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Prof. Dr. Gero Tenderich, heart surgeon, Chief Medical Officer at Cardisio GmbH and the driving force behind the new technology explains in an interview the principle of Cardisiography and talks about the benefits for patients, doctors and cardiological treatment.

Today’s advances in medicine are almost always based on developments to existing technology. Disruptive innovation, meaning that which changes the way we approach diagnosis and treatment from the ground up, rarely permeates the market. Cardisiography is an example of this kind of innovation. Cardisio makes it possible to quickly conduct ischaemic risk stratification non-invasively and in an at-rest state before showing any symptoms – and all at a low cost and with low technological requirements. Cardisiography was developed by doctors, computer scientists, biosignal experts, mathematicians, physicists and electrical engineers.


What’s new about the Cardisio method is the approach it takes. With Cardisiography, we are not looking primarily for causes of already existing symptoms. Instead, the Cardisio method seeks to identify the risk of a hypoperfusion of the heart muscle in seemingly healthy people, long before they show symptoms. This means we don’t need to wait for angina pectoris to target stenoses. We detect heart hypoperfusion long before it becomes a problem or leads to a heart attack in the worst cases, to allow for further preventative diagnosis and, if needed, treatment. Reacting early can significantly improve the quality of life of the person affected as, in some circumstances, it can help to avoid larger surgeries and permanent damage. If the Cardisiograph detects a hypoperfusion, further examination and localisation is then carried out by a cardiologist until final diagnosis and an invasive treatment in the catheter lab.
The Cardisiograph is thus a screening test and early-warning system for your heart’s health and, as such, is a highly accurate indicator and initiator for further cardiological diagnosis. We are by no means replacing an existing procedure. Instead, we are expanding the diagnostic spectrum with the possibility of early detection. Cardisiography is cost-effective, user-independent and the reading can be taken in an at-rest state – just what the world of cardiology has been looking for.


The Cardisiograph measures the heart’s electronic field with high sensitivity. The analysis is carried out using a computer-based infinitesimal, three-dimensional off-setting of the mammalian heart’s excitation processes. The heart of the procedure is an algorithm that carries out millions of arithmetic operations in just a few minutes of measuring time and analyses the heart’s excitation processes using neural networks. The algorithm correlates the excitation processes with intrinsic blood supply and the specific spatial alignment of the myocardium in the dipole field as a function of time starting from a defined point.


Five electrodes are attached to the skin of the patient following a simple predefined pattern and after a few minutes the doctor receives an analysis. This analysis provides a clear first look as to whether the patient is demonstrating a hypoperfusion. This can then be confirmed with further cardiological diagnosis. A hypoperfusion can be caused by much more than just coronary disease. Regardless of the root cause, cardisiography can demonstrate hypoperfusion with high sensitivity and specificity. In a study completed in 2018 and later published in the Journal for Electrocardiology, Cardisiography, Cardisiography found hypoperfusion with a sensitivity of over 95% and a specificity of over 75%. After improvements to the AI algorithms, a new study was completed in 2019 that shows the following: 95.3% sensitivity and 90.3% specificity.

This already makes Cardisiography now one of the most precise cardiological diagnosis procedures as we come closer and closer to the gold standard of coronary angiography. As the algorithm is constantly being developed and learns with each dataset, the already remarkable accuracy will only continue to improve. The simplicity of the Cardisio procedure makes it perfect for use in GP surgeries and for regular check-ups.


The idea for the Cardisiograph comes from the principles of electrophysiology. In the past, there have already been many attempts to analyse the electrical spread of excitation in multi-dimensional space. However, due to the high level of complexity, it is almost impossible for a person to detect and understand the correlations and carry out the required analysis/computing. This has meant that, until now, such an approach has remained simply theoretical.

Computing power needed to be developed to be able to put the theory into practice. When we got together in the middle of 2015 and validated ideas for implementing the approach using artificial intelligence, the idea for Cardisio was born. Cardisiography uses an algorithm that analyses and compares various measured values. The measured data is funnelled into a neural network that is constantly updated and optimised. Thanks to the high computing power available today, we can now feed and train an algorithm with the necessary data to ensure it is able to conduct calculations correctly. After almost four years of research and development, the Cardisiograph has now been approved as a medical device.

It wasn’t just computing power that contributed to the success, though. Personal interest in the subject also played a big part. Since the beginning of my medical studies I have been committed to the physiology of the heart and even completed my PhD in this area. Electrophysiology was always an interest of mine. I was already convinced relatively early on after my studies that ischaemia could be measured without stress and, more importantly, non-invasively. In my 30-year career as a heart surgeon, I have researched a lot in this area and supervised countless doctor theses.


To bring a disruptive innovation onto the market, you need an exciting idea, good timing, technological advance, the determination and stamina to pursue the execution of the idea and, last but not least, a great support network and a little bit of luck.

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