Angiotensin Sensitivity Test Research Articles

ANGIOTENSIN SENSITIVITY TEST REVISITED

Objective: To determinethe validity of a single angiotensin sensitivity test as predictor of pregnancy-inducedhypertension with special reference to the dietary sodium intake at the timeof testing.Methods: The angiotensin sensitivitytest was successfully performed at 32 weeks' gestation in 104 women.In 90 of these women, the 24-h urinary sodium–creatinine ratio was known.Using an effective pressure dose of 10 ng/kg/min as the cutoff level, testcharacteristics were assessed in both the total population and after subdivisioninto a sodium restricted (n = 23) and anunrestricted diet group (n = 67).Results: The incidence of pregnancy-inducedhypertension was 13.4%. The number of positive angiotensin sensitivity testswas 7.5%. Test characteristics showed poor sensitivity (22.2%) and high specificity(94.8%); positive and negative predictive values were 40.0% and 88.7%, respectively.None of the sodium-restricted women was angiotensin sensitive. Sodium restrictiondid not have a significant influence on sensitivity, specificity, and predictivevalues of the test.Conclusion: The angiotensin sensitivitytest is not an appropriate screening test to predict hypertensive disordersof pregnancy. No significant effect of dietary sodium restriction was found.

Effect of angiotensin infusion on plasma endothelin in pregnancy

Objective: To study a possible role of plasma endothelin in angiotensin-induced vasoconstriction. Study design: Plasma endothelin levels were measured before and after an angiotensin sensitivity test at 32 gestational weeks in 19 nulliparous women. Results: No significant change in plasma endothelin occured as a result of angiotensin infusion. Conclusion: The angiotensin-induced rise in diastolic blood pressure is not associated with changes in plasma endothelin

The angiotensin sensitivity test and low-dose aspirin are ineffective methods to predict and prevent hypertensive disorders in nulliparous pregnancy: Kyle P.M.; Buckley D.; Kissane J.; De Swiet M.; Redman C.W.G. GBR Am J Obstet Gynecol 1995 173/3 I (865–872)

The angiotensin sensitivity test and low-dose aspirin are ineffective methods to predict and prevent hypertensive disorders in nulliparous pregnancy: Kyle P.M.; Buckley D.; Kissane J.; De Swiet M.; Redman C.W.G. GBR Am J Obstet Gynecol 1995 173/3 I (865–872)

Diurnal variation in angiotensin sensitivity in pregnancy

OBJECTIVE: Our purpose was to study the diurnal variation in angiotensin II sensitivity. STUDY DESIGN: Angiotensin sensitivity tests were performed at 9 AM and at 2 PM in 12 normotensive pregnant women, with each woman serving as her own control. RESULTS: In all patients the effective pressor dose was higher in the afternoon. CONCLUSION: We suggest the greater sensitivity to angiotensin in the morning is related to an intrinsic circadian variation in vascular reactivity. When the result of an angiotensin sensitivity test is interpreted, the time of day it is performed should be taken into account. (A M J O BSTET G YNECOL 1996;174:259-61.)

The angiotensin sensitivity test and low-dose aspirin are ineffective methods to predict and prevent hypertensive disorders in nulliparous pregnancy

OBJECTIVE: Our purpose was to assess the efficiency of the angiotensin sensitivity test as a predictive test for preeclampsia and the effectiveness of low-dose aspirin to prevent preeclampsia when commenced at 28 weeks' gestation in angiotensin II-sensitive women. STUDY DESIGN: A total of 495 healthy nulliparous women underwent the angiotensin sensitivity test at 28 weeks' gestation. The angiotensin II-sensitive women were randomized to 60 mg of aspirin or placebo as a subset of a large multicenter, randomized, controlled trial of low-dose aspirin therapy in pregnancy. Assessment of the efficiency of the angiotensin sensitivity test and low-dose aspirin in pregnancy was performed after detailed review of case notes after delivery. The Oxford definition of preeclampsia was used. This includes women without proteinuria but requirs blood pressure increments that have been validated to bias the selection to primigravid women. RESULTS: Five women had proteinuric preeclampsia in the angiogensin II-sensitive group randomized to aspirin compared with none in the group randomized to placebo. Overall, 11 (25%) of the women randomized to aspirin had preeclampsia compared with four (11%) randomized to placebo ( p > 0.05, not significant). The positive and negative predictive values for the angiotensin sensitivity test were 19% and 87%, respectively. CONCLUSION: The angiotensin sensitivity test is not an effective screening test for preeclampsia, and low-dose aspirin does not prevent preeclampsia when commenced at 28 weeks' gestation in angiotensin II-sensitive women.

