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Handheld Echocardiography | Circulation
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Handheld Echocardiography

Current State and Future Perspectives
Originally publishedhttps://doi.org/10.1161/CIRCULATIONAHA.117.026622Circulation. 2017;136:2178–2188

    Abstract

    Echocardiography is the primary imaging modality for diagnosing cardiac conditions. Over the past 2 decades, technological advancements have resulted in the emergence of miniaturized handheld ultrasound equipment that is compact and battery operated, and handheld echocardiography can be readily performed at the point of care with reasonable image quality. The simplicity of use, availability at the patient’s bedside, easy transportability, and relatively low cost have encouraged physicians to use these devices for prompt medical decision making. As a consequence, the use of handheld echocardiography is on the rise even among nonechocardiographers (intensivists, emergency care physicians, internists, and medical students). One of the real utilities of ultrasound-augmented clinical diagnosis is in evaluating patients efficiently and selecting patients for appropriate downstream diagnostic testing including comprehensive echocardiography. Although clinical evidence supports the use of handheld devices in various clinical settings and by different users, proficiency in point-of-care ultrasound requires dedicated training in both performance and interpretation. This review summarizes the existing literature on the use of handheld echocardiography in conducting focused cardiac examinations: its training requirements, challenges, opportunities, and future perspectives in the care of the cardiovascular patient.

    I have no doubt whatever, from my own experience of its value, that it will be acknowledged to be one of the greatest discoveries in medicine ... That it will ever come into general use, notwithstanding its value, I am extremely doubtful; because its beneficial application requires much time, and gives a good deal of trouble both to the patient and the practitioner.

    —1821, on stethoscopes (Mehta and Kaul1)

    For the past 2 centuries, stethoscopes have been the principal tools used for bedside diagnosis of cardiac conditions. However, physical examination alone may not provide adequate confidence or accuracy for driving medical decision making. Among imaging modalities, echocardiography is the only one amenable to miniaturization and has thus emerged over the past 2 decades as a useful tool to aid healthcare professionals at the point of care, addressing specific cardiac-focused questions. With the rapid emergence of miniaturized portable devices, studies can be performed nowadays with reasonable image quality, relatively low cost, and high portability.2

    Handheld Echocardiography: Equipment and Instrumentation

    The concept of the ultrasonic stethoscope appeared in the literature as early as the 1970s.3 The subsequent increase in computing power and miniaturization of transistor technologies resulted in the emergence of compact ultrasound devices.4 The first-generation mobile instruments included laptop-based equipment weighing between 4 and 6 kg, which could be brought to a patient’s bedside. The second-generation devices were hand-carried systems, weighing between 2 and 3 kg. The recently introduced third-generation devices include handheld or pocket-sized systems that are battery operated and weigh less than half a kilogram (Figure 1). The capabilities of each device, however, vary substantially. Although the laptop-based equipment can house almost every state-of-the-art 2-dimensional echocardiographic application, not all currently available pocket-sized devices have full-scale color-flow and none have spectral Doppler capabilities. Figures 2 and 3 give examples of images obtained by handheld echocardiography (HHE) in various clinical scenarios.

    Figure 1. All-in-one handheld echocardiogram devices with electronic transducers. Vscan with dual probe (A) and Vscan Extend (B) (Image courtesy of GE Healthcare, Wauwatosa, WI). C, Acuson P10, © Siemens Healthineers 2017 (used with permission), Siemens Medical Solutions Inc, Malvern, PA. D, Iviz. E, 180 Plus. F, iLook. G, NanoMaxx (D-G Images courtesy of FUJIFILM SonoSite Inc, Bothell, WA). H, uSmart 3200T (Image courtesy of Terason Division, Teratech Corporation, Burlington, MA). I, Sonimage P3 (used with permission), Konica Minolta Healthcare Americas, Inc, Wayne, NJ.

    Figure 2. Examples of echocardiographic images obtained with a handheld device in a healthy individual (A and B), in a patient with pericardial effusion (C), and another with large atria (D). EPSS indicates E-point septal separation; LA, left atrium; and LV, left ventricle.

    Figure 3. An example of color Doppler acquisition from a handheld device demonstrating mitral regurgitation.

