Maternal Wave Reflections and Arterial Stiffness in Normal Pregnancy as Assessed by Applanation Tonometry

A Model for Interstitial Drainage Through a Sliding Lymphatic Valve

This study investigates fluid flow and elastic deformation in tissues that are drained by the primary lymphatic system. A model is formulated based on the Rossi hypothesis that states that the primary lymphatic valves, which are formed by overlapping endothelial cells around the circumferential lining of lymphatic capillaries, open in response to swelling of the surrounding tissue. Tissue deformation and interstitial fluid flow through the tissue are treated using the Biot equations of poroelasticity and, the fluid flux (into the interstitium) across the walls of the blood capillaries, is assumed to be linearly related to the pressure difference across the walls via a constant of proportionality (the vascular permeability). The resulting model is solved in a periodic domain containing one blood capillary and one lymphatic capillary starting from a configuration in which the tissue is undeformed. On imposition of a constant pressure difference between blood and lymphatic capillaries, the solutions are found to settle to a steady state. Given that the magnitude of pressure fluctuations in the lymphatic system is much smaller than this pressure difference between blood and lymph, it is postulated that the resulting steady-state solution gives a good representation of the state of the tissue under physiological conditions. The effects of changes to the Young's modulus of the tissue, the blood-lymphatic pressure difference, vascular permeability and valve dimensions on the steady state are investigated and discussed in terms of their effects on oedema in the context of age- and pregnancy-related changes to the body.

Effect of Different Phases of Menstrual Cycle on Reflection Index, Stiffness index and Pulse wave velocity in Healthy subjects

INTRODUCTION

Arterial compliance will result in stabilizing the fluctuations in arterial pressure and blood flow. So arterial stiffness can be a good indicator for monitoring the cardiovascular system. Arterial stiffness can be measured using indices like reflection index (RI), stiffness index (SI) and Brachial Finger Pulse Wave Velocity (BFPWV).

OBJECTIVES

Aim of our study was to evaluate the changes in RI, SI and BFPWV during different phases of the menstrual cycle and to correlate RI with SI in healthy female subjects between the age group of 18-30 years from Bangalore, India.

MATERIALS AND METHODS

Basal recordings of RI and SI were determined by Photo Pulse Plethysmography (PPG) picked up from the fingertip using BIOPAC system and BFPWV was obtained using Doppler. Recordings were obtained at three different time points during the menstrual cycle. Analysis was done using repeated measures ANOVA with Bonferroni correction.

RESULT

There was a significant decrease in above parameters p <0.05 during the mid-cycle. Correlation between RI and SI was also significant p<0.05.

CONCLUSION

These findings suggests that the menstrual cycle affects the arterial stiffness and one of the factor is oestrogen. Hence, women are less prone to the incidence of cardiovascular diseases before menopause. Screening for arterial stiffness in a general population, using these indices is valid, economical and reliable.

Longitudinal changes in maternal hemodynamics in a population at risk for pre-eclampsia

OBJECTIVE

To investigate longitudinal changes in maternal hemodynamics from the first trimester onward in women who develop pre-eclampsia (PE) or gestational hypertension (GH).

METHODS

This was a prospective longitudinal study of singleton pregnancies identified by screening at 11 + 0 to 13 + 6 weeks' gestation as being at high risk for PE. Measurements of augmentation index (AIx), pulsed wave velocity (PWV) and aortic systolic blood pressure (SBPao) were taken every 4 weeks until delivery. Values were compared between women who developed preterm PE requiring delivery before 37 weeks, term PE or GH, and those who remained normotensive.

RESULTS

A total of 1198 observations were recorded in 245 women, including 181 who were normotensive, 22 with preterm PE, 22 with term PE and 20 with GH. In the normotensive group, there was a U-shaped relationship between AIx and gestational age with a trough at 25 weeks' gestation, whereas changes in levels of PWV or SBPao were minimal, with a mild increase from 25 and 30 weeks' gestation onward, respectively. In the GH and preterm PE groups, compared to the normotensive group, SBPao was higher and the difference did not change significantly with gestational age. In the term PE group, SBPao did not differ significantly from that in the normotensive group. In the preterm PE group compared to the normotensive group, PWV and AIx were significantly higher from 16-17 weeks' gestation onward and the difference increased with gestational age in both cases. In the term PE and GH groups, PWV and AIx did not differ significantly from normal.

CONCLUSION

This study describes temporal changes in AIx, PWV and SBPao in normotensive pregnant women and in women who develop PE or GH.

Measurement of aortic augmentation index in pregnant women with raised blood pressure and subsequent outcomes: a preliminary prospective cohort study

OBJECTIVE

Preeclampsia is associated with arterial dysfunction and augmentation index (AIX%) is an established indicator of arterial dysfunction. Our aim was to investigate the relationship of AIX% with time-to-delivery and other outcomes in women admitted to an antenatal triage unit.

METHODS

We recruited 28 women with singleton pregnancies attending antenatal triage ward for assessment of hypertension. After 10 min rest, seated brachial blood pressure (Omron HEM-757) and AIX% (SphygmoCor applanation tonometry pulse wave analysis, PWA) were measured by a single investigator; other clinicians remained blinded to PWA results. Routine assessment included cardiotocography, urine analysis and blood tests. Subsequent outcomes were extracted from the obstetric records.

