Usefulness of live three-dimensional transesophageal echocardiography in a congenital heart disease center

Advanced echocardiographic imaging of the congenitally malformed heart

There have been significant advancements in the ability of echocardiography to provide both morphological and functional information in children with congenitally malformed hearts. This progress has come through the development of improved technology such as matrix array probes and software which allows for the off line analysis of images to a high standard. This article focuses on these developments and discusses some newer concepts in advanced echocardiography such is multi-planar reformatting [MPR] and tissue motion annular displacement [TMAD].

Our aim is to discuss important aspects related to the quality and reproducibility of data, to review the most recent published data regarding advanced echocardiography in the malformed heart and to guide the reader to appropriate text for overcoming the technical challenges of using these methods. Many of the technical aspects of image acquisition and post processing have been discussed in recent reviews by the authors and we would urge readers to study these texts to gain a greater understanding [1]. The quality of the two dimensional image is paramount in both strain analysis and three dimensional echocardiography. An awareness of how to improve image quality is vital to acquiring accurate and usable data.

Three dimensional echocardiography (3DE) is an attempt to visualise the dynamic morphology of the heart. Although published media is the basis for theoretical knowledge of how to practically acquire images, electronic media [eg.www.3dechocardiography.com] is the only way of visualising the advantages of this technology in real time.

It is important to be aware of the limitations of this technology and that much of the data gleaned from using these methods is at a research stage and not yet in regular clinical practice.

Novel System for Real-Time Integration of 3-D Echocardiography and Fluoroscopy for Image-Guided Cardiac Interventions: Preclinical Validation and Clinical Feasibility Evaluation

Real-time imaging is required to guide minimally invasive catheter-based cardiac interventions. While transesophageal echocardiography allows for high-quality visualization of cardiac anatomy, X-ray fluoroscopy provides excellent visualization of devices. We have developed a novel image fusion system that allows real-time integration of 3-D echocardiography and the X-ray fluoroscopy. The system was validated in the following two stages: 1) preclinical to determine function and validate accuracy; and 2) in the clinical setting to assess clinical workflow feasibility and determine overall system accuracy. In the preclinical phase, the system was assessed using both phantom and porcine experimental studies. Median 2-D projection errors of 4.5 and 3.3 mm were found for the phantom and porcine studies, respectively. The clinical phase focused on extending the use of the system to interventions in patients undergoing either atrial fibrillation catheter ablation (CA) or transcatheter aortic valve implantation (TAVI). Eleven patients were studied with nine in the CA group and two in the TAVI group. Successful real-time view synchronization was achieved in all cases with a calculated median distance error of 2.2 mm in the CA group and 3.4 mm in the TAVI group. A standard clinical workflow was established using the image fusion system. These pilot data confirm the technical feasibility of accurate real-time echo-fluoroscopic image overlay in clinical practice, which may be a useful adjunct for real-time guidance during interventional cardiac procedures.

Three-dimensional echocardiography in congenital heart disease

Complex intracardiac anatomy and spatial relationships are inherent to congenital heart defects (CHDs). Recognition of the limitations of two-dimensional echocardiography has stimulated clinical interest in three-dimensional imaging. The current review examines contemporary studies in the following areas where three-dimensional echocardiography has provided additive value in CHD: (1) visualization of morphology, (2) quantitation of chamber sizes and ventricular function, and (3) image-guided interventions.

Transesophageal Echocardiography in Tetralogy of Fallot

Transesophageal echocardiography (TEE) plays an important role in the anatomical, functional, and hemodynamic assessment of patients with congenital heart disease (CHD). This imaging approach has been applied to both children and adults with a wide range of cardiovascular malformations. Extensive clinical experience documents significant contributions, particularly in the perioperative setting. In fact, in the current medical era, many consider this technology to be an essential adjunct to surgical and anesthetic management in CHD. This review focuses on the applications of TEE in patients with tetralogy of Fallot (TOF), the most common form of cyanotic heart disease. Emphasis is given to the perioperative use of this imaging modality and benefits derived during the prebypass and postbypass periods. Limitations and pitfalls relevant to the TEE assessment in patients with this anomaly are also addressed.

Echocardiography as a hemodynamic monitor in critically ill children

Echocardiography is a widely used modality to assess myocardial structure and function in pediatric intensive care settings. While the use of echocardiography for diagnostic purposes remains important, its use as a hemodynamic monitoring tool has not been well established. The benefits of echocardiography are in its widespread availability, relative ease of use, and importance in diagnosing structural disease and simple changes in myocardial function. However, echocardiography in pediatric critical care is limited in its use because it requires the acquisition of quality images and the accurate interpretation of the study. To date, the literature on echocardiography in pediatric critical care is limited. The purpose of this review is to examine the scientific evidence for the usefulness of echocardiography as a hemodynamic monitoring tool in pediatric critical care.

Registration of 3D trans-esophageal echocardiography to X-ray fluoroscopy using image-based probe tracking

Two-dimensional (2D) X-ray imaging is the dominant imaging modality for cardiac interventions. However, the use of X-ray fluoroscopy alone is inadequate for the guidance of procedures that require soft-tissue information, for example, the treatment of structural heart disease. The recent availability of three-dimensional (3D) trans-esophageal echocardiography (TEE) provides cardiologists with real-time 3D imaging of cardiac anatomy. Increasingly X-ray imaging is now supported by using intra-procedure 3D TEE imaging. We hypothesize that the real-time co-registration and visualization of 3D TEE and X-ray fluoroscopy data will provide a powerful guidance tool for cardiologists. In this paper, we propose a novel, robust and efficient method for performing this registration. The major advantage of our method is that it does not rely on any additional tracking hardware and therefore can be deployed straightforwardly into any interventional laboratory. Our method consists of an image-based TEE probe localization algorithm and a calibration procedure. While the calibration needs to be done only once, the GPU-accelerated registration takes approximately from 2 to 15s to complete depending on the number of X-ray images used in the registration and the image resolution. The accuracy of our method was assessed using a realistic heart phantom. The target registration error (TRE) for the heart phantom was less than 2mm. In addition, we assess the accuracy and the clinical feasibility of our method using five patient datasets, two of which were acquired from cardiac electrophysiology procedures and three from trans-catheter aortic valve implantation procedures. The registration results showed our technique had mean registration errors of 1.5-4.2mm and 95% capture range of 8.7-11.4mm in terms of TRE.

Role of transesophageal echocardiography in the management of pediatric patients with congenital heart disease

Transesophageal echocardiography (TEE) has become a critical diagnostic and perioperative management tool for patients with congenital heart disease (CHD) undergoing cardiac and noncardiac surgical procedures. This review highlights the role of TEE in routine management of pediatric cardiac patient population with focus on indications, views, applications and technological advances.