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Background: Quantification of defect size and shunt flow is an important aspect of ventricular septal defect (VSD) evaluation. This study compared three-dimensional echocardiography (3DE) with the current clinical standard two-dimensional echocardiography (2DE) for quantifying defect area and tested the feasibility of real time 3D color Doppler echocardiography (RT3D-CDE) for quantifying shunt volume of irregular shaped and multiple VSDs., Methods: Latex balloons were sutured into the ventricles of 32 freshly harvested porcine hearts and were connected with tubing placed in septal perforations. Tubing was varied in area (0.13-5.22 cm²), number (1-3), and shape (circle, oval, crescent, triangle). A pulsatile pump was used to pump "blood" through the VSD (LV to RV) at stroke volumes of 30-70 mL with a stroke rate of 60 bpm. Two-dimensional echocardiography (2DE), 3DE, and RT3D-CDE images were acquired from the right side of the phantom., Results: For circular VSDs, both 2DE and 3DE area measurements were consistent with the actual areas (R² = 0.98 vs 0.99). For noncircular/multiple VSDs, 3DE correlated with the actual area more closely than 2DE (R² = 0.99 vs 0.44). Shunt volumes obtained using RT3D-CDE positively correlated with pumped stroke volumes (R² = 0.96)., Conclusions: Three-dimensional echocardiography (3DE) is a feasible method for determining VSD area and is more accurate than 2DE for evaluating the area of multiple or noncircular VSDs. Real-time 3D color Doppler echocardiography (RT3D-CDE) is a feasible method for quantifying the shunt volume of multiple or noncircular VSDs., (© 2017 Wiley Periodicals, Inc.)

Background: The aim of this study is to assess the accuracy and feasibility of left ventricular systolic function determined by four-dimensional echocardiography (4DE)., Methods: Latex balloons were sewn into the left ventricle (LV) of 20 freshly harvested pig hearts which were then passively driven by a pulsatile pump apparatus. Global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS) and left ventricular ejection fraction (LVEF) derived from 4DEand two-dimensional echocardiography (2DE)-derived LVEF were quantified at different stroke volumes (SV) 30-70 ml and correlated with sonomicrometry data., Results: In all comparisons, GLS, GCS, GAS, 2DE-LVEF, and 4DE-LVEF demonstrated strong correlations with sonomicrometry data (r = 0.77, r = 0.89, r = 0.79, r = 0.93, r = 0.96, all P <0.001). Bland-Altman analyses showed slight overestimations of echo-derived GLS, GCS, 2DE-LVEF and 3DE-LVEF over sonomicrometry values (bias = 2.88, bias = 3.99, bias = 3.37, bias = 2.78, respectively). Furthermore, there is better agreement between GCS, 4D LVEF and sonomicrometry values compared with GLS and 2D LVEF., Conclusion: Four-dimensional echocardiography accurately assesses LV function. GCS derived by 4DE is a potential alternative parameter to quantify LV systolic function.

Background: Left ventricular stroke volume, mass, and myocardial strain are valuable indicators of fetal heart function. This study investigated the feasibility of nongated real time three-dimensional echocardiography (RT3DE) to determine fetal stroke volume (SV), left ventricular mass (LVM), and myocardial strain under different conditions., Methods: To evaluate fetal hearts, fetal-sized rabbit hearts were used in this study. The in vitro portion of this study was carried out using a balloon inserted into the LV of eight fresh rabbit hearts and driven by a calibrated pulsatile pump. RT3DE volumes were obtained at various pump-set SVs. The in vivo experiments in this study were performed on open-chest rabbits. RT3DE volumes were acquired at the following conditions: baseline, simulated hypervolemia, inferior vena cava (IVC) ligation, and ascending aorta (AAO) ligation. Displacement values and sonomicrometry data were used as references for RT3DE-derived SV, LVM, longitudinal strain (LS), and circumferential strain (CS)., Results: Excellent correlations between RT3DE-derived values and reference values were demonstrated and accompanied by high coefficients of determination (R(2) ) for both in vitro and in vivo studies for SV, LVM, LS, and CS (in vitro: SV: R(2)  = 0.98; LVM: R(2)  = 0.97; LS: R(2)  = 0.87, CS: R(2)  = 0.80; in vivo: SV: R(2)  = 0.92; LVM: R(2)  = 0.98; LS: in vivo: R(2)  = 0.84; CS: in vivo: R(2)  = 0.76; all P < 0.05)., Conclusions: RT3DE is capable of quantifying the SV, LVM, and myocardial strain of fetal-sized hearts under different conditions. This nongated RT3DE may aid the evaluation of fetal cardiac function, providing a superior understanding of the progress of fetal heart disorders., (© 2015, Wiley Periodicals, Inc.)

Objective: To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis using adenosine-infusion cardiac magnetic resonance., Background: It is unclear whether asymptomatic children with mild/moderate aortic stenosis have myocardial abnormalities. In addition, cardiac magnetic resonance-determined normative myocardial blood flow data in children have not been reported., Methods: We studied 31 infants and children with either haemodynamically normal hearts (n=20, controls) or mild/moderate aortic stenosis (n=11). The left ventricular myocardium was divided into six segments, and the change in average segmental signal intensity during contrast transit was used to quantify absolute flow (ml/g/minute) at rest and during adenosine infusion by deconvolution of the tissue curves with the arterial input of contrast., Results: In all the cases, adenosine was well tolerated without complications. The mean pressure gradient between the left ventricle and the ascending aorta was higher in the aortic stenosis group compared with controls (24 versus 3 mmHg, p<0.001). Left ventricular wall mass was slightly higher in the aortic stenosis group compared with controls (65 versus 50 g/m², p<0.05). After adenosine treatment, both the absolute increase in myocardial blood flow (p<0.0001) and the hyperaemic flow significantly decreased (p<0.001) in children with mild/moderate aortic stenosis compared with controls., Conclusion: Abnormal myocardial blood flow in children with mild/moderate aortic stenosis may be an important therapeutic target.

