Background: Recent technological advances enabled miniaturization of echocardiographic machines and construction of portable "ultrasound stethoscopes", which enable rapid two-dimensional and color-Doppler imaging and supplement clinical examination of the heart. We present the results of systematic assessment of these devices in comparison with standard echocardiographic machines.
Methods: We prospectively examined with both ultrasound stethoscopes and standard echocardiographic machines 60 patients referred to our laboratory for routine echocardiographic examination. Image quality (score: 1 to 4; best to worst), accuracy in qualitative evaluation of valvular regurgitation and left ventricular function (ejection fraction) were directly compared. Color Doppler assessment of valvular regurgitation was graded on a standard four point scale. A two or more point difference was considered major. Ejection fraction was estimated (the ultrasound stethoscope is not equipped with appropriate software).
Results: Image quality was significantly worse in the case of ultrasound stethoscope (2.6 vs 2.1; p<0.0001). Major differences in the assessment of regurgitant jets were present in 3 cases (5%) (1 mitral and 2 tricuspid). The degree of agreement was good in the case of mitral and pulmonary regurgitation (kappa=0.61 and 0.74 respectively), very good in the case of aortic regurgitation (kappa=0.80) and moderate in the case of tricuspid regurgitation (kappa=0.48). The differences in the assessment of aortic and mitral regurgitant jets correlated with the image quality (p<0.05). A Bland-Altman graph comparing the results of ejection fraction assessment revealed good agreement between methods.
Conclusions: Results of the systematic evaluation of the use of ultrasound stethoscopes in the rapid evaluation of left ventricular systolic function and valvular regurgitation. Although image quality achieved with the hand-held stethoscope was worse, nevertheless it was adequate for the purpose of performing rapid limited assessment of cardiac and valvular function.