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Unstable Arterial Plaques

Curator & Author: Justin D Pearlman, MD, PhD, FACC

Vital blood delivery to organs such as the heart can be impaired by the development of cholesterol-rich lesions called plaques (atheromas), which occurs as a by- product of enzyme systems in the body that disassemble cholesterol esters in the blood stream and reassemble them within the muscular layer of an artery, particularly at regions of high flow. My theses investigations showed that the cholesterol esters are liquid crystals that can switch from liquid to solid at body temperature, adjustable by triglyceride concentration.

While mild plaques can add strength to an arterial vessel wall, the atheromatous plaques also can trigger inflammation, hemorrhage, and enlargement of the lesion. Excessive build up encroaches on the flow channel of the artery (the lumen), impeding blood delivery further along the artery. Also, the plaque can cut through then endothelial inner lining of the artery to access blood products in the lumen to activate thrombosis (clotting). A combination of plaque hemorrhage and thrombus formation can rapidly accelerate atheromatous lesion enlargement and impairment of blood flow in the artery.

The usual measure of the severity of obstruction from a plaque is diameter narrowing, expressed as a percentage of the normal inner diameter of the arterial vessel (percent stenosis). Logically, that is a rudimentary measure, as the flow impairment is well known to depend not only on the maximal percent stenosis, but also shape (entrance and exit flow effects, eddy currents) and on the length of the lesion. Also, percent stenosis does not address the risk of activating blood clots on the surface that dynamically impair blood flow further, and may onvert a minor percent stenosis to a sudden total occlusion.

http://www.medicalnewstoday.com/articles/268643.php
“Researchers from the University of Edinburgh in the UK say the test – carried out using positron emission tomography (PET) and computed tomography (CT) – is able to “light up” dangerous fatty plaques in the arteries that are in danger of rupturing. This is a process that can cause heart attacks.”

Dr. Marc Dweck, of the University of Edinburgh and lead study author, says their findings are a step toward heart attack prevention: “We have developed what we hope is a way to ‘light up’ plaques on the brink of rupturing and causing a heart attack. If we could know how close a person is to having a heart attack, we could step in with medication or surgery before the damage is done. This is a first step towards that goal.”

Prof. Peter Weissburg, Medical Director at the British Heart Foundation in the UK, which part-funded the study, notes that the technique looks promising: “Being able to identify dangerous fatty plaques likely to cause a heart attack is something that conventional heart tests can’t do. This research suggests that PET-CT scanning may provide an answer – identifying ‘ticking time bomb’ patients at risk of a heart attack. We now need to confirm these findings, and then understand how best to use new tests like this in the clinic to benefit heart patients.”

PET-CT imaging with contrast showed focal enhancement at 90% of culprit lesions for an acute myocardial infarction, and 40% for patients with angina.

SOURCE

http://www.medicalnewstoday.com/articles/268643.php