Maternal functional hemodynamics in uncomplicated twin pregnancies: A longitudinal study using impedance cardiography

Maternal Hemodynamics from Preconception to Delivery: Research and Potential Diagnostic and Therapeutic Implications: Position Statement by Italian Association of Preeclampsia and Italian Society of Perinatal Medicine

OBJECTIVE

 The Italian Association of Preeclampsia (AIPE) and the Italian Society of Perinatal Medicine (SIMP) developed clinical questions on maternal hemodynamics state of the art.

STUDY DESIGN

 AIPE and SIMP experts were divided in small groups and were invited to propose an overview of the existing literature on specific topics related to the clinical questions proposed, developing, wherever possible, clinical and/or research recommendations based on available evidence, expert opinion, and clinical importance. Draft recommendations with a clinical rationale were submitted to 8th AIPE and SIMP Consensus Expert Panel for consideration and approval, with at least 75% agreement required for individual recommendations to be included in the final version.

RESULTS

 More and more evidence in literature underlines the relationship between maternal and fetal hemodynamics, as well as the relationship between maternal cardiovascular profile and fetal-maternal adverse outcomes such as fetal growth restriction and hypertensive disorders of pregnancy. Experts agreed on proposing a classification of pregnancy hypertension, complications, and cardiovascular states based on three different hemodynamic profiles depending on total peripheral vascular resistance values: hypodynamic (>1,300 dynes·s·cm-5), normo-dynamic, and hyperdynamic (<800 dynes·s·cm-5) circulation. This differentiation implies different therapeutical strategies, based drugs' characteristics, and maternal cardiovascular profile. Finally, the cardiovascular characteristics of the women may be useful for a rational approach to an appropriate follow-up, due to the increased cardiovascular risk later in life.

CONCLUSION

 Although the evidence might not be conclusive, given the lack of large randomized trials, maternal hemodynamics might have great importance in helping clinicians in understanding the pathophysiology and chose a rational treatment of patients with or at risk for pregnancy complications.

KEY POINTS

· Altered maternal hemodynamics is associated to fetal growth restriction.. · Altered maternal hemodynamics is associated to complicated hypertensive disorders of pregnancy.. · Maternal hemodynamics might help choosing a rational treatment during hypertensive disorders..

The correlation between maternal serum sST2, IL-33 and NT-proBNP concentrations and occurrence of pre-eclampsia in twin pregnancies: A longitudinal study

The primary objective of this study was to determine the longitudinal profile of serum sST2 (soluble suppression of tumorigenicity 2), IL‐33 (interleukin‐33) and NT‐proBNP (N‐terminal pro‐brain natriuretic peptide) concentrations in twin pregnancies with pre‐eclampsia (PE) and those normotensive twins. The secondary objective was to test whether the change of serum sST2,IL‐33 and NT‐proBNP is related to PE in twin pregnancies. This is a longitudinal nested case–control study and all 156 dichorionic (DC) pregnancies were from a prospective cohort of twin pregnancies who received antenatal care and gave two live births at Peking University Third Hospital between October 2017 and September 2020. Four to five milliliters of peripheral blood of each pregnant woman were collected during the following three intervals: (1) 6–11⁺⁶ weeks; (2) 24–27⁺⁶ weeks; (3) 28–31⁺⁶ weeks. We found that sST2 and NT‐proBNP levels increased as pregnancy progressed in normotensive twin pregnancies and further increased in PE group, while no differences were found in IL‐33 levels throughout pregnancy. Then the correlation of biomarker levels with the occurrence of PE was assessed. Our results indicated that combining maternal serum sST2 and NT‐proBNP levels yielded the highest predictive value on the occurrence of PE significantly higher than the predictive value of any markers alone. Interestingly, the predictive value of second trimester (AUC = 0.876, 95%CI 0.824–0.928, LR−0.338, LR+7.67, p < 0.001)was higher than that of early‐third trimester (AUC = 0.832, 95%CI 0.769–0.896, LR−0.29, LR+3.845, p < 0.001). Serum sST2 and NT‐proBNP concentrations during second and early‐third trimester were associated with the occurrence of PE in twin pregnancies.

Maternal echocardiographic changes in twin pregnancies with and without pre-eclampsia

OBJECTIVE

Twin pregnancies are at increased risk of developing hypertensive disorders of pregnancy (HDP) compared with singleton pregnancies, resulting in a substantially higher rate of maternal and perinatal complications. The strain caused by twin pregnancy on the maternal cardiovascular system has not been studied extensively. The objective of this study was to evaluate the changes in maternal cardiac morphology and diastolic function in a cohort of women with normotensive and those with hypertensive twin pregnancies.

METHODS

This was a cross-sectional study conducted at a tertiary referral university center. Women with singleton or twin pregnancy were enrolled prospectively to undergo maternal transthoracic echocardiography throughout pregnancy. Multiples of the median (MoM) were calculated for each index using a reference group of uncomplicated singleton pregnancies (n = 411) in order to adjust for changes associated with gestational age. Cardiac findings were indexed for body surface area and compared among normotensive twin pregnancies, singleton pregnancies complicated by HDP and twin pregnancies complicated by HDP.

