Sounding Out Vascular Ultrasound

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Jeffrey W. Olin, DO, Director of Vascular Medicine and Professor, The Mount Sinai School of Medicine, New York City

William A. Zoghbi, MD, former president of the American Society of Echocardiography (ASE), says that vascular disease represents “a new frontier” for the ASE and its members. “As vascular disease takes center stage in medicine, we are seeing a new appreciation for vascular ultrasound as a cost-effective diagnostic modality for the early detection of atherosclerosis,” he states (Journal of the American Society of Echocardiography, April 2009, Vol. 22:4, p. A33).

Although vascular disease may be a new frontier for echocardiographers, it wasn’t so long ago that cardiologists and the echo lab didn’t put too much focus on the vascular system, says Emile Mohler III, MD, director of vascular medicine at the University of Pennsylvania Health System in Philadelphia and chairman of the ASE’s recently-formed Vascular Ultrasound Council. Instead, he says, they tended to focus on the heart.

A focus on the vascular system, says Mohler, was found “in vascular surgery labs in the past. But, more recently it has changed—cardiologists have expanded from the heart out to look at the carotids and even the kidney and intestinal arteries.”

This has been accompanied by new, and renewed, interest in techniques such as 3D ultrasound and contrast ultrasound. Three-dimensional ultrasound is a “sexy” technique that, according to Mohler, could be very useful in noninvasively imaging plaque carotid artery plaque.

While ultrasound contrast agents, on the other hand, have been around since the early 1990s, only recently has the technique taken on a higher profile—namely to improve the accuracy and quality of scans.

Stephen Feinstein, professor of medicine and director of echocardiography at Rush University Medical Center in Chicago, is bullish on the role contrast can play in carotid ultrasound. According to Feinstein, it is helpful in monitoring carotid plaque and preventing cardiovascular disease, heart attack, and stroke, particularly when it comes to delineating intimal medial thickness—a measurement of the thickness of the artery walls that can help detect and measure the progression of atherosclerosis—and identifying the structure and composition of plaque.

So, like many in the field of echocardiography, Feinstein was dismayed when, in 2007, the U.S. FDA required the makers of ultrasound contrast agents to include a black box warning on the products’ labels following reports of deaths after the use of ultrasound contrast agents.

Although the FDA’s action “certainly had a chilling effect” on the contrast ultrasound, says Feinstein, there has been “a tremendous grassroots response,” in defense of the technique.

“A polyglot of papers has come out,” says Feinstein, specifically pointing to a study by Mustafa Kurt, MD, and his colleagues at the Methodist DeBakey Heart & Vascular Center Imaging Institute in Houston ( Journal of the American College of Cardiology, March 2009, Vol. 53, pp. 802-810). The researchers concluded that the appropriate use of contrast ultrasound results in improved endocardial visualization, which positively affects diagnostic efficiency, resource utilization and can result in critical changes in patient management.

“It is spectacular,” says Feinstein, referring to the JACC study. “The data show that contrast ultrasound improves image quality, and that the failure to use it may cause patients more harm through receiving an incorrect diagnosis, undergoing more tests, and experiencing worse outcomes.”

Although the FDA modified its black box warning in 2008, several contraindications remain, such as those related to the use of contrast ultrasound on patients with pulmonary hypertension or unstable cardiopulmonary conditions. And Feinstein and his
colleagues, whether through research papers or forums such as the International Contrast Ultrasound Society, are continuing their lobbying efforts for a technique that, he says, “saves money, reduces risk, and makes a better diagnosis.”

And while he could have done without the controversy, he does see something positive coming out of the FDA’s action.

“You know, it actually makes for a pretty nice story,” says Feinstein. “When all this occurred, there wasn’t too much of a focus on contrast ultrasound. It was a smaller market, people really didn’t understand contrast ultrasound, and there were only two companies marketing it. So maybe in some way this [action