Quantification of hemodynamics during vascular development

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Abstract

The work described in this PhD thesis has been carried out to improve insight into the relation between changing vascular network structures and their corresponding hemodynamics. Accurate quantitative information about the changing hemodynamics has been obtained experimentally from developing extraembryonic vascular networks of chicken embryos, which are a commonly-used model for cardiovascular research. First, a two-dimensional velocity field is measured by an optical measurement method called Particle Image Velocimetry. From this velocity field, both characteristic hemodynamic parameters and the corresponding vascular structure are extracted. These parameters are used to model the vascular network to enable further analysis. The relation between the quantitative results and qualitative observations has been studied, as well as the agreement with theoretical design rules for optimal networks. The non-intuitive and complex hemodynamical and structural changes presents in all networks indicate that measuring these changes is crucial to gain more insight in this process. Further, the changes in hemodynamics parameters can be related to the observed structural development. The quality of the data sets is comparable, which means that the data set is suitable for further analysis with known accuracy, and it is particularly suitable for validation of vascular development models. The followed method for characterizing vascular networks can easily be applied to other two-dimensional networks having optical access. Besides, this method can also contribute to quantitatively describing the effects of, for example, mechanical and chemical interventions when applied to developing networks both before and after the interventions. This work is preceded by a study on the accuracy of the flow measurement method, microscopic Particle Image Velocimetry. The influence of experimental parameters has been investigated for a correct interpretation of the measured flow velocities.