a

What is FCU?

FCU is a focused examination of the cardiovascular system performed by a physician by using ultrasound as an adjunct to the physical examination to recognize specific ultrasonic signs that represent a narrow list of potential diagnoses in specific clinical settings.

b

Terminology

There are a variety of terms that have been used to describe a focused ultrasound of the heart. The importance of defining the nomenclature is the recognition that these procedures are distinct from the practice of echocardiography, as outlined in section 3. The American Society of Echocardiography (ASE) recommends the use of the term “focused cardiac ultrasound,” but recognizes that other terms are in use ( Table 1 ). The literature also contains hybrid terms that should be avoided because the expectations of the examination, equipment used, expertise in image acquisition, and proficiency in data analysis and interpretation are unclear if these terms are used. Such terms include “focused echocardiography,” “hand-held echocardiography,” “hand-carried echocardiography,” “point of care echocardiography,” and “directed echocardiography.” The appropriate terminology for echocardiography has previously been established and includes “complete” or “comprehensive” echocardiography and “limited” echocardiography.

a

Examination Expectations

With FCU, subjective interpretation of one or a few prechosen targets of interest is emphasized, with the intent that subsequent referral for an echocardiographic study will delineate and measure all findings, including incidental or associated findings, which may go unrecognized by FCU. Abnormalities when using FCU are typically classified as present or absent by using a predefined specific imaging protocol. The practitioner is “focused” on making a specific diagnosis or identifying a potentially significant valvular, hemodynamic, or structural abnormality. This approach allows rapid detection of a small number of evidence-based targets at the bedside that could provide clues to the patient’s cardiac status and requires less training and expertise than that considered adequate to perform echocardiography. The results of an FCU examination can be used in conjunction with other bedside measures, such as the physical examination, in formulating an initial diagnostic impression and guiding appropriate early triage and management.

Although a FCU evaluation may facilitate initial management, all patients with abnormal findings not previously documented on echocardiography should be referred for a comprehensive echocardiographic examination. A physician with only FCU expertise does not have the image acquisition or interpretation expertise to completely evaluate a symptomatic cardiac patient. Comprehensive echocardiography allows additional characterization of an abnormality from supplementary views, complete assessment of the hemodynamics associated with a lesion and further evaluation of a finding with additional ultrasound tools (Doppler, 3D, etc). When FCU evaluation fails to detect any prespecified abnormalities in a patient with symptoms or signs of cardiovascular disease, referral for comprehensive echocardiography is probably warranted. For example, in a patient with dyspnea, although FCU may allow rapid and accurate exclusion of a large pericardial effusion or significant left ventricle (LV) systolic dysfunction, numerous other cardiac pathologies missed by FCU, but detectable by comprehensive echocardiography, remain to be investigated as alternative causes of the patient’s breathlessness.

The implications of the FCU examination go beyond its terminology in regard to the perception of the act by the patients, their families, health care professionals, and the legal profession. Patients who undergo or witness an FCU examination should be informed that this particular use of ultrasound is a new method that is meant to enhance bedside examination by providing “early” or “preliminary” information that is used to formulate the physician’s initial impression. Importantly, it is not equivalent to a diagnostic echocardiographic study. The operator is incorporating his or her recognition and knowledge of specific findings within the scope of his or her clinical practice in the care of the patient. Patients and their families should be told that significant abnormal findings will be confirmed with a complete diagnostic echocardiogram. Patients should understand that an echocardiogram will be performed as soon as practical if their symptoms or signs warrant one. Likewise, when patients undergo echocardiography after an FCU examination, they should understand that this is not a duplicate or repeated examination but a comprehensive evaluation of their condition by an expert in cardiac imaging.

With echocardiography, the whole sum of knowledge is applied “upfront,” with measurements of normal structures and function, documentation of findings other than those that may have prompted the referral, and a thorough search to answer the referral question. The ASE has provided detailed recommendations for the performance, interpretation, documentation, and image storage that apply to comprehensive and limited echocardiographic examinations. These standards were developed to contribute to patient and provider satisfaction, and to improve patient outcomes.