Prevention of preeclampsia with calcium supplementation and vitamin D 3 in an antenatal protocol

Objectives: Using an angiotensin sensitivity test we carried out a prospective study in an attempt to predict the possible onset of preeclampsia and to prevent it by calcium supplementation (elemental calcium 156 or 312 mg/day per os) and treatment with vitamin D 3 (0.5 μg/3 day per os). Method: We used a study design in which 666 singleton pregnant women were managed with conventional antenatal care and 210 singleton pregnant women were managed with a protocol, together with conventional antenatal care. Result: Of the 666 women managed conventionally, 113 (16.9%) developed preeclampsia. However, the incidence of preeclampsia in the 210 women managed on the protocol was lower, at 10.9%. Conclusion: Our findings indicate that this protocol for the prediction and prevention of preeclampsia is useful for pregnant women at high risk of developing preeclampsia.

The effect of angiotensin II on utero-placental and umbilical circulation in normotensive pregnant women

OBJECTIVES: The angiotensin sensitivity test (AST) has been used to identify pregnant women likely to develop pre-eclampsia. The purpose of this study was to evaluate uteroplacental circulation and fetal response to angiotensin II (A-II). METHODS: We studied blood flow velocity waveforms in the uterine and umbilical arteries of 23 normotensive pregnant women before, during and after the AST by Doppler ultrasonography. Fetal well-being was documented with biophysical profiles (BPS). ANOVA and two-way analysis of variation were used to analyze the results. RESULTS: Infusion of A-II to normotensive pregnant women did not affect umbilical artery resistance at 20 or 30 weeks' gestation. Uterine artery resistance and maternal heart rate decreased significantly at 20 weeks' gestation with an AST-induced 10 mmHg or 20 mmHg rise in diastolic blood pressure. The BPS were not altered after the AST. CONCLUSIONS: The AST does not increase vascular resistance in the uterine or umbilical circulation, and may be considered a safe procedure for both the mother and fetus.

Low-Dose Aspirin Qualitatively Affects the Vascular Response to Angiotensin II in Hypersensitive Pregnant Women

Forty-four women underwent an angiotensin sensitivity test (AST) at 32.4±35 (mean±SD) weeks of gestation. They were divided into two groups according to the effective pressor dose (EPD) and were defined as AST positive (n=17) or AST negative (n=27) if the EPD was <10 or ±10 nanograms/Kg/min, respectively. A regression line of the diastolic blood pressor response to angiotensin II (A II) was obtained for each woman and the mean dose:response curve for each of the two groups was computed. The mean dose:response curves from the AST positive and AST negative groups show no difference between the intercepts (−91±8.2 vs −7.3±6.6, respectively; p NS), but significant difference between the slopes (34.3±8.9 vs 195±72; p<0.00001) and the calculated thresholds (2.6±1.0 vs 4.8±2.4; p<0.001). The administration of 100 mg per day aspirin for 7 days significantly lowered the slope of the mean dose:response curve in the AST positive group with no effect on that of the AST negative group, so resulting in two very similar...

Low-dose aspirin and vascular response in pregnant patients sensitive to angiotensin II

The angiotensin sensitivity test was performed in 25 high risk pregnant women before and after administration of low-dose aspirin (100 mg/day for 7 days). After aspirin administration there was a significant decrease in AII sensitivity in sensitive patients with no change in nonsensitive patients. Low-dose aspirin favorably affects sensitivity to AII in sensitive patients, thus indicating a reduced vascular reactivity as a consequence of this regimen.

