Tahar, you have been a doctoral student with Prof. Michael Gee since this year and are involved in the "Digital Heart Surgery" lighthouse project at the Munich Institute of Robotics and Machine Intelligence (MIRMI). What is it about?
Congenital heart defects can have serious consequences on the daily life of the patient and even be life-threatening. They are mostly discovered at infancy. Tetralogy of Fallot (ToF) is quite common, accounting for about six to seven per cent of congenital heart defects. In this case, a hole in the wall separating the ventricles leads to a mixing of oxygen-rich blood and oxygen-poor blood the blood flow in the heart. In addition, the pulmonary valve and the outflow tract of the right ventricle are narrowed (stenosis), which induces the hypertrophy of the right ventricular heart muscle. An operation is necessary to close the hole with a patch and remove the narrowing of the pulmonary valve. Patients who underwent this repair at an early age and reach adulthood often develop right ventricular insufficiency and dilatation. Since these patients may have abnormal heart geometry and function, a special care should be taken when creating and calibrating the respective digital twin.
You studied mechanical engineering. How can you support the medical profession here?
The heart is a biological pump that creates pressure to send nutrient- and oxygen-rich blood through circulatory vessels to supply body organs. This highly dynamical system has a very relevant mechanical aspect, which is measured and analyzed by clinicians for diagnostic purposes. This mechanical aspect can be modeled and simulated using applied mechanics and numerical methods, which are important pillars in a mechanical engineering program.
What is the goal of your doctoral thesis?
While it has been shown that pulmonary valve replacement improves symptoms and functional status in these patients, the optimal timing and indications for the replacement intervention after repaired ToF are still debated. Therefore, our objective is to create a patient-specific computational model, or also called a digital twin, of the cardiovascular mechanics and support the physicians in their decision-making by assessing the preoperative function of the right ventricle and estimating its postoperative performance. Already a few years ago, colleagues started to develop a digital twin of the heart and circulatory system, which has been constantly refined since. Today, we use so-called cardiac magnetic resonance imaging and catheter pressure measurements, to further develop these models and to adapt them to Tetralogy of Fallot patients. We can reconstruct the three dimensional geometry of the heart muscle with the temporal resolution of 20 geometries per heartbeat using "segmentation processes". The model still needs to be refined and validated. It is not yet used as a routinely performed examination today. I very much hope that we will succeed in developing an operational digital twin of the heart in the next few years.
MIRMI Lighthouse project "Digital Heart Surgery"