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The Stethoscope Evolved: Electrocardiogram Built In

The stethoscope is the quintessential doctor’s tool. It allows physicians to hear even minute sounds generated in the chest cavity, from the “whoosh” generated by a rough-edged valve to the gurgle of a quivering aorta. While the stethoscope is a powerful tool, it has its limits, and that limit may come as a surprise to you. New technology may provide an answer that could initiate a revolution in cardiological medicine.

Traditional Stethoscope Operation

Before Dr. René Laennec invented the stethoscope in the 1800s, doctors had to literally press their ear to a patient’s chest to make out the characteristic “lub-dub” of the heart. Laennec grew weary of the constant stench of unwashed Victorian bodies, so he began using a hollow wooden tube to channel the heart sounds to his ear. This worked reasonably well, but it came at the cost of sound sensitivity. The basic design was refined over the years, but it wasn’t until Dr. David Littmann came up with the stethoscope design that any child would recognize today that the device would come into its own.

This stethoscope is composed of a chestpiece, rubber and metal tubing and ear tubes. The design works well, and a well-trained physician can detect heart and lung sounds that were unknown in Laennec’s time. While the stethoscope can’t detect all heart problems, the sound sensitivity it affords has nevertheless extended countless lives.

Traditional stethoscope design calls for a chestpiece that contains both a plastic diaphragm and a bell. The diaphragm is a thin membrane that detects high-frequency sounds, while the metal cup-shaped bell detects low-frequency sounds. Together, they can detect virtually all of the sounds that a healthy heart generates as it contracts. These sounds are passed through the tubes to the ears, via gas trapped in the tubes themselves.


The primary drawback of the stethoscope has nothing to do with its design, but with its operators. While the human ear is capable of detecting the sounds that the stethoscope can convey, doctors must be able to properly interpret them in order for the device to be of any use. Unfortunately, a few studies have demonstrated that many doctors—mostly recent post-grads with little experience—have trouble interpreting the various murmurs the heart can produce. In fact, according to research published in the Journal of the American Medical Association, doctors were only able to accurately diagnose 20% of common cardiac problems the stethoscope is capable of detecting.

Referring to the results as “disturbingly low,” the researchers noted that they tested 453 doctors in all, many of which were only 3 years out of medical school. The researchers quizzed the participants on the 12 most common cardiac problems, and they are urging medical schools to spend more time educating these students in cardiac auscultation. They also noted that in the US, only one third of internal medicine programs offer structured cardiac auscultation training.

A New Approach

One potential solution for this issue are devices such as the CardioSleeve that convert sounds generated by a stethoscope into a visual readout that doctors can more easily interpret.


The CardioSleeve—which has received FDA approval—records the patient’s heartbeat for later manual analysis and also generates an on-the-spot electrocardiogram. The device then sends both of these pieces of information to the cloud, both to the patient’s electronic medical record and to the doctor’s office.


Doctors can then log in to a secure account and view their patients’ data from anywhere with their smart device. While devices like these have a lot to prove before they see widespread adoption, they may one day provide doctors with a near-foolproof way to quickly analyze their patients’ cardiovascular health, which will undoubtedly lead to even more saved lives.

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