Objective Maternal cardiovascular adaptations to pregnancy are necessary for an adequate fetomaternal circulation. However, the time course of physiological haemodynamic changes during the second half of pregnancy remains unclear. Various methods, invasive and noninvasive, are described to measure these changes. The thoracic electrical bioimpedance (TEB) technique is a method which is especially suitable to measure haemodynamic changes over time. The aim of the study was to determine both individual and group trends of haemodynamic changes in healthy pregnant women during the second half of pregnancy by means of TEB. Outcome variables are heart rate (HR), stroke volume (SV), cardiac output (CO) and blood pressure.Design Longitudinal study.Setting Outpatient antenatal care clinic of university hospital.Population A total of 22 healthy nonsmoking women with an uncomplicated singleton pregnancy and without pre-existing vascular disorders were invited.Methods TEB and blood pressure measurements were performed at each regular visit from about 24 weeks of gestation through term age.Main outcome measures Trends were calculated with the random effects model.Results Data obtained from 19 women were analysed, with a median of eight (range 3-11) measurements. HR showed a linear increase (P < 0.0005) and a quadratic trend (P < 0.0005). SV decreased linearly (P = 0.046), without a quadratic course. CO remained stable over time.Conclusion During the second half of physiological pregnancy, significant trends could be determined. An increase in HR, a decrease in SV, a stable CO and an increase in systolic and diastolic blood pressures were found.

The purpose of this study was to understand why patients with adult congenital heart disease (CHD) but no obvious shunt have an increased frequency of migraine headaches (MH). CHD patients with no known cardiac shunts (CHD-NKS), based on their echocardiographic or angiographic procedures, were tested for a right-to-left shunt using agitated saline contrast transcranial Doppler (TCD). Medical records of 2,920 patients from the UCLA Adult CHD Center were screened to participate in a study to evaluate the prevalence of MH in adults with CHD; 182 patients (6.23%) had CHD-NKS; of these, 60 (30%) underwent a TCD; 23 (38%) tested positive and 37 (62%) tested negative for a right-to-left shunt (P = 0.01 compared with controls). The frequency of MH was 43% in CHD-NKS compared with 11% in controls (P < 0.0001). TCD demonstrated right-to-left shunting in approximately 2/3 of patients with pulmonary stenosis, the Marfan syndrome and congenitally corrected transposition of great vessels, 1/4 of patients with bicuspid aortic valve, 1/5 of patients with mitral valve prolapse and all patients with Ebstein's anomaly. Approximately half of these experienced MH. Patients who had MH did not show a higher frequency of right-to-left shunt when compared with patients without MH (P = 0.57). In conclusion, CHD patients with conditions usually not associated with a shunt have a higher than expected prevalence of PFO which permits intermittent right-to-left shunting undetected by standard non-contrast TTE and TEE; the increased prevalence of right-to-left shunting may partially explain the higher than expected frequency of migraines.