    The design of pocket-sized equipment continues to evolve. Recently, mobile application–based ultrasound systems have emerged wherein a smartphone or tablet can turn into a handheld ultrasound simply by plugging in a transducer or connecting wirelessly (Figure 4). The transducer performs most of the beam forming, image acquisition, and reconstruction processing, and the smartphone serves as the display screen connected to a cloud-based application. Some of the devices have touchscreen displays and users can tap to start functions, pinch and drag to zoom in and out, and swipe to expand the images that can also be transferred to a picture-archiving and communication system wirelessly. Although HHE has a limited-spectrum functionality, it is expected to continue to evolve technologically (further miniaturization, incorporation of spectral Doppler) as a cost-effective tool to provide a focused cardiac examination at the point of care.

    Figure 4. Wireless and USB-probe handheld echocardiogram devices. A, Lumify (Image courtesy of Philips, Amsterdam, the Netherlands). B, Clarius C3 (Image courtesy of Clarius Mobile Health, British Columbia, Canada). USB indicates Universal Serial Bus.

    What is Focused Cardiac Ultrasound?

    Differences in ultrasound device design and the variability in terminology and clinical use prompted the American Society of Echocardiography (ASE) to provide recommendations for the use of portable and pocket-sized equipment for performing echocardiograms.5 The 2013 ASE guidelines differentiate a focused from a limited examination. Focused cardiac ultrasound refers to a point-of-care ultrasound examination that is goal oriented in a specific clinical setting to supplement the physical examination, whereas a limited echocardiogram refers to the performance of a limited number of views with otherwise full echocardiographic capabilities.5

    Because handheld devices and pocket ultrasound systems may not have the full functionality of larger machines, they are best used for focused examinations at the point of care. A parasternal view of the cardiac structures is the easiest to acquire and is correctly obtained even by briefly trained healthcare professionals. In contrast, the apical approach requires much more expertise because the correct position of the probe on the thorax varies widely; the 2-chamber view is the most difficult. In the critical or unconscious patient, the subcostal approach may be the only accessible window and it allows simultaneous evaluation of the heart and inferior vena cava (IVC); however, it may be limited in its information because of quality and lower image resolution in the far field. Last, while using a pocket ultrasound for qualitative cardiac assessment, a systematic approach is useful, as validated in ASE international programs.6,7

    HHE: The Scope of Practice

    Although cardiologists trained in standard echocardiography (SE) can readily use ultrasound for a variety of indications and types of ultrasound studies, nonechocardiographers can perform focused examinations after training, without the need for long experience in SE. The findings on these goal-directed examinations aid in early cardiac triage and management with great utility when used in intensive care units and emergency department settings where comprehensive echocardiography may not be readily available. Other additive values are short time acquisition (<5 minutes), rapid diagnosis in symptomatic patients, and detection of clinically significant pathologies in asymptomatic individuals.5,8

    To date, several guidelines addressing handheld cardiac ultrasound have been published from major organizations including the ASE,5,9 the American College of Emergency Physicians,10 and the European Association of Cardiovascular Imaging.11 With a wealth of data supporting the use of this technology and the enthusiasm surrounding it, dedicated training in acquisition and interpretation of images is needed to acquire and maintain competency, especially when the handheld echocardiographic examination is performed by nonechocardiographers.12

    HHE Versus Standard Echocardiography

    Several studies have demonstrated a good correlation of echocardiographic findings by HHE with SE.2,13 This included morphological, valvular, and functional assessment of cardiac chambers. In addition, it allows for early detection of previously unknown cardiac diseases in emergency units, during inpatient rounds, and in ambulances.14,15 A consensus statement published by the ASE found that left ventricular (LV) dilation, LV hypertrophy, LV systolic function, left atrial enlargement, right ventricular (RV) enlargement and systolic function, pericardial effusion, and IVC size have all been accurately detected.5Table 1 summarizes the diagnostic performance of most relevant evidence-based targets in HHE studies.

