This thesis provides insights in characteristics of newly introduced echocardiographic parameters in healthy children and their use in follow-up of patients with a congenital heart defect (CHD)... Show moreThis thesis provides insights in characteristics of newly introduced echocardiographic parameters in healthy children and their use in follow-up of patients with a congenital heart defect (CHD) after surgery. In healthy children, reference values and characteristics of two echocardiographic techniques, tissue Doppler imaging (TDI) and speckle-tracking strain imaging, are described. TDI-derived velocity parameters are reproducible and feasible in children. Yet use of age or growth-dependent reference values is recommended, especially in neonates. Speckle-tracking strain-derived global peak strain parameters have a good reproducibility, are age-independent and remain unchanged during periods of significant growth, such as the neonatal period. We encourage use of these parameters. In contrast, the limited reproducibility of parameters describing intraventricular time-differences is worrying. Our follow-up studies in CHD patients undergoing corrective surgery with cardiopulmonary bypass, describe a significant decrease in biventricular performance immediately postoperatively. Subsequently, left ventricular performance recovered to control values. In contrast, right ventricular performance remained impaired in most subgroups of CHD patients up to one year postoperatively. Considering the prognostic value of right ventricular performance parameters, these studies underline the need for careful evaluation of both left and right ventricular performance postoperatively. Furthermore, a longer-lasting negative influence of cardiopulmonary bypass on ventricular performance was suggested. Show less
Despite the impressive results of cardiac resynchronization theraphy (CRT) in recent large randomized trials a consistent number of patients fails to improve following CRT implantation when the... Show moreDespite the impressive results of cardiac resynchronization theraphy (CRT) in recent large randomized trials a consistent number of patients fails to improve following CRT implantation when the established CRT selection criteria (NYHA class III-IV heart failure, LV ejection fraction __35 % and QRS duration > 120 ms) were applied. For example, close analysis of the data from the MIRACLE trial revealed that 32% of patients did not improve or even worsened in NYHA class after 6 months of CRT. The presence of clinical non-responders to CRT has now been confirmed in several other studies and is usually around 30%. In addition, if response to CRT is defined using more objective parameters such absence of LV reverse remodeling or lack of improvement in LV ejection fraction on echocardiography at mid-term follow-up the number of non-responders is usually between 40-50%. In view of the unnecessary procedure risks and health care expenses in patients without response to CRT the percentage of non-responders among patients selected according to the current selection criteria is unacceptably high and should be reduced. Aim of the thesis: The relatively high number of patients without benefit from CRT (referred to as non-responders) indicates the need for refinement of the current selection criteria in order to 1] better identify those patients with the highest likelihood of response to CRT and 2] avoid device implantations in patients that are unlikely to respond to CRT. The aim of the current thesis was to improve and refine the current CRT selection criteria through the evaluation of the mechanismus underlying (non-) response to CRT. Show less
