Three-Dimensional Ultrasound Imaging Model of Mitral Valve Regurgitation: Design and Evaluation

Abstract

We describe the development of a cardiac flow model and imaging chamber to permit Doppler assessment of complex and dynamic flow events. The model development included the creation of a circulatory loop with variable compliance and resistance; the creation of a secondary regurgitant circuit; and incorporation of an ultrasound imaging chamber to allow two-dimensional (2D) and three-dimensional (3D) Doppler characterization of both simple and complex models of valvular regurgitation. In all, we assessed eight different pulsatile regurgitant volumes through each of four rigid orifices differing in size and shape: 0.15 cm 2 circle, 0.4 cm 2 circle, 0.35 cm 2 slot and 0.4 cm 2 arc. The achieved mean (and range) hemodynamic measures were: peak trans-orifice pressure gradient 117 mm Hg (40 to 245 mm Hg), trans-orifice peak Doppler velocity 560 cm/s (307 to 793 cm/s), Doppler time-velocity integral 237 cm (111 to 362 cm), regurgitant volume 43 mL (11 to 84 mL) and orifice area 0.32 cm 2 (0.15 to 0.4 cm 2 ). The model was designed to optimize Doppler signal quality while reflecting anatomic structural relationships and flow events. The 2D color Doppler, 3D color Doppler and continuous wave Doppler quality was excellent whether the data were acquired from the imaging window parallel or perpendicular to the long-axis of flow. This model can be easily adapted to mimic other intracardiac flow pathology or assess future Doppler applications.

Quantification of Chronic Functional Mitral Regurgitation by Automated 3-Dimensional Peak and Integrated Proximal Isovelocity Surface Area and Stroke Volume Techniques Using Real-Time 3-Dimensional Volume Color Doppler Echocardiography

“…15 The model consisted of a circulatory loop, regurgitant circuit, a flowmeter, and an ultrasound imaging chamber. Pulsatile flow was driven through the regurgitant loop incorporating a divider plate containing a modifiable orifice.…”

“…15,23 In the current PISA algorithm, although the peak PISA technique was automated, the integrated PISA technique required manual addition of RVol from each frame. However, this is more practical than any other integrated PISA method described in the literature.…”

Regurgitation Quantification Using 3D PISA in Volume Echocardiography

“…To probe the accuracy of the EROA measurement, we created an in vitro phantom (described in [6]) with several orifice shapes in which the flow could be controlled to lie within a physiologically relevant severity of regurgitation (12-57mL/beat). The flow loop was constructed to create physiologically relevant pressure differential and flow across the orifice of a regurgitant valve [6]. Data acquisition was performed using a standard clinical 3D full volume ultrasound scanner.…”

Assessment of Paravalvular Regurgitation Following Transcatheter Aortic Valve Replacement

“…64 Extension of this technology to 3D color Doppler volume sets is now possible and allows rapid, accurate, and reproducible quantitation of relative stroke volumes. 65, 66 Thavendiranathan and colleagues 66 used the velocity information encoded in the volume color Doppler data, targeting the appropriate region of interest by using the simultaneous 3D imaging of the mitral annulus and LVOT. Fig.…”