We investigated the effect of fetal sheep ductus arteriosus occlusion (DO) on the distribution of cardiac output and left and right ventricular function by tissue and pulsed Doppler at baseline; after 15 and 60 min of DO induced with a vascular occluder; and 15 min after release of DO. Ductal occlusion decreased fetal pO2. Mean left ventricular output increased (p < 0.001) from 725 to 1013 mL/min, and right ventricular (1185 mL/min vs. 552 mL/min) and systemic (1757 mL/min vs. 1013 mL/min) cardiac outputs fell (p < 0.001) after 15 min of DO, compared with baseline. Pulmonary vascular impedance decreased and volume blood flow increased more than threefold during DO, whereas foramen ovale volume blood flow remained unchanged. Left ventricular systolic function was unaffected, whereas isovolumic relaxation velocity deceleration decreased. Right ventricular functional indices remained unchanged. We conclude that DO increased pulmonary volume blood flow, not foramen ovale volume blood flow. Left ventricular output increased, although not as much as right ventricular output fell, resulting in decreased systemic cardiac output. During DO, left ventricular function exhibited diminished relaxation., (Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Purpose: Quantitative analysis of right ventricle (RV) motion is important for study of the mechanism of congenital and acquired diseases. Unlike left ventricle (LV), motion estimation of RV is more difficult because of its complex shape and thin myocardium. Although attempts of finite element models on MR images and speckle tracking on echocardiography have shown promising results on RV strain analysis, these methods can be improved since the temporal smoothness of the motion is not considered., Methods: The authors have proposed a temporally diffeomorphic motion estimation method in which a spatiotemporal transformation is estimated by optimization of a registration energy functional of the velocity field in their earlier work. The proposed motion estimation method is a fully automatic process for general image sequences. The authors apply the method by combining with a semiautomatic myocardium segmentation method to the RV strain analysis of three-dimensional (3D) echocardiographic sequences of five open-chest pigs under different steady states., Results: The authors compare the peak two-point strains derived by their method with those estimated from the sonomicrometry, the results show that they have high correlation. The motion of the right ventricular free wall is studied by using segmental strains. The baseline sequence results show that the segmental strains in their methods are consistent with results obtained by other image modalities such as MRI. The image sequences of pacing steady states show that segments with the largest strain variation coincide with the pacing sites., Conclusions: The high correlation of the peak two-point strains of their method and sonomicrometry under different steady states demonstrates that their RV motion estimation has high accuracy. The closeness of the segmental strain of their method to those from MRI shows the feasibility of their method in the study of RV function by using 3D echocardiography. The strain analysis of the pacing steady states shows the potential utility of their method in study on RV diseases.

Objective: This study aimed to evaluate the instantaneous biological response of canine myocardium in vivo to high-intensity focused ultrasound (HIFU) ablation, and thereby determine the feasibility of this method., Methods: Left ventricle myocardium HIFU ablation was performed on six dogs at four levels of HIFU energy (acoustic intensity was 3000 W/cm2 ; ablation durations were 1.2, 2.4, 3.6, and 4.8 sec, respectively). Gross lesion volumes were confirmed and assessed by tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and electron microscopy. Global cardiac function and focal wall motion were evaluated by echocardiography. Blood enzymes and cardiac troponin T (CTnT) were tested after ablation. HIFU ablation was repeated on another set of six fresh canine hearts in vitro at the same four energy levels. Focal maximum temperatures were detected both in vivo and in vitro., Results: Different sizes of ablation via HIFU can be created in beating hearts using controlled energy emission. Focal maximum temperatures varied from 62 ± 4.8 °C to 81 ± 12.9 °C. The lesion sizes were significantly smaller in vivo than in vitro, as verified by TTC and HE staining. Focal wall motion immediately decreased after ablation (P < 0.05), although the ejection fraction (EF) and E/A ratio were unchanged (P > 0.05). Enzymes and CTnT immediately increased., Conclusion: HIFU can be used for the controllable ablation of myocardial tissue, with instantly increased serum markers, decreased regional wall motion, and unaffected left ventricular global function., (© 2014, Wiley Periodicals, Inc.)

Aims: This study aimed to assess the feasibility and accuracy of nongated four-dimensional echocardiography (4DE) for determining left ventricular (LV) stroke volume (SV) and mass in a fetal heart-sized LV model., Methods: A balloon was inserted into the LV of 20 fresh rabbit hearts and attached to a calibrated pulsatile pump. Ten hearts retaining the right ventricle were imaged in Group A. Ten hearts without the right ventricles (RVs) attached were imaged in Group B. Nongated 4D volumes were obtained using a Philips iU-22 system with an X6-1 matrix probe at SVs ranging from 1 to 5 mL at increments of 1 mL. At each SV, the volume displacement of the heart was measured at end-systole and end-diastole. Mass was determined by displacement at the conclusion of the experiment., Results: The images were analyzed offline by manually tracing endocardial and epicardial boundaries of stacked contours. An excellent correlation in SV and mass between echo-derived values and displacement values was demonstrated and accompanied by high coefficients of determination (R2 ) in both groups (SV: Group A: R2 = 0.9461, Group B: R2 = 0.9811; Mass: Group A: R2 = 0.9223, Group B: R2 = 0.9602; all P < 0.001). Bland-Altman analyses showed a slight overestimation in both groups for both SV and LV mass., Conclusions: Nongated 4DE was demonstrated to be feasible and that it could accurately define SV and ventricular mass for a fetal heart-sized LV model., (© 2014, Wiley Periodicals, Inc.)