    Table 1. Sensitivity and Specificity of Handheld Echocardiography for Evaluating Cardiac Structures and Function

    Diagnostic Accuracy (%)
    Cardiac Targets Sensitivity Specificity
    Left ventricular dilation13,1619 73–100 64–93
    Left ventricular systolic function13,14,16,2023 >90 >90
    Left ventricular hypertrophy24 70 >90
    Inferior vena cava dilation16,20 ≈70 >80
    Left atrial dilation25 53–75 72–94
    Pericardial effusion16,17,22 89–91 ≈96
    Valvular heart disease13,17,22,26,27 ≈80 ≈80
    Right ventricle dilation and function14,20,22 Variable among studies

    HHE can be a gatekeeper to SE, especially in the setting of rarely appropriate indications. Pathan et al28 demonstrated that an HHE strategy has led to a 59% reduction in the need for SE, and has reduced significantly the total cost and time to decision making. It is important to remember that, although the major advantage of HHE over SE is its portability in a laboratory coat pocket, it still lags in image resolution, complex image enhancement, and image quality, particularly in technically difficult patients (instrumented, lung disease, etc). Furthermore, the fact that images are displayed on a small screen may have its own inherent limitation.

    Clinical Applications of HHE

    • LV size and function: One major advantage of HHE examinations is the rapid assessment of the LV. Many studies have examined the diagnostic accuracy of this approach in comparison with SE with good sensitivity and specificity.12 Although the interpretation of wall motion abnormalities by using HHE is feasible, it is the most demanding aspect of interpretation especially when the extent of the abnormality is small; a SE is commonly needed in this situation.9

    • Right ventricle: Technical and interpretative challenges exist in assessing RV size and function. HHE has been used in a few studies for detection of the signs of RV pressure overload in acute pulmonary embolism. Determining RV size is critical: a ratio of RV:LV >1 is suggestive of RV strain,29 carries an adverse prognosis, and may affect management.30

    • Right atrial pressure estimation: The size and collapsibility of the IVC provide compelling and accurate correlation to estimating right atrial filling pressures,20 which is commonly needed to assess volume status in critically ill patients and patients with heart failure. The ASE suggested the cutoff value of 2.1 cm with >50% IVC collapsibility with inspiration to denote normal right atrial pressures.5 Several studies have shown the utility of IVC size in changing management and predicting rehospitalization for decompensated heart failure.23,31,32 In the intensive care setting, fluid responsiveness in mechanically ventilated patients can be predicted by using the IVC distensibility index (maximal – minimal diameter / minimal diameter) with a cutoff of >18% to predict response to fluid therapy.33

    • Valvular heart disease: In patients with significant valvular pathologies, studies have shown good diagnostic accuracy with HHE in comparison with SE.12,26 However, it is best used to simply corroborate or clarify auscultatory findings. Adequate evaluation of valvular disease requires time, high-resolution imaging, and spectral Doppler for hemodynamic assessment. Thus, valvular lesions suspected to be beyond mild in severity should be referred to SE.

    • Rheumatic heart disease screening: Rheumatic fever is still the leading cause of valvular heart disease in developing countries. There is accumulating evidence that HHE used for screening in rural, less developed areas has high diagnostic accuracy for detecting rheumatic heart disease with reduced costs, eliminating long wait times in public facilities.34,35

    • Aortic diseases: The availability of HHE has allowed emergency department physicians to assess for aortic root dilation as a sign of possible aortic dissection. These devices have demonstrated good agreements in comparison with computed tomography and allowed timely diagnosis.36 Evaluation of the aorta, however, beyond the aortic root is limited with HHE and even SE.

    • Pericardial effusion: HHE is well suited for the assessment of pericardial effusion initially or serially after pericardiocentesis. The use of HHE for suspected tamponade has been incorporated in the FAST protocol (Focused Assessment with Sonography in Trauma) for >25 years with good accuracy.29,37 In the setting of invasive cardiac procedures, rapid assessment of postprocedural pericardial effusion is most effective and timely to guide management.

