Vivid Valves: The Role of 3D Echo

 
 
 
3d-echo.jpg - Ruptured P2 Chords
Ruptured chords involving P2 by 3D imaging.
Source: Circulation. 2013;128:653-658
 
Surgical findings confirm ruptured P2 chords but also an elongated chord and prolapse at A1.
Source: Circulation. 2013;128:653-658

3D echocardiography has swept the cardiology world off its feet, but can these new images transform any surgeon into a mitral valve repair expert?

The rapid adoption of 3D transesophageal echocardiography is a testament to the quality of images it creates. It provides beautiful views that are easy for surgeons to read and understand, and accurately displays the mitral valve during preoperative assessment. Despite all the positivity, 3D echo does have limits.

For Patrick M. McCarthy, MD, of Northwestern University Feinberg School of Medicine in Chicago, the first sign that the love affair with 3D echo might be going too far was when he listened to a cardiologist lecture an audience on the topic. The speaker asserted that since cardiac surgeons can now see everything with 3D echo, anybody could do a mitral valve repair, including less experienced surgeons.

“That’s really overstating the case for 3D echo,” says McCarthy.

This set the stage for a pair of published point-counterpoint articles on the merits of 3D echo (Circulation 2013;128:653-658). While McCarthy argued for some perspective on the benefits, Roberto M. Lang, MD, of the University of Chicago Medical Center, along with Wendy Tsang, MD, from Toronto General Hospital, wrote about how essential the advanced echocardiography technique has become.

What's in a Name? Rethinking Nomenclature
Physicians in the paravalvular leak program at the Mayo Clinic in Rochester, Minn., noticed an issue with communication in the cardiac catheterization laboratory ahead of surgery. There can be discrepancies between the interventionist, who is used to looking at fluoroscopy images, and the echocardiographer, who is helping to guide the procedure with transesophageal echo. Descriptions of orientation such as anterior or posterior can become confused because interventionists and echocardiographers are using different modalities from different perspectives. Additionally, patient characteristics also can have an effect. An elderly woman with chronic obstructive pulmonary disease may have a heart oriented more vertically, while obese patients may have more horizontal orientation of the heart, for example. "What we tried to do was come up with anatomic-based nomenclature that allowed us to have more facile communication in the lab," says Daniel B. Spoon, MD, of the Mayo Clinic. Spoon and colleagues developed a simple fix based on 2D and 3D echo nomenclature that would improve correlation with fluoroscopic localization of leaks. Anatomic structures were used to triangulate lesions, with the aortic valve labeled anterior, the atrial septum labeled medial and the left atrial appendage labeled anterolateral. An assessment of the new nomenclature found that 95 percent of lesions were localized accurately when the anatomical method was used in a cohort featuring 119 lesions. Spoon adds that the improved communication also shortened procedure times, improving workflow.

Pros & cons

The advantages of 3D echo in the assessment of the mitral valve are numerous, according to Lang and Tsang. It improves lesion localization, identification of the mechanisms causing mitral regurgitation and quantification of the severity of mitral regurgitation. Views offered by 3D echo can be displayed similarly to what the surgeon actually will encounter during a procedure. Measurements obtained from 3D parametric maps have shown that prolapsing height and anterior leaflet surface area are the strongest predictors of surgical repair complexity in degenerative mitral valve disease.

“This is a growing imaging modality that is gaining acceptance and people more and more understand … how it can help in the operating room and how this technique can help guide different types of percutaneous procedures for structural heart disease,” says Lang. “People are accepting this all over the world.”

While having great respect for 3D echo’s abilities—he uses it in 100 percent of his mitral valve procedures—McCarthy notes some shortcomings. “They see things quite well, but they don’t really see everything, not as well as when we do a good evaluation of the valve,” he says.

For McCarthy, the most important component in mitral valve repair is the operating surgeon, and 3D echo can potentially lull a cardiologist into a false sense of comfort about how simple a repair will be. Because the shape of the mitral