Objectives: The aim of this study was to assess the accuracy, feasibility, and reproducibility of determining stroke volume from a novel 3-dimensional (3D) color Doppler flow quantification method for mitral valve (MV) inflow and left ventricular outflow tract (LVOT) outflow at different stroke volumes when compared with the actual flow rate in a pumped porcine cardiac model., Methods: Thirteen freshly harvested pig hearts were studied in a water tank. We inserted a latex balloon into each left ventricle from the MV annulus to the LVOT, which were passively pumped at different stroke volumes (30-80 mL) using a calibrated piston pump at increments of 10 mL. Four-dimensional flow volumes were obtained without electrocardiographic gating. The digital imaging data were analyzed offline using prototype software. Two hemispheric flow-sampling planes for color Doppler velocity measurements were placed at the MV annulus and LVOT. The software computed the flow volumes at the MV annulus and LVOT within the user-defined volume and cardiac cycle., Results: This novel 3D Doppler flow quantification method detected incremental increases in MV inflow and LVOT outflow in close agreement with pumped stroke volumes (MV inflow, r = 0.96; LVOT outflow, r = 0.96; P < .01). Bland-Altman analysis demonstrated overestimation of both (MV inflow, 5.42 mL; LVOT outflow, 4.46 mL) with 95% of points within 95% limits of agreement. Interobserver variability values showed good agreement for all stroke volumes at both the MV annulus and LVOT., Conclusions: This study has shown that the 3D color Doppler flow quantification method we used is able to compute stroke volumes accurately at the MV annulus and LVOT in the same cardiac cycle without electrocardiographic gating. This method may be valuable for assessment of cardiac output in clinical studies.

Objectives: We sought to determine the feasibility and reproducibility of real-time 3-dimensional echocardiography (RT3DE) for evaluation of cardiac volume, mass, and function and to characterize maturational changes of these measurements in human fetuses., Methods: Eighty pregnant women in the 2(nd) and 3(rd) trimesters (59 with normal fetuses and 21 with fetuses with congenital heart disease [CHD]) were enrolled. We acquired RT3DE images using a matrix-array transducer. RT3DE measurements of volume, mass, stroke volume (SV), combined cardiac output (CCO), and ejection fraction (EF) were obtained. Images were scored and analyzed by two blinded independent observers. Inter- and intraobserver variabilities and correlations between fetal cardiac indices and gestational age were determined., Results: Fifty-two of 59 normal data sets (88%) and 9 of 21 CHD data sets (43%) were feasible for analysis. In normal fetuses, the right ventricle (RV) is larger than the left ventricle (LV) (P<0.05), but no difference exists between the LV and RV in mass, SV, CO, and CO/CCO. The EFs for the LV and RV were diminished; the RVSV/LVSV was reduced in CHD fetuses compared with normal fetuses (P<0.05). Fetal ventricular volumes, mass, SV, and CCO fit best into exponential curves with gestational age, but LVEF, RVEF, and RVSV/LVSV remain relatively constant., Conclusions: RT3DE is feasible and reproducible for assessment of LV and RV volume, mass, and function, especially in normal fetuses. Gestational growth of these measures, except for EF, is exponential in normal and CHD fetuses. CHD fetuses exhibit diminished LV and RV EFs.

Background: Echocardiography with speckle tracking is a novel, angle-independent technique for assessing global and regional cardiac function. Normal data on longitudinal strain have been reported for human fetuses. The aim of this study was to define circumferential left ventricular (LV) strain in a normal fetal population., Methods: Singleton fetuses between 17 and 42 weeks in gestational age with no adverse maternal health issues or fetal abnormalities were studied. Regional and averaged cardiac strain were measured using syngo Velocity Vector Imaging software., Results: Data from 81 fetuses were analyzed (mean gestational age, 29.2 ± 5.7 weeks). Overall, average midventricular circumferential strain was 18.7 ± 3.3%, LV longitudinal strain was 15.2 ± 2.7%, and right ventricular longitudinal strain was 16.0 ± 3.3%, with no correlation with gestational age., Conclusion: This is the first study to report normal fetal LV circumferential strain. These data may be useful as a reference for assessing fetal cardiac function. The retrospective study design and relatively low frame rates used in this study were important limitations., (Copyright © 2012. Published by Mosby, Inc.)

The right ventricular (RV) volume is commonly measured from magnetic resonance images using Simpson's method from the stack of short-axis images acquired for analysis of the left ventricle. We compared the RV volume measured using Simpson's method to the RV volume measured using 3-dimensional reconstruction and the piecewise smooth subdivision surface (PSSS) method. We studied 6 normal subjects and 18 patients whose right ventricles carried a systemic pressure load, 1/2 with dexto-transposition of the great arteries repaired with an atrial baffle and 1/2 with levo-transposition of the great arteries. The right ventricle was reconstructed from manually traced borders from the short- and long-axis views using the PSSS method. Simpson's analysis was performed on short-axis views alone. The RV volumes were smaller when analyzed using Simpson's method than using the PSSS method. The underestimation averaged 12 +/- 19 ml (7 +/- 12% of PSSS volume; p <0.001), without a significant difference between the groups. The ejection fraction was similar using both methods in patients with transposition of the great arteries and was overestimated in normal subjects. Image review revealed that the volume underestimation using Simpson's method was more frequently due to difficulty in interpreting the basal short-axis images than the apical images. In conclusion, to obtain accurate analysis of the short-axis views for RV volume measurement, it would be helpful to incorporate information from additional images, such as the long-axis views, to assist in delineating this chamber's complex anatomy., (Copyright 2010 Elsevier Inc. All rights reserved.)

Objective: Left ventricular (LV) twist is manifested in oppositely directed apical and basal rotation. We studied a new 3-dimensional (3D) echocardiography program (wall motion tracking; Toshiba America Medical Systems, Inc, Tustin, CA) for left ventricular rotation., Methods: We used a rotation model with a variable-speed motor to rotate hearts in a water bath. We studied 10 freshly harvested pig hearts, which were mounted on the rotary actuator of our twist phantom with the heart base rotating and the apex held fixed to avoid translational motion, at rotations of 0 degrees , 15 degrees , 20 degrees , and 25 degrees . Full-volume 3D image loops were acquired on a Toshiba Aplio Artida ultrasound system at a maximized frame rate., Results: As the actual heart rotation increased, computed segmental and global rotation also increased accordingly, with the measured rotations of the basal and middle segments greater than that of the apex (both P < .001). Segmental and global rotation at all 3 levels correlated well with the actual rotation (base: r = 0.93; middle: r = 0.92; apex: r = 0.82; global: r = 0.95; all P < .001)., Conclusions: The new 3D program tracked LV rotation accurately.