    • Heart failure: Accumulating evidence has shown the superiority of HHE in helping manage patients with heart failure (HF). In 1 study, HHE allowed directed therapy to start 18 hours (on average) before a SE was performed.23 Another trial demonstrated reduced length of stay when an internist used a focused examination to guide HF care.38 Serial follow-up addressing specific questions (LV function, volume status) is easily obtained with HHE and strongly predicts readmission for HF.9,39

    • Intensive care unit: In critically ill patients, the need for evaluating cardiac function and volume status is crucial in patient management. Among patients with septic shock, myocardial dysfunction is observed in one-third of cases, which complicates fluid resuscitation management. Currently, most of the educational curriculum of intensive care trainees has incorporated focused ultrasound for cardiopulmonary assessment.

    When comparing HHE with SE, one has to balance the advantages of portability and availability of echocardiography at the bedside with its current technological limitations. Although a significant number of cardiac parameters can be assessed with HHE, LV wall motion, cardiac masses, RV function, LV thrombus, valvular vegetations, and aortic dissection are difficult to accurately detect.21,40Table 2 summarizes the most relevant clinical indications where HHE can be used.

    Table 2. Most Relevant Clinical Presentations for Use of Handheld Echocardiography

    • Heart failure (chamber size, global left ventricular function, inferior vena cava size and collapsibility)
    • Shock (left ventricular function and volume status)
    • Cardiac tamponade (pericardial effusion, chamber collapse)
    • Cardiac arrest, pulseless electric activity (cardiac function, effusion)
    • Respiratory distress (right ventricular size and function, volume status)
    • Chest trauma (left ventricular/right ventricular function, effusion, volume status)
    • Acute chest pain (left ventricular and right ventricular size and global function, regional wall motion abnormalities, aortic root, pericardial disease)
    • Basic localization and evaluation of murmurs/valvular pathology

    HHE and the Physical Examination

    Ever since its introduction in 1816 by Laennec,41 stethoscopes have become symbolic tools of physical examination for assessing a patient’s cardiac status. Conceptually, the stethoscope is a 4-dimensional instrument (sound travels in 3 dimensions and time), and one can argue that this may be advantageous over echocardiography for precise detection of certain conditions such as significant valvular regurgitation, ventricular septal defect, patent ductus arteriosus; lesions that may be difficult to detect by casual tomographic imaging. However, with increasingly less emphasis on physical examination, modern studies have observed variability in auscultatory skills and a decrease in accuracy. HHE at the bedside has been shown to have incremental value over physical examination with regard to accuracy and cost-effectiveness.15,21,42,43 In asymptomatic at-risk patients, it is practical to assess left atrial and LV size and function. The detection of LV hypertrophy by using HHE is more accurate than the traditional findings of an S4 or a sustained apical impulse.5 Moreover, there has been increasing utility of HHE in evaluating patients with HF to help in triaging and assessing volume status.32

    Despite the existing debate in the value of cardiac auscultation, the physical examination and HHE (when available) can be viewed as providing complementary sets of information, which mitigates the risks of overreliance on 1 technique over the other. For example, in the presence of a murmur, HHE examination is targeted to identify its etiology among other findings; in its absence, HHE will emphasize cardiac structure and function and less time spent on valves, improving overall efficiency and accuracy.

    HHE for Clinical Decision Making

    Focused cardiac ultrasound examinations using HHE are performed at the point of care, aimed to clarify a clinical problem in a time-sensitive fashion. Over the years, efforts to expand the use of HHE among noncardiac medical specialists have continued. Several studies have shown promise in training medical students,16 residents,23,44,45 and internists.46,47 This has broadened the application of such technology, provided that adequate technical and interpretative training is achieved.

    Internists’ Utilization of HHE

    With the increased use of SE, challenges exist in a busy tertiary care hospital echocardiography laboratory to accommodate patients in a timely fashion. Avoidance of long waiting times and hospital stay has made HHE an attractive alternative as a point-of-care examination. The number of noncardiologists performing such examinations is expected to increase.12 Early studies have evaluated the feasibility and diagnostic accuracy of HHE performed by internists and have shown promise with regard to LV function assessment, but poor performance in evaluating valvular pathologies.47 More recently, HHE examinations performed by family physicians with remote expert support have shown reasonable image quality and a significant reduction in the need for referral to SE.48

