Secundum atrial septal defect is a dynamic three-dimensional entity

A comparison of echocardiographic modalities to guide structural heart disease interventions

Percutaneous techniques to treat structural heart disease are rapidly evolving based on innovative interventions and the considerable advancement in image guidance technology. While two-dimensional transthoracic and transesophageal echocardiography have been integral to procedural planning and execution, intracardiac and three-dimensional echocardiography supply unique visualization of target structures with a potential improvement in patient safety and procedural efficacy. The choice of image guidance modality is based on specific differences between imaging systems, as well as other variables including cost, patient safety, operator expertise, and complexity of procedure. We will compare the adjunctive imaging tools for structural heart disease interventions, with a focus on intracardiac echocardiography and real-time three-dimensional transesophageal echocardiography.

Assessment of atrial septum morphology by live three-dimensional echocardiography

To evaluate the morphology of atrial septum by the live three-dimensional echocardiography (L3DE) and its value of clinical application, L3DE was performed in 62 subjects to observe the morphological characteristics and dynamic change of the overall anatomic structure of atrial septum. The study examined 49 patients with atrial septal defect (ASD), including 3 patients with atrial septal aneurysm, and 10 healthy subjects. ASD in the 35 patients was surgically confirmed. The maximal diameters of ASD were measured and the percentages of area change were calculated. The parameters derived from L3DE were compared with intraoperative measurements. The results showed that L3DE could directly and clearly display the morphological features of overall anatomic structure of normal atrial septum, repaired and artificially-occluded atrial septum, atrial septal aneurysm. The defect area in ASD patients changed significantly during cardiac cycle, which reached a maximum at end-systole and a minimum at end-diastole, with a mean change percentage of 46.6%, ranging from 14.8% to 73.4%. The sizes obtained from L3DE bore an excellent correlation with intraoperative findings (r=0.90). It is concluded that L3DE can clearly display the overall morphological features and dynamic change of atrial septum and measure the size of ASD area accurately, which is important in the decision to choose therapeutic protocols.

Real Time Three-Dimensional Echocardiography in Assessing Ventricular Septal Defects: An Echocardiographic-Surgical Correlative Study

BACKGROUND

Two-dimensional echocardiography (2DE) enhanced by combining with color Doppler technology has significant limitations in providing precise quantitative information, geometric assumptions to calculate chamber volume, mass, and ejection fraction. Reconstructed three-dimensional echocardiographic (3DE) systems (from multiple cross-sectional echocardiographic scans) are still cumbersome and time-consuming. Real time 3DE (RT-3DE) with shorter imaging time than with 3D reconstruction techniques can obtain qualitative and quantitative information on heart disorders. Our purpose was to investigate the feasibility and potential value of RT-3DE as a means of accurately and quantitatively estimating the size of VSD to correlate with the surgical findings.

MATERIALS AND METHODS

38 patients with VSD were examined with RT-3DE. 3D image database was postprocessed using TomTec echo 3D workstation. The results were compared with the results measured by 2 DE and surgical findings. RT-3DE produced novel views of VSD and improved quantification of the size of the defect. The sizes obtained from 3DE have equivalent correlation with surgical findings as diameter measured by 2DE (r = 0.89 vs r = 0.90). Good agreement between blinded observers was achieved by little interobserver variability.

CONCLUSION

RT-3DE offers intraoperative visualization of VSD to generate a "virtual sense of depth" without extending examining time. From an LV en face projection, the positions, sizes, and shapes of VSDs can be accurately determined to permit quantitative recording of VSD dynamics. It is a potentially valuable clinical tool to provide precise imaging for surgical and catheter-based closure of difficult perimembranous and singular or multiple muscular VSD.

Assessment of atrial septal defect size with 3D-transesophageal echocardiography: comparison with balloon method

BACKGROUND

Transcatheter closure of atrial septal defect (ASD) is an alternative approach to surgery in selected patients. Balloon stretched diameter (BSD) is considered as the standard way of measuring ASD size. Three-dimensional transesophageal echocardiography (3D-TEE) provides views of the ASD allowing its measurement and identifying its spatial relation with neighboring structures. Our aim was to compare the BSD and 3D-TEE methods to measure the ASD size before transcatheter closure.

