Hand-held echocardiography: added value in clinical cardiological assessment

Ever since the birth of echocardiography, 50 years ago, this non-invasive diagnostic tool became a milestone in the clinical evaluation of cardiovascular patients, due to its diagnostic accuracy. Owing to advances in technology, the ultrasonic industry has recently produced hand-held devices (HHD) that are miniaturized, compact and battery-equipped echocardiographic systems. Basic versions of HHD usually allow only bidimensional imaging and colour flow Doppler analysis, but M-Mode visualization, continuous and pulsed wave Doppler imaging, ECG synchronization and other tools have recently been integrated in better-equipped HHD. These machines could offer some advantages compared with standard echocardiographic devices (SED), due to their simplicity of use, immediate availability at the patient's bedside, transportability and relatively low cost.

The potential usefulness of HHD has been successfully assessed in a wide range of clinical conditions. HHD has been reported to improve detection of relevant cardiovascular pathologies [1] or unknown cardiac disorders [2], and to allow a good assessment of cardiac anatomy and function [3‐5]. Furthermore they also have been shown to ensure a reliable assessment of left ventricular hypertrophy [6] and abdominal aortic aneurysm [7, 8]. It has also been suggested that internists may use HHD without formal training in echocardiography and after a limited echo-training period [9‐11]. In addition, HHD has demonstrated acceptable accuracy during patient transport [12] and in the context of ultrasound-guided pericardiocentesis and thoracentesis [13]. However, HHD seems to have a narrower diagnostic field when compared with SED in the evaluation of critically ill patients [14, 15].

Based on this evidence, HHD may be expected to become an important additional diagnostic tool during outpatients cardiologic consulting or in non-cardiologic hospital sections. Nevertheless, the potential role of HHD in these settings has never been investigated.

Eighty-seven consecutive patients (47 males and 40 females, mean age 66.1 ± 15.2 years), who visited our Hospital for cardiologic consulting, have been included in this study. Each participant in the study had one or more referral questions among the following: hypertension, dyspnoea, chest pain, palpitations (Table 1).

The cardiologist, whenever possible, formulated a diagnosis at the end of the exam. The percentage of subjects for whom the diagnosis was considered satisfactory – i.e., when findings were judged to be reasonably adequate for final diagnostic and therapeutic conclusions and no further diagnostic evaluation was needed – was used to quantify the "conclusiveness" of HHD evaluation. Within 24 hours, all patients underwent a second echocardiographic evaluation, performed by a second cardiologist with similar experience and echocardiographic competence, blinded to the results of the other investigator. The examination has been performed by using a SED (Agilent Technologies, Sonos 5500). The agreement between the first and the second echocardiographic exam has been assessed by controlling the percentage of concordant diagnostic conclusions between the two evaluations.

Data are shown as mean ± SD for continuous variables. The comparison of the examination time between HHD and SED has been assessed using one-way ANOVA. The chi-squared test was used to compare the percentages of conclusiveness between the two ultrasound machines. In the case of expected frequencies ≤ 5, the Fisher's exact test was performed. A P value <0.05 was considered for statistical significance. The statistical analysis was performed using the SPSS (Statistical Package for the Social Sciences, Chicago, Illinois) software.

This is the first study, which evaluates the clinical utility of a basic model of HHD in the context of cardiologic consulting for outpatients or in non-cardiologic hospital sections. The clinical usefulness of the HHD has been reported in previous studies [16‐21]. Potential advantages which could result from the use of a basic HHD include brief examination time, simplicity of use, fast availability at the patient's bedside, easy transportability and relatively low cost. Despite limitations due to the lack of M-mode imaging and power, and continuous Doppler analysis, our findings suggest that a basic model of HHD may provide a useful and reliable adjunctive diagnostic tool for cardiologic examination of both outpatients and patients admitted in non-cardiologic sections. The ecocardiographic examination, performed using the HHD, was satisfactory and conclusive in about 85% of subjects, and a good agreement between the diagnosis derived using the HHD and that obtained using the SED was obtained in this subset of patients (83.8%). Thus, a correct diagnosis was made in 71.3% of the total study population. It should also be considered that better-equipped HHD show similar advantages and may ensure further higher diagnostic accuracy in comparison with basic models, thanks to several improvements (M-mode imaging, pulsed and continuous wave Doppler facilities, ECG synchronisation, storage memories, multiple peripheral connections) [22], but they are more expensive. It is also to be expected that such hand-carried ultrasound devices will soon become smaller, simpler to be used and cheaper [23], similar to an "ultrasound stethoscope" [22].

Some examinations resulted "unconclusive" or unsatisfactory due to a poor acoustic window, either for HHD than SED, so this bias represents a limit for both of them.

However, basic HHD should not be considered equivalent to SED. The diagnostic accuracy of the HHD seems to be affected by the type of referral question. The HHD showed a good reliability in the examination of patients referred for arterial hypertension or palpitations -also allowing a rapid screening of left ventricular hypertrophy [6] and of abdominal aortic aneurysm [7] – but was less accurate for those who presented dyspnoea or chest pain. In the subset of subjects with dyspnoea, the percentage of satisfactory examinations tended to be higher – although not significantly – using the SED compared with the HHD. Also, in the subgroups of patients with dyspnoea or chest pain the agreement between the results obtained using the two ultrasound machines was suboptimal, mostly as a result of biases in the measurements of wall thicknesses, and in the assessment of valvular diseases and regional wall motion. These results suggest that the diagnostic information obtained using the HHD should be critically considered in patients with chest pain or dyspnoea.

In this study we evaluated HHD comparing its clinical utility to SED: so, SED was our Gold Standard; the number of patients was also very limited (87 patients examined).

HHD real utility is allowing evaluating patients with a gain in terms of time, shortening patients waiting lists, and reducing healthy costs. Moreover, HHD evaluation can help the physician in the choose of the therapy and in the follow-up of the patient.

On these basis, HHD may generally allow a reliable cardiologic basic evaluation of outpatient or subjects admitted to non-cardiologic sections. However, in patients with chest pain and dyspnoea, the use of such devices should be performed with caution, and the diagnostic results should be considered critically.