Background
The aim of this study was to assess the usefulness of a new miniaturized echocardiographic system (MS) to perform bedside echocardiography in initial outpatient cardiology consultations, in addition to physical examination.
Methods
One hundred eighty-nine patients referred for initial cardiology outpatient consultations at two tertiary hospitals in two countries were studied. Each patient was submitted to physical examination followed by MS assessment. Scanning time, the number of examinations with abnormal results after physical examination and the MS, and the information obtained by physical examination alone and followed by the MS (in terms of its importance in reaching a diagnosis, in the necessity of performing routine echocardiography, and in the decision to release the patient from the outpatient clinic) were assessed.
Results
The scanning time with the MS was 180 ± 86 seconds. Its use after physical examination led to diagnoses in 141 patients (74.6%) and to an additional 37 patients (19.6%) being released from the outpatient clinic. After physical examination followed by MS assessment, only 64 patients (33.9%) were sent to the echocardiography lab. The MS modified the decision of whether to send a patient to the echocardiography lab, with referral determined by the MS in 27 patients (14.3%) and no referral determined by the MS in 58 patients (30.7%).
Conclusions
The new MS caused a negligible increase in the duration of consultations. It showed additive clinical value over physical examination, increasing the number of diagnoses, reducing the use of unnecessary routine echocardiography, increasing the number of adequate echocardiographic studies, and determining a large number of releases from the outpatient clinic.
Cardiology is a medical specialty in which clinical evaluation plays a central role. During physical examination, physicians use their senses to assess a set of auditory, visual, olfactory, and tactile signals that, together with medical history information, contribute to the formulation of preliminary diagnoses that will be confirmed or invalidated by the complementary diagnostic techniques available. The technological evolution of these complementary diagnostic techniques in the cardiovascular area has experienced exponential increases in recent decades. Among these, echocardiography plays a central role in daily cardiologic practice. This noninvasive and innocuous diagnostic tool provides, at low cost and with high reproducibility, detailed morphologic and functional information on the heart and great vessels, with significant impact on diagnosis, therapeutic orientation, and definition of prognosis.
According to conventional hospital organizational models, echocardiographic studies are in most cases performed in echocardiography laboratories. Because standard echocardiographic equipment is heavy and difficult to maneuver, in the vast majority of cases, the performance of echocardiographic studies directly at bedside is neither practical nor feasible with the additional risk for damaging expensive equipment and injuring personnel. Bedside echocardiography remains limited to a small percentage of cases.
Typical echocardiography labs in tertiary hospitals are usually busy and overcrowded areas, where large numbers of echocardiographic studies are performed daily: in inpatients and outpatients, basic and advanced procedures, and remarkably, large numbers of unnecessary studies. This enormous movement is often associated with patient discomfort and physiologic stress for staff members. One possible way to reduce some of these disadvantages is to increase the number of bedside echocardiographic studies, considering echocardiography as an extension of the cardiac physical examination. However, this task has been limited over time by the size and minimal portability of echocardiographic machines. To overcome this limitation, there has been in recent decades a considerable effort aimed at miniaturizing these devices without losing accuracy, to transform them into real echocardiographic laptops. Very recently, real handheld, small, and lightweight ultrasound machines have been developed ( Figure 1 ). Because their dimensions are similar to those of conventional stethoscopes—but unlike stethoscopes, they are used to see, not to hear—they may be considered a kind of “visual stethoscopes.”
The use of this new tool at the bedside for initial cardiology consultations in outpatients as an extension of the physical examination may have clear benefits for all participants in the process: patients, physicians, echocardiography labs, departments, and hospitals. Moreover, these benefits may be even higher in our “digital age, when the time-honored skills in physical examination of cardiac patients are decreasing, with physical exams frequently imperfect, even among trained cardiologists. However, at present, no study has been published evaluating the clinical usefulness of this new, truly handheld ultrasound machine in this organizational model.
The aim of this study was to assess the usefulness of a new miniaturized echocardiographic system (MS) to perform echocardiographic studies at bedside in initial cardiology consultations in outpatients in addition to conventional cardiac auscultation.
Methods
This study took place at two tertiary hospitals in two different countries (University Hospital San Carlos, Madrid, Spain, and Hospital da Luz, Lisbon, Portugal). The MS used was the V-Scan (GE Vingmed Ultrasound AS, Horten, Norway). This ultrasound device consists of a display unit (135 × 73 × 28 mm) connected to a broad-bandwidth phased-array probe (1.7–3.8 MHz; 120 × 33 × 26 mm). Its total weight (unit and probe) is 390 g. The total possible scanning time is 1 hour with a fully charged battery. This platform provides two-dimensional (a two-dimensional field of view for black and white imaging up to 75° with a maximum depth of 25 cm) and color Doppler echocardiographic images (color flow sector, 30°) on a 3.5-inch screen (resolution, 240 × 320 pixels). There are a limited number of controls, including those for adjusting imaging depth and gain. Images can be frozen and scrolled for review. An electronic caliper and touchpad allow distance and area measurements to be performed. Data are stored on micro-SD or micro-SDHC cards upgradeable to 32 GB, in generic formats (Joint Photographic Experts Group for still frames and Moving Picture Experts Group for loops). Data may be stored in examination folders, and all data can be recalled using a gallery function and downloaded into any conventional computer in both formats.
