Hemodynamic adaptation during pregnancy in chronic hypertension.

OBJECTIVE: To assess hemodynamic and NT-proANP changes in women with chronic hypertension during pregnancy. METHODS: Stroke volume index (SI), heart rate (HR), cardiac output index (CI), systemic vascular resistance index (SVRI), pulse wave velocity (PWV), and left cardiac work index (LCWI) were measured using whole-body impedance cardiography. Systolic blood pressure (SAP), mean arterial pressure (MAP), diastolic blood pressure (DAP), and pulse pressure (PP) were also measured. Arterial compliance was defined as the SI-to-PP ratio (SI/PP). Hemodynamic parameters and NT-proANP concentrations were assessed during the early and late second trimester, the third trimester, and after delivery in 20 women with essential hypertension and 30 normotensive women. RESULTS: Arterial blood pressure, SVRI, and PWV remained higher during the whole study period in chronic hypertensive compared with healthy pregnancies. In the early second trimester, women with chronic hypertension had significantly lower SI and NT-proANP concentrations than did normotensive women. CONCLUSION: The hemodynamics of chronic hypertension during pregnancy are characterized by persistent high vascular resistance. Lower SI and NT-proANP values found in chronic hypertensive pregnancies during the early second trimester may suggest a reduced intravascular volume increase during pregnancy.