Venous adjustments in healthy and hypertensive pregnancy

Abstract

Gestational hypertensive (GH) disease is generally preceded by a poor first trimester circulatory adaptation. However, the initial arterial response (i.e., drop in peripheral vascular resistance and rise in renin–angiotensin–aldosterone system activity) seems largely comparable. We reviewed the venous adjustments in healthy and GH pregnancy. Changes in plasma volume (PV), venous compliance (VC), α-atrial natriuretic peptide (α-ANP) levels, inferior vena cava diameter and left atrial diameter were compared with the nonpregnant state. All showed an increase during healthy pregnancy. By contrast, GH pregnancy is characterized by an attenuated or even absent rise in PV and VC with an exaggerated rise in α-ANP. We propose that a blunted venous adaptation in GH disease originates from an inadequate venous reserve capacity. The venous compartment is unable to accommodate the increasing PV and becomes relatively overfilled. Subsequently, α-ANP levels increase, hampering further PV expansion. With increasing arter...