Six cardiologists (three from each center) participated in the study. All had 1 week to become familiar with the system and its commands and menus, to optimize the time required for scanning, having performed 10 to 15 examinations before study initiation. Training recommendations were oriented to fulfill a specifically designed report form. All cardiologists were experienced in the performance and interpretation of echocardiographic images (level III competence in general adult transthoracic echocardiography of the European Association of Echocardiography ). Taking into account operator expertise and the simplicity of the MS controls, the learning curve was minimal.
From March 1 to April 1, 2010, 189 consecutive patients (University Hospital San Carlos, n = 124; Hospital da Luz, n = 65) referred for initial cardiology consultations were enrolled. During the consultation, each patient was submitted to a conventional physical examination (the exam protocol and use of maneuvers were performed according to each physician’s usual practice), and findings were recorded. Immediately afterward, cardiac scanning with the new MS was performed in the same consultation room. No preset ultrasound exam protocol was followed. After completion of the echocardiographic study, the physician recorded the imaging findings in a specifically designed report form. For diagnostic, teaching, and liability reasons, data were stored in examination folders and blindly supervised by a different cardiologist participant in the study.
The demographic characteristics of the population and the time needed to scan each patient were recorded, as well as the number of examinations with abnormal results after physical examination alone and after physical examination followed by the use of the MS. We also recorded the information obtained by physical examination alone and by physical examination followed by the MS in terms of (1) its importance (essential or nonessential) in reaching a diagnosis (primary or secondary), according to the physician’s opinion; (2) the necessity of requesting or not a conventional echocardiographic study in the echocardiography lab; and (3) the decision to release the patient from the outpatient clinic after the first consultation, informing the patient that there was no need to return because no additional diagnostic tests were necessary. However, for liability reasons, to ensure that the triage decisions based on the MS were correct, these “discharged” patients were informed that they would be contacted later for clinical and echocardiographic follow-up evaluations. Finally, other requested diagnostic tests after each type of assessment as well as impact on the therapeutic decision were also evaluated.
Statistical Analysis
Results are presented as absolute and relative frequencies with exact binomial 95% confidence intervals (CIs). Calculations were made using Stata version 11 (StataCorp LP, College Station, TX).
Results
We studied 189 patients (mean age, 53 ± 16 years; age range, 14–89 years; 99 male [52.4%], 90 female [47.6%]).
Physical Examination
Findings on physical examination were abnormal in 54 patients (28.6%; 95% CI, 22.2%–35.6%) and were considered important to the diagnosis in 44 patients (23.3%; 95% CI, 17.5%–30.0%). After physical examination, 17 patients (9.0%; 95% CI, 5.3%–14.0%) patients were released from the outpatient clinic.
MS Assessment
The mean scanning time spent with the new equipment was 180 ± 86 seconds (range, 45–420 seconds). All MS examinations were considered to have adequate quality for analysis. Findings on MS examination were considered abnormal in 89 patients (47.1%; 95% CI, 39.8%–54.5%). When used after physical examination, the MS led to diagnoses in 141 patients (74.6%; 95% CI, 67.8%–80.6%). After physical examination followed by the MS (in addition to the 17 patients “discharged” after physical examination alone), 37 additional patients (19.6%; 95% CI, 14.2%–26.0%) were released from the outpatient clinic because of no need for additional diagnostic testing ( Table 1 ).