RESULTS

The total cohort included 119 HDP singleton pregnancies, 52 normotensive twin pregnancies and 24 HDP twin pregnancies. Left ventricular mass index (LVMi) MoM (median (interquartile range)) did not differ between singleton pregnancies complicated by HDP and normotensive twin pregnancies, but was significantly higher in HDP twin compared with HDP singleton pregnancies (1.31 (1.08-1.53) vs 1.17 (0.98-1.35), P = 0.032). Two diastolic indices, left atrial volume index MoM (1.12 (0.66-1.38) vs 0.65 (0.55-0.84), P = 0.003) and E/e' MoM (1.29 (1.09-1.54) vs 0.99 (0.99-1.02), P = 0.036), were significantly higher in HDP twin compared with normotensive twin pregnancies. In normotensive twin compared with HDP singleton pregnancies, stroke volume index (SVi) MoM was higher (1.20 (1.03-1.36) vs 1.00 (0.81-1.15), P = 0.004) and total vascular resistance index (TVRi) was lower (0.73 (0.70-0.86) vs 1.29 (1.04-1.56), P < 0.0001). In contrast, SVi MoM was lower (1.10 (1.02-1.35) vs 1.20 (1.03-1.36), P = 0.018) and TVRi was higher (1.00 (0.88-1.31) vs 0.73 (0.70-0.86), P = 0.029) in HDP twin compared with normotensive twin pregnancies.

CONCLUSION

The maternal cardiovascular system is altered severely in twin pregnancy with or without HDP. Despite the low total vascular resistance, cardiac changes in normotensive twin pregnancies are comparable to those seen in singleton pregnancies complicated by HDP, reflecting the high cardiovascular demand imposed by twin pregnancy. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Special Considerations Regarding Antenatal Care and Pregnancy Complications in Dichorionic Twin Pregnancies

Twin pregnancies account for about 3.3% of all deliveries in the United States with the majority of them being dichorionic diamniotic (DCDA). Maternal physiological adaption in twin pregnancies is exaggerated and the rate of almost every maternal and fetal complication is higher when compared to singleton pregnancies. Therefore, twin pregnancies necessitate closer antenatal surveillance by care providers who are familiar with the specific challenges unique to these pregnancies, and there is evidence that following women with twins in a specialized twin clinic can result in improved obstetrical outcomes. The importance of the first antenatal visit in twin pregnancies cannot be over emphasized and should preferably take place early in gestation as it is the optimal period to correctly identify the number of fetuses and the type of placentation (chorionicity and amnionicity). This will allow the patients, families, and caregivers to make the appropriate modifications and to tailor an optimal antenatal follow-up plan. This plan should focus on general recommendations such as weight gain and level of activity, education regarding complications specific to twin pregnancies along with the relevant symptoms and indications to seek care, as well as on close maternal and fetal monitoring. In this review, we summarize available evidence and current guidelines regarding antenatal care in DCDA twin pregnancies.

Comparison of maternal third trimester hemodynamics between singleton pregnancy and twin pregnancy

OBJECTIVES

The impedance cardiography (ICG) technique measures the variation of impedance in the thorax due to the physical contractile activity of the heart. Twin pregnancy is characterized by greater maternal hemodynamic changes than a singleton pregnancy.

METHODS

In a study on 121 pregnant women in the last trimester we performed ICG, evaluating the following hemodynamic parameters: stroke volume, heart rate, cardiac output, ventricular ejection time, left ventricular ejection time, thoracic impedance, and systemic vascular resistance.

RESULTS

The study included singleton and twin pregnancies. Heart rate values in women with single fetus was lower than in those carrying twins (85 vs. 100 beats/min, p=0.021) as were the stroke volume values (64 vs. 83 mL, p=0.010) and the cardiac output (p<0.0001). Systemic vascular resistance decreased in twin pregnancies compared to singleton pregnancy (p=0.023).

CONCLUSIONS

ICG studies are rare, and the validation of their results is an ongoing process. However, the ICG technique is applicable in the third trimester of pregnancy and can yield important information regarding the hemodynamic profile of singleton and twin pregnancies, revealing maternal heart changes specific to twin pregnancies.

Morphofunctional cardiac changes in singleton and twin pregnancies: a longitudinal cohort study

Background

This study aimed to compare the echocardiographic changes and cardiac biomarkers between women with singleton and twin pregnancies.

Methods

From April 2014 to March 2016, this longitudinal cohort study invited pregnant women who were scheduled to give birth at Hokkaido University Hospital. We analyzed prospectively collected data on simultaneously determined echocardiographic parameters and blood cardiac markers of 44 women with singleton and 22 women with twin pregnancies. Furthermore, we tested the mixed-effect models for echocardiographic parameters and cardiac biomarkers.

Results

During the third trimester and immediately postpartum (within 1 week after childbirth), the mean left atrial volume index and brain natriuretic peptide (BNP) level were significantly higher in women with twin pregnancies than in those with singleton pregnancies. Women with twin pregnancies also had significantly smaller second-trimester inferior vena cava diameters and significantly higher third⁻trimester creatinine levels than those with singleton pregnancies. BNP positively correlated with the left atrial volume index (β = 0.49, p < 0.01) and the ratio of early diastolic transmitral to mitral annular velocity (E/e’) (β = 0.41, p < 0.01). At 1 month after childbirth in women with singleton pregnancies, BNP and N-terminal precursor protein BNP (NT-proBNP) fragments immediately postpartum negatively correlated with the later E/e’ (r = − 0.33, p = 0.02 and r = − 0.36, p < 0.01, respectively).

Conclusions

The intravascular cardiac load reached maximum within 1 week after childbirth and was greater in women with twin pregnancies than in those with singleton pregnancies. BNP/NT-proBNP significantly positively correlated with LA volume index and E/e’. In women with singleton pregnancies, BNP secreted immediately after childbirth might improve the diastolic functions 1 month after childbirth.