RESULTS

Mean AIX% was 19.7% (SD 11.5; range -4% to +36%), maternal age 31 years, gestation 37 weeks, brachial BP 145/95, proteinuria 39%. Nine women had preeclampsia at assessment and six subsequently developed preeclampsia. Median time-to-delivery was 10 d (IQR 1.6-25 d) and was shorter for AIX% ≥ 20% (median 8.9 versus 19.8 d). AIX% was higher with preeclampsia (24.0%; SD 9.5) versus gestational hypertension (15.2%; SD 12.4); absolute difference 8.8% (95%CI 0.1-17.5; p = 0.05). A one-point higher AIX% (adjusted for age, urate and gestation) was associated with 0.3 d (95%CI -0.5 to 0.0; p = 0.06) reduced time-to-delivery. A higher AIX% was also associated with induction for preeclampsia, severe preeclampsia, peripartum-anti-hypertensives and discharge-on-anti-hypertensives. Area under the curve (AUC) for AIX% predicting preeclampsia was 0.80 (95%CI 0.59-1.00; p = 0.04).

CONCLUSION

AIX% is associated with time-to-delivery and other outcomes in pregnancy.

Is abnormal glucose metabolism during pregnancy related to endothelial dysfunction?

OBJECTIVE

Endothelial dysfunction is an independent risk factor for cardiovascular events. We aimed to investigate the relationship between endothelial dysfunction and gestational diabetes mellitus and impaired glucose tolerance.

METHODS

Pregnant women who had impaired glucose metabolism in the 75-g oral glucose tolerance test (OGTT) and their age- and body mass index-matched controls were included in the study and assessed for flow-mediated vasodilatation to evaluate endothelial dysfunction.

RESULTS

A total of 51 patients participated in the study. There were 20 patients in the control group, 13 in the impaired glucose tolerance group and 18 in the gestational diabetes mellitus group. Flow-mediated vasodilatation measured at the 60th and 120th seconds were significantly lower in the impaired glucose tolerance and gestational diabetes mellitus groups than in the control group (8.5 ± 5.7 and 8.9 ± 6.5 versus 14.9 ± 9.0, p=0.022 and 6.2 ± 6.7 and 5.2 ± 5.0 versus 12.0 ± 8.3, p=0.011, respectively).

CONCLUSIONS

Patients with gestational diabetes mellitus and impaired glucose tolerance have impaired endothelial dysfunction. Delivery might have protective effects on endothelial functions. The significance of impaired endothelial dysfunction for pregnant women must be investigated, and if needed, lifestyle changes might be suggested, according to the determined importance of the endothelial dysfunction.

Ultrasound study of carotid and cardiac remodeling and cardiac-arterial coupling in normal pregnancy and preeclampsia: a case control study

BACKGROUND

Cardiovascular adaptions, such as cardiac and uterine spiral arterial remodeling, and aortic arterial stiffening during pregnancy have been extensively investigated, while the interactions between the elastic artery and the left ventricle are poorly understood. This study was to evaluate the cardiac-arterial coupling in both normal pregnancy and preeclampsia using ultrasound techniques.

METHODS

Twenty-three preeclamptic women with no antihypertensive treatment prior to admission, and 40 age- (27.2 ± 3.0 y vs. 29.1 ± 5.7 y, p = 0.0805) and gestational week- (35.6 ± 3.4 wk vs. 34.8 ± 3.6 wk, p = 0.3573) matched normotensive pregnant women were included. All women signed informed consent. All were nulliparas, had singleton pregnancies, and had no other risk factors for arterial stiffening. Carotid and cardiac ultrasound was performed using a MylabTwice ultrasound unit (Esaote, Italy). Cardiac and carotid remodeling and their associations were analyzed. Left ventriculo-carotid coupling was characterized by the ratio between the arterial elastance (Ea) and the left ventricular systolic elastance (Ees). Follow-up study was performed 16-20 months after parturition.

RESULTS

Left ventricular and carotid arterial remodeling was seen more frequently in preeclamptic women than in normal pregnant controls (96% vs. 40%, 82% vs. 48%, both p < 0.0001). The relative carotid arterial wall thickness showed no significant difference between the two groups. However, the carotid cross-sectional area, a surrogate for carotid arterial mass, was significantly greater in preeclampsia than that in normal controls (11.23 ± 0.17 mm2 vs. 8.58 ± 1.88 mm2, p < 0.00001). Carotid arterial stiffness and intima-media thickness correlated significantly with cardiac diastolic function parameters and blood pressures (p < 0.05). Both Ea and Ees were significantly greater in preeclampsia, compared with values in normal pregnant controls (Ea: 2.41 ± 0.57 mmHg/ml vs. 1.98 ± 0.46 mmHg/ml, p = 0.0005; Ees: 11.68 ± 9.51 m/s2 vs. 6.91 ± 6.13 m/s2, p = 0.002). However, there was no significant difference in the left ventriculo-carotid coupling index, Ea/Ees, between the two groups. Carotid remodeling persisted in both preeclamptic women and normal pregnant controls 16-20 months after parturition.