| Abnormal finding | n |
|---|---|
| Mitral regurgitation (more than mild) | 31 |
| Left atrial dilatation | 30 |
| LV hypertrophy | 25 |
| Aortic regurgitation (more than mild) | 15 |
| LV dilatation | 15 |
| Wall motion abnormality | 14 |
| Aortic stenosis | 13 |
| Tricuspid regurgitation | 13 |
| Abnormal LV ejection fraction | 12 |
| Mitral stenosis | 4 |
| Abnormal inferior vena cava | 2 |
| Others | 5 |
Echocardiography Laboratory Referral After Physical Examination and After MS Assessment
After physical examination, it was decided to refer 95 patients (50.3%; 95% CI, 42.9%–57.6%) to the echocardiography lab, while in 94 patients (49.7%; 95% CI, 42.4%–57.1%), it was decided not to perform echocardiography ( Table 2 ). In contrast, after the use of the new MS, only 64 patients (33.9%; 95% CI, 27.1%–41.1%) were sent to the echocardiography lab, and in the other 125 patients (66.1%; 95% CI, 58.9%–72.8%), it was decided not to perform routine echocardiography. The reasons for echocardiography lab referral after MS were exclusively related to the need for spectral Doppler, not available with the MS, for
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assessment of diastolic function (in patients with left atrial dilatation and/or left ventricular hypertrophy to grade diastolic dysfunction and estimate filling pressures);
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evaluation of the severity of valve disease (aortic stenosis: gradients, aortic valve area, velocity-time integral ratio ( Figure 2 ); mitral regurgitation: proximal isovelocity surface area, pulmonary venous flow measurements; mitral stenosis: gradients, pressure half-time; aortic regurgitation: pressure half-time, evaluation of flow in the descending aorta) and
Figure 2
An 80-year-old man referred for initial outpatient cardiology consultation by a primary care physician to evaluate a systolic murmur. MS assessment, apical four-chamber view: calcified aortic valve, left ventricular hypertrophy, mild left atrial dilatation. The patient was sent to the echocardiography lab for quantification of the severity of stenosis. Moderate aortic stenosis was found (mean left ventricle–aortic gradient, 30 mm Hg; aortic valve area, 1 cm 2 ; velocity-time integral ratio, 0.28).
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quantification of pulmonary artery pressure (tricuspid regurgitant jet, pulmonary regurgitant flow).
| MS assessment | |||
|---|---|---|---|
| Physical examination | No referral | Referral | Total |
| No referral | 67 (35.4%) | 27 (14.3%) | 94 (49.7%) |
| Referral | 58 (30.7%) | 37 (19.6%) | 95 (50.3%) |
| Total | 125 (66.1%) | 64 (33.9%) | 189 (100%) |
No patient was sent to the echocardiography lab because of inadequate image quality with the MS.
Moreover, in 67 patients (35.4%; 95% CI, 28.6%–42.7%), there was agreement between physical examination and the MS to not refer patients to the echocardiography lab, and in 37 patients (19.6%; 95% CI, 14.2%–26.0%), there was agreement between the two methods in referring for echocardiography ( Table 2 ). However, in other cases, the MS modified the clinical decision of whether to send a patient to the echocardiography lab (referral determined by the MS in 27 patients [14.3%; 95% CI, 9.6%–20.1%]). The reasons for echocardiography lab referral based exclusively on the MS were some unexpected echocardiographic findings requiring spectral Doppler assessment. These findings, neither suspected during anamnesis (atypical symptoms, no risk factors for heart disease) nor detected on physical examination (normal results), were unexpected abnormal left ventricular systolic function (three patients), unexplained left ventricular hypertrophy (five patients) or dilatation (two patients), enlarged left atrium (five patients), inaudible more than mild tricuspid (six patients) or aortic regurgitation (four patients), and abnormal inferior vena cava dimensions or kinetics (two patients). These 27 patients would not have been referred for routine echocardiography had the MS not been used ( Figure 3 ).
Finally, no referral for routine echocardiography determined by the MS was observed in 58 patients (30.7%; 95% CI, 24.2%–37.8%; Table 2 ). Most of these patients were referred to cardiology for evaluation of symptoms (chest pain, shortness of breath, palpitations) or for evaluation of murmurs, most of them clinically innocent. Completely normal results on MS evaluation (normal systolic function, no suspicion of diastolic dysfunction on two-dimensional echocardiography, no chamber dilatation, normal wall thickness, and less than moderate regurgitation) precluded the necessity of routine echocardiography. Most murmurs were found to correspond to flow murmurs, corresponding to minimal or mild physiologic valvular regurgitation on MS assessment ( Figure 4 ).
Other Diagnostic Tests and Therapeutic Decisions After Physical Examination and After MS Assessment
Physical examinations led to other diagnostic tests in 17 patients (9.0%; 95% CI, 5.3%–14.0%) and were determinant of therapeutic decisions in 20 patients (10.6%; 95% CI, 6.6%–15.9%). Additionally to physical examination, the new MS led to other diagnostic interventions (excluding echocardiography) in 17 additional patients (9.0%; 95% CI, 5.3%–14.0%), with the tests requested to exclude coronary artery disease and to investigate secondary hypertension. Also after physical examination, MS assessment changed the therapeutic strategies in 36 additional patients (19.0%; 95% CI, 13.7%–25.4%; Table 3 ). For instance, the presence of left ventricular dilatation and systolic dysfunction on MS assessment (in some patients, these data were unobtainable on history and physical examination) led to the initiation of angiotensin-converting enzyme inhibitors, β-blockers, or angiotensin II receptor antagonists ( Figure 5 ). The presence of chest pain associated with the detection of wall motion abnormalities led to the prescription of anti-ischemic therapy; the presence of a dilated left atrium in a patient with paroxysmal palpitations led to the initiation of arrhythmic therapy to prevent paroxysmal atrial fibrillation.