Prediction of pregnancy‐induced hypertensive disorders by angiotensin II sensitivity and supine pressor test

An angiotensin II sensitivity test and a supine pressor test were done consecutively at 28 weeks gestation in 90 healthy, normotensive nulliparous women. None of the supine pressor tests was positive, applying the predefined threshold of a rise of 20 mmHg in diastolic blood pressure after rolling over; nine tests were positive using a corrected 9 mmHg cut-off level. Ten women had a positive angiotensin sensitivity test using a threshold of the effective pressor dose of 8 ng/kg/min; 22 women were positive using an effective pressor dose of less than or equal to 10 ng/kg/min. Later in pregnancy 12 women (13%) developed pregnancy-induced hypertensive disease (PIH). The specificity of both tests of predicting the development of PIH was about 90%. The sensitivity of the angiotensin sensitivity test at the 10 ng/kg/min level was 92%. Because of its low sensitivity of 25% the supine pressor test appears to have no value for the prediction of PIH. There was a significant positive association between angiotensin II refractoriness and birthweight.

Effects of Low-Dose Aspirin on Vascular Sensitivity to Angiotensin II and on 24 Hours Arterial Blood Pressure in Pregnancy

The angiotensin sensitivity test (AST) was performed in a group of 40 high risk pregnant women before and after oral administration of low doses of aspirin (ASA) (100 mg). AST performed before ASA characterized two groups of patients: 18 with positive AST (AST+) (effective pressor dose (EPD) = 6.91±1.69 (mean ± S.D.) ng/Kg/min of angiotensin II (A II)) and 22 with negative AST (AST-) (EPD = 22.44±11.23 ng/Kg/min of All). After ASA administration there was a significant increase in EPD in AST+ patients (15.00±9.54 ng/Kg/min, p<0.001). In AST- patients the mean EPD was significantly but non-homogeneously changed (18.33±8.11 ng/Kg/min). Nineteen pregnant high risk patients also underwent AST between weeks 24 and 39 of gestation. Then systolic, diastolic and mean arterial blood pressure were recorded using a portable device for indirect noninvasive automatic arterial pressure measure before and after seven days of low-dose aspirin therapy. In AST- patients no significant difference was observed before and after ASA regimen, whereas in AST+ patients post ASA mean blood pressure values were lower than pre ASA values, and during nighttime this difference became significant.

Effect of angiotensin infusion during pregnancy on fetal heart rate and on fetal activity

The angiotensin sensitivity test is of value in predicting patients at increased risk of pregnancy-induced hypertension and preeclampsia. Studies on the effects of angiotensin II on uterine blood flow in various species showed contradicting results. In the present study, 15 pregnant women were monitored by cardiotocography before, during and after an infusion of angiotensin II-amide (maximal infusion rates 6.3–23.2 ng · kg −1 · min −1). No remarkable changes in fetal heart rate, oscillatory frequency and amplitude, as well as in the number of accelerations and fetal movements could be observed. It may be concluded from these results that the fetal condition is not compromised by an angiotensin sensitivity test.

The value of the angiotensin sensitivity test in the early diagnosis of hypertensive disorders in pregnancy

Normal pregnant women are resistant to the pressor effect of intravenously administered angiotensin II (AII), but women who are destined to develop hypertensive complications in pregnancy show an increased sensitivity to AII several weeks before the onset of the first clinical symptoms. In 231 normotensive nulliparous women (age 25 +/- 5 years), an angiotensin sensitivity test (AST) was performed between weeks 28 and 32 of gestation. If an effective angiotensin pressor dose (APD) of less than 10 ng . kg-1 . min-1, is considered to be a positive test result, 58 subjects had a positive AST and 173 had a negative AST. Twenty-six of 34 women who ultimately developed pregnancy-induced hypertension (PIH) or preeclampsia had a positive test, and the diagnosis was made early. Each of the eight pregnant subjects with a false negative test developed only a mild form of the hypertensive disorder. In this series, 11 women had a premature onset of labor; eight of them also had an APD of less than 10 ng . kg-1 . min-1. The study confirms the high predictive value of negative test results. Therefore, the AST can be used as an appropriate method for identifying women who are destined to develop hypertensive complications in pregnancy. However, because of the low practicability of the test, it may not be recommended as a screening method in routine prenatal care.