The digital stethoscope has made it possible for doctors and medical students to record heart sounds in high fidelity and to transmit these sounds in real time if need be. The electronic stethoscope was, for a long time, subject to interference and noise, but innovations from firms like 3M, Thinklabs Medical and Eko Devices have made the digital stethoscope the device of choice for doctors all over the world. Thinklab Medical’s stethoscope, the Thinklabs One, for instance, can amplify body sounds over 100 times with minimal quality loss.
These devices typically utilize piezoelectric crystals that become excited when vibrations from the diaphragm travel to them via a metal shaft. The crystal converts the vibrations into a digital signal. Once captured, these devices can send the data directly to a server for processing and storage. Thinklabs Medical takes advantage of this connectivity through their innovative iPhone app, iMurmur.
Thinklabs Medical was founded by Clive Smith in 1991. Smith, a native of South Africa, set out to bring the stethoscope into the new century, lamenting the fact that the device’s design has remained unchanged through much of its nearly-200-year history. An electrical engineer, Smith has partnered with medical experts for over two decades to bring to the public a digital stethoscope that could consistently surpass the acoustic quality of the manual stethoscope. His device, the Thinklabs One, achieves this via an electromagnetic diaphragm that’s the first of its kind. The device went to market recently with a price tag of around $500. Well before the One was released, however, the company made headlines with their cutting-edge iPhone app.
iMurmur gives users access to 21 pre-recorded heart murmurs, and comes complete with a visual waveform of each. This is an invaluable aid for medical students as medical schools don’t spend much class time on the various heart sounds that can indicate potentially-fatal conditions. Instead, students are expected to get their stethoscope experience during their internships. Unfortunately, it can be extremely difficult to find patients with particular heart issues.
iMurmur also allows users to create custom quizzes so that they can work on their trouble sounds, and Thinklabs is always adding new clips. The app also has visual indicators that specify particular aspects of each sound, such as the S1 and S2 phase of the heartbeat. Of course, the app allows users to compare murmurs to healthy heart sounds on the fly, so students can hone in on the differences. What’s more, each murmur comes complete with a “Details” tab that lists the critical data for the sound.
The Big Four
iMurmur provides a vast library of sounds for the four big killers: aortic regurgitation, the ejection systolic murmur, aortic stenosis, and atrial septal defect. Each of these conditions have their own characteristic sound, and doctors that readily recognize them save lives. Aortic regurgitation occurs when the aortic heart valve leaks. This causes a characteristic “whoosh” sound as blood flow reverses in the heart. The ejection systolic murmur is due to turbulent blood flow in the left ventricle and has a chaotic thumping sound. Atrial septal defect is characterized as a hole in the heart’s muscle wall. The condition occurs in children and newborns, and it creates a whooshing sound as blood flows from chamber to chamber. Finally, hypertrophic cardiomyopathy is characterized by thickening of the heart muscle, and it presents as an extended S1 that is readily visible on the iMurmur waveform.
As Thinklabs Medical adds new murmurs to the app’s repertoire, the company will cement it as a must-have tool for medical students. Note that the app requires headphones as the iPhone’s speaker is not capable of representing all of the heart sounds faithfully.