New York, NY - An echocardiography system that conveniently slips into a coat pocket might seem a natural for cardiologists: a readily available window into the heart and how it's functioning, far more informative and flashy than the venerable stethoscope. And some of the first published outpatient data comparing the iPhone-sized devices to more familiar "lab-sized" systems showcase their potential in screening and in evaluating outpatients with suspected cardiac disease.
But that might not be enough for the cardiovascular specialist. US experts who spoke with heartwire said that while the pocket-sized devices seem exceptionally useful and possibly game-changing for certain situations, they will probably be more valuable to general internists, hospitalists, or emergency-department personnel, at least in the US, where they haven't really caught on with cardiologists.
Why not? Echo exams using current pocket models like the Vscan (GE Healthcare) and Acuson P10 (Siemens) can't replace echocardiography performed by larger, more fully featured systems, observed Dr James N Kirkpatrick (University of Pennsylvania, Philadelphia).
"I think the best use of these hand-carried machines is in places where we don't have a full echo and by people who don't have access to full echo," according to Kirkpatrick. "We have one of them, and I do carry it around on the consult service, and I have brought it to the clinic occasionally. But the reality is that I have such easy access to full echocardiography that it's less useful for me than I think it would be for a well-trained general internist who doesn't have the same kind of access and perhaps isn't necessarily asking the same questions."
Kirkpatrick and Dr Kirk T Spencer (University of Chicago, IL), both of whom have studied cardiovascular uses for the devices, told heartwire that they aren't popular with US cardiologists probably because they don't give all the information a larger system can provide and using them isn't specifically reimbursed.
"In this country, there's probably very little role for these things in the hands of cardiologists. Because if you're seeing a cardiologist, you deserve a full echo," Spencer said.
The devices are inexpensive compared with full-function systems for the lab. The Vscan goes for less than $8000, for example, while larger-scale "hand-carried" models can go for tens of thousands and the largest, most sophisticated systems for many times that. But there's no financial incentive to use the pocket devices if a full echo study is going to be ordered anyway.
And ordering a full echo exam is comparatively easy in the US, Spencer observed. "You just check a box to get a complete echo, and it doesn't involve your time and effort," he noted. But in some European countries, the cardiologist performs the full echo exam and might save time and effort if it's sometimes done with a pocket device.
In fact, much of the literature on "hand-carried" echocardiography in the past decade, which includes use of the heavier but still-portable laptop- and suitcase-sized systems that have been around a lot longer than the pocket devices, is from Europe.
So, both experts noted, and as several recently published studies seem to suggest[1,2], the appeal of pocket echo systems to cardiologists may largely depend on their country's healthcare delivery and financing system.
The studies in the February 2011 Journal of the American Society of Echocardiography looked at the performance and usefulness of outpatient echo examinations by cardiologists using pocket-sized devices: in one, during their first examination of referred patients; in another, in patients they decided needed a standard echo examination.
Vscan vs the "gold standard"
In the study from Dr Christian Prinz (Catholic University Leuven, Belgium) and Dr Jens-Uwe Voigt (Ruhr-University Bochum, Bad Oeynhausen, Germany), 349 consecutive patients referred for echocardiography underwent examinations using both the Vscan ("performed by an experienced cardiologist") and a fully featured "high-end" system ("performed independently by an experienced echocardiographer"), in no prespecified order.
Endocardial visibility grades and regional wall-motion scores with the two types of system were comparable and significantly correlated (p<0.01), as were estimates of cardiac structural dimensions and LV ejection fraction. Both types of echo system identified all six patients with pericardial effusions, according to the authors.
There was also "good concordance" between the devices for measurements of mitral-, aortic-, and tricuspid-valve regurgitations; with the pocket system, "assessment of regurgitations tended to result in a slight overestimation of the lesion severity, but the overall accuracy was more than appropriate for clinical use."
Valve stenoses were evaluated conventionally with the full-featured echo system, which had the required spectral Doppler-imaging capability. While the pocket-sized devices have color-flow imaging, they lack spectral Doppler. So the investigators used a surrogate to measure valve stenoses with the Vscan, an index based on valve thickening, calcification, and motion along with color-Doppler assessment of turbulence.
Compared with the gold-standard full-featured system, the Vscan underestimated aortic-stenosis severity in half the patients.
Still, "it was possible to perform adequate imaging and quantitative assessment of even enlarged hearts in every case of our study population," according to Prinz and Voigt.