CONCLUSIONS

Significant cardiac and carotid remodeling and similar left ventriculo-carotid coupling were observed in both preeclampsia and normal pregnancy. Carotid remodeling may persist postpartum. Further studies with larger populations are needed to confirm these findings.

Carotid artery elasticity decreases during pregnancy - the Cardiovascular Risk in Young Finns study

Background

The aims were to evaluate the effect of pregnancy on carotid artery elasticity and determine the associations between maternal lipids, endothelial function and arterial elasticity during pregnancy.

Methods

We examined 99 pregnant and 99 matched non-pregnant control women as part of a population-based prospective cohort study. Carotid artery elasticity indexes; carotid artery distensibility (CAD), Young’s elastic modulus (YEM) and stiffness index (SI) as well as brachial artery flow-mediated dilation (FMD) were assessed using ultrasound; serum lipid levels were also determined.

Results

SI was 57% and YEM 75% higher and CAD 36% lower in the third trimester group than the corresponding values in the first trimester group. Serum cholesterol and triglyceride levels were significantly higher in women at the end of the pregnancy than at the beginning of pregnancy (P < 0.001) and in controls (P < 0.001). In multivariate analysis, gestational age was the only independent correlate of arterial elasticity in pregnant women. In controls, age (P ≤ 0.001) and common carotid diameter (P = 0.001-0.029) were associated with SI, YEM and CAD.

Conclusions

The present study revealed that carotid artery elasticity declined towards the end of the pregnancy; this neither is straight correlating with maternal hyperlipidemia or the diameter of the carotid artery nor is it associated with changes in endothelial function.

Repeatability of SphygmoCor pulse wave analysis in assessing arterial wave reflection in pregnancy using applanation tonometry

OBJECTIVE

To estimate clinical agreement in relation to measuring aortic augmentation index (AIX-75) in pregnancy in a routine clinical setting.

METHODS

A hospital-based clinical agreement study of 20 women in which two trained nurses alternated in measuring arterial function (AIX standardized to a heart rate of 75 beats-per-minute, AIX-75) on a single occasion in triplicate, after participants had rested semi-recumbent for 15 min. Right brachial blood pressure (BP) was measured using the Microlife 3BTO-A oscillometric device. Radial applanation pulse wave analysis (PWA) was undertaken according to current guidelines using the SphygmoCor device with a hand-held Millar tonometer applanated at the right radial artery. Each nurse was blinded to others PWA results. Observer agreement was assessed using the Bland-Altman "limits of agreement" (LOA, mean difference ±2 SD) approach.

RESULTS

Median gestation was 37 weeks (range: 12-42), mean age 31 years, 30% nulliparous, mean brachial BP 128/79 mm Hg. Based on all six PWA measurements, mean AIX-75 was 11.7 (range: -18 to +35). The between-observer LOA was 0.1 ± 11.0 and the within-observer LOA's were 1 ± 10 and -2 ± 8 for the two nurses. Observer differences did not vary systematically with the magnitude of AIX-75.

CONCLUSION

AIX-75 can be measured by nurses using PWA in pregnancy with a high level of observer agreement.

Non-invasive assessment of maternal hemodynamics in early pregnancy

OBJECTIVES

Non-invasive assessment of maternal hemodynamics in early pregnancy may be promising in evaluating maternal hemodynamic (mal)adaptation to pregnancy. We explored usage of applanation tonometry and Doppler ultrasound for assessment of cardiac output (CO), systemic vascular resistance (SVR) and arterial stiffness in early pregnancy.

METHODS

Pregnant healthy nulliparous women were studied during first trimester. Radial artery pressure waveform (augmentation index(AIx)), carotid-femoral pulse wave velocity (PWV) and cardiac output (CO) were measured by applanation tonometry (SphygmoCor), electrocardiogram and Doppler ultrasound (USCOM) and related to maternal demographic characteristics and literature concerning advanced pregnancy and non-pregnant subjects.

RESULTS

116 women were studied during gestational age range of 7(+2)-14weeks. Systolic and diastolic central blood pressure were correlated with systolic and diastolic brachial blood pressure respectively. Both measures of arterial stiffness (heart rate corrected AIx(AIx@75) and PWV) were correlated. AIx@75, PWV and SVR were correlated with central mean arterial pressure. CO was negatively correlated with AIx and associated with BMI. PWV was associated with age and BMI, whereas SVR was associated with age.

CONCLUSIONS

Applanation tonometry and Doppler Ultrasound for assessment of maternal hemodynamics in early pregnancy revealed similar associations between different hemodynamic parameters and maternal characteristics as have previously been reported in advanced pregnancy and non-pregnant subjects. The SphygmoCor and the USCOM appear to be reliable methods for the assessment of maternal hemodynamics in early pregnancy. Obtaining a comprehensive hemodynamic profile using these modalities may offer insight in maternal (mal)adaptation to pregnancy. Future work needs to be done relating such measures to pregnancy outcome.

Ambulatory arterial stiffness index in type 1 diabetes mellitus: any different during pregnancy?

