Cardiovascular haemodynamics in pre-eclampsia using brain naturetic peptide and tissue Doppler studies

To determine early haemodynamic changes in preeclampsia (PE) using tissue Doppler echocardiography and brain natriuretic peptide (BNP), and to relate these changes to obstetric outcomes.

Consenting primigravidae patients in the third trimester of pregnancy were included in the study, which was carried out in a large regional hospital in Durban, South Africa; 115 primigravidae (52 pre-eclamptics and 63 normotensive pregnant patients) attending the maternity unit including the antenatal clinics at the study site were studied. The patients, matched for maternal and gestational age, were examined during pregnancy and within the puerperium. Transthoracic echocardiography (TTE), tissue Doppler imaging (TDI), umbilical artery Doppler and laboratory investigations were performed.

BNP levels were significantly increased in the antepartum period [23.8 (2-184.1) vs 6.0 (0.5-45.2) pmol/l; p < 0.0001] and during labour [15.0 (1.8-206.4) vs 8.7 (1.9-24.8) pmol/l; p < 0.01] in the pre-eclamptic group compared to the normotensive controls. In the postpartum period, mean BNP levels were 4.2 (1.7-51.4) and 5.95 (2.2-38.7) pmol/l in the preeclamptic and normotensive groups, respectively (p > 0.05). Tissue Doppler Em/Ea ratios were elevated in the pre-eclamptic compared to the normotensive group (11.02 ± 5.6 vs 9.16 ± 2.6; p < 0.05). Mean left atrial size was larger (38 mm) in the pre-eclamptic group than in the normotensive group (35 mm) but this difference was not significant (p > 0.05). The umbilical artery resistance index was significantly higher in the pre-eclamptic group compared to the normotensive group (0.68 ± 0.06 vs 0.63 ± 0.05; p < 0.001). There was an increased rate of Caesarean sections performed in the pre-eclamptic group (n = 24) compared to the normotensive group (n = 18; p < 0.001). There were two stillbirths in the pre-eclamptic group and none in the normotensive group. As expected, birth weight (2.6 ± 0.8 kg vs 3.14 ± 0.42 kg; p < 0.0001) was lower in the pre-eclamptic group compared to the normotensive group.

In pregnancies complicated by pre-eclampsia, BNP levels were increased in comparison to normotensive pregnancies and this was accompanied by early changes in left ventricular diastolic function as determined by the tissue Doppler Em/Ea ratios. These changes reverted to baseline values, as indicated by return of BNP levels in the pre-eclamptic group to levels seen in the normotensive group. These changes were associated with an increased Caesarean section rate and lower birth weights in pre-eclamptic mothers.