Echocardiography at the Point of Care: An Ultra Sound Future

In the past half century, numerous imaging modalities have contributed to cardiologic practice and research, revealing heretofore unimaginable detail. Among these modalities, echocardiography has distinguished itself for its safety, power, and versatility: it is noninvasive, it presents no radiation risk, and it is powerful enough for numerous applications and yet portable enough to be performed at the point of care. Evolutions in image quality, anatomic definition, physiologic data, and the breadth of applications have derived from advances in technology, incorporation of the Doppler principle, and, more recently, speckle tracking. Perhaps most impressively, the revolution in electronics has positioned echocardiography to go miniature: it is now possible to make devices small and light enough to be carried by physicians and health care professionals in their daily encounters with patients. In fact, a hand-carried ultrasound (HCU) device was conceived as early as 1978, but we now have ready access to “ultrasound stethoscopes.” Such tools could exert a significant impact on cardiovascular health care delivery. But are portable devices sufficiently accurate? Will portability and apparent simplicity of use lead to the “democratization” of echocardiography and a loss of standards?

The current issue of JASE presents three complementary studies that assess the accuracy, utilization, and impact of HCU devices in real-world clinical practice. Prinz and Voigt compared the feasibility and accuracy of a new HCU device, as used by an experienced cardiologist, with high-end studies performed by an experienced sonographer. Among 349 patients examined, the authors found that image quality was similar in those patients with adequate images; the advantage of the higher end instrument appeared most notable in the technically difficult patient. There was a very good agreement in simple cardiac chamber linear measurements (dimension, wall thickness) and comparable evaluation of regional and global left ventricular (LV) function. HCU captured all cases of pericardial effusion and valve stenosis, the latter being detected by valve structure and color Doppler, as no spectral Doppler is available on the HCU device used for this study. Valve regurgitation was mildly overestimated by HCU, with an overall very good concordance in detection of regurgitation with color Doppler.

In the study conducted by Cardim et al. , 189 patients referred for their first outpatient cardiology consultations were evaluated by physical examination followed by HCU. The scanning time per patient averaged 3 ± 1.5 min. After physical examination alone, 9% of patients were managed without further testing and were discharged from the clinic. Normal results on HCU increased discharge from the clinic without need for further testing by another 19.6%. After the physical exam, 50.3% of patients were referred for echocardiography, but this figure was lowered to 33.9% after HCU. The reasons for the lingering need for referral to full echocardiography after HCU were predominantly the lack of spectral Doppler for the evaluation of diastolic function, pulmonary pressure, valvular stenosis, and supplemental data to corroborate the severity of regurgitant lesions beyond color Doppler. Importantly, HCU modified the clinical decision in 14.3% of the cases, as it enabled detection of findings (e.g., depressed ventricular function, inaudible valvular disease) that were not suspected clinically and thus for which full echocardiography was not contemplated. Last, on the basis of HCU, 30.7% of consultations were determined not to need full echocardiographic studies; the majority of these cases were patients with flow murmurs, shortness of breath with normal cardiac structure and function, palpitations, and chest pain. Those who were discharged from the clinic were followed and had good outcomes.

Last, in the study by Lipczynska et al. , an internist trained in basic echocardiography used HCU and measured levels of N-terminal pro–B-type natriuretic peptide to evaluate 175 patients with heart failure or risk factors for heart failure. Abnormalities of depressed ejection fraction, increased LV size, LV hypertrophy, increased left atrial size, or valve pathology were found in 55% of the patients. Over a mean follow-up period of 48 months, 25% either were hospitalized because of cardiac events or died (not necessarily of cardiovascular causes). Abnormal echocardiographic results predicted 24% of events, whereas abnormal N-terminal pro–B-type natriuretic peptide levels predicted 5% of events. The positive predictive value of HCU was 37%, with negative predictive value of 91%. Although these results are very encouraging for the prognostic importance of the findings by HCU, the end points chosen may raise questions: the deaths were not necessarily cardiovascular, and the inclusion of acute coronary syndromes and any cardiac surgery may have influenced the prognostic power observed.

These three studies on HCU in this issue highlight the growing interest in this evolving technological field and its possible clinical applications. Nevertheless, HCU devices are used only sporadically in current practice, usually in settings such as intensive care units, emergency departments, or operating rooms to provide a quick, urgent diagnosis or guide interventions. HCU devices are much less commonly used in outpatient settings. Should HCU be more broadly used? What are the challenges for its implementation? What would the future of HCU look like?

The Need for Hand-Carried Ultrasound at the Point of Care

A good history and integrative physical examination provide the irreplaceable foundation for any further investigations that may be needed to clinch a medical diagnosis or set the path for therapy. Although we have seen both parts of this foundation slip over time, the skills of physical examination, including the cardiac examination, have suffered the most, being so readily subsumed into more “objective” testing, such as echocardiography. To be fair, some cardiac conditions, such as subtle LV dysfunction, a target of diagnosis and therapy, may be hard to diagnose, even for a skilled examiner. 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. This in turn would require that the quality of imaging with HCU be consistently high. The studies published in this issue lend support to the notion that current HCU devices provide good image quality in the outpatient setting. We should expect, however, that the use of HCU in inpatients, particularly those who are critically ill, would be more problematic and its efficacy more limited.

As Cardim et al. show, HCU would be well used to decrease the number of full echocardiographic studies that turn out to have normal results, such as those ordered for a flow murmur (by an unsure physician or on behalf of a concerned patient) or in some patients with palpitations or syncope and normal results on physical examination and electrocardiography. HCU can also provide a glimpse of cardiac status at the bedside, thereby improving the overall efficiency and quality of health care delivery: a physician can start medical therapy for a new diagnosis of heart failure during the same initial visit instead of waiting for the results of an echocardiogram a few days later, usually relayed by another professional, then communicating the results to the patient along with instructions and prescriptions. In such cases, HCU would clearly reduce the amount of indirect communication and shorten the time for the patient to reach the treatment goal. HCU can also significantly lessen the “hassle factor” and cost for patients, who otherwise have to schedule echocardiographic studies usually for different visits and then receive communication of results and treatment. Such benefits would undoubtedly increase both patients’ and physicians’ satisfaction. Last, HCU enables at the bedside a quick follow-up of patients treated for conditions such as pericardial effusion or heart failure, with images being documented and archived for serial follow-up.

The impact of HCU in different clinical settings would depend on the patient mix and underlying disease, image quality, efficiency, and training of the operator. HCU would not replace full echocardiography, particularly when it comes to a comprehensive evaluation of valvular heart disease and hemodynamics, but it could certainly prove to be a cost-efficient and time-efficient complement.

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Jun 15, 2018 | Posted by in CARDIOLOGY | Comments Off on Echocardiography at the Point of Care: An Ultra Sound Future

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