Doppler assessment of the venous heart-brain axis in normotensive and hypertensive pregnancies

Abstract

Cerebrovascular events due to hypertensive disorders during pregnancy are major contributors of maternal and neonatal morbidity and mortality worldwide, accounting for an estimated 62,000-77,000 maternal deaths each year. They have an unpredictable nature, and until today the knowledge about their pathophysiology remains limited, however evidence is growing that the VHBA may be a major player the (patho)physiology of cerebrovascular haemodynamics. Doppler-ultrasound combined with ECG is a safe and easily accessible tool to use in pregnant women. For this thesis, a CDE technique to assess the venous pulse waveform at the level of a neck-vein, the IJV, was developed. The following two parameters were assessed: (1) VPT, which provides information about the stiffness of the blood vessel wall, and (2) VI, which is related to the compliance of the blood vessel wall. Statistical analyses showed an acceptable repeatability and reproducibility. For both the sonographic assessment, as the interpretation of the obtained pulse waveform, a well-trained researcher is mandatory. During the course of an UP, it was proved that there is a decrease in wall stiffness and an increase in compliance at the IJV. During the course of pregnancies complicated by hypertensive disorders, there is a difference between the different types of HT. EPE is characterized by an increased vascular tone compared to UPs. GH, LPE, and normotensive pregnancies with a SGA baby showed values of VPT similar to the reference range of UPs at corresponding gestation. To the best of our knowledge, this thesis is the first study focusing on the VHBA in pregnancies complicated by hypertensive disorders. The observations in this PhD are an invitation to further investigate the maternal cerebral outflow. The better the pathophysiology, the specific risk markers and triggers to cerebrovascular complications due to hypertensive disorders are elucidated and understood, the better at-risk women can be identified.