BOSTON (AP) - Researchers have taken a step toward solving one of modern medicine's mysteries: why so many people get chest pain without classic signs of heart disease.
The simple answer: They have unseen heart disease.
The condition, known as cardiac syndrome X, has befuddled doctors since
it was identified about 30 years ago. For all its mystery, it is
widespread, striking perhaps tens of thousands of Americans, mostly
women.
Many doctors have long viewed it as an unexplained form of heart
disease. But others see it a puzzling hypersensitivity to pain _ that is, a
neurological problem, not a cardiovascular one.
The latest research, published Thursday in The New England Journal of
Medicine, blames syndrome X on irregular blood flow in microscopic arteries
within the heart wall.
However, there is no evidence that the blood-flow problem raises
patients' risk of a heart attack or other deadly heart trouble, the
researchers said.
Syndrome X patients suffer from angina, the common chest pain of heart
disease. Their hearts also show abnormalities during exercise testing on a
treadmill. But there is no apparent reason for the pain. X-ray angiogram
tests fail to show the blocked blood vessels that choke off blood flow to
the heart in typical angina patients.
Syndrome X itself is not life-threatening. However, some doctors, in an
effort to ease the chest pain, treat syndrome X with the same beta blocker
drugs given to other heart patients. Too often, they do not work.
The scientists conducted the new research at a London hospital,
performing magnetic resonance imaging on 20 syndrome X patients and 10
healthy ones. Electromagnetic MRI scans, which yield 3-D images, can show
blood flow in finer detail than angiograms.
The images showed poor distribution of blood flow in the syndrome X
patients: too little in the inner heart wall and too much in the outer
layer.
The tests suggest poor blood movement within tiny heart arteries,
whether from a biochemical signaling failure, minute spasms or similar
causes, according to chief scientist Dr. Dudley Pennell of Royal Brompton
Hospital.
Dr. Julio Panza of Washington Hospital Center in Washington, D.C., said
in an accompanying article that the research adds to evidence that syndrome
X is a heart disease.
But he said the drug adenosine, which was given to the patients to
simulate the stress of exercise, could have caused the effect seen on
MRIs.
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On the Net:
New England Journal of Medicine: http://nejm.org
British Heart Foundation Q&A:
http://www.bhf.org.uk/questions/index.asp?secondlevel370&thirdlevel511
