Abstract
ObjectiveTo explore noninvasively the complex interactions of the maternal hemodynamic system throughout pregnancy and the resulting after-effect six weeks postpartum.MethodsEighteen women were tested beginning at the 12th week of gestation at six time-points throughout pregnancy and six weeks postpartum. Heart rate, heart rate variability, blood pressure, pulse transit time (PTT), respiration, and baroreceptor sensitivity were analyzed in resting conditions. Additionally, hemoglobin, asymmetric and symmetric dimethylarginine and Endothelin (ET-1) were obtained.ResultsHeart rate and sympathovagal balance favoring sympathetic drive increased, the vagal tone and the baroreflex sensitivity decreased during pregnancy. Relative sympathetic drive (sympathovagal balance) reached a maximum at 6 weeks postpartum whereas the other variables did not differ compared to first trimester levels. Postpartum diastolic blood pressure was higher compared to first and second trimester. Pulse transit time and endothelial markers showed no difference throughout gestation. However, opposing variables PTT and asymmetric dimethylarginine (ADMA) were both higher six weeks postpartum.ConclusionsThe sympathetic up regulation throughout pregnancy goes hand in hand with a decreased baroreflex sensitivity. In the postpartum period, the autonomic nervous system, biochemical endothelial reactions and PTT show significant and opposing changes compared to pregnancy findings, indicating the complex aftermath of the increase of blood volume, the changes in perfusion strategies and blood pressure regulation that occur in pregnancy.
Highlights
IntroductionThe course of a normal pregnancy is characterized by several profound changes of the maternal cardiovascular system in order to adapt blood pressure to the needs of pregnancy and prepare for delivery
Maternal cardiovascular and endothelial function pregnancy findings, indicating the complex aftermath of the increase of blood volume, the changes in perfusion strategies and blood pressure regulation that occur in pregnancy
The course of a normal pregnancy is characterized by several profound changes of the maternal cardiovascular system in order to adapt blood pressure to the needs of pregnancy and prepare for delivery
Summary
The course of a normal pregnancy is characterized by several profound changes of the maternal cardiovascular system in order to adapt blood pressure to the needs of pregnancy and prepare for delivery These changes include increases in maternal cardiac output, heart rate, and intravascular volume, and are accompanied by a decreased vascular resistance, mainly due to a reduction of the total peripheral resistance and an increase of the vascular compliance [1,2,3,4]. The mechanisms of biochemical and physiological interactions during normal pregnancy are still not fully understood and are topic of ongoing debates. The autonomic nervous system, which leads to a shift towards a lower sympathetic and a higher vagal modulation during the 1st trimester and a continuing shift towards a higher sympathetic and lower vagal modulation at late pregnancy collaborates with biochemical factors, such as the Asymmetric Dymethylarginine-Nitric Oxide- Pathway (ADMA-NO-Pathway) or the NO-antagonist endothelin-1 (ET-1) secreted by the endothelium to regulate these changes [6,7,8,9,10,11].
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