OBJECTIVE

To analyze the ambulatory arterial stiffness index (AASI) and pulse pressure (PP) during pregnancy and 3 months after delivery in type 1 diabetes mellitus (T1DM) and compare it to healthy pregnant controls.

STUDY DESIGN

Prospective, descriptive study of 59 women with T1DM and 42 non-diabetic women. Blood pressure was measured using a portable oscillometry monitor and AASI was calculated as 1 minus the regression slope of diastolic on systolic blood pressure obtained from 24-h monitoring. Main outcome measures were comparisons of the AASI and PP between T1DM women and controls examined during pregnancy, and of the AASI and PP during and after pregnancy in T1DM women.

RESULTS

PP and AASI were higher at all times during pregnancy in T1DM compared to postpartum (p<0.01). AASI and PP were significantly associated with albumin excretion rate when adjusting for retinopathy, preeclampsia, duration of diabetes, HbA1c, age, and BMI. The AASI was positively correlated with night-day ratio in the 1st and 3rd trimesters during pregnancy. No difference was found in AASI compared with non-diabetic controls during pregnancy.

CONCLUSIONS

AASI and PP increased during diabetic pregnancy and were associated with the women's albuminuria grade.

Maternal carotid remodeling and increased carotid arterial stiffness in normal late-gestational pregnancy as assessed by radio-frequency ultrasound technique

BACKGROUND

The adaption of elastic arteries to transient increase in hemodynamic load in normal pregnancy (NP) remains controversial. The purpose of this study was to investigate the NP carotid remodeling and regional arterial stiffness before and after parturition.

METHODS

Fifty-one NP women and 30 age-matched non-pregnant women were included. All women underwent right common carotid artery (RCCA) measurements with MylabTwice ultrasound instrument (Esaote, Italy). Carotid intima-medial thickness (IMT), pulse wave velocity (PWV, m/s), distensibility coefficient (DC, 1/KPa), α, β, augmentation index (AIx, %) and carotid arterial pressure were obtained by the newly developed ultrasound vascular wall tracking methods: automatic QAS (Quality Arterial Stiffness) and QIMT (Quality Intima-Medial Thickness) Follow up study was performed.

RESULTS

Compared to the non-pregnant controls, the arterial pressures were significantly increased and RCCA diameter was significantly enlarged in late gestational NP women. Twenty months after parturition, carotid diameter, DC, AIx, PWV and arterial wall tension were significantly decreased and had no significant difference with those in non-pregnant controls.

CONCLUSIONS

Carotid arterial remodeling and stiffening could be seen in the normal pregnant women, which seems to be a physiological adaption and could be recovered post partum. QIMT and QAS together could provide a comprehensive assessment of the maternal carotid arterial changes during pregnancy.

Pulse waveform analysis as a bridge between pulse examination in Chinese medicine and cardiology

Pulse examination was probably the earliest attempt to distinguish between health and illnesses. Starting at the pre-Hippocratic era, Chinese medicine practitioners developed techniques for pulse examination and defined pulse images based on their perceptions of pulse waveforms at the radial artery. Pulse images were described using basic variables (frequency, rhythm, wideness, length, deepness, and qualities) developed under philosophical trends such as Taoism and Confucianism. Recent advances in biomedical instrumentation applied to cardiology opened possibilities to research on pulse examination based on ancient Chinese medical theories: the pulse wave analysis. Although strongly influenced by philosophy, some characteristics used to describe a pulse image are interpretable as parameters obtained by pulse waveform analysis such as pulse wave velocity and augmentation index. Those clinical parameters reflect concepts unique to Chinese medicine - such as yinyang - while are based on wave reflection and resonance theories of fluids mechanics. Major limitations for integration of Chinese and Western pulse examination are related to quantitative description of pulse images and pattern differentiation based on pulse examination. Recent evidence suggests that wave reflection and resonance phenomena may bridge Chinese medicine and cardiology to provide a more evidence-based medical practice.

Maternal arterial stiffness in normotensive pregnant women who subsequently deliver babies that are small for gestational age

OBJECTIVE

To assess the association between maternal arterial stiffness and delivery of a baby that is small for gestational age (SGA) in normotensive pregnant women.

STUDY DESIGN

Pulse wave analyses were performed to assess maternal arterial stiffness at 26-33 weeks of gestation in 40 normotensive women who subsequently delivered SGA babies (SGA group) and 111 normotensive women who delivered babies with normal growth (control group).

RESULTS

Central systolic pressure (CSP), augmentation index (AIx) and AIx at a heart rate of 75 beats/min (AIx-75) were significantly higher in the SGA group compared with the control group, but this was not the case for brachial systolic pressure, brachial diastolic pressure or brachial pulse pressure. Birth weight was significantly correlated with CSP (r=-0.26, p<0.01), AIx (r=-0.33, p<0.01) and AIx-75 (r=-0.27, p<0.01), but not with brachial systolic pressure, brachial diastolic pressure or brachial pulse pressure.

CONCLUSION

Increased arterial stiffness may be involved, in part, in the pathogenesis of SGA in normotensive women, suggesting an association between fetal growth and maternal endothelial function. Pulse wave analysis may be a clinically applicable method for assessment of maternal arterial stiffness, and may be more relevant to intrauterine fetal growth than conventional brachial blood pressure.