METHODS AND RESULTS

Seventy-six consecutive patients were enrolled for ASD device closure. Three-dimensional transesophageal echocardiography and balloon sizing were adequately performed in 70 patients before the defect closure. The mean maximal diameter measured by 3D-TEE was 20 +/- 15 mm (range 10-28) while the mean BSD was 22 +/- 4.8 mm (range 9-31). When comparing the 3D-TEE and transcatheter measurements, there was a good correlation between the two methods (y = 3.15 + 0.77x; r = 0.8). The defect as viewed by 3D-TEE was unique in 54 patients and multiple in 16 patients. In patients with a single defect, the correlation between the two methods was high (y = 1.74 + 0.84x; r = 0.85) while patients with multiple ASDs, the correlation was poor (y = 12.4 + 0.4x; r = 0.45). Transcatheter closure was performed successfully in 86%. The mean size of the Amplatzer device was 23 +/- 4.8 mm (range 4-32). The reference to choose the size of the device was the BSD in single defects and the 3D-TEE maximal diameter in multiple defects.

CONCLUSION

Three-dimensional transesophageal echocardiography and transcatheter methods are two complementary techniques for the success of transcatheter ASDs closure.

Usefulness of three-dimensional echocardiographic reconstruction of the Amplatzer septal occluder in patients undergoing atrial septal closure

Eighty-eight patients referred for transcatheter closure of atrial septal or patent foramen ovale defects underwent 3-dimensional transesophageal echocardiography to correlate preclosure anatomy with the morphology and positioning of the atrial septal occluder. Despite the effectiveness of the trancatheter closure and absence of complications, 2 linear indentations of the aortic root by the 2 discs of the device were clearly demonstrated in 16 cases, suggesting caution in the choice of very large occluders.

Three- and four-dimensional reconstruction of intra-cardiac anatomy from two-dimensional magnetic resonance images

The present study was designed to evaluate the feasibility and clinical usefulness of three-dimensional (3D) reconstruction of intra-cardiac anatomy from a series of two-dimensional (2D) MR images using commercially available software. Sixteen patients (eight with structurally normal hearts but due to have catheter radio-frequency ablation of atrial tachyarrhythmias and eight with atrial septal defects (ASD) due for trans-catheter closure) and two volunteers were imaged at 1T. For each patient, a series of ECG-triggered images (5 mm thick slices, 2-3 mm apart) were acquired during breath holding. Depending on image quality, T1- or T2-weighted spin-echo images or gradient-echo cine images were used. The 3D reconstruction was performed off-line: the blood pools within cardiac chambers and great vessels were semi-automatically segmented, their outer surface was extracted using a marching cube algorithm and rendered. Intra- and inter-observer variability, effect of breath-hold position and differences between pulse sequences were assessed by imaging a volunteer. The 3D reconstructions were assessed by three cardiologists and compared with the 2D MR images and with 2D and 3D trans-esophagal and intra-cardiac echocardiography obtained during interventions. In every case, an anatomically detailed 3D volume was obtained. In the two patients where a 3 mm interval between slices was used, the resolution was not as good but it was still possible to visualize all the major anatomical structures. Spin-echo images lead to reconstructions more detailed than those obtained from gradient-echo images. However, gradient-echo images are easier to segment due to their greater contrast. Furthermore, because images were acquired at least at ten points in the cardiac cycles for every slice it was possible to reconstruct a cine loop and, for example, to visualize the evolution of the size and margins of the ASD during the cardiac cycle. 3D reconstruction proved to be an effective way to assess the relationship between the different parts of the cardiac anatomy. The technique was useful in planning interventions in these patients.

Three-dimensional (3D) echocardiographic analysis of congenital heart disease in the fetus: comparison with cross-sectional (2D) fetal echocardiography

OBJECTIVE

We attempted to assess the ability of Doppler-gated three-dimensional (3D) fetal echocardiography to reconstruct and display specific cardiac structures in fetuses with cardiac anomalies and to determine whether any advantage is offered by 3D sonographic cardiac examination over conventional fetal echocardiography.

DESIGN

After 2D fetal echocardiographic examination, 3D cardiac data were collected prospectively in 22 fetuses with various congenital heart defects. Their ages ranged from 19 to 35 weeks' gestation. Basic echocardiographic key views of the venoatrial, atrioventricular and ventriculoarterial connections were derived from volume data sets and selected for 3D reconstruction and analysis. Comparisons were made with 2D echocardiographic imaging of the fetal hearts and the diagnostic image quality of visualized structural details was evaluated.

