The Study On The Adaptive Changes Of Maternal Cardiovascular Structure And Hemodynamics During Normal Pregnancy

Objective Maternal cardiovascular adaptation to pregnancy involves enormous changes. The purpose of the study is to demonstrate the maternal cardiovascular hemodynamic, structural and functional changes during the course of gestation by echocardiography, and by measuring the plasma RENIN, ANG II and serum ALD, E2, PRO to explore their effects on the maternal adaptations .Methods 15 healthy nonpregnant women , 35 early pregnant, 37 second and 35 third trimester normal pregnant women were selected in this study. All of them were studied by echocardiography in left lateral decubitus position, synchronusly recording EKG . And blood was taken in all groups to measure the associated hormones .Results l.The dimension of LA increased significantly from 27.73 +2.98mm, in nonpregnant group to 34.00+2.20 mm in late pregnant group(P<0.01). LVEDd enlarged in the third trimester from 44.83 + 1.69 mm to 47.63 + 2.24 mm (PO.01), accompanied by LVM increasing from 123.51 + IS.OOg to 156.19+ 20.06g(P<0.01), showing the presence of left ventricular hypertrophy.2. Blood pressure changed slightly throughout pregnancy . CO and HR increased in early pregnancy ,peaked in the last weeks of pregnancy . Stroke volume began to increase until midpregnancy , and remained elevated afterward . TPR decreased during all three trimesters of pregnancy from 1044.85 +318.95, to 992.95 + 174.51 , 926.24+ 170.98 ,and lastly to 853.15 + 187.40 dynes/sec/cm-5 (p<0.01). es/ Vcfc decreased a little in midpregnancy .3. The mitral A wave velocity increased throughout gestation with the peak at the third trimester(0.59+0.10m/s),while E wave changing slightly, following the decrease of E/A. In late pregnancy, the mitral EF slope decreased(P<0.01).4. Both the renin-angiotensin-aldosterone system and the steroid hormones increased throughout the course of normal pregnancy . ALD initially increasedin early pregnancy, from 10.93 +2.93, 14.32+3.76 , 25.81 +7.21 and finally to54.68+ 13.43ng/dl (p<0.05). E2 and PRO increased nearly 200 times in the fullterm, and correlated closely(r=0.869).5. Both ALD and E2 correlated with LA, r=0.578 ,r=0.581 .respectively . Andthere were some correlations between E2 and RENIN ,ALD and PRO,ALD andE2, r=0.361, 0.846, 0.830, respectively. LVEDV and SV correlated linearly withr=0.846.Conclusions 1. CO increases in early pregnancy .initially as a result ofan increased HR, soon followed by an increased stroke volume . There is ahigh-flow , low-resistance hemodynamic state during normal pregnancy .2. During normal pregnancy the maternal cardiovascular system remodels, characterized with LVEDV increase , LV hypertrophy and enhanced vascular distensibility.The LV contractility seems to be increased during midpregnancy . While the LV diastole function decreases a little through gestation ,but remains in the normal range.3. The decrease in TPR throughout gestation may be mediated by ?- The Renin-Angiotensin system, stimulated by E2, may contribute to maitain the blood pressure . With the pregnancy-associated refractoriness to ANG II. The blood volume increase and homeostasis are regulated by the interaction ofE2, PRO and ALD etc.4. Maternal cardiovascular adaptive changes in pregnancy are active preparations, not passive ones.