| Abstract |
Introduction
During the process of normal pregnancy, several hemodynamic alterations are taking place, in order the pregnant woman to meet the demands of the growing fetus. The maladaptation, which may be attributed to the defective trophoblast penetration, not rarely leads to pregnancy induced hypertension and/or preeclampsia. Under this concept, pregnancy represents a “stress test” for the woman. In this case, the manifestation of preeclampsia, alludes the inability to complete this test and is associated to a high incidence of cardiovascular events in woman’s later life. The evaluation of the pregnant’s cardiovascular adaptability, especially when she carries risk factors, contributes in timely recognition of those women who have a high probability of pregnancy-related complications, including the syndrome of preeclampsia.
Aim
The aim of this prospective study was the evaluation of the way and the magnitude of the hemodynamic alterations taking place in high risk pregnancies. We also determined the utility of one of the hemodynamic parameters, specifically the pulse wave velocity, in timely prediction of preeclampsia.
Material and Methods
In total, 118 pregnant women, following-up at the High Risk Pregnancies outpatient clinics of PAGNI hospital, participated in the study. Moreover, 13 non-pregnant women, with equivalent demographic data, were studied. Forty-one of the pregnants (group A), were examined in 6th-8th (1st trimester) and in 18th-21th (2nd trimester) week of gestation. Blood pressure, cardiac pulse, cardiac output, pulse wave velocity, and systemic vascular
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resistance were evaluated. These women and 77 more (N=118, group B), were examined in 22th-26th gestational week. In this phase, blood pressure, pulse wave velocity, 24-hour urine protein and calcium excretion, as well as plasma uric acid and sFlt-1 levels (the receptor-1 of the vascular growth factor, VEGF), were recorded.
For group A, the associations among the parameters in the 1st and 2nd trimester were evaluated. Moreover, the magnitude of the alteration of each parameter, from the 1st to the 2nd trimester, was determined. A further investigation of certain characteristics that influence the way and the magnitude of cardiovascular alterations, was achieved comparing the nulliparous to multiparous women. In addition, all women of group A were compared to 13 non-pregnant women, regarding their cardiovascular parameters in the 1st trimester.
For group B, the cardiovascular and biochemical parameters, as well as the sFlt-1 levels, were evaluated and compared between preeclamptic and non-preeclamptic women. The same parameters were compared between women with early-onset and late-onset preeclampsia. The ability of prediction of preeclampsia of each parameter was evaluated.
Results
For group A, the cardiac output has a negative correlation to vascular resistance, in the 1st and the 2nd trimester, as well. Running from the 1st to the 2nd trimester, the cardiovascular parameters were changing significantly, except from systolic blood pressure and cardiac output. Specifically, cardiac beats increased, whereas diastolic blood pressure, pulse wave velocity and systematic vascular resistance decreased. Evaluating these alterations based on the number of previous pregnancies, we found a slight decrease in cardiac output and in vascular resistance, in nulliparous. On the contrary, the multiparous appeared to increase their cardiac output and decrease their vascular resistance in a greater degree than nulliparous did. In the comparison of 1st trimester in group A and control group, cardiac output was higher and vascular resistance was lower in pregnants.
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For group B, pulse wave velocity was 30% higher in preeclamptic compared to non-preeclamptic women. The women who manifested preeclampsia later on, had higher values of blood pressure, serum uric acid and sFlt-1, and lower values of urinary calcium. Women with early-onset (before the 34th gestational week) preeclampsia had even higher values of blood pressure and pulse wave velocity. The later parameter showed the best sensitivity of all others in predicting preeclampsia, in all cases and in early-onset preeclampsia. The combination with the sFlt-1 levels improved even more the predictive performance.
Conclusions
In high risk pregnancies, cardiac output and systemic vascular resistance are the first to be affected compared to the pre-pregnancy status. Diastolic blood pressure, pulse wave velocity and vascular resistance decrease, while cardiac frequency increase, running from the 1st to 2nd trimester. All these changes contribute to the best adaptation of woman’s cardiovascular system during pregnancy. In our study, the multiparous seemed to correspond better in this process than the nulliparous did.
Among women carrying aggravating factors, pulse wave velocity, measured in 22th-26th weeks of gestation, seems to be the most reliable method in the identification of them who have the highest risk of preeclampsia, especially those cases of early-onset. Combining pulse wave velocity with sFlt-1 levels during the same period of gestation, increases even more the predictive value, in this population of pregnant women.
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Μελέτη των παραγόντων,οι οποίοι μεταβάλλουν την καρδιαγγειακή λειτουργία σε φυσιολογική εγκυμοσύνη και σε προεκλαμψία