The “limited” descriptor of a limited echocardiogram simply refers to the fact that, compared with a comprehensive examination, the number of views obtained and the number of images that are acquired are fewer. Every other aspect of limited echocardiography is the same as for comprehensive echocardiography. The practitioner will completely interpret all available data from all images, albeit in a limited echocardiogram from a more “limited” number of images. The clinical decision to perform a limited echocardiogram, as opposed to a comprehensive examination, requires expertise in echocardiography and specific knowledge of the appropriate indications. When performing a limited echocardiogram, the imager must have the knowledge of all views necessary to characterize or exclude the referral diagnosis. In addition, a clinician performing a limited echocardiogram must be cognizant of the potential to miss findings not in the field of view that (1) could offer an alternative explanation for the patient’s referral or (2) are incidental but clinically significant. A limited echocardiogram is more often used as a follow-up examination, after a prior comprehensive echocardiogram has delineated all findings. When performing limited echocardiography, report generation and comparison with prior studies must follow standard requirements of echocardiography.

b

Equipment

Ultrasound machines have evolved from large, poorly moveable devices to hand-carried ultrasound instruments and now pocket-sized devices. It is not the size or weight characteristics that define an echocardiographic machine. The use of FCU in this document generally applies to a nonechocardiographer imager who is using a basic ultrasound device. However, nonechocardiographer users who acquire images with a high-end platform or users trained in echocardiography who use pocket ultrasound devices are also performing FCU ( Table 4 ).

The equipment used for limited echocardiography should be capable of performing two-dimensional (2D) echocardiography, M-mode, color-flow imaging, and spectral and tissue Doppler ultrasound. Although all of these modalities may not be used in every case, their availability is critical in preserving the expectation that a patient referred for echocardiography (whether limited or complete) will receive the examination needed to delineate all abnormalities. Platforms for FCU are intended to answer a specific clinical question within the technologic limitations of a small device and thus do not require all these modalities.

Echocardiographic examinations (comprehensive and limited) require that a broad selection of transducers be available for use, whereas FCU does not. In the process of miniaturization, many of the fundamental capabilities of an echocardiogram have been omitted, including advanced signal processing and electrocardiographic (EKG) gating. The small screen size and reduced image resolution on devices used in FCU may limit recognition of diagnostic findings. The platform of a typical FCU device is incompatible with the performance of detailed or gated measurements that are the minimum professional standard for echocardiography. Echocardiographic platforms must store images in a method compatible with DICOM (Digital Imaging and Communications in Medicine) standards. Platforms that do not export in the DICOM format should not be used to perform echocardiography (limited or comprehensive).

c

Image Acquisition

Differentiating the image acquisition aspects of FCU and “Limited TTE” is best made by noting the requirements for image acquisition for limited echocardiography. Guidelines for specific training and credentialing of sonographers and physicians to acquire images in echocardiography have been published. Specific imaging components for completion of a comprehensive examination are specified. Practitioners who perform limited echocardiography need familiarity with all the windows and views of a comprehensive examination, because different clinical situations may require a particular subset of a comprehensive examination. Limited echocardiographic examinations may require any or all of the modalities used in a comprehensive examination. Practitioners who perform limited echocardiography need to be proficient in 2D, pulsed-wave and continuous-wave Doppler, color-Doppler, tissue Doppler, and M-mode echocardiography. The limited echocardiographic acquisition skill set must include familiarity with all transducers used in comprehensive echocardiography, because the clinical question, which may be answered with a limited echocardiogram examination, may require any of a number of transducers. Image quality of a limited echocardiographic examination is expected to be equal to comprehensive echocardiography to provide comparable data for side-by-side comparisons during assessment of temporal changes in patient status.

d

Image Interpretation

In the practice of limited echocardiography, the user is responsible for interpretation and delineation of primary, associated, and “incidental” findings that are apparent or became apparent while obtaining the views. Similar to the radiographic standard of chest X-ray interpretation in which the radiologist is accountable for the diagnosis of a solitary pulmonary nodule even when the primary cardiac finding of the radiograph is cardiomegaly, a limited echocardiogram that “excludes” a pericardial effusion is still accountable for a diagnosis of any evident wall-motion abnormality, valvular disease, or significant finding clearly present in the specific views recorded. Moreover, the interpretation must include assessment of key structures and cardiac function, including performance of measurements when feasible. Finally, there must be a report that includes key elements of cardiac structure and function, findings, and interpretation.

