Hypertension in pregnancy: Classification and pathophysiology [Hipertensión en el embarazo: Clasificación y fisiopatología]
There are four major hypertensive disorders complicating approximately 10%of all pregnancies. Preeclampsia classified as mild or severe refers to the newonset of hypertension and proteinuria after 20 weeks of gestation in apreviously normotensive woman. Eclampsia, a variant of severe preeclampsia,refers to the development of grand mat seizures that should not be attributableto another cause. HELLP syndrome (hemolysis, elevated liver enzymes, and lowplatelets) is also a severe form of preeclampsia. Chronic hypertension isdefined as systolic pressure = 740 mm Hg, diastolic pressure = 90 mm Hg, orboth, that antedates pregnancy, is present before the 20 weeks of pregnancy, orpersists longer than 12 weeks postpartum. Superimposed preeclampsia is diagnosedwhen a woman with preexisting hypertension develops new onset proteinuria after20 weeks of gestation. Gestational hypertension refers to hypertension (usuallymild) without proteinuria (or other signs of preeclampsia) developing in thelatter part of pregnancy. It should resolve by 12 weeks postpartum. Preeclampsiais a syndrome characterized by maternal endothelial cell dysfunction. Oxidativestress, inflammation, circulatory maladaptation, as well as humoral, mineral,or metabolic abnormalities all appear to play a role in the pathogenesis ofpreeclampsia. Newer studies suggest that placental release of circulatingfactors that interfere with the action of vascular endothelial growth factor andplacental growth factor plays a central role in its presentation. In thisreview, classification and pathophysiology of preeclampsia with its severeforms, eclampsia and HELLP syndrome, are discussed. Copyrigth © Sociedad Iberoamericana de información Cientifica (SIIC), 2009.