Cutting Edge Medicine: New Look Inside the Heart

New technology provides faster, clearer images of heart vessels, experts say

May 19, 2010, 6:33 PM

May 20, 2010— -- When Mack Bailey, 60, of Cleveland, Ohio, experienced his first heart attack earlier this month, his doctor knew exactly what to do.

"All of a sudden I had tightness in my chest and about 2 minutes after that I broke out in a sweat," Bailey said.

Doctors at University Hospitals in Cleveland, Ohio, placed a stent to unblock one of Bailey's arteries. And, like many doctors across the United States, they chose where and how to place the stent by relying on intravascular ultrasound, a procedure that uses sound waves that send back images that show blockages in the heart arteries.

Weeks later, Bailey returned for one more procedure. This time, Dr. Marco Costa, an interventional cardiologist at University Hospitals Case Medical Center, placed two more stents in Bailey's artery using a cutting-edge device called Optical Coherence Tomography.

Optical Coherence Tomography, or OCT, approved by the FDA in April 2010, forms images by reflecting light inside blood vessels, which allows doctors to see 10 times more detail of an artery than the conventional ultrasound.

"When I first saw this, I was like, oh my God, this is unbelievable," said Costa, who was the first doctor to implement the OCT procedure after FDA approval. "It's like walking into a different world."

Before an angioplasty, cardiologists normally use an intravascular ultrasound to detect blockages. But OCT uses light, which travels faster than sound, to detect more precise details of the calcium buildup in the heart. After an angioplasty, OCT enables doctors to see whether tiny parts of stents, called struts, have been covered by tissue, or remain uncovered in the months after the stents have been put in place.

"Angiograms don't really tell the whole story because it doesn't show the plaque," said Dr. Jeffrey Moses, director of the center for interventional vascular therapy at New York-Presbyterian Hospital Columbia University Medical Center. "Ultrasounds have a certain resolution, and OCT has 10 times that resolution. That lets us see the artery in very fine detail; so we can define the actual plaque, how much fat there is [and] how much clot there is."

Costa said he was able to detect a new blockage in one of Bailey's heart vessels that was not detected previously with the ultrasound. Costa determined that it was another artery -- not the one previously thought -- that caused the heart attack.

"It's like a volcano trying to explode right in that corner," Costa said.

Many patients undergoing invasive diagnostic procedures, such as intravascular ultrasound or an angiogram, may experience chest pain because the catheter may restrict blood flow through the vessel. Because OCTs are quick, patients may experience less chest pain, Costa said.

According to Dr. William Fearon, an interventional cardiologist and associate professor of medicine at Stanford University Medical Center, OCT is equivalent to intravascular ultrasound, but the OCT is better able to detect the success of a stent over time.

"There's a lot of promise and it has a lot of potential," Fearon said. "We may be able to get more information than we get from an ultrasound."

While both procedures use a contrast dye to help doctors detect the blockage through images, OCT uses a larger burst of dye in a shorter amount of time than intravascular ultrasound, said Costa. This may contribute to the more precise imaging and the less pain some patients may experience.

According to Costa, unlike other procedures, OCT provides better image resolution of stents after they've been placed in the heart. The images allow doctors to measure the thickness of the artery linings, measure the thin caps on plaque buildups in the arteries, observe how tissues grow around stents and track over time the dissolution of bioabsorbable stents that dissolve over time.

But the technology does not come without risk, many experts said. For patients who already have advanced kidney disease, the contrast dye could cause additional kidney damage, Costa said.

According to Moses, the same risks apply for OCT as for other heart imaging procedures.

"There's always a risk of manipulating the artery," Moses said. "If you're just looking at the artery, there are a few patients who may get a clot or spasms."

Since there are no set guidelines for doctors to identify the right patients for the technology, each patient should be evaluated individually, Moses said.

Even though many experts agreed that more research is needed to better understand the potential risks of OCT, Moses said the technology could improve the way blocked vessels are identified.

"We're getting such phenomenal fine detail," Moses said. "We will learn so much about atherosclerosis as a disease."

Disclosure: Costa has received research grants and consulting honoraria from LightLab and Cordis/Johnson & Johnson.

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