Raised uterine artery impedance is associated with increased maternal arterial stiffness in the late second trimester

OBJECTIVE

To assess the relationship between uterine artery Doppler pulsatility index (PI) and maternal global arterial stiffness and aortic stiffness in women at high a priori risk of preeclampsia in the late second trimester of pregnancy.

METHODS

A prospective cohort study was performed. 99 women were recruited from the high-risk obstetric ultrasound clinic in the second trimester; median (±IQR) age and gestation were 33 (29-37) years and 23(+6) (23(+3)-24(+4)) weeks respectively. Transabdominal uterine artery Doppler was performed and mean values recorded. Women returned at a later date, median gestation (±IQR) 26(+5) (25(+6)-28(+0)) weeks, for measurement of blood pressure, augmentation index (AIx) and aortic pulse wave velocity (aPWV).

RESULTS

Uterine artery PI is positively associated with both AIx (r = 0.4, P <0.0001, 95% CI: 0.22-0.55) and aPWV (r = 0.22, P = 0.03, 95% CI: 0.02-0.40). No relationship was found between uterine artery PI and mean arterial pressure or pulse pressure. AIx was significantly higher in women with uterine artery PI > 1.45 (P = 0.003, 95% CI: 3.1-14.9) but not aPWV (P = 0.45). AIx, but not aPWV, was significantly higher in women who developed preeclampsia (14% vs 9%, 95% CI: 2.0-8.6, P = 0.0018) or IUGR (11% vs 9%, 95% CI: 0.3-4.2, P = 0.027). AIx showed a negative correlation with birth weight z-score (r = -0.25, 95% CI: -0.43 to -0.06, P = 0.013).

CONCLUSION

Increasing uterine artery Doppler PI reflects impaired placentation and increasing risk of preeclampsia. We show a positive association between uterine artery Doppler PI and both global arterial and aortic stiffness. We also show that increased maternal arterial stiffness is associated with a lower birth weight. These findings may represent evidence of an early effect of impaired placentation on the maternal vasculature. Alternatively, given the association between preeclampsia and later cardiovascular disease, ineffective placentation may result from impaired arterial function.

The association between preeclampsia and arterial stiffness

A systematic review and meta-analysis was conducted using MEDLINE, EMBASE, and the Cochrane Library to investigate the association between preeclampsia and arterial stiffness. Twenty-three relevant studies were included. A significant increase in all arterial stiffness indices combined was observed in women with preeclampsia vs. women with normotensive pregnancies [standardized mean difference 1.62, 95% confidence interval (CI) 0.73-2.50]; carotid-femoral pulse wave velocity (cfPWV) and augmentation index (AIx) were also significantly increased (weighted mean difference, WMDcfPWV 1.04, 95% CI 0.34-1.74; WMDAIx 15.10, 95% CI 5.08-25.11), whereas carotid-radial PWV (crPWV) increase did not reach significance (WMDcrPWV 0.99, 95% CI -0.07 to 2.05). Significant increases in arterial stiffness measurements were noted in women with preeclampsia compared with those with gestational hypertension. Arterial stiffness measurements may also be useful in predicting preeclampsia and may play a role in the increased risk of future cardiovascular complications seen in women with a history of preeclampsia.

Peripheral arterial tone: assessment of microcirculatory function in pregnancy

OBJECTIVE

Endothelial dysfunction is known to play a key role in the pathogenesis of preeclampsia, but the majority of methods for its detection are too invasive to be used in pregnancy. In this study we report a novel method - peripheral arterial tonometry (PAT) - for examining microcirculatory function in pregnancy.

METHODS

One hundred and eighty women with at least two risk factors for preeclampsia were examined at gestational weeks 16 and 28; 80 women were examined at 6-9 months postnatally. Twenty-four women developed preeclampsia or pregnancy-induced hypertension (cases), 156 remained normotensive (controls). PAT was measured using fingertip pneumatic probes; after baseline recordings the study arm was occluded with a blood pressure cuff then released after 5 min, causing reactive hyperaemia. PAT recordings pre and post occlusion were used to generate the reactive hyperaemia index (RHI).

RESULTS

RHI was significantly lower at gestational week 28 compared to week 16, both in cases and controls. Baseline pulse amplitude was significantly higher at week 28 compared to week 16. There was no difference in RHI at either week 16 or 28 between cases and controls. Postnatally, there was no difference in RHI between cases and controls, but baseline pulse amplitude was lower in affected women.

CONCLUSION

PAT and other methods which rely on flow-mediated dilatation for detection of endothelial dysfunction are less likely to be reliable in later pregnancy, when women are more vasodilated. PAT did not predict the development of hypertensive pregnancy complications, but demonstrated a relative peripheral vasoconstriction in affected women postnatally.

The pulse spectrum analysis at three stages of pregnancy

OBJECTIVES

This study is the first to detect the radial pulses of the three diagnosis positions (inch, bar, and cubit) in both wrists (six positions) by pulse spectrum analysis. The purpose of this study was to identify the difference among pulses of the six positions at three stages of pregnancy and to examine whether the results of this study agree with the theory of Traditional Chinese Medicine (TCM), which states that the cubit pulse shows unique changes for an expectant woman and that the pulse changes coincide with the progression of gestation.