    The Use of HHE in Emergency Care Settings

    HHE examinations have gained popularity in the emergency care setting, and are currently considered a core application by the American College of Emergency Physicians.10 In patients presenting with acute chest pain syndrome, a quick assessment of chamber size and function, ascending aorta, and pericardium can help triage patients and alter management. In unstable patients, a rapid evaluation for the presence of a large pericardial effusion, LV failure, or RV strain in massive pulmonary embolism is effective in delivering expedited care49; determining volume status is crucial, and size of IVC has been validated for assessing right atrial pressures.5

    The Use of HHE by Nurses

    More specialized nurses are following patients with HF after discharge to identify volume overload before recurrent decompensation. Studies have shown that, after training, nurses can perform high-quality ultrasound with good agreement to SE. Gundersen et al32 studied the use of HHE performed by 2 specialized nurses to assess volume status (IVC size and collapsibility, the presence of pleural effusion) in an outpatient HF clinic. Only volume status led to the dose adjustment of diuretics at the first visit and follow-up.

    The Use of HHE by Medical Students/Residents in Training

    In a recent survey of US medical schools, 62% reported that ultrasound was fundamental in their training curriculum.50 Previous studies have shown that, with adequate training, medical students can acquire and interpret diagnostic imaging.51,52 After 3 months of training, students could acquire diagnostic images using HHE in <6 minutes.14 However, as with any new skill, not performing these examinations regularly impacts performance negatively.5 In a recent study, well-trained residents were noted to lose their ultrasound skills after 2 years of no scanning.53

    Training to Perform Handheld Echocardiographic Examinations

    HHE has been incorporated in cardiology practice and other specialties and has been endorsed by various societies.5,10,54 Several training protocols and standards have been proposed.5,10,5557 Although there is no universal agreement for training, in particular, for the noncardiologists, all agree on the need for didactic education (ultrasound principles, cardiac anatomy and function, image acquisition), hands-on training, and interpretation experience.5,10,5557 The background in imaging of the users is variable (emergency care, intensivists, and anesthesiologists may have some ultrasound training, whereas internists and residents do not); hence, it is important for noncardiologists to undergo dedicated training to avoid over- or underdiagnosis of cardiac diseases.54 Because an HHE examination has important implications in the management of patients, it is essential to define training parameters, image acquisition criteria, and reporting requirements, and to evaluate the overall competence of professionals performing such examinations.

    One of the early experiences of incorporating a didactic curriculum for residents to use HHE came from Kimura et al58 and was first implemented in 2005. This involved 12 lectures (1-hour each) on a monthly basis. Once-weekly 1 hour of bedside teaching was given during rounds; the expectation of residents was to perform 10 to 30 examinations under the supervision of sonographers. Other programs and modules have been proposed for basic didactics.5,10,5557 After acquiring the basic knowledge about cardiac anatomy in relation to ultrasound, a great emphasis lies on applying this core knowledge, preferably on patients and volunteers rather than simulators only, so that the user is familiar with probe orientation, image acquisition from the different views, and image optimization. The last step is an interpretation of the studies performed: an accurate description of the findings, assessment of overall study quality, and acknowledgment of relevant structures that could not be assessed.

    Technical difficulties go along with miniaturized devices with regard to image resolution, limited processing, a small screen, and lack of spectral Doppler. Challenges exist in training novice learners on how to obtain good echocardiographic windows.59 Parasternal long- and short-axis views are typically easier to master, need less positioning of the patient, and are more reliable landmarks for less experienced users. One study by Hellman et al44 showed that, for a novice user, 20 to 30 studies are needed to acquire the basic acceptable skill necessary to perform and interpret images. Most professional societies have proposed a minimum number of ≈30 scans for basic training (range between 20 and 100).5,10,5557 In our experience, although this is a bare minimum for image acquisition, it would fall short for accurate interpretation: there are a multitude of pathologies that interpreters need to be exposed to despite a focused cardiac scope; this limited exposure would not be adequate for assessing critically ill patients, where images are more difficult to obtain and the diagnostic implications are the highest. This experience would need to be supplemented with case studies of other pathologies. In fact, short-duration training has been associated with an increased false-positive rate among medicine residents: hence, the critical need for specific training recommendations and maintenance of competency.45 Last, frequent reviews of the stored data, comparing interpretations with other modalities and pathology data, are useful for quality assurance and improvement.9

