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The quantification of transvalvular blood flow through the mitral valve (MV) and regurgitant flow in particular is difficult with echocardiography, which is the method of choice to diagnose patients selected for valve repair or replacement. With magnetic resonance imaging, information on the intraventricular blood flow can be obtained. Several scanning techniques have attempted to assess the regurgitant flow. These techniques either do not directly assess the complete flow through the MV, or they do not measure the flow at the location of the valve.To investigate the accuracy of a novel method using three-directional velocity-encoded MRI to acquire the transvalvular blood flow directly from the intraventricular blood flow field, also representing the regurgitant flow during systole.Ten volunteers without cardiac valvular disease were recruited. The transvalvular MV flow volume was measured with three-directional velocity-encoded MRI (3-dir MV flow).The transvalvular flow measurements correlate very well with the flow measured in the aorta (rThree-directional velocity-encoded MRI is a patient-friendly and easy-to-use method suitable for quantifying the regurgitant MV flow in clinical practice.

In this thesis, we evaluated the acute and chronic hemodynamic effects of non-pharmacological heart failure therapies. In particular, the effects of surgical treatment and biventricular pacing therapy were investigated by left ventricular pressure-volume loop analyses. We demonstrated that restrictive mitral annuloplasty effectively restored mitral leaflet coaptation without inducing significant acute changes in ventricular function. This indicates that this procedure can be safely applied in patients with heart failure. Surgical ventricular restoration was shown to achieve acute normalisation of left ventricular volumes, improved systolic function, and decreased left ventricular wall stress and mechanical dyssynchrony. At the expense of a higher diastolic pressure resulting from altered diastolic properties, stroke work and cardiac output were not importantly altered, but mechanical efficiency was significantly improved. Chronically, surgical therapy resulted in improved clinical status evidenced by improved NYHA class, quality of life score, and 6-min walking distance. Left ventricular function and dyssynchrony remained significantly improved at 6 months follow-up. In addition, we observed a decrease in pulmonary artery pressure, right ventricular reverse remodeling and reduced tricuspid regurgitation. Acute and chronic hemodynamic effects of cardiac resynchronization therapy (biventricular pacing) were demonstrated by pressure-volume loop analysis. Hemodynamic improvements, previously only shown in acute studies, were shown to be maintained at 6 months follow-up. In addition, ventricular-arterial coupling, mechanical efficiency, and chronotropic responses were improved. In conclusion, the acute and chronic hemodynamic effects of these non-pharmacological heart failure therapies were demonstrated by ventricular pressure-volume analysis. These findings provide insight in the underlying mechanisms and help to explain improved functional status achieved with these therapies.