SUBJECTS AND METHODS

One hundred and fifty (150) healthy pregnant women were divided into three groups according to gestational age (9-14 weeks, 20-28 weeks, and 32-37 weeks of gestation) and 50 healthy nonpregnant women were used as controls. A pulse analyzer was used to detect the six positions of the radial pulses and to calculate the 10 relative energy values of the spectrum's harmonics of the six positions.

RESULTS

Results show that most of the 10 relative spectral energy values of the right and left cubits are statistically (p<0.01) higher than those of the inch for the pregnant women as compared with the nonpregnant women. In addition, the 10 relative spectral energy values of the six positions are not identical at the three stages of pregnancy.

CONCLUSIONS

The cubit pulse is unique for pregnant women, which is consistent with the theory of TCM. In addition, the pulse conditions at the three stages of pregnancy are dissimilar.

Central aortic blood pressure and augmentation index during normal pregnancy

The current study tested the hypothesis that pregnancy-related changes are more pronounced in central hemodynamics, and both central aortic systolic blood pressure (cSBP) and augmentation index (AIx) are independent from brachial systolic blood pressure (bSBP) in normal pregnant subjects. In 830 healthy pregnant women from 12 to 36 weeks gestation, we measured cSBP and AIx-75 (AIx at heart rate of 75 beats per minute) non-invasively by pulse waveforms of the radial artery using an automated applanation tonometric system. In 69 pregnant women, we recorded these data longitudinally. cSBP and AIx-75 significantly declined during pregnancy, reaching its nadir in mid-pregnancy and rising towards term. Pregnancy-related changes were more pronounced in AIx-75 compared with cSBP, but less evident in bSBP. AIx-75, but not cSBP, was independent from bSBP throughout pregnancy. cSBP and AIx-75, but not bSBP, were significantly increased in healthy pregnant women older than 35 years. This study established normal values for pulse wave analysis parameters throughout pregnancy, and indicated that pulse wave analysis might offer additional and independent information about maternal arterial compliance to conventional brachial blood pressure measurements. These data may be used as the basis for further investigation into the role of pulse wave analysis in the assessment, management and prediction of disorders, which might interfere with pregnancy-related cardiovascular adaptations.

Influence of hyperglycemia during and after pregnancy on postpartum vascular function

Endothelial dysfunction is commonly observed in women with a previous diagnosis of gestational diabetes mellitus (GDM). Whether arterial stiffness is also related to pregnancy and/or postpartum glucose intolerance has not been determined. We examined the influence of GDM during pregnancy and hyperglycemia in the postpartum period on arterial function. Thirty postpartum women were stratified into one of three groups: 1) normoglycemic pregnancy, normoglycemic postpartum (NORM), 2) GDM during pregnancy, normoglycemic postpartum (GDM-N); and 3) GDM during pregnancy, hyperglycemic postpartum (GDM-H). Ten never-pregnant controls were also recruited (Control). All measures were made at 2 mo postpartum or in the early follicular phase in Control women. Arterial stiffness was assessed by pulse wave velocity (PWV) and brachial and carotid artery distensibility. Endothelial function was determined by flow-mediated dilation (FMD). PWV was not different between the four groups. Distensibility of the brachial and carotid arteries was lower in GDM-N women (brachial: 1.1 × 10(-3) mmHg(-1) ± 3.6 × 10(-4); carotid: 2.0 × 10(-3) ± 3.3 × 10(-4)) and GDM-H (brachial: 1.4 × 10(-3) mmHg(-1) ± 4.1 × 10(-4); carotid: 1.8 × 10(-3) mmHg(-1) ± 5.0 × 10(-4)) compared with NORM women (brachial: 3.4 × 10(-3) mmHg(-1) ± 7.0 × 10(-4); carotid: 3.9 × 10(-3) ± 7.4 × 10(-4)). However, only brachial artery distensibility returned to Control levels by 2 mo postpartum in the NORM women. FMD was lower in previously GDM women (GDM-N: 4.1% ± 2.3; GDM-H: 4.4% ± 0.9) compared with NORM women (10.8% ± 1.3; P < 0.01). These findings suggest that the vascular function of women in the early postpartum period is influenced by GDM during pregnancy and the persistence of clinical and/or subclinical hyperglycemia after delivery.

Arterial stiffness is associated with minimally elevated high-sensitivity cardiac, troponin T levels in a community-dwelling population

OBJECTIVES

Arterial stiffness predicts an increased risk of future cardiovascular events, possibly via myocardial damage. Minimally elevated levels of plasma cardiac troponin T (TnT), a marker of cardiomyocyte injury, can be detected by the high-sensitivity TnT (hsTnT) assay. The current study investigated the relationship between plasma hsTnT levels and alterations in arterial stiffness in a community-based population.

METHODS

We related levels of plasma hsTnT to measures of arterial stiffness (carotid-femoral pulse wave velocity [PWV], office pulse pressure [PP] and carotid-radial PWV) in 1479 participants (mean age, 62.3 years; 619 men, 860 women) from a community-based population in Beijing, China.

