Hemodynamic assessment in patients with congenital heart disease using magnetic resonance imaging

Abstract: AbstractAround 1000 children are born with a heart disease in Sweden every year and today most of these children survive and reach adult age. There are around 2.3 million grownups with congenital heart disease in Europe today, a number that is expected to continue to increase. Further, the prevalence of patients with complex malformations has been growing significantly the last 10 years. There is thus a need to increase knowledge of the pathophysiology of these diseases to avoid and treat heart failure and complications, which could lead to great suffering for the patients but also great economic costs for the health care system. This thesis therefore aims to assess the cardiac function with new magnetic resonance techniques in order to increase knowledge of the pathophysiology and to better individualize treatment and optimize the timing of intervention. The first study of this thesis investigated the ventricular kinetic energy in patients with Fontan circulation. The results showed that kinetic energy is dependent on the morphology of the heart and seems to be very specific for each individual. In study II, III and IV the cardiac pumping in patients with Tetralogy of Fallot and pulmonary regurgitation was explored by quantifying the intraventricular kinetic energy and hemodynamic forces, as well as the atrioventricular coupling. Kinetic energy was affected in both the right and left ventricle, even if left ventricular ejection fraction was normal. Patients with pulmonary regurgitation had higher right ventricular hemodynamic forces than controls, but also affected left ventricular forces, with less alignment of force and blood flow which has been suggested to lead to pathological cardiac remodelling. Further, pulmonary regurgitation resulted in decreased right ventricular longitudinal function, decreased left ventricular preload and lower left ventricular stroke volumes. Before pulmonary valve replacement patients, similar to controls, had a clear atrioventricular coupling with a strong correlation between atrial inflow and ventricular longitudinal function. After operation however this coupling was lost, possibly because the loss of pericardial integrity.After pulmonary valve replacement patients still had disturbed hemodynamic forces, pumping mechanics and loss of atrioventricular coupling, which is energetically unfavourable. Further studies will tell if these changes will normalize in time.The potential role of kinetic energy and hemodynamic forces for treatment evaluation and decision making in patients with Tetralogy of Fallot can be the aim for future studies.