In these circumstances, an echocardiogram, comprehensive or limited, provides the maximum ultrasonic diagnostic capabilities and expert interpretation and upholds the perceived standards and justified costs of the echocardiogram held by the referring physician, patient, and payers. FCU does not require quantitation or provide equivalent diagnostic capability, and it is not the expectation of the user to delineate and quantify all findings viewed.

e

Billing

In the United States, the Center for Medicare Service’s Current Procedural Terminology (CPT) codes provides a system in which a participating health care provider can bill for the particular services rendered. The calculated reimbursement for a procedure is determined on a “relative value” scale that takes into account practice expense, physician work, malpractice costs, and the relative value of the procedure adjusted to regional factors where the service was rendered, the so-called resource-based relative value scale. In calculating the physician work component for limited echocardiography, the following factors are considered: physician time, technical skill, physical effort, mental effort, judgment, and stress due to potential risk to the patient. The submission of limited echocardiographic CPT (93308) for FCU would be inappropriate because the components used in the resource-based relative value scale cost estimates for FCU and limited echocardiography are different.

Practice expenses are different primarily due to the substantial differences in machine, room, documentation, image storage, and personnel costs. Liability is different because the echocardiographer is responsible for interpretation and delineation of primary, associated, and “incidental” findings that are apparent or became apparent while obtaining the images. FCU users are responsible for recognizing a focused list of potential diagnoses in specific clinical settings within their scope of practice. Finally, the physician work component, which includes time, technical skill, and mental effort, is entirely different between FCU and limited echocardiography. FCU is not a procedure described under current echocardiographic CPT codes. Use of the limited echocardiography code for FCU is not appropriate because the resource-based determination for reimbursement was made by assuming the standards established for echocardiography.

a

Personnel

Rapid evaluation to expedite patient triage and early management is an important role of specialists in emergency medicine. Assessment of critically ill patients after hours or at the bedside after a sudden change in clinical status is a role of critical care physicians. Internists, surgeons, and hospitalists perform serial evaluations of hospitalized adult patients daily. These are all situations when a sonographer or level II/III trained physician in echocardiography are potentially not immediately available or cannot be present for daily image acquisition. All these physicians could potentially use FCU to augment their cardiac physical examination assessment. As long as the training requirements are met and maintenance of competency and quality assurance are documented, many adult medical and surgical specialties could potentially use FCU. It is essential that physicians who use FCU have realistic expectations of their abilities to image and interpret as well as knowledge of the limitations of FCU devices. Inappropriate interpretation or application of FCU beyond a defined scope of practice may have adverse consequences for patient care.

Sonographers and physicians with level II or III training in echocardiography can acquire images without additional training, and physicians with level II or III training in echocardiography can interpret FCU images. Although these practitioners have the required expertise for image acquisition and interpretation, if using a device typically used for FCU, then they would not be performing echocardiography. For the purposes of distinction, this document refers to this as expert FCU (eFCU). Use of FCU by medical students should be for educational or training purposes only, under the direct supervision of an echocardiographer or a trained FCU physician. Likewise, use by nurses or other allied health care professionals who are not registered cardiac sonographers should be for research purposes only and not for clinical use.

b

Equipment

Ultrasound platforms for cardiac imaging can be broadly characterized into 4 groups:

• (1)
  

  Full functionality platforms. These devices have the complete range of echocardiographic image acquisition capabilities (M-mode, 2D, color-Doppler, spectral Doppler, tissue Doppler), have advanced quantification and analysis packages, permit acquisition, and processing of stress images, have advanced image processing for contrast enhancement, and have a wide array of specialized transducers for advanced functions such as transesophageal and 3D echocardiography.

  
  
• (2)
  

  Small ultrasound platforms. These machines typically support the standard echocardiographic modalities (M-mode, 2D, color Doppler, spectral Doppler, transesophageal echocardiography, and stress) but are smaller and may lack advanced imaging options.

  
  
• (3)
  

  Hand-carried platforms. These machines, which generally weigh 6-12 pounds, are readily carried by a user to the bedside or may be cart based. These typically have standard cardiac ultrasound capabilities and may have fundamental quantification packages.

  
  
• (4)
  

  Pocket platforms. These devices are compact and can be placed in a lab coat pocket. Pocket ultrasound instruments include basic ultrasound functionality such as 2D imaging and may or may not have color Doppler.

Although an FCU examination can be performed with a full functionality ultrasound platform, the size, expense, and complexity of these instruments are disparate with the clinical settings in which FCU is useful as well as the abilities of an FCU provider. Small ultrasound platforms can also be used by a nonechocardiographer to perform an FCU assessment. However, the cost of these devices makes their use solely as an adjunct to the physical examination impractical. In some hospital intensive care units (ICU) or emergency department settings, these machines are used for other diagnostic (noncardiac) procedures and, therefore, available for FCU use. Use of these small platforms capable of performing echocardiography by a practitioner without echocardiographic training and imaging and/or interpretation expertise should be considered FCU, not limited echocardiography. In practice, these devices are typically used by practitioners with comprehensive echocardiographic acquisition and interpretation skills in settings in which their smaller size is an advantage.