Preliminary speckle-tracking echocardiographic studies show that patients with single ventricles (SVs) have significantly decreased twisting and dyssynchrony of twisting. This could be related to abnormal cardiac looping, which leads to hearts that lack helical fiber patterns. The aim of this study was to analyze gradient cine magnetic resonance imaging (MRI) using Velocity Vector Imaging to assess cardiac mechanics. Subjects were 38 patients (aged 8 to 37 years) with SVs of left ventricular (n = 30) and indeterminate (n = 8) type who underwent cardiac MRI. Controls were 14 normal children and adults. Gradient cine MRI sequences close to the apex were subjected to a Velocity Vector Imaging analysis program adapted for MRI. In the control group, mean circumferential strain was -18.02 +/- 7.31%, mean dispersion of peak circumferential strain was 44.23 +/- 37.14 ms, and average rotation was -7.7 +/- 1.38 degrees . The rotation values were negative, or counterclockwise. In patients with SVs, mean circumferential strain was -8.87 +/- 7.30%, mean dispersion of peak circumferential strain was 181.55 +/- 76.07 ms, and average rotation was -2.6 +/- 1.24 degrees (p <0.001). Mean dispersion of the peak of rotation in the control group was 39.6 +/- 22.8 ms, compared to 166.5 +/- 72.4 ms in patients with SVs. In conclusion, this study showed a dramatic decrease in apical rotation and circumferential strain in the SV group compared to the control group. Strain and rotation mechanics at the apex in patients with SVs showed marked dyssynchrony., (Copyright 2010 Elsevier Inc. All rights reserved.)

We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks. We measured the RV volume using KBR from magnetic resonance images in 20 patients with repaired tetralogy of Fallot at end-diastole and end-systole. We entered points in the long- and short-axis and/or oblique views. The true volume was computed by manually tracing the RV borders for 3-dimensional reconstruction using the piecewise smooth subdivision surface method. The reference database included 54 patients with tetralogy of Fallot patients. The KBR values agreed closely with the true values for the end-diastolic volume (r = 0.993), end-systolic volume (r = 0.992), and ejection fraction (EF; r = 0.930). KBR slightly overestimated the end-diastolic volume (4 +/- 10 ml, p = NS), end-systolic volume (1 +/- 9 ml, p = NS), and EF (4 +/- 3%, p = NS). No bias in the error was found by Bland-Altman analysis (p = NS for end-diastolic and end-systolic volume and EF). The KBR volumes had approached the true volumes (235 +/- 93 vs 243 +/- 93, p = 0.012, r = 0.978 for end-diastolic and end-systolic volumes combined) already after the first run and the entry of 19 +/- 3 points. In conclusion, KBR provided accurate measurement of the RV volume and EF with minimal user input. KBR is a clinically feasible alternative to full manual tracing of the heart borders from imaging data., (Copyright 2010 Elsevier Inc. All rights reserved.)

Objectives: To compute left ventricular (LV) twist from 3-dimensional (3D) echocardiography., Background: LV twist is a sensitive index of cardiac performance. Conventional 2-dimensional based methods of computing LV twist are cumbersome and subject to errors., Methods: We studied 10 adult open-chest pigs. The pre-load to the heart was altered by temporary controlled occlusion of the inferior vena cava, and myocardial ischemia was produced by ligating the left anterior descending coronary artery. Full-volume 3D loops were reconstructed by stitching of pyramidal volumes acquired from 7 consecutive heart beats with electrocardiography gating on a Philips IE33 system (Philips Medical Systems, Andover, Massachusetts) at baseline and other steady states. Polar coordinate data of the 3D images were entered into an envelope detection program implemented in MatLab (The MathWorks, Inc., Natick, Massachusetts), and speckle motion was tracked using nonrigid image registration with spline-based transformation parameterization. The 3D displacement field was obtained, and rotation at apical and basal planes was computed. LV twist was derived as the net difference of apical and basal rotation. Sonomicrometry data of cardiac motion were also acquired from crystals anchored to epicardium in apical and basal planes at all states., Results: The 3D dense tracking slightly overestimated the LV twist, but detected changes in LV twist at different states and showed good correlation (r = 0.89) when compared with sonomicrometry-derived twist at all steady states. In open chest pigs, peak cardiac twist was increased with reduction of pre-load from inferior vena cava occlusion from 6.25 degrees +/- 1.65 degrees to 9.45 degrees +/- 1.95 degrees . With myocardial ischemia from left anterior descending coronary artery ligation, twist was decreased to 4.90 degrees +/- 0.85 degrees (r = 0.8759)., Conclusions: Despite lower spatiotemporal resolution of 3D echocardiography, LV twist and torsion can be computed accurately., (Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging (2DS). Twenty-five piglets were studied. The short axis views were acquired. Peak systolic radial strain was measured from 6 circumferential points related to 6 standard segments in the inner and outer layers respectively using 2DS methods. The peak positive first derivative (dp/dt) of left ventricular pressure was compared to the radial strain from 2DS. The inner band showed higher peak radial strain values as compared to the outer band at all of the segments (P<0.0001), but the differences had significance just in anteroseptal, posterior, inferior and septal segments (P<0.05). Good correlation could be found between radial strain of inner and outer layers and peak dp/dt (P<0.001). These preliminary results showed that the degree of local deformation or wall thickening of the ventricular wall in its inner layer was more obvious than its outer layer. It is suggested that the 2DS technique is useful and sensitive for better understanding the regional and global myocardial motion and its relationship to the complex architecture of myocardium.

