Researchers at Baptist Health Lexington in Kentucky, using optical coherence tomography (OCT), were able to view the interior of blood vessels and, in turn, peer into the composition of plaques that can obstruct blood vessels that feed the brain and cause a stroke. OCT has the potential to alter how physicians understand and treat carotid artery disease, which is one of the leading causes of strokes.
Related: Noninvasive optical method promises personalized stroke treatment
A study conducted at the facility, conducted between September 2010 and May 2012, involved a retrospective review of 53 symptomatic and asymptomatic patients suspected of having carotid artery stenosis, a narrowing caused by the buildup of plaque. The patients underwent diagnostic carotid angiography, a standard imaging technique used to detect carotid artery stenosis. They also underwent OCT, which creates images 10 times clearer than older imaging techniques.
"Because OCT offers such high-resolution images of the walls of blood vessels, we were able get an extremely clear look at the type of plaque and identify some of it as 'vulnerable' or 'unstable' plaque," explains Dr. Michael R. Jones, an interventional cardiologist at Baptist Health Lexington who served as the principal investigator of study.
Physicians have suspected for a while that some plaque is stable and some unstable and inflamed. It is the unstable plaque that is at risk for rupture. That rupture on the inside of the blood vessel is then treated like a wound by the body. One of the first things that occur in wound healing is that a blood clot is formed to stop any bleeding. Thus, the body forms a blood clot on the ruptured plaque. This clot then can be dislodged from the plaque and travel to the brain, causing a stroke. Less commonly, the fatty substance itself can break off and travel to the brain.
The study revealed that symptomatic patients had a larger percentage of unstable or vulnerable plaque, but actually less blockage when compared to the plaque found in vessels of asymptomatic patients.
It has long been thought that opening carotid arteries severely narrowed by plaque—either with surgery or a stent—is one of the most effective ways to prevent stroke. "This study, for the first time ever, was able to reveal that severity of the narrowing was not as much of a predictor of a stroke as the composition of the plaque itself," Jones says.
"This study, along with others that are sure to come in the future, could change the way we test patients with carotid artery disease," Jones says. "It could be that they might be better served with looking at the type of plaque they have rather than by measuring the severity of their blockage."
The study also included neurosurgeons Dr. William H. Brooks and Dr. Christian N. Ramsey, neurointerventional radiologist Dr. Curtis A. Given II, and colleagues from Case Western Reserve University (Cleveland, OH) and Pitangueiras Hospital (Jundiai, Brazil).
Full details of the study appear in the Journal of the American College of Cardiology (JACC) Cardiovascular Interventions; for more information, please visit http://dx.doi.org/10.1016/j.jcin.2014.01.163.
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