Cardiac Changes In Maternal Structure And Function During Preeclamptic Pregnancy: A Three-Dimensional Speckle-Tracking Echocardiography Study

BackgroundDuring pregnancy, there are important hemodynamic variations which result in a physiological situation of transient preload and afterload in the maternal heart. Those changes are necessary for the progression of a successful pregnancy, but which may also impose further load on the heart. Moreover, heart disease is the leading cause of nonobstetric mortality during pregnancy, and the number of pregnant women at risk for cardiovascular complications is on the rise. Therefore, identification and understanding maternal cardiac structure and function is of clinical importance and is essential for the management of cardiology patients in pregnancy.Preeclampsia(PE) is a pregnancy complication affecting 5% to 8% of pregnant patients, and remains a main cause of maternal morbidity and mortality. Autopsy data have demonstrated that, compared to deaths in pregnancy from other causes, there is a 10-fold prevalence of myocardial contraction band necrosis in PE cases. PE is commonly subdivided into early-onset(EP) and late-onset(LP) preeclampsia. Growing evidence shows that EP and LP have different etiologies and should be regarded as two different types of the disease. Dissimilar hemodynamic states have also been reported between EP and LP. However, it is not clear whether there are differences in terms of chamber and myocardial function.Echocardiography is the first choice for clinical assessment of cardiac structure and function. However, traditional echocardiographic parameters are load-dependent, so the use of them is limited by the variations in ventricular loading conditions in pregnancy. Despite many reports on maternal cardiac adaption being published, there is controversy about the change in left ventricular(LV) performance during pregnancy. Recently, two-dimensional echocardiographic(2DE) indices of myocardial longitudinal deformation, strain imaging, have been shown decreased significantly in late pregnancy while the traditional parameters did not reflect those functional changes. However, the accuracy of 2D strain could be affected by the use of foreshortened views and out-of-plane motion. Further technological advance of three-dimensional(3D) speckle-tracking echocardiography(STE) has developed to obtain all components of myocardial displacement vectors, which is more representative of the morphological state of the heart and provides a new opportunity to further our understanding myocardial deformation.Part I Structural and Functional Changes in Maternal Heartduring Pregnancy: A Three-Dimensional Speckle-Tracking Echocardiography Study 1 ObjectiveThis study aimed to investigate maternal LV performance during normal pregnancy by 3D STE parameters and use the real time three-dimensional echocardiograph to examine the time changes in left atrial(LA) volume and function, as well as LV diastolic function. 2 Methods 2.1 Study SubjectsNa group includes 68 healthy pregnant women for LV examination. Four visits were planned during the study: 12-14 weeks, 24-26 weeks, 36-38 weeks and 6~9 weeks after delivery. Nb group includes 43 healthy pregnant women for LA examination. Three visits were planned in Nb group during the study: 11 ~14weeks,24~32weeks and 35~39weeks. Meanwhile, thirty age-matched, healthy, nonpregnant women served as controls, respectively. 2.2 Echocardiographic ExaminationSequential two- and three-dimensional echocardiographs were performed. All image acquisitions were performed at three consecutive beats during breath-holds. All data sets were analyzed using the 4DAuto LVQ package(Echo PAC PC version 110.1.8). The surface of the LA was reconstructed and the LA volume was acquired throughout the cardiac cycle, resulting in LA volume-time curves. 2.3 Echocardiographic parametersThese following parameters were performed by M-Mode in the parasternal long-axis view as recommended: interventricular septum, posterior wall, left ventricular end-diastolic and end-systolic diameters. After three-dimensional full-volume data sets were analyzed, end-diastolic volume, end-systolic volume, ejection fraction(EF) and sphericity index as well as global longitudinal strain(GLS), global circumferential strain(GCS), global area strain(GAS), and global radial strain(GRS) were calculated.LA maximum, pre-contraction, and minimum volumes were measured using retrospective gating at the end of the T wave, at the onset of P wave, and at the onset of QRS wave, respectively. The LA total, active and passive emptying fractions were calculated. 2.4 Statistical AnalysesDescriptive data are shown as means ± SD. ANOVA for repeated measures was used to compare data between sequential studies in the pregnant group. Pregnancy data were compared with controls using independent sample t tests. 3D strain data were compared with 2D approach by paired t test. Pearson correlation coefficient was used to analyze the relationship between two parameters. 3 ResultsIn the group Na, increased cardiac index and progressive eccentric hypertrophy was detected, which subsequently recovered postpartum. In late pregnancy, GLS, GCS, GAS and GRS significantly decreased(P < 0.05) accompanied by a slight reduction of LVEF(P < 0.05), and these values returned postpartum to baseline level. The indexed LA maximum and total, passive as well as active emptying fraction increased gradually in the group Nb, the ratio of early diastolic peak velocity of mitral flow E and tissue Doppler velocity of mitral annulus e, namely the E/e, increased significantly. Meanwhile the ratio of tissue Doppler velocity e and late diastolic velocity a, the e/a, declined in the group Nb. 4 ConclusionsCardiac hypertrophy in normotensive pregnancies was observed in this study.3D STE demonstrated modified myocardial deformation and changes in maternal LV structure and function during the gestation period. The phasic volume and function of LA are improved gradually in each trimester as an adaptive response to increased cardiac preload uniformly associated with physiological cardiac performance.Part II Structural and Functional Change in Maternal Left Ventricle during Preeclampsia Pregnancy: A Three-Dimensional Speckle-Tracking Echocardiography Study 1 ObjectivePregnancy represents a physiological adaptation to the transient load changes of maternal heart. This study aimed to assess ventricular performance in PE as well as to compare maternal cardiac function between EP and LP by novel 3D STE parameters while considering LV loading and shape. 