Objective: The purpose of this study was to develop a high-resolution, near-field-optimized 14-MHz, 24-element broad-bandwidth forward-looking array for integration on a steerable 9F electrophysiology (EP) catheter., Methods: Several generations of prototype imaging catheters with bidirectional steering, termed microlinear (ML), were built and tested as integrated catheter designs with EP sensing electrodes near the tip. The wide-bandwidth ultrasound array was mounted on the very tip, equipped with an aperture of only 1.2 by 1.58 mm. The array pulse echo performance was fully simulated, and its construction offered shielding from ablation noise. Both ex vivo and in vivo imaging with a porcine animal model were performed., Results: The array pulse echo performance was concordant with Krimholtz-Leedom-Matthaei model simulation. Three generations of prototype devices were tested in the right atrium and ventricle in 4 acute pig studies for the following characteristics: (1) image quality, (2) anatomic identification, (3) visualization of other catheter devices, and (4) for a mechanism for stabilization when imaging ablation. The ML catheter is capable of both low-artifact ablation imaging on a standard clinical imaging system and high-frame rate myocardial wall strain rate imaging for detecting changes in cardiac mechanics associated with ablation., Conclusions: The imaging resolution performance of this very small array device, together with its penetration beyond 2 cm, is excellent considering its very small array aperture. The forward-looking intracardiac catheter has been adapted to work easily on an existing commercial imaging platform with very minor software modifications.

Understanding of right ventricular (RV) remodeling is needed to elucidate the mechanism of RV dysfunction in the overloaded right ventricle, but is hampered by the chamber's complex shape. We imaged 15 patients with repaired tetralogy of Fallot (TOF) and 8 normal subjects by magnetic resonance imaging in long- and short-axis views. We reconstructed the right ventricles in 3 dimensions using the piecewise smooth subdivision surface method. Shape was analyzed from cross-sectional contours generated by intersecting the right ventricle with 20 planes evenly spaced from apex to tricuspid annulus. Patients with TOF had dilated right ventricles compared with normal (end-diastolic volume index 216 +/- 99 vs 81 +/- 16 ml/m(2), p <0.001) but near-normal function (ejection fraction 40 +/- 9% vs 48 +/- 12%, respectively, p = NS). RV shape in patients with TOF differed from normal subjects in several ways. First, the right ventricle had a larger normalized cross-sectional area in patients with TOF (p <0.01 in apical planes). Second, the cross-sectional shape was rounder in patients with TOF (p <0.05 in apical planes). Also, the interventricular septum underwent relatively less enlargement so that it comprised only 27 +/- 4% of total RV surface area in patients with TOF, compared with 33 +/- 2% in normal subjects (p = 0.0001). In addition, the right ventricle in patients with TOF exhibited bulging basal to the tricuspid valve (4 +/- 4% of total RV length), unlike normals (1 +/- 2%, p <0.001). This basal bulging was amplified by tilting of the tricuspid annulus (29 +/- 11 degrees vs 15 +/- 7 degrees , respectively, p <0.005). In conclusion, the right ventricle remodels in several directions rather than following a shape continuum. Characterization of RV remodeling from 3-dimensional reconstructions provides novel insights.

Objectives: We tested a newly developed 4-dimensional (4D) right ventricular (RV) analysis method for computing RV volumes for both 3-dimensional (3D) ultrasound (US) and magnetic resonance (MR) images., Background: Asymmetry and the anatomical complexity of the RV make accurate determination of RV shape and volume difficult., Methods: Thirty patients, 14 with grossly normal cardiac anatomy and 16 with major congenital heart disease, were studied at the same visit with both 3D echocardiography (echo) and magnetic resonance imaging (MRI) for RV size and function. Ultrasound images were acquired on a Philips 7500 system (Philips Medical Systems, Andover, Massachusetts) with a matrix-array transducer (real-time 3D echo) with full volume sweeps from apical and subcostal views. Sagittal, 4-chamber, and coronal views were derived for contour detection (all 12 to 24 slices). The MR images were acquired with a 3-T MRI magnet with segmented cine-loop gradient echo sequences in short- and rotated long-axis views to cover the RV inflow, body, and outflow tract. The RV volumes were analyzed with the new software applicable to 3D echo MR images., Results: New software aided delineation of the RV free wall, tricuspid valve, RV outflow tract, and apex on 3D echo volumes. Although there was a slightly higher variability measuring right ventricular ejection fraction (RVEF) and volumes obtained by US compared with MRI, both imaging methods showed closely correlated results. The RVEF was measured with 4% variability for US and 5% variability for MRI with a correlation coefficient of r = 0.91. The RV end-diastolic volume was measured at 70.97 +/- 15.0 ml with 3D US and at 70.06 +/- 14.8 ml with MRI (r = 0.99), end-systolic volume measured 39.8 +/- 10.4 ml with 3D US and 39.1 +/- 10.2 ml with MRI (r = 0.98)., Conclusions: The new RV analysis software allowed validation of the accuracy of 4D echo RV volume data compared with MRI.

Background: We sought to assess the accuracy and reproducibility of an automated real-time (RT) 3-dimensional (3D) Doppler echocardiography (RT3DDE) technique for measuring volumetric flow (VF) in children., Methods: A total of 19 healthy children (age = 11.5 +/- 3.5 years) were studied to measure VF through mitral valve (MV), aortic valve (AV), pulmonary valve (PV), and tricuspid valve (TV) by RT3DDE. RT 3D echocardiography was also performed to measure left ventricular (LV) end-systolic volume, LV end-diastolic volume, and stroke volume (stroke volume = LV end-diastolic volume--LV end-systolic volume), which served as a reference standard for comparison with VF by RT3DDE., Results: Compared with stroke volume by RT 3D echocardiography, the correlation with VF was excellent for MV (r = 0.91), good for AV (r = 0.89) and PV (r = 0.89), but poor for TV (r = 0.20) by RT3DDE. There were good agreements for AV (bias = 0.9 +/- 5.0 mL), PV (bias = -0.4 +/- 5.7 mL), and MV (bias = 4.1 +/- 4.7 mL), and marked underestimation for TV (bias = -24.4 +/- 14.6 mL)., Conclusions: Our data demonstrated that VF measurement by RT3DDE is feasible and reasonably accurate for MV, AV, and PV but problematic for TV.