"No clinically relevant findings were missed [at Vscan imaging]. Only spectral Doppler features are missing to make examinations complete and clinically valid," they write.
"Given the future implementation of full standard echocardiographic functionality, this new class of device has the potential to be safely used by experienced echocardiographers as diagnostic tool in routine clinical practice."
They continue, "High-end scanning will remain an indispensable part of good cardiologic practice, although the new [pocket-sized] devices allow experienced echocardiographers to safely answer clinical questions within the scope of the devices' capabilities."
Commenting on the study from Prinz and Voigt, Kirkpatrick said the surrogate measurement of valvular stenosis in the absence of spectral Doppler "worked relatively well for them, although they did find, as others have found, that it's actually more difficult to accurately diagnose valvular lesions with the hand-carried machines than it is to look at chamber size and ventricular function."
As for the spectral Doppler needed for more accurate measurements, "we are anticipating that it will eventually be available on the small devices."
Spencer said the study suggests that in the hands of experienced cardiologists, the pocket devices "can answer some questions pretty well." But for the authors to claim that they "missed no relevant findings" understates the devices' shortfalls in the absence of some key features of full-on echocardiography systems.
"The devices don't rule out everything; they're good for very specific questions," he said. "You're going to miss things if you're using a device that can only look for certain things."
Few people, he noted, are referred to the echo lab with a narrowly specific question in mind. "Is my heart big? Is there fluid around my heart? The devices can answer those two questions." But it's more likely for patients to come in with nonspecific complaints like dizziness, for which there may be dozens of causes. "Well, the hand-carried [devices] can't exclude them all."
Vscan as an extension of the physical
In the other paper, from Dr Nuno Cardim (Hospital da Luz, Lisbon, Portugal) and colleagues, 189 patients referred for an initial cardiology outpatient consultation underwent a physical examination provisionally followed by evaluation with the Vscan at two major tertiary-care centers. The examinations were performed by cardiologists experienced in echocardiography who had been previously given a week to become familiar with the device.
Physical exam and the Vscan study "agreed" not to refer patients to the echo lab in 35% of cases. The two methods agreed to refer to the echo lab in about 20% of cases.
The Vscan exam led to referral while the physical pointed to no referral in about 14% and obviated referral indicated by the physical in about 31%.
"Reasons for echocardiography lab referral after [Vscan evaluation] were exclusively related to the need for spectral Doppler," Cardim et al write, and in no case to "inadequate image quality."
Detection of LV dilatation and systolic dysfunction using the Vscan that was often undetected from the history and physical led to initiation of ACE-inhibitor, beta-blocker, or angiotensin-receptor-blocker therapy, according to the group. Similarly, its detection of wall-motion abnormalities associated with chest pain prompted anti-ischemic therapy. And disclosure of left-atrial dilatation in patients with paroxysmal palpitations led to initiation of antiarrhythmic therapy, they write.
The pocket-sized echo system "showed additive clinical value over the physical examination, contributing to an increased number of diagnoses, reducing the performance of unnecessary conventional echocardiographic studies, increasing the number of adequate echocardiograms, and allowing many patients to be released from the outpatient clinic without the need for further testing after the initial consultation."
Commenting on the study for heart wire , Spencer said the "extended-physical-exam" model of pocket-echo use is a good one. "We should be using them to examine the heart to find unsuspected things or to make better decisions."
But he said it was "absurd" to use the pocket device to identify such patients who can avoid a complete echo exam. Again: "If you're seeing a cardiologist for cardiovascular symptoms or signs, you need a full echo."
Kirkpatrick contends much the same. "If somebody has signs and symptoms suggestive of cardiovascular disease, they really need to have an echocardiogram, and they probably should have the best echocardiogram that they can have," he said.
"Many of these symptoms are very difficult to pin down. They're not necessarily the result of traditional causes, and it's actually important to have a comprehensive echocardiogram to see what in fact is contributing to or causing these symptoms."
In an editorial accompanying the two reports, valve expert Dr William A Zoghbi (Methodist DeBakey Heart and Vascular Center, Houston, TX) is optimistic about pocket-sized echo devices but circumspect about their current capabilities and suitable applications. Such a diagnostic tool would be a welcome addition to physical examination, which he says is "the irreplaceable foundation for any further investigations that may be needed" but has limitations.
"In the interest of early disease detection, we should welcome a diagnostic modality that could be available at the point of care. Such a tool would be a readily accessible, prompt aid to physical diagnosis and help us better discern which patients truly require more resource-intensive and time-consuming studies such as full echocardiography or other testing." For pocket-echo systems to fill this role, image quality would have to be "consistently high."
