Last May at Student Research Day, Hardean Achneck, M.D. ’05, described a link between atherosclerosis and aortic aneurysms. The aneurysms, he found, seemed to protect against atherosclerosis, a deadly form of arteriosclerosis.
By summer’s end Achneck’s research was published in the journal Chest and reported in The Wall Street Journal. Achneck was first author of the journal paper; the senior author was his advisor, John A. Elefteriades, M.D. ’76, HS ’81, FW ’83, professor and chief of cardiothoracic surgery. “I am very happy to see the results become so well-received,” said Achneck, now a surgical resident at Duke University School of Medicine.
The research began years ago and arose from repeated observations in the operating room. “Operating every day we noticed that in patients with aneurysms at the top of the chest, their arteries were pristine,” said Elefteriades. “They were like babies’ arteries, teen-agers’ arteries.” Typically, he said, even men in their early 20s have fatty streaks and plaque in their arteries.
Elefteriades has long welcomed medical students working on their theses, and he first assigned this project to Biren P. Modi, M.D. ’02. With the research still ongoing when Modi graduated, Achneck picked up the project and spent a fifth year at Yale working on it.
Literature searches, he said, yielded no articles exploring the links between two types of aneurysms located in the ascending aorta—annuloaortic ectasia and type A dissection—and atherosclerosis. The next step was to find 64 patients with both types of aneurysm, and a control group of 84 patients with no history of aneurysms. The control patients came from the emergency department, where they had received treatment for trauma and had had CT scans of their chests.
The patients who had aneurysms, the study found, were less likely to have atherosclerosis. This was independent of all common risk factors for atherosclerosis. “It was a statistically powerful finding,” Elefteriades said, adding that it fits with the results of laboratory research. “There are some strains of rodents that have been developed that are prone to aneurysms, and they are protected from arteriosclerosis.”
Why and how aneurysms offer protection from atherosclerosis remains unclear. Elefteriades and his colleagues are looking at enzymes called matrix metalloproteases (MMPS), which degrade material that accumulates on arterial walls. “It may be, and this is not proven,” said Achneck, “that some of these MMPS are causing aneurysms on the one hand and chewing up atherosclerosis on the other.
The gene for MMP3 is on a section of chromosome 11 that is known to cause mutations that increase the risk of aortic aneurysms. Elefteriades and colleagues are working with Celera Diagnostics to explore the underlying genetics.
Since his graduation Achneck has been focusing on his residency. “I’m trying to survive,” he said.