Background: Torsion is an essential component of left ventricular (LV) function. Systolic rotation, as a component of torsion, winds the heart muscle up like a spring, setting up recoil for early diastole. We used a new 2-dimensional speckle tracking strain method to study differences in twisting in subendocardial and subepicardial layers of the LV in open-chest pigs. Our aim was to identify the relative contributions of the inner or outer layers of the LV wall to rotation and, hence, systole., Methods: A total of 23 juvenile pigs were imaged in the short axis, epicardially, to obtain images at a level just below the papillary muscles with high-frequency (14 MHz) ultrasound. Speckle tracking software using scanline files was used to measure the torsional contribution of septum, anterior, posterior, and inferior LV wall segments. Two zones on the septum were evaluated separately: one with apparent circumferential fiber orientation in the inner layer and one with a speckle pattern suggesting longitudinal fiber orientation on the right ventricular aspect of the septum. Pressure rate changes (dP/dt) during the cardiac cycle were measured as an index of LV function and correlated with the regional torsion., Results: Mean peak rotations measured by speckle tracking echocardiography at the apex showed counterclockwise rotation of LV septal wall (10.68 +/- 2.67 degrees for the inner layer and 8.27 +/- 1.73 degrees for the outer layer). The time difference for time to peak rotation was 213.22 +/- 77.95 and 241.17 +/- 54.67 milliseconds for inner and outer layers, respectively. Significant differences were shown between the inner and outer layer of the LV for both rotation (P = .000) and timing of rotation (P = .02). The dP/dt measurements correlated well with the inner rotation magnitude of the LV and with the difference of short-axis rotation between inner and outer layers of the LV wall., Conclusions: Inner and outer layers of the LV wall, especially at the septum, have different rotational behaviors. When used with very high-resolution imaging, this method could contribute to the understanding of functional contributions of the LV wall and their relative contribution to cardiac segmental twisting.

Automated motion reconstruction of the left ventricle (LV) from 3D echocardiography provides insight into myocardium architecture and function. Low image quality and artifacts make 3D ultrasound image processing a challenging problem. We introduce a LV tracking method, which combines textural and structural information to overcome the image quality limitations. Our method automatically reconstructs the motion of the LV contour (endocardium and epicardium) from a sequence of 3D ultrasound images.

Objectives: Our purpose was to evaluate a tissue Doppler-based index-peak myocardial acceleration (pACC)-during isovolumic relaxation and in evaluating left ventricular (LV) diastolic function., Background: Simple, practical indexes for diastolic function evaluation are lacking, but are much desired for clinical evaluation., Methods: We examined eight sheep by using tissue Doppler ultrasound images obtained in the apical four-chamber views to evaluate mitral valve annular velocity at the septum and LV wall. The pACC thus derived was analyzed during isovolumic relaxation (IVRT) and during the LV filling period (LVFP). We then changed the hemodynamic status of each animal by blood administration, dobutamine, and metoprolol infusion. We compared the pACC values during IVRT and LVFP over the four different hemodynamic conditions with a peak rate of drop in LV pressure (-dP/dt(min)) and the time constant of LV isovolumic pressure decay (tau), as measured with a high-frequency manometer-tipped catheter., Results: The pACC of the septal side of the mitral valve annulus during IVRT showed a good correlation with -dP/dt(min) (r = -0.80, p < 0.0001) and tau (r = -0.87, p < 0.0001). The mean left atrial pressure (LAP) correlated well with the septal side pACC during LVFP (r = 0.81, p < 0.0001). There was a weak correlation between the mitral valve annulus pACC at the LV lateral wall and mean LAP., Conclusions: The pACC during IVRT is a sensitive, preload-independent marker for evaluation of LV diastolic function. In addition, pACC during LVFP correlated well with mean LAP.

Background: Estimation of ventricular volume and mass is important for baseline and serial evaluation of fetuses with normal or abnormal hearts. Direct measurement of chamber wall volumes and mass can be made without geometric assumptions by 3D fetal echocardiography. Our goals were to determine the feasibility of using fast nongated 3D echocardiography for fetal volumetric and mass assessments, to validate the accuracy of the ultrasound system and the measurement technique, and if satisfactory, to develop normal values for fetal ventricular mass during the second and third trimesters., Methods and Results: This was a prospective outpatient study of 90 consecutive normal pregnancies during routine obstetric services at Oregon Health & Science University (Portland). Optimized 3D volumes of the fetal thorax and cardiac chambers were rapidly acquired and later analyzed for right and left ventricular mass by radial summation technique from manual epicardial and endocardial traces. Experiments to validate the ultrasound system and measurement technique were performed with modified small balloon models and in vivo and ex vivo small animal experiments. Our study established the feasibility of fetal ventricular mass measurements with 3D ultrasound technology and developed normal values for right and left ventricular mass from 15 weeks' gestation to term., Conclusions: Nongated fast 3D fetal echocardiography is an acceptable modality for determination of cardiac chamber wall volume and mass with good accuracy and acceptable interobserver variability. The method should be especially valuable as an objective serial measurement in clinical fetal studies with structurally or functionally abnormal hearts.