The devices ideally suited for FCU extension of physical examination use a simpler technology compared with full-functionality echocardiographic platforms. Most reports that evaluated FCU by nonechocardiographer users have been with hand-carried platforms. Although pocket-sized instruments have shown clinical promise, the published literature consists primarily of their use by experienced imagers or cardiology fellows. It is possible that the reduced imaging abilities and smaller screen will make it more difficult for nonechocardiographer practitioners to use pocket devices accurately.

FCU equipment must consist of a transducer with a frequency appropriate for adult patients. Minimum display requirements include the ability to label the images with at least 2 patient identifiers, date and time of examination. Electronic calipers are not required, but there should be markers that indicate scale or image depth. Measurement packages are not standard, because much of the clinical functionality of FCU is for rapid qualitative assessment. Minimum functionality consists of 2D grayscale imaging and controls for depth and gain adjustment. Studies or images used to evaluate a symptomatic patient to direct management because formal echocardiography is not available should be stored in a retrievable location. Ideally, stored images should be in the DICOM format and be exportable to the digital archive where the patient’s echocardiographic images are stored.

Additional functionality is available on hand-carried and pocket devices. These capabilities (color-Doppler, spectral Doppler and tissue Doppler) require more training to appropriately use and interpret, which would extend the duration of FCU instruction. In addition, these capabilities are typically not needed for the scope of FCU practices. Demonstrating that the extra training and device costs for color-Doppler FCU adds clinical value would require that (1) FCU augmented physical examination could detect clinically important valvular lesions not already apparent by physical examination, and (2) the early bedside identification of the valvular lesion makes a clinically important difference over having it detected at the time of a standard TTE. Supplementary functionality only seeks to increase the costs of the devices, potentially reducing their cost-effectiveness. There also is concern that users may attempt to implement features or functionality without the proper training, which potentially results in erroneous clinical conclusions and adverse patient outcomes. Although an echocardiographer or qualified sonographer would have the training to acquire images by using these additional functionalities of a hand-carried or pocket ultrasound, the clinical scenarios when this would be preferred over a standard platform with better quality imaging and more capabilities are infrequent and discussed in a later section of the article (eFCU).

c

Potential Limitations of FCU

Using FCU as an adjunct to physical examination is facilitated by using smaller ultrasound devices (hand carried or pocket). However, these devices may not have the capabilities to image all findings. A system that weighs less than 10 pounds with an estimated cost between $8,000-$30,000 should not be expected to produce the image quality of a 200 pounds, $200,000 system. The transducer technology is not the same, and the complex image enhancement and artifact reduction abilities cannot be reproduced on an FCU machine. In addition, the images are visualized on a screen with significantly lower resolution and size compared with those available with state-of-the-art echocardiography. Commonly performed acquisition modifications, such as the ability to zoom, alter the ultrasound beam focus, narrow sector width, adjust dynamic range, use harmonic imaging, use settings optimized for contrast, change grayscale maps, or optimize transducer frequency, may be lacking. These restrictions make identification of subtle abnormalities inappropriate for FCU scope of practice. Despite these limitations, small devices with specifications that are inadequate for performing echocardiography can generate clinically useful images.

Instruments used for FCU have been miniaturized to improve functionality at the bedside. The compromise of smaller devices is loss of features, including spectral Doppler, tissue Doppler, and 3D. This concession is certainly worthwhile because it allows the devices to be smaller and less expensive. Lack of spectral Doppler makes FCU inappropriate for the assessment of pericardial constriction, pulmonary hypertension, and diastolic dysfunction. Quantitation of regurgitant or stenotic valvular lesion severity is also not appropriate with FCU. However, the morphology of stenotic valves and secondary findings, such as chamber enlargement and hypertrophy, to suggest pressure or volume overload or left ventricle (LV)-right ventricle (RV) interaction may still be detected by the astute user. Color Doppler is available on most systems and has been used to qualitatively assess for potentially severe regurgitant lesions of the aortic and mitral valve.

