Isabelle Fabry

The use of diameter distension waveforms as an alternative for tonometric pressure to assess carotid blood pressure

Proper non-invasive assessment of carotid artery pressure ideally uses waveforms recorded at two anatomical locations: the brachial and the carotid artery. Calibrated diameter distension waveforms could provide a more widely applicable alternative for local arterial pressure assessment than applanation tonometry. This approach might be of particular use at the brachial artery, where the feasibility of a reliable tonometric measurement has been questioned. The aim of this study was to evaluate an approach based on distension waveforms obtained at the brachial and carotid arteries. This approach will be compared to traditional pulse pressures obtained through tonometry at both the carotid and brachial arteries (used as a reference) and the more recently proposed approach of combining tonometric readings at the brachial artery with linearly or exponentially calibrated distension curves at the carotid artery. Local brachial and carotid diameter distension and tonometry waveforms were recorded in 148 subjects (119 women; aged 19-59 years). The morphology of the waveforms was compared by the form factor and the root-mean-squared error. The difference between the reference carotid PP and the PP obtained from brachial and carotid distension waveforms was smaller (0.9 (4.9) mmHg or 2.3%) than the difference between the reference carotid PP and the estimates obtained using a tonometric and a distension waveform (-4.8 (2.5) mmHg for the approach using brachial tonometry and linearly scaled carotid distension, and 2.7 (6.8) mmHg when using exponentially scaled carotid distension waves). We therefore recommend to stick to one technique on both the brachial and the carotid artery, either tonometry or distension, when assessing carotid blood pressure non-invasively.

Diagnosis and treatment of hypertensive disorders during pregnancy

Abstract Pregnancy is a cardiovascular and metabolic challenge to the human female body. This review summarizes current knowledge on the regulation of blood pressure and plasma volume in normal and hypertensive pregnant women. During pregnancy, systemic vascular resistance and blood pressure decrease, whereas cardiac output and blood volume increase to safeguard an adequate circulation in the utero-placental arterial bed. Hypertension affects 10% of all pregnancies and is accompanied by an increase in foetal and maternal morbidity and mortality. Hypertension in pregnancy includes a wide spectrum of conditions, including pre-eclampsia and eclampsia, pre-eclampsia superimposed on chronic hypertension, chronic hypertension, and gestational hypertension. Endothelial dysfunction, oxidative stress and an exaggerated inflammatory response are features related to hypertensive disorders. Microangiopathic disorders can easily mimic hypertensive disorders during pregnancy. Although they have some symptoms in common, they require another type of management. To reduce the risk of maternal and foetal complications due to haemodynamic maladaptations, the current management includes rest at home or in the hospital, close monitoring of maternal and foetal signs and symptoms, early start of antihypertensive therapy, and timely delivery regarding maternal and foetal survival chances. Thresholds to initiate blood pressure lowering treatment during pregnancy are 160 mmHg systole or 110 mmHg diastole. Below these thresholds, treatment must be individualized because current evidence does not support aggressive medical interventions. Alpha-methyldopa and dihydropyridinic calcium channel blockers are among the recommended antihypertensives.

The influence of tocolytic drugs on cardiac function, large arteries, and resistance vessels