Objective: The purpose of our study was to test the applicability of calculating the difference between left ventricular (LV) and right ventricular (RV) stroke volume (SV) for assessing the severity of aortic (Ao) regurgitation (AR) using a real-time 3-dimensional (3D) echocardiographic (RT3DE) imaging system., Methods: The Ao valve was incised in 5 juvenile sheep, 6 to 10 weeks before the study, to produce AR (mean regurgitant fraction = 0.50). Simultaneous hemodynamic and RT3DE images were obtained on open-chest animals with Ao and pulmonary flows derived by Ao and pulmonary electromagnetic flowmeters balanced against each other. Four stages (baseline, volume loading, sodium nitroprusside, and angiotensin infusion) were used to produce a total of 16 different hemodynamic states. Epicardial scanning was done with a 2.5-MHz probe to sequentially record first the RV and then the LV cavities. Cavity volumes from the 3D echocardiography data were determined from angled sector planes (B-scans) and parallel cutting planes (C-scans, which are planes perpendicular to the direction of the volume interrogation). AR volumes were determined from 3D images by computing and then subtracting RV SVs from LV SVs and then these were compared with electromagnetic flowmeter-derived SV and regurgitant volumes., Results: There was close correlation between RV and LV SVs of the RT3DE and electromagnetic methods (C-scans: LV, r = 0.98, standard error of the estimate [SEE] = 2.62 mL, P =.0001; RV, r = 0.89, SEE = 2.67 mL, P <.0001; and B-scans: LV, r = 0.95, SEE = 3.55 mL, P =.0001; RV, r = 0.77, SEE = 2.78 mL, P =.0003). Because of the small size of the RV in this model, the correlation was closer for C-scans than B-scans for RV SV. AR volume estimation also showed that C-scan (r = 0.93, SEE = 4.23 mL, P <.0001) had closer correlation than B-scan (r = 0.89, SEE = 4.87 mL, P <.0001). However, B-scan-derived AR fraction showed closer correlation than did C-scan (r = 0.82 vs r = 0.85, respectively)., Conclusion: In this animal model, RT3DE imaging had the ability to reliably quantify both LV (B- and C-scans) and RV SVs and to assess the severity of AR.

Objective: The complex structural geometry of the right ventricle hinders accurate assessment of right ventricular volume and function on conventional two-dimensional echocardiography. We sought to evaluate the accuracy of real-time three-dimensional echocardiography for quantifying the volume of the right ventricle in an in vitro experimental study., Methods: We developed 39 anatomically accurate latex phantoms of human and porcine right ventricles (range, 24-108 mL) for 39 static and 10 pulsatile models. Real-time three-dimensional scanning was performed with the models placed in a water bath and with a 3.5-MHz probe. In the dynamic models a pulsatile flow pump generated 2 different stroke volumes (29 and 64 mL/beat). Static chamber volumes and stroke volumes were verified by water displacement, which served as a reference standard. Three-dimensional echo right ventricle volumes were determined by tracing derived B- and C-scans, using the Simpson rule., Results: Multiple regression analyses showed an excellent correlation between real-time three-dimensional echocardiographic determinations and the static volumes (B-scan, r = 0.99; C-scan, r = 0.98; P < .001), as well as stroke volumes in the dynamic model (B-scan, r = 0.90; C-scan, r = 0.86; P < .001). However, the C-scans tended to underestimate cavity and stroke volumes more than the B-scans (mean difference for static volume: B-scan, 1.4% +/- 9.8%; C-scan, -7.4% +/- 8.0%; P < .001; mean difference for stroke volumes: B-scan, 3.0% +/- 19.1%; C-scan, -2.5% +/- 20.9%; P < .001)., Conclusions: Real-time three-dimensional echocardiography can accurately quantify right ventricle cavity volumes and stroke volumes without geometric assumptions.

Fetal ductal constriction (DC) can depress right ventricular (RV) function. However, noninvasive assessment of fetal RV function remains difficult. We evaluated RV and left ventricular (LV) performance in fetuses with DC using the Doppler-derived Tei index. The Tei index measures the ratio of total time spent in isovolumic contraction and relaxation (isovolumic time) to the ejection time. Tricuspid inflow and RV outflow Doppler traces for the derivation of RV Tei indexes and mitral inflow and LV outflow traces for LV Tei indexes were measured in 78 fetuses of pregnant women who received indomethacin and 70 normal fetuses (gestational ages ranging from 20 to 39 weeks). DC occurred in 23 fetuses, defined as pulsatility index <1.9. In fetuses with DC, the RV isovolumic time was prolonged and RV ejection time was shortened, and the RV Tei index was high compared with those in fetuses that received indomethacin without DC and normal fetuses. Also, the RV Tei index clearly separated the fetuses with DC from normal and fetuses that received indomethacin without DC (0.74 +/- 0.14 vs 0.35 +/- 0.07 and 0.37 +/- 0.06, respectively; p <0.0001). The LV Tei index was not affected by DC. Serial study in 7 fetuses with DC showed that the RV Tei index decreased from 0.69 +/- 0.12 to 0.38 +/- 0.04 (p = 0.0002) after discontinuation of indomethacin coincident with ductal relaxation, although it remained elevated in 2 cases at the time of ductal relaxation. Thus, the Tei index is a useful and sensitive indicator for detecting abnormal RV performance in fetuses with DC.

Background: Real-time 3-dimensional (3D) echocardiography avoids geometric assumptions in volume analysis and permits immediate visualization in any plane without the need for cardiac or respiratory gating or computation time. This study compared the accuracy of volume and mass assessments between standard long-axis (B-scan) and short-axis (C-scan) views in a simplified but quantifiable left ventricular phantom., Methods and Results: The model comprised an inner balloon within an outer balloon separated by ultrasonographic gel. First, to mimic different chamber volumes, 12 volumes (40 to 180 mL) of water within the inner balloon were scanned with a real-time 3D system. Second, 10 volumes (80 to 170 mL) of gel were inserted between the balloons to mimic varying cardiac mass, and the gel volume space (mass) was calculated by subtracting the inner from the outer balloon volume. "Chamber" and "mass" measurements for both B and C scans correlated closely with the actual values (r = 0.99). However, chamber volumes from C scans were consistently less than B-scan values (mean difference from reference for C scans: -5.2 +/- 1.2 mL, P <.0001; for the 2 orthogonal B scans: 0.03 +/- 1.4 mL and -0.9 +/- 1.5 mL, respectively, P = NS). Similarly, for gel volume measurements, B-scan results were closer to actual mass volumes (mean difference 0. 3 +/- 2.5 and 1.7 +/- 2.9 mL) than those of C scans, which tended to underestimate (-4.5 +/- 2.5 mL, P <.0001)., Conclusion: Our study suggests that real-time 3D echocardiography should provide an accurate means of determining chamber volumes and cardiac mass. However, measurements performed from B-scan views may be closer to the actual values than those from C-scan views, presumably since they are less highly influenced by distortions related to lateral resolution.

