P ϭ 0.0102), with no change in PMCmax. We conclude that the sigmoidal model quantifies important changes in RV diastolic function in alert dog models of pressure overload, volume overload, and ischemia. diastole; dynamics; heart failure; myocardial compliance; right ventricle RIGHT VENTRICULAR (RV) diastolic abnormalities such as reduced myocardial compliance (MC) may impair systolic function by limiting filling and play an integral role in cardiac adaptations to disease. Nevertheless, the development of indexes for RV function has evolved slowly, and numerous gaps remain in our understanding of RV diastolic function (10,13,28). Limitation of our understanding of the right ventricle can be attributed to the paucity of information from animal analogs of human RV disease and the lack of mathematical models for the analysis of RV performance. In contrast, comparable aspects relating to the left ventricle (3, 9, 17, 23) are much more highly developed. However, the simple application of indexes developed for the left ventricle to RV function has led to confusing and conflicting results.The primary aim of the current study is to derive and validate new mathematical models and indexes specifically for the analysis of RV diastolic dynamics and the quantitative assessment of diastolic RV dysfunction and failure. Recognizing that a consensus has not been reached on what constitutes a correct mathematical descriptor of diastolic pressure-volume relations even for the extensively studied left ventricle, we propose that these new conceptual approaches will also contribute to the study of left ventricular function. Our present focus, however, is on RV diastolic pressurevolume relations and corresponding myocardial properties utilizing newly developed, chronically instrumented, awake dog models of RV volume overload (VO) and RV free-wall ischemia (IS) and a conventional model of RV pressure overload (PO). METHODS Sensor ImplantationExperimental animals (20-30 kg dogs) were premedicated with cefazolin (500 mg) an...