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Link
on Hard Arteries, Vein Clots Found
A study has found a link between
hardening of the arteries and blood clots in veins, a discovery
that could spur new research on ways to prevent the life-threatening
blockages.
Researchers concluded that either hardening of the arteries can
induce blood clots in veins or the two conditions share common
risk factors.
Dr. Paolo Prandoni, the lead researcher and an associate professor
of internal medicine at the University of Padua Medical School
in Italy, said he believes hardening of the arteries, or atherosclerosis,
somehow causes the blood clots, but can't yet prove it.
His team found patients hospitalized with unexplained deep-vein
clots were nearly 2 1/2 times more likely to also have atherosclerosis
than patients with deep-vein clots attributed to other health
problems.
Prandoni said researchers now should study mechanisms that might
connect artery and vein disorders, and whether cholesterol-lowering
or anti-clotting drugs can prevent deep-vein clots as well as
control atherosclerosis to prevent heart attacks and strokes.
The study was reported in Thursday's edition of the New England
Journal of Medicine.
"It's one more reason that patients ought to understand whether
they're at risk for heart disease and take steps to lower those
risk factors," said Dr. Sidney Smith, past president of the American
Heart Association.
Arteries, which carry blood from the heart throughout the body,
can harden over time from factors including smoking, high blood
pressure and cholesterol, or plaque, which stays in arteries and
attaches to their walls.
Veins, which have thinner walls, don't harden or build up plaque.
But blood clots can form in veins from surgery, cancer, leg injury
or immobilization, pregnancy, recent childbirth or use of the
hormone estrogen. In about one-third of patients with a vein clot,
there's no identifiable reason and thus no way to prevent it.
If part of a clot breaks free, it can travel to the lungs and
lodge there, causing a blockage called a pulmonary embolism. Pulmonary
embolisms kill at least 60,000 Americans annually, according to
the Centers for Disease Control and Prevention; one apparently
killed NBC war correspondent David Bloom on Sunday.
Smith said Prandoni's study must be repeated on more patients.
Rather than atherosclerosis causing deep-vein clots, or thrombosis,
he thinks the two conditions have the same risk factors standard
causes of heart disease such as smoking, high blood pressure and
high cholesterol.
"We need to understand how the risk factors that contribute to
atherosclerosis might also contribute to heightened thrombosis,"
said Smith, who directs the Center for Cardiovascular Science
and Medicine at University of North Carolina-Chapel Hill.
Doctors know patients with hardened arteries have more blood
clots in their arteries than other people, probably because of
platelets clumping together too much, Smith said. But this is
the first report of patients with atherosclerosis having vein
clots.
"From a basic science perspective, it makes sense," said Carl
Hock, acting chairman of the cell biology department at the University
of Medicine and Dentistry of New Jersey-Stratford.
He suggested the link may be endothelial cells, which line blood
vessels and release substances that prevent clotting. The cells
function abnormally in patients with both atherosclerosis and
deep-vein clots.
Atherosclerosis is the main underlying cause of heart disease,
which kills about 13 million Americans annually. Meanwhile, there
are 200,000 to 600,000 new cases of vein clots each year.
The study included 449 patients hospitalized from March 1996
to April 2001. Two-thirds had deep-vein clots but no symptoms
of atherosclerosis; the other third were a comparison group with
unrelated conditions.
Smith said controlling cardiac risk factors through smoking cessation,
taking a daily baby aspirin, getting more exercise and losing
weight would slow progression of atherosclerosis and might also
prevent or limit vein clots.
In some cases, risk factors and symptoms such as chest pain or
shortness of breath could warrant expensive imaging tests to detect
buildup of plaque indicating a patient's arteries have hardened
and that medication or more aggressive treatment is needed.
Reference
Source 102
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