Craig E. Fleishman

Real-time Three-dimensional Echocardiography for Determining Right Ventricular Stroke Volume in an Animal Model of Chronic Right Ventricular Volume Overload

BACKGROUND The lack of a suitable noninvasive method for assessing right ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our animal study was to test a new real-time three-dimensional (3D) echo imaging system for evaluating RV stroke volumes. METHODS AND RESULTS Three to 6 months before hemodynamic and 3D ultrasonic study, the pulmonary valve was excised from 6 sheep (31 to 59 kg) to induce RV volume overload. At the subsequent session, a total of 14 different steady-state hemodynamic conditions were studied. Electromagnetic (EM) flow probes were used for obtaining aortic and pulmonic flows. A unique phased-array volumetric 3D imaging system developed at the Duke University Center for Emerging Cardiovascular Technology was used for ultrasonic imaging. Real-time volumetric images of the RV were digitally stored, and RV stroke volumes were determined by use of parallel slices of the 3D RV data set and subtraction of end-systolic cavity volumes from end-diastolic cavity volumes. Multiple regression analyses showed a good correlation and agreement between the EM-obtained RV stroke volumes (range, 16 to 42 mL/beat) and those obtained by the new real-time 3D method (r=0.80; mean difference, -2.7+/-6.4 mL/beat). CONCLUSIONS The real-time 3D system provided good estimation of strictly quantified reference RV stroke volumes, suggesting an important application of this new 3D method.

Real-time, three-dimensional echocardiography : Feasibility of dynamic right ventricular volume measurement with saline contrast

BACKGROUND The asymmetry and complex shape of the right ventricle have made it difficult to determine right ventricular (RV) volume with 2-dimensional echocardiography. Three-dimensional cardiac imaging improves visualization of cardiac anatomy but is also complex and time consuming. A newly developed volumetric scanning system holds promise of obviating past limitations. METHODS Real-time, transthoracic 3-dimensional echocardiographic images of the right ventricle were obtained with a high-speed volumetric ultrasound system that uses a 16:1 parallel processing schema from a 2.5 MHz matrix phased-array scanner to interrogate an entire pyramidal volume in real time. The instrumentation was used to measure RV volume in 8 excised canine hearts; dynamic real-time 3-dimensional images were also obtained from 14 normal subjects. RESULTS Three-dimensional images were obtained in vitro and in vivo during intravenous hand-agitated saline injection to determine RV volumes. The RV volumes by real-time 3-dimensional echocardiography are well correlated with those of drained in vitro (y = 1.26x - 9.92, r = 0.97, P <.0001, standard error of the estimate = 3.26 mL). For human subjects, the end-diastolic and end-systolic RV volumes were calculated by tracing serial cross-sectional, inclined C scans; functional data were validated by comparing the scans with conventional 2-dimensional echocardiographic indexes of left ventricular stroke volume. CONCLUSIONS These data indicate that RV volume measurements of excised heart by real-time 3-dimensional echocardiography are accurate and that beat-to-beat RV quantitative measurement applying this imaging method is possible. The new application of real-time 3-dimensional echocardiography presents the opportunity to develop new descriptors of cardiac performance.

Real-time volumetric echocardiography: the technology and the possibilities.

The heart is a dynamic organ with complexities in its shape. As such, it places special demands on three‐dimensional techniques for reconstruction. Real‐time volumetric echocardiography, which is based on phased array and parallel processing principles to enhance line density within a scan volume, provides rapid image acquisition. We introduce the principle, potential clinical importance, current limitations, and future of volumetric imaging methods.

Active contour based on the elliptical Fourier series, applied to matrix-array ultrasound of the heart

We describe an active contour based on the elliptical Fourier series, and its application to matrix-array ultrasound. Matrix-array ultrasound is a new medical imaging modality that scans a 3D-volume electronically without physically moving the transducer, allowing for real-time continuous 3D imaging of the heart. Unlike other 3D ultrasound modalities which physically move a linear array, matrix array ultrasound is rapid enough to capture an individual cardiac cycle, yielding a temporal resolution of 22 volumetric scans per second. With the goal of automatically tracking the heart wall, an active contour has been developed using the elliptical Fourier series to find perpendicular lines intersecting an initial contour. The neighborhood defined by these perpendiculars is mapped into a rectangular space, called the 1D swath, whose vertical axis represents the inside-vs.-outside dimension of the contour (along the perpendicular), and whose horizontal axis represents parametric distance along the contour (tangent to the contour). A dynamic programming technique is then used to find the optimum error function traversing the rectangle horizontally, and this error function is mapped back into image space to yield a new contour. The method does not iterate, but rather simultaneously searches for the optimum contour within a limited domain. Results are presented applying the technique to 3D ultrasound images of in vivo hearts.

ACC/AAP/AHA/ASE/HRS/ SCAI/SCCT/SCMR/SOPE 2014 Appropriate Use Criteria for Initial Transthoracic Echocardiography in Outpatient Pediatric Cardiology

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XX PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XX

Fontan Fenestration Closure Prior to Posterior Spinal Fusion in Patients With Single-Ventricle Heart Disease.

Study Design. Case series. Objective. To describe transcatheter closure of the Fontan fenestration prior to posterior spinal fusion in two children to prevent paradoxical venous air embolism during the operation. Summary of Background Data. Scoliosis is common among patients with single-ventricle congenital heart disease who have undergone Fontan operation and spinal surgery can offer physiologic benefits. Venous air embolism is a rare, but important reported complication during spinal surgery performed in the prone position. Patients with Fontan circulation can have significant right to left shunting via a patent Fontan fenestration that can increase the risk of paradoxical systemic embolization of any entrained venous air. Methods. We retrospectively reviewed the charts of two patients with single-ventricle congenital heart disease who had undergone fenestrated Fontan operation and underwent transcatheter fenestration closure prior to spinal fusion. Results. Two patients with Fontan circulation underwent successful transcatheter fenestration closure with Amplatzer Ductal Occluder II devices. Five to 6 months after closure, both underwent uncomplicated posterior spinal fusion. Conclusion. Transcatheter closure of the Fontan fenestration prior to spinal fusion in two with Fontan circulation and scoliosis is a rare, but important indication for fenestration closure that warrants emphasis. Level of Evidence: N/A