RESULTS

In multiple logistic regression models, carotid-femoral PWV (OR: 1.84; 95% CI: 1.06-3.17; P=0.028) and office PP (OR: 2.02; 95% CI: 1.31-3.11; P=0.002) were associated with a higher likelihood of detectable hsTnT. In addition, carotid-femoral PWV (OR: 2.34; 95% CI: 1.03-5.30; P=0.042) and office PP (OR: 2.30; 95% CI: 1.13-4.66; P=0.022) were significantly related to elevated hsTnT levels. A subsequent subgroup analysis found that, in subjects aged 60 years and older, the associations between carotid-femoral PWV and office PP and hsTnT levels were strengthened. The associations between hsTnT with any of the arterial stiffness measures were not present in the younger subgroup (<60 years old).

CONCLUSIONS

Carotid-femoral PWV and office PP are associated with minimally elevated hsTnT levels in the elderly, indicating a relationship between central artery stiffness and subclinical myocardial damage.

Maternal arterial stiffness in women who subsequently develop pre-eclampsia

Background/Objectives

Pre-eclampsia (PE) is associated with profound changes in the maternal cardiovascular system. The aim of the present study was to assess whether alterations in the maternal arterial stiffness precede the onset of PE in at risk women.

Methodology/Principal Findings

This was a cross sectional study involving 70 pregnant women with normal and 70 women with abnormal uterine artery Doppler examination at 22–24 weeks of gestation. All women had their arterial stiffness (augmentation index and pulse wave velocity of the carotid-femoral and carotid-radial parts of the arterial tree) assessed by applanation tonometry in the second trimester of pregnancy, at the time of the uterine artery Doppler imaging. Among the 140 women participating in the study 29 developed PE (PE group) and 111 did not (non-PE group). Compared to the non-PE group, women that developed PE had higher central systolic (94.9±8.6 mmHg vs 104.3±11.1 mmHg; p = <0.01) and diastolic (64.0±6.0 vs 72.4±9.1; p<0.01) blood pressures. All the arterial stiffness indices were adjusted for possible confounders and expressed as multiples of the median (MoM) of the non-PE group. The adjusted median augmentation index was similar between the two groups (p = 0.84). The adjusted median pulse wave velocities were higher in the PE group compared to the non-PE group (carotid-femoral: 1.10±0.14 MoMs vs 0.99±0.11 MoMs; p<0.01 and carotid-radial: 1.08±0.12 MoMs vs 1.0±0.11 MoMs; p<0.01).

Conclusions/Significance

Increased maternal arterial stiffness, as assessed by pulse wave velocity, predates the development of PE in at risk women.

Maternal arterial stiffness in pregnancies complicated by gestational and type 2 diabetes mellitus

OBJECTIVE

We sought to investigate whether maternal arterial stiffness is altered in pregnant women with gestational diabetes mellitus (GDM) and type 2 diabetes compared to normoglycemic women.

STUDY DESIGN

We conducted a cross-sectional study involving 34 women with GDM and their controls (n = 34), and 34 women with type 2 diabetes and their controls (n = 34). Maternal arterial stiffness was assessed using applanation tonometry.

RESULTS

In patients with GDM, compared to their controls, augmentation index (a measure of arterial wave reflection) was higher (13.1 +/- 8.9% vs 0.7 +/- 11.4%; P < .001) and pulse wave velocity (PWV) (arterial stiffness of the carotid-femoral) was marginally increased (6 +/- 1.5 vs 5.4 +/- 0.6 m/s; P = .07). In type 2 diabetics, compared to their controls, both augmentation index and PWV were increased (11.5 +/- 11.4% vs 3.3 +/- 12.5%; P = .006, and 6.8 +/- 1.2 vs 5.6 +/- 1 m/s; P < .001). When all groups were considered together, there was a significant trend of increasing augmentation index (P = .001) and PWV (P < .001) from controls to those with GDM to type 2 diabetes.

CONCLUSION

Pregnancies complicated by GDM and type 2 diabetes are associated with increased maternal arterial stiffness.

Effects of magnesium on central arterial compliance in preeclampsia

OBJECTIVE

The objective of the study was to investigate the effect of MgSO4 infusion on central arterial compliance, using radial artery applanation tonometry in women with preeclampsia.

STUDY DESIGN

Seventy women with preeclampsia were prospectively recruited. Radial pulse waveforms were obtained and the aortic waveforms constructed. The arterial compliance surrogates, augmentation pressure (AP) and augmentation index (AIx-75), were derived from the aortic waveform and then compared: prior to MgSO4 (t1), 1 hour after MgSO4 bolus (t2), 4 hours after MgSO4 infusion (t3), and 24 hours after MgSO4 cessation (t4). Statistical analysis was performed using differences of least squared means with Tukey Kramer adjustments.

RESULTS

The AP and AIx-75 at t2-t4 were significantly lower compared with t1, with the greatest decrease in arterial stiffness at t3 (P<.05).

CONCLUSION

In preeclampsia, MgSO4 improved central arterial compliance. This effect was most exaggerated after 4 hours of infusion and remained 24 hours following MgSO4 completion, suggesting either a sustained arterial compliance effect or resolution of the vasoconstrictive effect of preeclampsia.