2 Methods 2.1 Study SubjectsA total of 84 preeclampsia women(PEa), including 43 women with EPa, 41 women with LPa, were entered into the study. Normotensive healthy women matched for maternal age and gestation were recruited as control subjects from the routine antenatal clinic.The pregnancy trimester was confirmed by ultrasound scanning in the first half of pregnancy. Meanwhile, thirty age-matched, healthy, nonpregnant women served as controls(Ca). 2.2 Echocardiographic ExaminationSequential two-dimensional echocardiography(2DE) and 3D STE were performed. All image acquisitions were performed at three consecutive beats during breath-holds. All data sets were analyzed using the 4DAuto LVQ package(Echo PAC PC version 110.1.8). 2.3 Echocardiographic parametersThese following parameters were performed by M-Mode in the parasternal long-axis view as recommended: interventricular septum, posterior wall, left ventricular end-diastolic and end-systolic diameters. After three-dimensional full-volume data sets were analyzed, end-diastolic volume, end-systolic volume, ejection fraction(EF) and sphericity index as well as global longitudinal strain(GLS), global circumferential strain(GCS), global area strain(GAS), and global radial strain(GRS) were calculated. 2.4 Statistical AnalysesDescriptive data are shown as means ± SD. Pregnancy data were compared with controls using independent sample t tests. 3D strain data were compared with 2D approach by paired t test. Pearson correlation coefficient was used to analyze the relationship between two parameters. P < 0.05 was considered to indicate statistical significance. 3 Results1. There were eccentric hypertrophy and reduced left ventricular ejection fraction in PEa; meanwhile, GLS, GCS, GAS and GRS significantly decreased in PEa versus Na and Ca.2.Compared to EPa group, there were more eccentric hypertrophy, higher LV mass index and lower GCS、GAS as well as GRS in LPa group.3.All 3D strain indices correlated well with gestation age(P < 0.01), while compared to other components, GAS exhibited the strongest association with 3D EF(r = 0.549) and sphericity index(r = 0.328), and was the only parameter that correlated well with LV mass index(r = 0.22). 4 Conclusions1.PE cases exhibited significant eccentric hypertrophy, ventricular dysfunction, and left atrium remodeling as well as impaired atrial function. Furthermore, myocardial deformation abnormalities preceded chamber dysfunction in this hypertensive disorder complicated pregnancy.2.Compared with LP, women with EP demonstrated more remarkable cardiac impaction.Part III Quantitative Analysis of Left Atrial Volume and Functionduring Preeclampsia Pregnancy: A Real-Time Three-DimensionalEchocardiography Study 1 ObjectiveThe present study used the real time three-dimensional echocardiograph to examine the time changes in LA volume and function, as well as LV diastolic function during preeclampsia pregnancy. 2 Methods 2.1 Study SubjectsA total of 70 preeclampsia women(PEb), including 36 women with EPb, 34 women with LPb, were entered into the study. Normotensive healthy women matched for maternal age and gestation were recruited as control subjects from the routine antenatal clinic. The pregnancy trimester was confirmed by ultrasound scanning in the first half of pregnancy. Meanwhile, thirty age-matched, healthy, nonpregnant women served as controls. 2.2 Echocardiographic ExaminationSequential two- and three-dimensional echocardiographs were performed. All image acquisitions were performed at three consecutive beats during breath-holds. All data sets were analyzed using the 4DAuto LVQ package(Echo PAC PC version 110.1.8). The surface of the LA was reconstructed and the LA volume was acquired throughout the cardiac cycle, resulting in LA volume-time curves. 2.3 Echocardiographic parametersLA maximum, pre-contraction, and minimum volumes were measured using retrospective gating at the end of the T wave, at the onset of P wave, and at the onset of QRS wave, respectively. The LA total, active and passive emptying fractions were calculated. 2.4 Statistical AnalysisDescriptive data are shown as mean ± SD. Pregnancy data were compared with controls using independent sample t tests. Pearson correlation coefficient was used to analyze the relationship between two parameters. P < 0.05 was considered to indicate statistical significance. 3 Results1.The dilated chamber and reduced action of LA occurred in PE associated with increased emptying fraction as an adaption to risen cardiac preload. In the PEb group, indexed LA volumes were significantly enlarged and the values of LA emptying fraction were markedly decreased resulting from elevated ventricular filling pressure and diastolic dysfunction.2.Compared with LPb, less LA volume and greater atrial emptying fraction were shown in EPb despite a higher afterload and more hypertrophied ventricle.3.The maximum volume of the LA and all emptying fraction value were positively correlated with gestational age. LA volume index was not only negatively correlated with heart rate, cardiac output and mitral annulus early diastolic velocity e, but also positively correlated with left ventricular mass and left ventricular filling pressure. However, the relationship between LA emptying fraction and the indicators above is just the opposite. 4 Conclusions1.In the women with PE, significantly dilated LA and decreased atrial emptying fraction had been a result of elevated LV filling pressure characteristically associated with myocardial diastolic dysfunction.2.Compared with LP, EP showed less volume and greater emptying fraction of LA despite in a higher afterload and more hypertrophied ventricle.