Nov. 12, 2001 ANAHEIM, Calif. – In clinics and doctors' offices of the future, small handheld echocardiography machines will be used to quickly screen patients' hearts for structural abnormalities that could indicate the need for more detailed and thorough cardiac testing. The stethoscope, currently the ubiquitous symbol of the medical profession, will no longer be used in the initial assessment of a patient's heart.
That's how cardiologist Dr. John Alexander sees the potential of the latest advances in echocardiography technology and miniaturization, based on the results of his new study at Duke University Medical Center. While the new, smaller machines do not provide the same level of detail as their larger and more expensive counterparts, it appears they can detect heart abnormalities needing further attention, even when used by physicians with just minimal training.
"These handheld devices are not as good as standard echocardiography for everything, but as a screening tool, they are a major step forward over what we currently use," Alexander said. "As a practical matter, they could pick up a large number of patients who have heart abnormalities that cannot be detected by a stethoscope or who have heart disease but are not yet having symptoms."
Alexander prepared the results of his study for presentation during the 74th annual scientific sessions of the American Heart Association.
For years, cardiologists have recommended that patients with suspected heart disease undergo hourlong standard echocardiography exams, which, like ultrasound exams of babies in utero, use sound waves to provide moving pictures of the heart. These machines cost hundreds of thousands of dollars, the technicians require years of training to operate them and physicians undergo years of experience to interpret the images.
In the past few years, however, miniaturization has reduced these echocardiography systems to the size of a laptop computer. While cardiologists have been debating the proper role of these new devices and their accuracy, Alexander asked a different question. "We didn't want to know whether or not the new echo machines are better than standard echo machines, but whether the new machines could provide useful information when used during a routine physical exam by someone with minimal training," he said.
For their study, the Duke researchers recruited Duke second-year medical residents and cardiology fellows who had no prior experience with echocardiography and gave them three hours of point-of-care echo (POCE) training. They were then asked to perform POCE exams on patients who had just undergone or were about to undergo a standard echocardiography exam. A total of 533 patients were enrolled and the average POCE examination took a little more than eight minutes.
The researchers then compared the results of the POCE studies to the standard echocardiography findings on four major heart abnormalities: left ventricular ejection fraction (the strength of the heart's major pumping chamber); pericardial effusion (fluid in the sac surrounding the heart); mitral regurgitation (leaking of one of the major heart valves); and aortic valvular thickening (thickening of another major heart valve). The results were most positive with the first two abnormalities.
"We found that clinicians with limited echocardiography training can use POCE to reasonably detect left ventricular dysfunction and pericardial effusion," Alexander said. "Low ejection fraction is an incredibly important indicator of heart health. For patients who might come to their doctor with shortness of breath, a quick POCE could determine if there was indeed a low ejection fraction. A stethoscope cannot reliably detect these abnormalities."
Screening is especially important for older patients, many of whom have reduced ejection fraction but do not yet have symptoms that would get them referred for a standard echocardiogram, Alexander said.
While POCE with minimal training was not as accurate in detecting mitral regurgitation or thickening of the aortic valve, Alexander did say that this would improve with additional training.
"POCE shouldn't be seen as a replacement for standard echocardiography, which will always have its place in answering important questions about the heart," Alexander. "As a screening tool, however, POCE could play an important role in quickly determining which patients should be sent on for further echocardiography testing.
"In reality, for most patients the only screening test is their personal physician using a stethoscope," Alexander continued. "This study shows that with minimal training, any physician can use POCE to screen for heart problems."
While the new devices cost about $10,000, Alexander believes that as their systems become more accepted by the medical profession, the price will come down, making it feasible for them to be used routinely in doctor's offices, clinics, emergency rooms and hospital units.
Alexander's team included the following colleagues from the Duke Clinical Research Institute (DCRI): Dr. Eric Peterson, Anita Chen, Tina Harding, David Adams and Dr. Joseph Kisslo. The study was funded by the DCRI.
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