Hypertension in pregnancy.

Normal pregnancy is characterized by a marked reduction in peripheral vascular resistance. Blood pressure is diminished, while cardiac output, blood volume, renal blood flow and the glomerular filtration rate are increased. These hemodynamic changes are reversed in preeclampsia-eclampsia (PE-E), a condition considered to be related to a dysfunction of the endothelium. Decreases in the production of nitric oxide (NO) and prostacyclin (in association with an increased synthesis of thromboxane A2) may play a role in the pathogenesis of PE-E. Recent reports have supported the concept that an imbalance between vasodilators and vasoconstrictors may explain the clinical, laboratory and hemodynamic disturbances observed in PE-E. Particular attention has been given to the fact that a state of L-arginine NO deficiency may be present. The control of hypertension, rest, and close clinical and laboratory surveillance remain the gold standard to minimize the severity of the complications of PE-E. However, on the basis of its physiology and pathophysiology, low-dose aspirin has been recommended in pregnancies at risk to prevent or, at least, to delay the occurrence of PE-E. Although initial reports showed promising results, recent conclusions from large trials have moderated this optimism. The use of supplemental L-arginine may be considered another possibility of treatment, and experimental data have given convincing results, but there are no reports on PE-E. Therefore, the practical management of PE-E requires prudence, careful follow-up and prompt decisions on the precise moment for delivery (which remains the most effective therapeutic procedure).