Matters of the Heart

Examining the heart using X-ray technology
Depiction of the judgment of the dead, c. 1250 BC: In ancient Egypt, tradition held that the heart would be weighed in the next world to determine whether the individual would be admitted to the afterlife

Depiction of the judgment of the dead, c. 1250 BC: In ancient Egypt, tradition held that the heart would be weighed in the next world to determine whether the individual would be admitted to the afterlife

Image source: Getty Images

The seat of the soul, the sign of love, and the symbol of life – for millennia, there has been a certain mythology associated with the heart. Although advances in scientific research gradually debunked the myths surrounding the organ, it remained a mystery to the medical profession for a long time. Indeed, it was almost impossible to examine the heart of a living person until the early 20th century.

A key turning point came with the discovery of X-rays. For the first time, it was possible to visualize the heart inside the bodies of living people – although an X-ray examination required considerable patience around the turn of the 20th century. In those days, the process of capturing the image took several minutes, during which the patient was required to stay perfectly still. As the heart would beat hundreds of times over an exposure time of this length, it appeared as nothing more than a blurry shadow in the resulting X-ray image.

X-ray of the heart taken with the Blitzapparat, c. 1909
X-ray of the heart taken with the Blitzapparat, c. 1909

The key breakthrough came when Friedrich Dessauer designed his “Blitzapparat” in 1909. This X-ray unit allowed results to be obtained quite literally in a flash: Once the Blitzapparat was powered up, there was a small explosion and a brief flash of the X-ray tube – and the image was in the can. Soon afterwards, the physician would be holding an X-ray image showing a clear outline of the heart. For the first time, images could be captured with an exposure time of just a few milliseconds, allowing the heart to be depicted clearly in X-ray images.

X-ray image to document cardiac catheterization, showing the catheter extending into the right atrium

X-ray image to document cardiac catheterization, showing the catheter extending into the right atrium

Image source: Forssmann, Werner: “Die Sondierung des rechten Herzens” [“Probing of the right heart”], Klinische Wochenschrift, No. 45, 1929

Now that the exterior of the heart could be visualized in X-ray images, the question was: How could the same be done for the interior of the heart and its vessels? The young intern Werner Forssmann had an idea. In 1929, he performed a daring self-experiment that involved threading a rubber tube into his heart via a venous access site, thereby proving the feasibility of cardiac catheter examinations. Despite this successful experiment, however, no one but Forssmann himself believed in the effectiveness of the examination technique. The targeted use of cardiac catheter examinations did not begin until the 1950s. With the Angiograph in 1950, Siemens presented the first system that allowed physicians to observe the catheter on a fluorescent screen as it passed through the blood vessels and into the heart.

In the 1970s, the advent of computed tomography ushered in completely new ways of imaging the heart. However, it was first necessary to overcome the same challenge as had plagued researchers in around 1900: Our heart is in a state of constant motion. In the 2.5 seconds that it took Somatom, the first whole-body CT scanner from Siemens, to scan a 4 cm slice of the body, the heart would beat approximately three times and was therefore blurry in the resulting images.

Visualization of the coronary arteries in end systole with SOMATOM Definition, 2006
Visualization of the coronary arteries in end systole with SOMATOM Definition, 2006

Source: Mayo Clinic, Rochester, USA

Yet, what if the CT scanner were faster than the movement of the heart? The answer to this question was provided by SOMATOM Definition in 2005. Equipped with Dual Source technology, the scanner featured two tubes and two detectors that rotated around the patient and was so fast that it could capture an entire image of the moving heart in just 0.083 seconds. This resulted in high-quality images with an excellent level of detail, and the device could be used to visualize not only the coronary vessels themselves but also details such as narrowing and fine calcareous deposits on the vessel walls.

In addition to imaging procedures, today’s cardiologists have numerous options at their disposal when it comes to diagnosing and treating heart diseases. Every patient is different, however, and there are many factors that influence the effectiveness of treatment. Will the drug work? Will the planned operation succeed in its objectives? Until now, it was impossible to answer these questions in advance with sufficient certainty.

Yet, what if we had a digital twin on which we could test procedures safely? It may sound like science fiction, but this technology has already become a reality. A digital twin combines the real and digital worlds and is based on a multitude of individual patient data. The anatomy and function of the patient’s heart are modelled from this huge volume of data with the help of artificial intelligence (AI). Artificial neuronal networks are trained so that the digital heart twin works and responds exactly as the patient’s heart does. This model could, for example, be used to trial heart medications or simulate operations with a view to selecting a treatment option that was perfectly tailored to the patient. It will still be some time before we have a digital twin of our entire body that accompanies us to doctor’s visits throughout our lives, but the heart twin is currently being tested in research projects in collaboration with university hospitals.

Thanks to advances in medicine and technology, the heart has now been researched down to the last detail and has largely lost its mystique. Nevertheless, there are still moments that get our heart racing: When we fall in love, the heart flutters like a butterfly – and this intoxicating feeling may be the reason why the heart remains a symbol of love to this day.