Morphofunctional Cardiac Changes in Singleton and Twin Pregnancies

Abstract

Objectives To compare heart echocardiographic changes between women with singleton and twin pregnanciesMethods We enrolled pregnant and postpartum women for this longitudinal cohort study in a tertiary center from 2014 through 2016. We analyzed 166 and 83 prospectively collected longitudinal data on simultaneously determined echocardiography parameters and blood variables in 44 and 22 normotensive women with either singleton or twin pregnancies, respectively. We tested mixed effect models for echocardiographic parameters and cardiac biomarkers.Results 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 during the 3rd trimester and immediately postpartum (within 1 week after childbirth). The 2nd trimester inferior vena cava diameters were significantly smaller and the 3rd trimester creatinine levels were significantly higher in women with twin pregnancies than in those with singleton pregnancies. BNP was positively correlated with left atrial volume index (β=0.49, p<0.01) and with the ratio of early diastolic transmitral to mitral annular velocity (E/e') (β=0.41, p<0.01). BNP and N-terminal precursor protein BNP (NT-proBNP) fragments immediately postpartum were negatively correlated with the later E/e', at 1 month postpartum in women with singleton pregnancies (r=−0.33, p=0.02 and r=−0.36, p<0.01, respectively).Conclusions The intravascular cardiac load at postpartum within 1 week after childbirth was greater in women with twin pregnancies than in those with singleton pregnancies. BNP/NT-proBNP was significantly positively correlated with LA volume index and E/e', BNP may be secreted to reduce the volume and pressure overload on the myocardial wall by diuretic action and may have improved the diastolic functions 1 month after childbirth. Our results provide evidence to deepen the understanding of the pathophysiological hemodynamic changes after delivery.