Chicago, IL - Published appraisals of real-time three-dimensional transesophageal echocardiography (TEE) are trickling into the medical literature. One such study, appearing in the August 5, 2008 issue of the Journal of the American College of Cardiology (JACC) [1], suggests that the breakthrough technology is feasible in most patients, permits faster image acquisition, and delivers superior images of certain cardiac structures than can be obtained with either real-time transthoracic echocardiography (TTE) or reconstructed 3D TEE imaging technology.

Echocardiographers who have used the new 3D fully sampled matrix-array TEE (3D-MTEE) transducer (Philips Medical Systems) say the published papers simply can't capture their excitement or convey the extent to which the technology will revolutionize an imaging modality that is already an essential tool for surgical planning and percutaneous procedures.

Senior author on the study and one of the pioneers of 3D-MTEE, Dr Roberto M Lang (University of Chicago, IL), told heartwire that 3D-MTEE "will become, in the near future, part of the routine TEE examination."

But other echocardiographers—a group not known for superlatives—who commented on the technology for heartwire were more effusive, using phrases like "unbelievable advance," "absolutely fantastic," and "blown away" to convey their enthusiasm and struggled to list any shortcomings of the technology. Not only will 3D-MTEE revolutionize their day-to-day jobs, they say, it also makes the images they obtain instantly accessible to nonechocardiographers.

"You can essentially produce images, in real time, that look exactly like what you would see if you had the heart in front of you," Dr Linda Gillam (Columbia University, New York) told heartwire. "It's a display that surgeons, or anyone else with any knowledge of the structure and function of the heart, can immediately relate to."

This could be the key to opening up a wide range of procedures [to patients] in whom they otherwise would not have been possible.

"Even for the trained eye, a picture is worth a thousand words, and this is a three-dimensional animated picture that you can see in real time," Dr Robert A Levine (Massachusetts General Hospital, Boston) told heartwire. "This is much more than an incremental advance. Just like TEE has overcome some of the limitations of TTE, 3D-MTEE will overcome some of the limitations of 3D-TTE. And that will have its greatest impact on the ability to guide procedures and treat patients better, both surgically and in a minimally invasive interventional manner. This could be the key to opening up a wide range of procedures [to patients] in whom they otherwise would not have been possible."

In their paper, Lang and colleagues, including Dr Lissa Sugeng (University of Chicago), explain that 3D TEE first evolved as a multiplane probe using a rotational approach to acquire sequential data that were then gated to electrocardiography and respiration. Since its development, 3D echo has been used as a research tool, but not routinely in the clinical setting because of the time needed to acquire the data and radial artifacts and because it requires offline processing.

For their analysis, Sugeng et al tested 3D-MTEE in 211 patients to image the interatrial septum, the left atrial appendage, and the mitral, aortic, and tricuspid valves. They report that visualization of the mitral valve, interatrial septum, left ventricle, and left atrial appendage were "excellent," whereas native aortic and tricuspid valves were optimally visualized less frequently.

"The use of 3D-MTEE imaging, which is feasible in most patients, provides superb imaging of native mitral valves, making this modality an excellent choice for mitral-valve surgical planning and guidance of percutaneous interventions," they conclude. "Optimal aortic and tricuspid valve imaging will depend on further technological developments."

Gillam, commenting on the study, said less optimal imaging of the aortic and tricuspid valves is not unexpected. "The images will always be best of the structures that are closest to the imaging probe, and, since the probe is in the esophagus, images of structures that are immediately adjacent to the esophagus will always be better," she said.

This by no means diminishes the magnitude of improvement that 3D-MTEE provides, she adds.

"I think that the promise of this technology is ultimately a paradigm shift in terms of how we view ultrasound images," Gillam said. "It will bring a shift in the way we acquire ultrasound data and, on the display end, it gives us the ability to have an infinite number of images from any given patient and the ability to display those images in a way that even an inexperienced observer could understand."

Ultimately she said, "this definitely has the potential to improve patient selection for procedures, to provide improved imaging guidance during procedures, and therefore to improve outcomes. . . . Going forward, 3D echo, I believe, will replace 2D echo as the default mode for echo imaging within 10 years."

Levine called the technology "a huge accomplishment from an engineering standpoint," likening the probe to a human retina. Unlike the multiplane TEE probe widely in use today, which contains 64 elements, the 3D-MTEE probe uses approximately 3000 elements, permitting volume scanning.

"The human retina is part of the central nervous system, yet it is separated by the optic nerve from the brain . . . and a lot of the initial processing occurs in the retina before the information gets to the brain. They've basically done the same thing with this transducer, having much of the processing occurring up front," Levine explained.

Lang predicts that the technology will be used predominantly for the preoperative assessment of the mitral valve and, going forward, for the guidance of percutaneous procedures, such as interatrial septal occluders, occlusion of the left atrial appendage, and reduction of mitral regurgitation, using either clips or annuloplasty devices.

"As we show in this paper, it is possible to obtain routinely excellent views of the mitral valve, interatrial septum, left atrial appendage, and pulmonic veins," he said. "In its current stage of development, the aortic valve leaflets are less well visualized; nevertheless, the aortic valve annulus and outflow tract can be nicely visualized, which might be useful for guiding the placement of percutaneous aortic valves."

Gillam says the technology is reinvigorating echocardiography—a field she says she's been in "for a long time."

"This late in the game, I didn't think there would be something new enough to really get me enthused about what new toys I had to play with," she said. "And this makes that threshold. I think it's great."

All of the major imaging companies are developing real-time 3D TEE systems, but Philips currently has the only commercially available technology.