Ultrasound waves may be as effective as magnetic resonance imaging at detecting small blood vessel blockage after a heart attack, according to researchers at Johns Hopkins.
The Hopkins team found that contrast echocardiography (CE) -- using a contrast medium with ultrasound waves to study heart function -- could detect blockage of the small vessels of the heart leading to a reduction in tissue blood flow to 60 percent of normal functioning. Magnetic resonance imaging (MRI) detected reduced tissue blood flow only when it was as low as 40 percent of normal functioning.
"Our study validates CE as an effective, non-invasive technique for measuring post-heart attack small vessel obstruction," says Katherine C. Wu, M.D., lead author of the paper and a cardiology fellow. "CE may be as good as MRI and, since it is easier to perform, may be a more practical way of measuring small vessel blockage."
Results of the study, supported by the American Heart Association and the National Heart, Lung and Blood Institute, will be presented at 2:45 p.m., March 31, at the American College of Cardiology's 47th annual Scientific Sessions in Atlanta.
When the heart suffers from inadequate blood flow, such as during a heart attack, dying blood cells and debris can clog the heart's capillaries -- the body's narrowest blood vessels, says Wu. If the vessels stay clogged for a long time, the capillaries remain blocked, preventing return of normal blood flow even after the body recovers from a heart attack. This can put a patient at risk for later complications, such as another heart attack, congestive heart failure or stroke.
Researchers compared CE to MRI by blocking coronary arteries in animal models for 90 minutes to simulate a heart attack. Then they observed the return of blood flow two days and nine days later using both CE and MRI.
The team found the same amount of blood vessel blockage occurred at two and nine days after the heart attack.
The study's other authors were David A. Bluemke, M.D., Ph.D.; Carlos E. Rochitte, M.D.; Elias A. Zerhouni, M.D.; Lewis C. Becker, M.D.; and Jo o A.C. Lima, M.D., of Hopkins; and Raymond J. Kim, M.D., of Northwestern University Medical School in Chicago.
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