To distinguish the limitations of the smaller devices from the skill of the user, the writing group reviewed studies that included at least 50 patients in which a small platform was compared with traditional echocardiography, with all images acquired and interpreted by experts to determine which pathologies FCU devices are capable of detecting despite their reduced functionality. Articles that use cardiology fellows as imagers were not included. Cardiac abnormalities that have been accurately detected included the following:

• •
  

  LV enlargement

  
  
• •
  

  LV hypertrophy

  
  
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  LV systolic function

  
  
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  LA enlargement

  
  
• •
  

  RV enlargement

  
  
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  RV systolic function

  
  
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  Pericardial effusion

  
  
• •
  

  Inferior vena cava (IVC) size

There are a variety of both standard and nonstandard echocardiographic windows used to assess cardiac structures. From each window, multiple views and sweeps of the heart are typically acquired. There is no question that certain windows and/or views are easier to learn than others. The parasternal and subcostal views, for example, are typically easier to master. The landmarks for these windows are characteristically more reliable. Imaging from the parasternal window is easier to hold stable and consistently provides more interpretable images than the apical views. Parasternal views are less dependent on patient positioning and less subject to interference from patient body habitus. The parasternal window is preferred for the assessment of LV systolic function by less experienced users. Proficiency in acquiring adequate parasternal views by novices under direct proctoring is similar to acquiring an apical 4-chamber view but much easier than the apical 2-chamber view.

Other views, such as the apical planes, are more difficult to optimize and require expertise to correctly adjust patient position and breathing cycle to acquire. In addition, apical views require a more powerful transducer with higher penetration, which may not be available with hand-carried or pocket-sized platforms. Optimization of cardiac views is critical to obtaining a correct diagnosis. Nonexpert imagers obtain adequate images from the parasternal view nearly twice as often as from the apical views with an FCU device. It is also clear that off-axis imaging and foreshortening from the apical views can lead to incorrect conclusions and erroneous clinical management. Nonexpert imagers must be aware of the pitfalls and limitations of apical imaging before imaging is attempted. Because of these factors, the parasternal and subcostal views are preferred for FCU imaging. Diagnoses that depend on nontraditional windows (right parasternal, suprasternal) should not be made or excluded with FCU.

Complex or unusual cardiac disorders should not be expected to be diagnosed by a physician solely trained in FCU. In addition, some pathologies are subtle and are difficult to recognize (LV wall motion). Other abnormalities require assimilation of data from multiple views to correctly define (RV systolic function and size). Certain findings on a cardiac ultrasound image may only make sense considered in the context of a broader picture, which requires extensive training in cardiovascular disease, such as in patients with congenital heart disease or other uncommon disorders. Because these are beyond the experience of FCU training and experience, the following pathologies are unlikely to be accurately detected by FCU examination: aortic dissection, hypertrophic cardiomyopathy, LV regional wall-motion abnormalities, LV aneurysm, cardiac masses, RV hypertrophy, LV thrombus, and valvular vegetations.

Although small ultrasound devices have been used to demonstrate a broad range of pathology in the hands of a sonographer or echocardiographer (cardiovascular specialist with level II or III echocardiographic training), this document seeks to review the cardiac abnormalities that nonechocardiographer users have successfully identified. It is important to realize that most FCU studies are designed to evaluate the ability to image and interpret significant abnormalities, such as moderate or severe deviations from normal. Most abnormalities are defined by FCU users as present or absent. The broader experience to characterize pathologies into severities of abnormality should not be expected with FCU.

The available published studies are methodologically inconsistent in regard to the duration and nature of training, provider background, patient population, devices used, and the clinical settings for the FCU examination. The writing group reviewed studies, including at least 50 patients in whom a small platform was compared with traditional echocardiography or another criterion standard, with all images acquired and interpreted by physicians with no or minimal prior training in cardiac ultrasound, to determine which pathologies a physician performing FCU can discern. The most commonly studied pathology that was adequately detected by using FCU was LV systolic dysfunction, in which sensitivities of 73%-100% and specificities of 64%-96% have been demonstrated. Other abnormalities with significantly less validation include LV enlargement, LV hypertrophy, LA enlargement, RV enlargement, pericardial effusion, and IVC size.

Most importantly, although the ability to detect abnormalities at the bedside by FCU users is lower than having a comprehensive TTE, it is clearly better than traditional bedside assessment. FCU use allows detection of cardiac pathology more accurately than physical examination, which supports its use as an adjunct to physical examination, not as a replacement for echocardiography. When used by physicians without formal echocardiographic training, FCU is superior to physical examination for the detection of cardiac abnormalities, including LV enlargement, LV systolic dysfunction, LA enlargement, LV hypertrophy, pericardial effusion, and RA pressure elevation.