 Katja Zeppenfeld is a professor of clinical electrophysiology and head of the Clinical Electrophysical Research and Treatment Center in Leiden, the Netherlands. Professor Zeppenfeld's main research interest is the treatment of complex cardiac arrhythmias and she is one of the world's foremost experts in this area. Professor Zeppenfeld has a close collaboration with the Department of Cardiology at Orhus University Hospital and she visits the department on a monthly basis to participate in clinical trials and treatment. Probably my most important research contribution has been in the field of arrhythmias and continental heart disease. So my interest in this subject started many years ago with the clinical challenge. In technology I follow otherwise young and healthy patients who have undergone a very successful repair operation can experience life-threatening ventricular arrhythmias later in life. So while treating these patients and analyzing the clinical data, I recognize a certain pattern and by systematically performing measurements during catheter treatment I could identify the precise areas in the heart responsible for these arrhythmias. This work has actually defined the current approach to management of these arrhythmias and the findings now allow us to treat patients even before a life-threatening arrhythmia occurs. Clinically Katja focuses on the type of heart-rhythm disorders originating from the heart chambers. How to understand the mechanisms and how to treat with catheter ablation. We hope that the collaboration with Katja about these often very complex procedures will enable even higher success rates in treating these patients suffering from often life-threatening disorders. I first met Jens Nilsen-Kozidis from ours many years ago when we both worked together for the European Heart Rhythm Association Committee. What followed was a very close cooperation with a fantastic EP group in Ahrus and while discussing potential solutions for complex arrhythmias and how we may improve our understanding we got talking about the animal work already performed in Ahrus. And I realized that combining their animal models and related expertise in our experience here in Leiden with multimodal arrhythmias substrate analysis including the three-dimensional integration of EP data, imaging data and histology would be a fantastic opportunity to move the field forward.