Plaque in a heart artery looks threatening, but cardiologists know that many of these buildups will not erupt, dislodge and block a vessel, causing a heart attack that can be fatal. Some will, however, and the challenge is to figure out atherosclerotic plaque that is dangerous and treat or remove it.
Now, researchers at Mayo Clinic have shown that iron, derived from blood, is much more prevalent in the kind of plaque that is unstable and is thus more likely to promote a myocardial infarction (MI) — heart attack — and possibly sudden death.
The team of researchers has demonstrated through a variety of experiments that iron buildup may be suitable as a marker of risk for a future MI, they reported today at the American Heart Association's Scientific Sessions 2010 in Chicago.
For example, they have found that Dual Energy Computed Tomography (DECT) and three-dimensional computerized tomography (CT) micro scans can detect excess iron in plaque, thus holding promise that in the future a scanning device might be able to noninvasively detect dangerous plaque formations in patients.
"We know that 70 percent of heart attacks are caused by unstable plaque, so what we really need for our patients is a way to identify the plaque that turns evil and puts them at jeopardy," says cardiologist Birgit Kantor, M.D., the study's lead researcher. "The scans we use now just show narrowing of heart arteries from plaque buildup but that doesn't tell us if the plaque inside those vessels walls is imminently dangerous."
"We think it is possible, based on these findings, to use iron as a natural marker for risk," she says. Dr. Kantor predicts that probably 5-10 years will pass before novel diagnostic scanners to identify these plaques become available in cardiology clinics.
Cardiologists now know that plaque can be classified as stable or unstable. Mayo Clinic researchers believe that the amount of iron in the plaque can be seen as a "readout" of prior hemorrhagic, or bleeding, events that put a person at risk for plaque eruption.
In normal heart arteries, small blood vessels known as vasa vasorum bring nutrients to the vessel wall, and when plaque starts to build up inside the artery wall, some of these tiny vessels grow as well to feed them. These vessels can rupture, depositing iron, a component of blood, into the growing plaque. This unstable plaque, which has a large core of dead cells covered by a thin fibrous cap, can eventually rupture, forming a big blood clot that can shut down a heart artery.
"This kind of plaque can bleed and heal, bleed and heal, depositing iron into the buildup," Dr. Kantor says. "This plaque is at risk of breaking up and causing a heart attack."
To conduct this study, the researchers used samples from a unique Mayo Clinic biobank of heart arteries collected over time from autopsies of 400 patients who died from a suspected heart attack. Small sections (1–1.5 inches) from the three main coronary arteries of each patient have been preserved.
In this study, pathologists examined 97 artery samples and separated them into stable and unstable groups based on their appearance under a microscope (dead zones and fiber cap). They classified 31 plaques as stable, 24 as "vulnerable," and 22 as normal and then linked them to patient clinical records to see which patients died from a heart attack.
Then Yu Liu, M.D., Ph.D., the study's first author, applied a stain to the samples to detect iron content. She found iron content in the unstable plaque group was significantly higher than in the other groups.Iron was absent in normal arteries.
In a third step, the researchers scanned a subset of the artery segments using a benchtop micro-CT scanner, and created 3-D images to look for iron deposits in plaque. The CT could identify iron in plaque without the need for staining. "There was a high correlation between the vulnerability of the plaque and the quantity of iron in it," says Dr. Kantor.
Still, non-invasive imaging for plaque does not yet have the necessary resolution to differentiate high risk from low risk plaque in patients, she says, and so the research team is testing other imaging modalities such as photon counting that can overcome these barriers.
Other study authors are Nitin Garg, M.B.B.S.; Joseph Maleszewski, M.D.; Steven Jorgensen; Jia Wang, Ph.D.; Xinhui Duan, Ph.D.; Shuai Leng, Ph.D.; Kay Parker; Cynthia McCollough, Ph.D.; and Erik Ritman, M.D., Ph.D.; all of Mayo Clinic.About Mayo Clinic
Penn vet research identifies new target for taming Ebola
12.01.2017 | University of Pennsylvania
The strange double life of Dab2
10.01.2017 | University of Miami Miller School of Medicine
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction