Clinical Value of Handheld Echocardiography
December 1, 2014
By Michael H. Crawford, MD, Editor
SOURCE: Mehta M, et al. Handheld ultrasound versus physical examination in patients referred for transthoracic echocardiography for a suspected cardiac condition. JACC Cardiovasc Imaging 2014;7:983-990.
Small handheld ultrasound units are being deployed in emergency departments and other sites to aide in point-of-care cardiac diagnosis. However, little is known about the clinical value of handheld echocardiography (HHE). Thus, this group of investigators from the University of Oregon compared conventional echocardiography (CE) to HHE and physical examination findings in 250 patients referred to the echo lab for the possible diagnosis of left ventricular (LV) dysfunction, valve disease, cardiac source of embolism, and possible structural heart disease in arrhythmia patients. The physical examination was performed by an attending cardiologist, who was only told the reason for the echo request. Another cardiologist blinded to the other clinical findings performed the HHE. HHE did not include saline or contrast injections, and it does not have spectral Doppler. A cost analysis of further tests needed to make the diagnosis after physical examination or HHE was done. Of the 250 patients, 142 had a significant abnormal finding on CE. HHE correctly identified 82% of these abnormal findings and physical examination identified 47%. When broken down by abnormality, HHE was superior at identifying abnormal LV and right ventricular function and moderate or severe valve disease, with the exception of aortic stenosis. However, physical examination rivalled HHE for detecting pulmonary hypertension and excluding significant valve disease. Further testing was recommended in the patients with abnormalities detected by CE (90% after physical exam and 91% after HHE). In those with no abnormalities on CE, further testing was recommended after HHE in 56% and after physical examination in 82% (P < 0.001). Costs were not appreciably altered by the addition of HHE. The authors concluded that when used by cardiologists, HHE was superior to physical examination for identifying most cardiac abnormalities, and a negative HHE results in less additional testing vs physical examination alone.
COMMENTARY
As small handheld portable echo machines have gotten smaller and included color Doppler, their use has increased. They are frequently used in emergency departments and critical care units to rapidly diagnose severe LV systolic dysfunction, pericardial effusion, and pulseless electrical activity. Some, like the authors of this paper, are recommending its routine use to supplement or replace the cardiac physical examination. In fact, some medical schools are now issuing these machines to incoming first-year students. Using CE as the gold standard, this study compared the results of physical examination vs HHE for diagnosing common cardiac conditions. In many ways, this is an apples to oranges comparison, and the results are predictable. One wouldn’t expect physical exam to be terribly good at detecting mild LV systolic dysfunction or moderate tricuspid regurgitation, and it wasn’t. On the other hand, physical exam was highly accurate at detecting severe aortic stenosis vs an HHE machine with no spectral Doppler.
The most important issue in the adoption of this technology for routine practice is cost. This paper hypothesized that by making better diagnoses at the bedside, downstream testing costs would decrease and the health system overall would see reduced cost. The results could not conclusively confirm this hypothesis, partly because the study wasn’t designed as a proper cost analysis study. On the other hand, there are clear costs associated with employment of this approach that were barely touched upon. First, the device costs several thousand dollars and the service is not billable. Also, in the authors’ hands, HHE took an additional 8 minutes to perform. Once cardiologists have seen three patients and used HHE, they have decreased their patient throughput by one patient (24 minutes for 3 HHE exams). A full clinic day’s patient volume would be reduced by 25%, with no additional billing to compensate. That just isn’t economically feasible today.
A strength of this study was that the physical exam and HHE were done by staff cardiologists. Since echocardiography is part of every cardiologist’s training and is tested at a basic level on the Board exam, presumably HHE was well done. Physical examination is known to be a declining skill. It would have been useful to know if a particular protocol was used by all. Since the average cardiac physical exam took 5 minutes in this study, it sounds comprehensive, but I would like more details. Also, what stethoscopes were used. In cardiac auscultation unlike lung auscultation, equipment does matter. Not a week goes by when I don’t hand a resident my $300 stethoscope so they can hear the murmur that they missed with the free stethoscope they got in medical school.
So the debate goes on. At this point HHE has a clear role in specific hospital settings and is superior to physical examination for many subtle diagnoses. However, for routine clinical use, the benefits don’t yet outweigh the costs. As these machines become part of your phone in the future, acceptance will grow, but it won’t take off until the economics of their use improves.
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