PurposeBeta-2 adrenoceptor agonistic drugs like ritodrine have been the reference tocolytic drugs, but are associated with cardiovascular side-effects. Atosiban, a newer drug, is a competitive antagonist of oxytocin and has been claimed to have fewer cardiovascular side effects. Until now, there has mainly been a subjective reporting of adverse reactions and few objective cardiovascular data. Evaluation of the acute effects of therapeutic doses of ritodrine and atosiban compared with placebo on cardiac function, large artery properties, blood pressure, and resistance vessels.MethodsA double-blind, randomized trial was carried out in 20 non-pregnant female volunteers. Hemodynamic measurements were made under standardized conditions during kinetic steady state. Cardiac output was measured with echocardiography, large artery properties with an echo-tracking device. The effect on the microcirculation was estimated using the total peripheral resistance index (TPRI).ResultsAtosiban did not differ from placebo. With ritodrine, cardiac function increased by 79% compared with placebo because of a rise in heart rate (91%). TPRI decreased by 48%. Ritodrine increased the distensibility of the common carotid artery by 62% and the compliance by 83%, independent of blood pressure. Compliance of the common femoral artery increased independently of pressure by 33% and the distensibility by 59%. Aortic pulse wave velocity was not influenced by either medication.ConclusionsThe present study shows potential beneficial vascular effects of ritodrine that are counterbalanced by the cardiac effects. Atosiban has no clinically relevant cardiovascular effects and may be a good alternative for ritodrine in pregnant women at risk of cardiovascular complications.

Different effects of tocolytic medication on blood pressure and blood pressure amplification

BackgroundThe importance of tocolysis has been discussed extensively. Beta-2 adrenoceptor agonistic drugs like ritodrine have been the reference tocolytic drugs in most countries. Cardiovascular side-effects are frequent. Atosiban, a newer tocolytic drug, is a competitive antagonist of oxytocin and has fewer cardiovascular side effects. Although large studies exist, there is mainly subjective reporting of adverse reactions with a focus on blood pressure data.ObjectivesEvaluation of the acute effects of therapeutic doses of ritodrine and atosiban in comparison to placebo on central and peripheral blood pressures, central-to-peripheral blood pressure amplification and the augmentation index (AIx) in healthy non-pregnant female volunteers.MethodsA double-blind, randomized, crossover trial was carried out in 20 healthy non-pregnant female volunteers. Hemodynamic measurements were performed under standardized conditions.ResultsAt steady state, central and peripheral pressures did not differ from placebo in the atosiban group. During ritodrine -infusion, central SBP increased by 11% versus placebo (p = 0.012) and peripheral SBP by 10% (p = 0.004). In contrast to atosiban and placebo, blood pressure amplification was absent in the ritodrine group. While the AIx did not change in the atosiban group, with ritodrine, the AIx tended to decrease.ConclusionsThe present study shows the significant effects of ritodrine on the cardiovascular system. Atosiban has no significant effects and may be an appropriate alternative to tocolyticum, particularly in cardiovascularly complicated pregnancies.

PERIPHERAL AND CENTRAL HEMODYNAMIC EFFECTS OF TOCOLYTIC MEDICATIONS IN HEALTHY NON-PREGNANT WOMEN: PP.33.331

Objective: Atosiban and ritodrine are frequently used tocolytics. Only a few studies investigated the hemodynamic effects of atosiban. We therefore aimed to study the central and peripheral hemodynamics of both medications. Methods: Twenty healthy female volunteers (19–41 yrs) were given atosiban (300 μg/min over 2 h) and placebo intravenously (IV) in a random crossover design. Eight of them also received ritodrine IV in escalating doses up to 400 μg/min over 2 h. The hemodynamics were investigated at steady state using blood pressure (BP) at the brachial artery (BA), pulse wave analysis on the common carotid artery and echocardiography for cardiac output (CO). Statistical analysis was done using Friedman and Wilcoxon tests (value of significance at 0.05). Results: Effects on atosiban/placebo on n=20 did not differ from n = 8. Figure 1. No caption available. SBP (systolic BP); DBP (diastolic BP); HR (heart rate); AIx@HR75 (augmentation index at heart rate 75); TPR (total peripheral resistance).

INFLUENCE OF TOCOLYTICS ON CENTRAL AND PERIPHERAL HEMODYNAMICS

Friedman-test; * significant vs. atosiban; # significant vs. placebo. Conclusion: Ritodrine has important hemodynamic effects reflected by cardiac stimulation (increase in CO and HR increase) and a decrease in peripheral resistance (TPR) with a trend for decreasing wave reflections (AIx@HR75). The effect of atosiban did not differ from placebo.