    Role in Telehealth and Mhealth

    Pocket echocardiography now forms a part of mobile health (mHealth) devices enabled by the convergence of 4 technologies: telemedicine with wearable devices, smartphone apps, unobtrusive sensing with in vivo nanosensors, and ubiquitous computing with miniaturized laboratory-on-a-chip devices. A major step in this direction was first investigated in the ASE-REWARD study (American Society of Echocardiography: Remote Echocardiography with Web-Based Assessments for Referrals at a Distance) where >10 000 patients with symptoms of cardiac disease were screened in a remote part of India and >1000 were imaged with handheld ultrasound.6 Performed within a 2-day period, the studies were uploaded to a cloud-based server and distributed to 75 cardiologists scattered over 60 medical centers in 4 countries. Scans were uploaded within 4 minutes and interpreted within 12 hours. Results identifying structural and congenital heart disease were delivered back to the local clinicians, effectively creating a digital platform for providing specialty cardiac services where they may be needed the most.7 Among the various design properties of mHealth devices, the portability, ease of use, and lower cost are among the features ideally suited for use in resource-constrained areas. To assess the benefit of multiple mHealth devices, the ASE-VALUES trial (A Randomized Trial of Pocket-Echocardiography Integrated Mobile Health Device Assessments in Modern Structural Heart Disease Clinics) randomly assigned 253 consecutive patients with symptomatic rheumatic and structural heart disease to an initial diagnostic strategy with mHealth including HHE, smartphone-connected ECG, blood pressure and oxygen measurements, activity monitoring, and point-of-care laboratory testing in wireless mHealth clinics or to standard-care medical clinics.60 During follow-up, 34% of the study population underwent treatment with valvuloplasty or valve replacement. The mean duration from the time of enrollment to the primary outcome was significantly shorter in the mHealth arm, and the occurrence of a hospitalization and death was lower in the mHealth than in the standard-care arm.60

    Is HHE Cost-Effective?

    Multiple studies have evaluated the cost-effectiveness of HHE versus SE strategy. On average, the total charges of an HHE study including the cost of device and operator charge ranged between $11 and $116, in comparison with $170 to $1500 for an SE.28,43,61 In the era of appropriate use and testing costs, Mehta et al43 compared the diagnostic accuracy of HHE versus physical examination and whether its use reduced overall costs in patients referred for a transthoracic echocardiogram. HHE correctly identified abnormal findings (significant valvular pathologies) in 82% of the patients in comparison with 47% identified by physical examination. HHE was associated with the reduced charge of $63 per patient (average of $644.43 versus $707.4). In another study, a strategy of HHE in comparison with SE resulted in savings up to $72 per study.28 Greaves et al61 demonstrated that if HHE was performed on all inpatients for LV function assessment (based of 2000 standard echocardiograms performed per annum), this would result in savings up to $23 000 and 29% reduction in departmental workload.

    Challenges and Barriers to Implementation

    For HHE to be successful at the point of care, devices must provide reliable imaging, be easy to use, and be affordable. The examination should be short enough in duration so as not to prevent physicians from seeing their patients in an expeditious manner. Although it is relatively easy for physicians already trained in echocardiography to acquire and interpret images, nonechocardiographers would need to be trained in acquisition and interpretation to meet consistently high standards. Physicians using handheld devices must be able to discern when information from a handheld device is diagnostic or of suboptimal quality to merit a full echocardiographic study. Education and training are therefore critically important and need standardization. Last, among the major challenges for adoption is the lack of incentive to use HHE. In the current US healthcare model of fee for service, there is no reward for spending more time at the bedside to arrive at a quick diagnosis, although the immediate knowledge from imaging expedites care; the viability and sustainability of a clinical practice or hospital institution currently depends on referrals to the more established diagnostic modalities (comprehensive or limited echocardiography) where time and effort are accounted for and built into the reimbursement scheme.

    Despite these challenges, several trends in health care will undoubtedly promote the incorporation of HHE into patient management and improve the patient-physician encounter. Healthcare reform has stipulated a more integrated healthcare system, the implementation of electronic health records and evaluation of new payment models that reward value, quality, and outcomes over quantity of care. Handheld devices are poised to help facilitate the delivery of cost-effective, quality care. The more empowered and informed a healthcare professional is at the point of care, the more effective is the rendition of care. Table 3 lists the advantages and limitations of HHE technology and its use in the clinical setting.

