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

Objectives<br />Twin pregnancies are at increased risk of developing hypertensive disorders of pregnancy (HDP) compared to singletons resulting in a substantially higher rate of maternal and perinatal complications. Despite this, the strain caused by a twin pregnancy on the maternal cardiovascular system is still poorly studied. The objective of this study was to evaluate the changes in maternal cardiac morphology and diastolic function in a cohort of women carrying normotensive and hypertensive twin pregnancies.<br /><br />Methods<br />This was a cross-sectional study conducted at a tertiary referral university centre. Women with singleton or twin pregnancies were enrolled prospectively to undergo maternal transthoracic echocardiography throughout pregnancy. Multiple of median (MoM) were calculated for measured indices using a reference group of uncomplicated singleton pregnancies (n=411) in order to adjust for changes with gestational age. Cardiac findings were indexed to body surface area and compared among normotensive twins, singleton pregnancies complicated by HDP and twin pregnancies complicated by HDP.<br /><br />Results<br />119 HDP singletons, 52 normotensive twins and 24 HDP twins were included in the analysis. Left ventricle mass index (LVMi) MoM did not differ between singletons complicated by HDP and normotensive twins, but LVMi was significantly higher in HDP twins [1.31 (1.08-1.53) vs 1.17 (0.98-1.35), p=0.032]. Left atrial volume index MoM [1.12 (0.66-1.38) vs 0.65 (0.55-0.84), p=0.003] and diastolic index such as E/e’ MoM [1.29 (1.09-1.54) vs 0.99 (0.99-1.02), p=0.036] were significantly higher in HDP twins when compared to normotensive twins. In normotensive twins compared to HDP singletons, 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 hypertensive twins compared to normotensive twin pregnancies.<br /><br />Conclusions<br />The maternal cardiovascular system is severely altered by a twin pregnancy with and without HPD. Despite a low total vascular resistance, cardiac changes in normotensive twins are comparable with those seen in singletons complicated by HDP reflecting the high cardiovascular demand imposed by a twin pregnancy.