While the current studies suggest their image quality may be high in outpatients, Zoghbi writes, it's likely that their use in inpatients, "particularly those who are critically ill, would be more problematic, and [their] efficacy more limited."
Settings where echo can't go
One good use for the pocket devices would be in settings "where echo can't go or it's too expensive to go," Kirkpatrick said. That would include poor and underserved communities, where there would likely be a lot of cardiovascular disease. "Given the cost of maintaining a full-featured echocardiography machine plus a highly trained sonographer and interpreter and so forth—that might be the place where this could do a lot of good."
Another would be in screening patients with cardiovascular risk factors "for whom there isn't enough suspicion to get a full echo," he said. "There would be a substantial number whom you would do something about."
Use of the devices in that setting would often produce equivocal findings and so could conceivably lead to more full echocardiographic examinations, not fewer, observed Spencer. "If you're an intern, and you're screening a patient, and you think you see something bad that would initiate therapy, you'd say you may have found something [otherwise] undetected and order a full echo."
Still, he said, screening patients with cardiovascular risk factors like high blood pressure or diabetes—but nothing that would trigger a full echo exam—is a superb role for the pocket echo systems. So is screening athletes.
"Would we find things? Absolutely, and we would find things that are important. We can find LV dysfunction, which is one disorder we know if we treat early, we make a difference."
Noncardiologist in-hospital use
The devices have also attracted a lot of attention in emergency-department and critical-care settings, observed Spencer, especially after hours.
"They want to start a therapeutic plan at the bedside tonight, and not wait for a sonographer to come in in the morning. To do that, they need to know only a few basic things. In that setting, the devices are great: small, quick, and pretty easy to use." The patients still get a confirmatory full echo in the morning, "but for the ER intensivist, for early triage and initiation of bedside therapy, it's going to be an incredibly powerful device, I have no doubt."
His own research, Spencer said, focuses on use of the devices by noncardiologists such as internists and hospitalists. In one study, such physicians were asked to predict LVEF conventionally, based on examination, ECG, and X-ray. Then they used the pocket echo devices. "The echo outperformed the others phenomenally," he said.
The patients still needed a full echo exam, but the hospitalists could, for example, make a treatment decision in the middle of the night that otherwise might have been delayed.
Kirkpatrick pointed out another promising role for the devices: regular measurement of filling pressures and other signs to follow a patient's progress. "A hand-held machine can be used like a stethoscope to make these frequent assessments to guide and track response to therapy. In this way I think it is especially useful in the hands of noncardiologists such as residents, physician assistants, and nurse practitioners."
Lack of reimbursement may be one issue "holding this technology back" in the US, observed Kirkpatrick, but it doesn't necessarily have to be that way, he said. Current reimbursement levels for echocardiography more or less consider the purchase and operating costs of full-featured systems, substantial training needs, and other expenses associated with their use. As a result, reimbursement for using the inexpensive, less training-intensive pocket systems could be discounted to a level commensurate with its lesser cost and demands, he proposed.
"If the general internist could get even a little bit of reimbursement, it'll never reach the point where it's a substantial moneymaker for them, but it might recoup some of the cost of their training and the time they spend doing the exam," Kirkpatrick said.
But Spencer said about reimbursement for the pocket devices, "I think it'll never happen, and I think it shouldn't happen." He agreed, however, that the lack of it "may also be why it hasn't taken off so much."
Medicare, he observes, has famously targeted echocardiography and other imaging modalities for reimbursement cuts, and in all the patient-care models he sees for the pocket systems, the patient "has another echo coming."
Physicians should use the devices, Spencer said, "because it's the right thing to do, because they know it's so much better than the unbelievably primitive stethoscope and the laying of hands on our enormous patients, trying to hear their heartbeat."
If the price of the pocket systems drops further, "my hope is that we'll be using them as extensions of the exam."
Editor's note: For anyone inspired enough by the pocket systems' size and superficial resemblance to a smartphone to think one day there might be an "echo app," it's been thought of—or nearly so .
Neither the study >papers
nor the editorial from Zoghbi include disclosure statements. Both Kirkpatrick and Spencer said they have no relevant financial relationships.
Heartwire from Medscape © 2011
Cite this: Echo system in your pocket: Rich in potential, niche uses for now - Medscape - Mar 14, 2011.