To assess gestational age- and growth-related changes in left ventricular (LV) size, LV wall, and LV transmitral flow velocity patterns, 2-dimensional (2-D) and Doppler echocardiographic studies were performed in 89 normal fetuses aged 16 to 38 weeks. Serial studies were designed in 7 fetuses. Variables measured from 4-chamber views were chamber areas and myocardial wall areas. From these measurements, area shortening fraction and ratio of myocardial wall area to end-diastolic chamber area were calculated. LV end-diastolic chamber area and myocardial wall area increased exponentially with advancing gestational age (r = 0.88 and 0.90, respectively, p < 0.001). Area shortening fraction showed no significant changes with gestational age. Ratio of myocardial wall area to LV end-diastolic chamber area decreased gradually with increasing gestational age (r = -0.77, p < 0.001). With increasing gestational age, mitral peak velocities of early diastole increased (r = 0.82, p < 0.01) with little change in peak velocity during atrial contraction. Multiple regression analysis showed that age-related increases in peak velocity of early diastole were related to advancing gestational age and also to decreases in ratio of myocardial wall area to LV end-diastolic chamber area. Low peak filling velocities during early diastole in younger fetuses may be related partly to relative increase in LV wall mass. The gestational age-related decreases in LV wall mass may be one of the important mechanisms of gestational age-related alterations in diastolic properties, especially relaxation processes.

Qualitative and quantitative changes in left ventricular shapes were analyzed in 14 normal fetuses, 29 normal newborns, and 12 normal infants. Qualitative observations demonstrated that most fetuses and newborns with dominant right ventricles had flattened or even indented interventricular septae, which changed left ventricular shape into an ellipse. In contrast, left ventricular shapes in infants were round, similar to shapes described in older children and adults. When changes in shape or septal distortions were gross, interobserver agreement was 100%; when changes were less altered from a circular shape, interobserver agreement was 78%. To avoid subjective misinterpretations, quantitative analyses were performed, including M mode echocardiographic comparisons of right ventricular/left ventricular dimensions and left ventricular cavity anterior-posterior/lateral diameters, as well as Fourier analysis of digitized tracings of the entire left ventricular shape. The right ventricular/left ventricular ratio, determined by M mode echocardiography, showed significant differences between fetuses (1.07 +/- 0.07) and newborns (0.62 +/- 0.12) (p less than .001). Infants had a significantly lower right ventricular/left ventricular ratio (0.45 +/- 0.01) when compared with newborns (p less than .01). Ratios of left ventricular anterior-posterior/lateral diastolic diameters were significantly lower (p less than .001) in newborns (0.66 +/- 0.08) when compared with those of infants (0.82 +/- 0.10). All diameters tended to increase (toward roundness) with systole and with aging. Fourier analysis allowed evaluation of the entire left ventricle, including that portion of the septum that qualitatively appeared most indented and could not be analyzed by either of the above techniques. Shape factor derived from idealized shapes ranging from a circle to an indented ellipse allowed comparison with digitized left ventricular tracings. This technique allowed accurate quantitation of the observed changes in shape. Fetuses had the highest diastolic shape factor (7.47 +/- 0.92), whereas infants' shape factors were lowest (2.12 +/- 0.41). A tendency toward roundness and loss of distortion occurred with aging. Systolic shape factor was lower with aging in each group studied. The Fourier technique used in this study allows evaluation of an arbitrarily large number of components of a shape, and thus a complete description of that shape is permitted. Comparisons of right ventricular/left ventricular diastolic dimensions and left ventricular anterior-posterior/lateral comparisons are subsets of this technique, which allow evaluation of only two points (circular component-first harmonic) or four points (elliptical component-second harmonic) of an overall shape.(ABSTRACT TRUNCATED AT 400 WORDS)

We reviewed anatomic observations (surgical or autopsy), angiograms and echocardiograms from 44 patients with documented univentricular hearts. Thirty-three patients had univentricular heart of left ventricular type with an outflow or rudimentary chamber. Five had univentricular heart of right ventricular type, and six had univentricular heart of indeterminate types without a rudimentary chamber. Univentricular heart was correctly diagnosed by two-dimensional echocardiography in all but two of the 44 patients, including 25 of 27 double-inlet univentricular hearts, all five with absent left and all 12 with absent right atrioventricular connection. One of the two blind trabecular pouches was missed on echocardiography; the other was not seen on the angiogram but was present at autopsy. In 30 of 33 patients, univentricular heart of left ventricular type was correctly identified by imaging an anterosuperior and leftward or rightward outlet chamber, and in four of five patients with univentricular heart of right ventricular type, the anomaly was correctly identified by imaging the inferior and posterior position of the rudimentary outflow chamber near the crux of the heart. Two-dimensional echocardiography provides detailed analysis of atrioventricular connections, main chamber morphology, and rudimentary chamber size and position of noninvasive diagnosis and anatomic subclassification of univentricular hearts.

The purpose of this study was to evaluate young asymptomatic patients with thalassemia major by utilizing an echocardiographic technique which traces an expanded image of the left ventricular posterior wall (LVPW). This technique separates global cardiac function from segmental changes in LV free wall thickness during systole and diastole. The study population consisted of 13 patients aged 2 to 15 years with classical homozygous beta-thalassemia. Thirty-one normal healthy individuals age 4 to 13 years served as controls. Echocardiograms, height, weight, and blood pressure were measured in all patients at their lowest hemoglobin level. Traces of the expanded LVPW were analyzed and measured; while total net thickening relative to baseline was similar in both groups at all times during systole and diastole, the LVPW in children with thalassemia was statistically thinner than in controls (p less than 0.001). Contraction was a nearly linear process in controls, but for patients with thalassemia, it was significantly faster at 50% and 75% of systolic time (p less than 0.05). Relaxation, on the other hand, was not linear for either controls or thalassemic patients. In both groups, diastolic thinning was biphasic; however, LV walls of thalassemic children thinned more slowly than normal for each time point in diastole (p less than 0.001). These results demonstrate that young children with thalassemia major, even if kept at strict transfusion and chelation regimens, have defects in LV segmental wall motion which antedate the appearance of clinical symptoms.