RESULTS

The underlying cardiac malformation was well or satisfactorily visualized in 20 fetuses using 2D imaging. Gated 3D volume data sets enabled diagnostically acceptable visualization of all affected cardiac structures in 7 of 22 fetuses. High-quality 3D reconstruction of the site and spatial orientation of ventricular septal defects was obtained in 9 of 13 patients. Two-dimensional imaging remained the principal diagnostic modality in all cases with additional structural detail being obtained by 3D imaging in only two fetuses.

CONCLUSIONS

Three-dimensional imaging of fetal heart disease is feasible for a wide range of lesions, and may provide additional information of clinical value in a small number of cases when compared with 2D imaging.

Assessment of the geometric profile of the Amplatzer and Cardioseal septal occluders by three dimensional echocardiography

OBJECTIVE

To apply three dimensional echocardiography to describe the geometric profile of the Amplatzer and Cardioseal occluders after deployment for closure of atrial septal defect.

METHODS

20 patients (mean (SD) age, 14 (5) years) were enrolled for transcatheter closure of a secundum atrial septal defect with the Amplatzer occluder (10) or with the Cardioseal occluder (10). The two populations were matched for the stretched diameter of the defect (mean 18 (6) mm). The profile of the two occluders was examined.

RESULTS

Transoesophageal echocardiography did not show any residual shunts after Amplatzer occluder deployment, whereas three patients had a small residual leak after Cardioseal deployment. One patient had transient atrioventricular block with the Amplatzer device. The mean surface area of the Amplatzer occluder was 6.9 (2) cm(2), and that of the Cardioseal device 5.4 (3) cm(2) (p = 0.03). The mean volume of the Amplatzer occluder was 9.2 (1) cm(3), while that of the Cardioseal occluder was 3.5 (1) cm(3) (p < 0.0001). From the three dimensional views, the Cardioseal occluder looked like a flat square after deployment whereas the Amplatzer occluder took up a ball shape in the atrial cavity.

CONCLUSIONS

Three dimensional views by multiplane transoesophageal echocardiography allow a realistic in vivo description of atrial septal occluders. The Amplatzer occluder, with its high geometric profile, allows complete closure of large atrial septal defects but with some risk of mechanical complications. Use of the Cardioseal device, with its small surface coverage and high residual shunt rate, should be limited to transcatheter closure of a patent foramen ovale or small atrial septal defects.

In vitro simulation and quantification of temporal jitter artifacts in ECG-gated dynamic three-dimensional echocardiography

The image quality of dynamic 3-D echocardiography is limited by temporal jitter artifacts that result from the asynchronous acquisition of video frames with the cardiac cycle. This paper analyzes the source and extent of these artifacts using in vitro studies. Dynamic 3-D images of a myocardial motion phantom were reconstructed and analyzed for eight cardiac motion patterns. The extent of temporal jitter artifacts was quantified, first, from the images by computing temporal jitter maps and, second, predicted from the motion waveforms. Temporal jitter appeared as a pattern of streak artifacts converging at the axis of rotation of the imaging plane, for the rotational scanning approach used in our study. The results of the experimental analysis techniques were compared with the waveform analysis using linear regression analysis. The least squares line showed good correlation between the data (r > 0.9) and its deviation from the line of identity was calculated to be <9%.

Clinical use of Real-time three-dimensional echocardiography in pediatric cardiology

Real-time three-dimensional echocardiography is a technique that allows three-dimensional imaging without any geometrical assumptions or need for reconstruction from two-dimensional images. This imaging technique should be particularly useful in the pediatric population, for whom a complex cardiac anatomy must be defined. We review the potential usefulness of real-time three-dimensional imaging in the pediatric population and the potential limitations associated with this technique.

Interventional catheterization

Several investigations have been performed to evaluate the mid-term results of coil embolization for patent ductus arteriosus. Excellent results were obtained with coils if the minimum diameter of the ductus was less than 4 mm. Balloon dilation of native coarctation and recoarctation may be associated with complications such as aneurysm formation. Stent placement may solve some of the problems of balloon dilation, but the stents currently available are not perfect. Results of transcatheter closure of atrial septal defect using new devices have been were reported. The self-expanding nitinol double-disk device (Amplatzer septal occluder) (AGA Medical Corporation, Golden Valley, Minnesota) is becoming popular because it is easy to implant, is easy to retrieve before its release, can occlude a relatively large defect, and has a low rate of residual leak. Although the immediate results with this device were excellent, surgical closure is still the standard treatment and we need to see the long-term results of transcatheter closure.