    Table 3. Advantages and Limitations of Handheld Echocardiography and Its Use in Clinical Practice

    Advantages Limitations
    Lightweight, pocket size, portable at the bedside Lower resolution, limited ultrasound frequencies, and image optimization in comparison with larger systems
    Time and cost-effective Limited to 2-dimensional (some with color Doppler); no spectral Doppler
    Adjunct to clinical examination Small screen size
    Allows early diagnosis and triaging in emergency settings, when comprehensive echocardiography may not be available Incidental or equivocal findings need confirmation by conventional echocardiography
    Daily use as needed during rounds or clinics Lack of hemodynamic measurements and limited valve assessment
    Use in frequent serial echocardiographic examinations (eg, heart failure, pericardial effusion) Not reimbursed
    Allows assessing heart disease in underserved or remote populations Specific training for image acquisition and interpretation is needed for nonechocardiographers

    New Technology and Future Applications

    Newer designs of miniaturized cardiac ultrasound systems that are currently being evaluated include wireless transducers62 (Figure 4), fingertip probes, and other wearable ultrasound transducers as a belt-like ultrasound device for continuous ultrasonography and vascular imaging.63,64 There has also been significant interest in the development of ultrasound-on-chip designs with capacitive micromachined ultrasonic transducers as an effective alternative to piezoelectric transducers for ultrasound-imaging applications.65 These developments soon will have potential not only for B-mode and Doppler processing, but also as an area- and power-efficient solution for 3-dimensional real-time volumetric imaging on a portable scale for point-of-care diagnostic applications.

    Application of artificial intelligence techniques to point-of-care ultrasound in the development of machine-learning systems may aid in the optimization of acquisition and interpretation of a high volume of images, reduce variability, and improve diagnostic accuracy, in particular, for novice users.66 Such algorithms may be delivered to the care provider in real time by using cloud computing–based solutions for avoiding delays in clinical diagnosis and therapeutic interventions. Moreover, the combination of digital imaging and telerobotics may expand the use of ultrasound even further, allowing an expert to perform an examination from a distance, virtualizing both ultrasound image acquisition and interpretation.67,68 These applications will help lend expertise to remote and dangerous locations, expand the applicability of community screening procedures, and expedite point-of-care remote examinations for patients who are hospitalized or waiting in emergency triage locations.

    As point-of-care cardiac ultrasound evolves, it may become impossible for an expert to review every ultrasound examination, which exacerbates the potential for harm with inadequately trained providers. The training requirements and standardization of protocols could potentially be performed using universally available online-training platforms and simulation environments.69 Development of such point-of-care simulation at a low cost will enable cardiac ultrasound training and simulation to be broadly affordable for developing countries. Furthermore, the emergence of machine vision (like automated security cameras) may enhance the development of an infrastructure and algorithm that provide quality assurance while minimizing patient risk.

    As ultrasound technology continues the impressive trend toward miniaturization, we foresee that handheld devices of the future will incorporate additional diagnostic tools, beyond those of ultrasound of the heart or vessels such as auscultation and electrocardiography to help physicians obtain the maximum diagnostic quest at the bedside and thus allow them to initiate timely and cost-effective care.70 Such information including other vital signs would be uploaded wirelessly into the electronic health record under the cardiac section of the physical examination, thus keeping a record of the totality of the patient encounter for serial follow-up. Healthcare professionals will embrace handheld devices if they see that the extra time spent at the bedside is enhancing care. This time is valuable and needs to be accounted for in a new sustainable, integrated, and value-based healthcare system.

    Footnotes

    Circulation is available at http://circ.ahajournals.org.

    Correspondence to: William A. Zoghbi, MD, MACC, Professor and Chairman, Department of Cardiology, Elkins Family Distinguished Chair in Cardiac Health, Houston Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, 6550 Fannin Street, SM1901, Houston, TX 77030. E-mail [email protected]

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    handheld echocardiography machines