Prof. Dr. Natasja de Groot: "I have lost my heart to electrophysiology"

A heartbeat is generated by electrical signals. In a healthy heart, the signals move through the tissue in a uniform pattern. When the tissue becomes damaged, those patterns become more complex and even chaotic, until they eventually cause arrhythmias. Prof. Natasja de Groot, Scientific Leader of Medical Delta Cardiac Arrhythmia Lab, wants to gain insight into this complex electropathology with her research. Ultimately, this should lead to an effective treatment of cardiac arrhythmias. She will give her inaugural lecture on Friday 22 November.

Is there no effective treatment yet?

No Unfortunately. And that while more and more people suffer from it - cardiac arrhythmias are the cardiovascular epidemic of the 21st century. Atrial fibrillation, also known as "atrial fibrillation," is the most common cardiac arrhythmia. You can treat it with pills, but that often doesn't produce much, while the medication can cause severe side effects. It is also possible to eliminate a heart rhythm disorder with a shock. Then it is cured for that moment, but the patient can get the same problems again later. You cannot prevent this in any case. Ablation therapy is also a possibility. This is an invasive treatment in which electrically damaged tissue is burned away. This sometimes has to be repeated several times and ultimately does not always have an effect.

With the Medical Delta program we want to better map out what causes a specific heart rhythm disorder. If we know that, we will ultimately be able to treat patients specifically and thereby more effectively. This saves a lot of unnecessary or sometimes harmful medication and unnecessary operations and leads to better results for the patient.

How will this research lead to more effective treatment?

We do not yet know much about the mechanism behind cardiac arrhythmias. In our research we measure the electrical waves in the heart to find out more about that mechanism. This is only possible with people who undergo open heart surgery. We ask them to participate in the research. Among them are people who do not have cardiac arrhythmias, so that we can make comparisons. Because with people who don't have them, the electric waves look very different.

For the purpose of the research, we have established the Atrial Fibrillation Innovation Platform, a foundation within which patients actively participate in thinking and cooperating. The experiences and findings of patients help us as scientists to map and understand cardiac arrhythmias.

The electrical signals from patients with cardiac arrhythmias do not form an even wave motion. What causes that?

Damaged tissue conducts the waves differently than healthy tissue. The tissue is damaged by, for example, overweight, diabetes and old age, but also by a heart attack. We see that with damaged tissue, the waves not only move unevenly through the tissue, but actually shoot in all directions in three dimensions. In addition, the inside of the fabric suddenly behaves very differently than the outside, what normally is one movement. If the so-called electropathology exceeds a certain value, the patient will experience arrhythmias. A first episode only lasts a few seconds, then it becomes longer, until it can’t stop anymore.

We also discovered that the Bachmann bundle, which forms a kind of highway between the left atrium and the right atrium, is not really a highway. This is because it is damaged very quickly, so that the signals are not transmitted properly.

Why do the electrical signals in damaged tissue act so crazy?

For that you have to look at the structure level. Within the Medical Delta Cardiac Arrhythmia Lab, I collaborate with prof. Dr. Bianca Brundel, a molecular biologist. She tries to find a good explanation for this.

A few years ago, Bianca spoke after me at a symposium and saw an opportunity to do research together. I in the field of electrophysiology, she in the field of heart tissue. We, two very young women,  then applied for a grant known for being awarded to established names. We were naturally very proud when we got it and therefore were able to continue working together. We have since gone through several research projects together.

Who else do you work with?

To be able to measure the signals, you need very specific technology that did not exist at the time we started our investigation. My colleague Prof. Ton van der Steen, chairman of Medical Delta, took me to TU Delft at a certain point and introduced me to Prof. Alle-Jan van der Veen and Prof. Wouter Serdijn. Alle-Jan deals with signal analysis techniques, such as those used in radio astronomy, for example. Wouter is involved with bio-electronics and has developed the electrodes with which we can take the measurements.

In the Medical Delta program different disciplines come together and we work towards the same goal, which means we can do even better research.

You have now collected a lot of data through this collaboration. What will that ultimately deliver?

We are working towards treatment that focuses on restoring the structure of the tissue and thus the electrical conduction. The first pilot study has now been started and the first blood samples are being examined.

You speak with passion about your research field. Where does it come from?

That actually started in high school. I found it very interesting when we discussed the heart, much more interesting than, for example, molecular systems. I could very well understand that heart: a pump with tubes that behaves according to physical laws. When I later studied medicine, I attended a lecture by a cardiologist and I immediately loved it. From that moment on I have done all my studies in cardiology. When it was time for an AIO place I wanted to do that at the echocardiography department, but there was no place there. That is why I ended up with electrophysiology. From the moment I attended an ablation procedure, I, as they say, pledged my heart.