Assessment of the cardiac response during exercise remains challenging. So far, no ready-touse, accurate methods for assessment of biventricular function have been available. However, such a method could greatly improve assessment of cardiac physiology, early detection and prognostic stratification of heart diseases. In this PhD a new technique for quantification of cardiac function during exercise with cardiac magnetic resonance imaging (exercise CMR) was developed. Subsequently, this method was utilized to answer the core questions of this PhD project: 1)
What is the role of the sub-pulmonary ventricle in cardiac function during exercise? and 2)
What is the impact of its absence in patients with Fontan circulation? In this thesis, the process of development and validation of exercise CMR was presented. This showed that exercise CMR is a valid tool for assessing cardiac volumes during exercise. Next, exercise CMR was used to investigate the fundamental physiological mechanism of biventricular cooperativity during exercise in the healthy heart. These experiments demonstrated that the RV plays a key role in biventricular synergy and is vital in optimization of cardiac performance during exercise. Subsequently, exercise CMR was used to investigate the impact of the absence of the RV on exercise haemodynamics in patients with Fontan circulation. These results showed that the absence of a sub-pulmonary ventricle significantly impairs cardiac performance during exercise in patients with Fontan circulation and that the physiological heart rate response to exercise is inappropriate in the single-ventricle circulation. Selective heart rate inhibition improves acute exercise haemodynamics in this small group of patients and might be a potential new treatment target for optimization the Fontan circulation. Finally, the potential added value of computational modelling for the diagnostic interpretation of stress / exercise exams was evaluated. It was demonstrated that computational models can help improve diagnostic assessment of stress examinations in patient with Fontan circulation. This thesis present the results of a cross-disciplinary, translational research project that involved the fields of MRI physics, image processing, mathematical modelling and medicine. It demonstrates the value of such cross-disciplinary work for clinical medicine.
The sub-pulmonary ventricle during exercise and impact of its absence in the Fontan circulation
Ruijsink, J. B. (Author). 1 Apr 2019
Student thesis: Doctoral Thesis › Doctor of Philosophy