Purpose The hypertensive disorders of pregnancy (HDP) include preeclampsia (PE), gestational hypertension (GH), underlying chronic hypertension (CHTN), or PE superimposed on CHTN. Most maternal and fetal morbidity may be ascribed to PE and to the consequences of severe uncontrolled hypertension. PE is often difficult to distinguish from other HDP, as proteinuria may lag behind onset of hypertension (Wolf, 2004). This pilot study investigates utility of non-invasive indices of large artery stiffness (aortic pulse wave velocity, aPWV and augmentation index, AIx) for early diagnosis of PE.
Study Design Normotensive at term, CHTN at term, and clinically apparent primigravid women with PE (new onset hypertension and proteinuria) were recruited from our labor and delivery suites.
Methods Pulse wave analysis (PWA) by noninvasive applanation tonometry (SphygmoCorTM) was performed at radial and carotid arteries in supine and sitting positions.
Results To date, n = 11 per group: aPWV did not differ significantly between groups. By contrast, AIx (radial artery, supine position) reliably distinguished normotensives (Aix<0%) from CHTN (AIx 6-25%) and PE (AIx 30-57%), similar to Koomans et al (2004). Carotid AIx was elevated even more so in women with PE, though variability was increased compared with data from the radial artery.
Conclusion Aortic AIx may distinguish preeclampsia from other hypertensive disorders of pregnancy, whereas aPWV, another measure of arterial stiffness, does not. AIx is increased by angiotensin AT1 receptor activation and decreased by nitric oxide availability, in accord with pathophysiologic hypotheses regarding hypertension in PE. An ongoing prospective study is designed to compare diagnostic utility of PWA with circulating and urinary markers of PE and to assess its sensitivity to underlying medical disorders and to antihypertensive agents. Early and more certain diagnosis of preeclampsia by PWA would allow more appropriate allocation of medical resources to pregnancies at greatest risk, avoid unnecessary hospitalization and testing in women with lower-risk HDP, as well as allow earlier treatment if effective therapies are developed. Supported in part by grant M01RR13297 from the National Center for Research Resources, NIH.