We read with great interest the recent article by Silverman and Balk, and agree that the sound quality of the digital stethoscope is just as good, or superior to an analog stethoscope.1 This is important to today’s practice of medicine where cardiovascular physical examinations are abridged, poorly executed, and minimal effort is undertaken to optimize the auscultatory milieu for a higher yield exam.2 Amplification of sound does not necessarily result in clearer appreciation of heart sounds and murmurs as motion artifacts and surrounding noises are amplified as well.
In addition to the sound element, digital stethoscopes have the unique ability to incorporate the visual element of heart sounds and murmurs through phonocardiography. This can occur in real time, and in the palm of one’s hand, thus greatly enhancing the examination experience for both clinicians, trainees, and the patient. One does not even have to purchase a new stethoscope, but rather can purchase a stethoscope attachment, at a lower cost, which can digitalize the sound with the push of a button (e.g. the FDA cleared EKO Core stethoscope attachment, Berkeley, CA).
Aside from murmur detection, phonocardiography has historically been the tool of choice to detect the third (s3) and fourth (s4) heart sounds3, and detection of these sounds by standard auscultation requires a certain level of experience.4 The s3 and s4 are related to the echocardiographic Doppler indicies of mitral inflow E and A wave velocities, respectively. This is relevant in the era of hand held ultrasound devices where assessment of diastolic function is not possible, and volume assessment is focused mainly on the characteristics of the inferior vena cava.5
This is important clinically since the identification these heart sounds is specific for diagnosing an elevated left ventricular end-diastolic pressure (LVEDP)3, and this can be visualized clearly with the phonocardiogram feature of digital stethoscopes.
Recently our group was able to better characterize the unique sounds produced by three FDA approved durable left ventricular assist devices using phonocardiography.6 Identifying changes in sound vibrations may be of theoretical benefit for detection of early pump thrombosis, which is something that echocardiography is not able to do.
Finally, until the price of a hand held ultrasound device is reduced to that of a digital stethoscope, we believe the digital stethoscope may be able to save the bedside cardiovascular exam, at least for now.
Faris G Araj, MD
University of Texas Southwestern Medical Center-Dallas, Texas
Julie Cox BSN, RN
Baylor Scott &White Health-Dallas, Texas
Read the full manuscript at The American Journal of Cardiology