The noble art of listening to figure out whether a heart valve still works properly From bloodletting to AI: the evolution of medical diagnostics – part 2

With a stethoscope, you can hear murmurs when a heart valve is abnormal. From the 1940s onward, a new technique was added: a bulky device that recorded murmurs on paper in a so‑called phonocardiogram. This device even traveled along on a NASA space mission to measure whether the heart could handle a trip to the moon. Since the 1980s, the technique has been replaced by ultrasound.

Cardiologist Arie van Dijk of Radboudumc began his career in cardiology in the late 1980s, when the phonocardiogram was still part of the required curriculum. 'The device recorded the sound of the heart with a microphone and printed it out. In addition, we used a ballistocardiograph, which measured the heartbeat through the pulse. The combination of these two techniques often led to a diagnosis. But I have never used it in actual practice.'

NASA even took such a heavy device on a space mission in the 1960s during the Gemini project. NASA wanted to find out whether a person could spend two weeks in space—and ideally also step out of the capsule. This was necessary for a round trip to the moon. It turned out that the heart could handle it: in 1969, the first human set foot on the moon.

The first heart ambulance, 1970. Source: Radboudumc Heritage Archive.

Ultrasound on the smartphone

In the 1950s, a new and very promising method emerged for measuring the heart: echocardiography. Van Dijk: 'This technique is based on sonar, which was developed during World War II. For the first time, it was possible to visualize the heart, the valves, and the blood flow from the outside. Echocardiography makes it much easier to detect abnormalities and determine the severity of a narrowing or leakage. That made the phonocardiogram unnecessary.'

Those first ultrasound machines were also large and bulky. 'But today we use devices that fit in your hand and connect to a smartphone. We also call these modern stethoscopes', Van Dijk explains. 'We use ultrasound to produce moving 3D images, which we can use for all kinds of measurements and calculations—such as determining the speed of blood flow.'

Still, listening to the heart has not disappeared: the stethoscope is still used. 'General practitioners in particular still use it, for example when someone is short of breath', says Van Dijk. 'In the past, some doctors could immediately identify a specific abnormality from the sound of a heart murmur. Most are no longer that highly trained, but if GPs hear a murmur, they often refer someone for modern imaging such as an ultrasound.'

Image above: this is an old‑fashioned heart ultrasound. That was already a more modern technique than the phonocardiogram. Source: Radboudumc Heritage Archive, photographer Jan van Teeffelen.

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