Pulse pressure amplification a mechanical biomarker of cardiovascular risk

OBJECTIVES

The aim of this study was to determine whether the carotid/brachial (C/B) ratio is an independent predictor of cardiovascular (CV) risk.

BACKGROUND

Brachial and carotid pulse pressure (PP) are independent predictors of CV risk, mainly in elderly patients. Because PP is physiologically lower at the brachial than at the carotid arterial site, PP amplification is represented by the C/B ratio and could independently predict CV risk.

METHODS

In a Paris population (n = 834), brachial and carotid PP were measured from sphygmomanometry and pulse wave analysis. With stepwise multiple regression, carotid PP was calculated from a nomogram including age, sex, body height, brachial PP, and plasma glucose. This model was applied to 125,151 subjects, followed for 12 years, during which 3,997 deaths occurred (735 of CV origin). With Cox regression analysis, multi-adjusted hazard ratios (HRs) were calculated for 1 SD increase of brachial PP, calculated carotid PP, and C/B ratio.

RESULTS

Brachial PP was significantly associated with both CV and all-cause mortality (HR: 1.16, 95% confidence interval [CI]: 1.13 to 1.19, and HR: 1.13, 95% CI: 1.10 to 1.17, respectively). Calculated carotid PP predicted a similar risk (HR: 1.21, 95% CI: 1.15 to 1.28, and HR: 1.18, 95% CI: 1.12 to 1.25, respectively). Finally, the C/B ratio was a strong risk predictor (HR: 1.22, 95% CI: 1.12 to 1.32, and HR: 1.41, 95% CI: 1.14 to 1.73, respectively). Addition of drug treatment and other confounding variables did not statistically modify the results.

CONCLUSIONS

Brachial PP, calculated carotid PP, and C/B PP amplification all predict CV mortality. In contrast to brachial and carotid PP, the C/B ratio is less dependent on blood pressure calibration and thus can be directly applicable to large population studies.

Maternal arterial stiffness in pregnancies affected by Type 1 diabetes mellitus

AIM

There is little information about maternal central haemodynamics and arterial stiffness in pregnancies affected by Type 1 diabetes mellitus. The aim of the current study was to investigate whether maternal arterial stiffness is altered in pregnant women with Type 1 diabetes mellitus compared with women with uncomplicated pregnancies.

METHODS

This was a cross-sectional study involving 37 pregnant women without diabetes and 37 pregnant women with Type 1 diabetes mellitus during the second trimester of pregnancy. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-femoral and carotid-radial part of the arterial tree were assessed non-invasively using applanation tonometry.

RESULTS

Pregnant women with normal pregnancies and Type 1 diabetes mellitus had similar augmentation index (3.7 +/- 12.8 vs. 5.1 +/- 12.6%, P = 0.6), even after adjusting for possible confounders. Within the group of diabetic women, augmentation index was associated with duration of diabetes (P = 0.003, r(2) = 0.22) but not with glycated haemoglobin. Pulse wave velocities were similar between the two groups of women (carotid-femoral: 5.6 +/- 0.9 vs. 5.7 +/- 1.1 m/s, P = 0.4; carotid-radial: 7.4 +/- 1.2 vs. 7.8 +/- 1 m/s, P = 0.1). In the diabetic women there was no significant association between the pulse wave velocities and either duration of diabetes or glycated haemoglobin.

CONCLUSIONS

Pregnancy in women with Type 1 diabetes mellitus is not associated with altered maternal systemic arterial stiffness. However, maternal wave reflections increase with the duration of diabetes.

Maternal arterial stiffness in pregnancies affected by preeclampsia

Preeclampsia (PE) is characterized by an aberrant maternal cardiovascular adaptation to pregnancy and increased cardiovascular risk later on in life. The aim of this study was to compare the maternal wave reflections and arterial stiffness in women with established PE and those with normotensive pregnancies, after systematic adjustment for known confounders. This was a cross-sectional study involving 69 normotensive, pregnant women and 54 women with established PE. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-radial and carotid-femoral parts of the arterial tree were assessed noninvasively using applanation tonometry. The measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the control group. In the PE group, compared with controls, there was an increase in the median pulse wave velocity of both the carotid to femoral [1.1, interquartile rage (IQR) 1.0–1.3 MoM vs. 0.9, IQR 0.9–1.0 MoM; P < 0.0001] and carotid to radial (1.0, IQR 0.9–1.1 MoM vs. 0.9, IQR 0.9–1.0 MoM; P = 0.01) parts of the arterial tree. In contrast, there were no significant differences between the two groups in the median augmentation index (0.9, IQR 0.7–1.1 MoM vs. 1.0, IQR 0.5–1.8 MoM; P = 0.46). In conclusion, we found that established PE is characterized by increased maternal arterial stiffness but not altered maternal wave reflection.

Pulse wave analysis in normal pregnancy: a prospective longitudinal study

Background

Outside pregnancy, arterial pulse wave analysis provides valuable information in hypertension and vascular disease. Studies in pregnancy using this technique show that vascular stiffness is raised in women with established pre-eclampsia. We aimed to establish normal ranges for parameters of pulse wave analysis in normal pregnancy and to compare different ethnic groups.

Methodology/Principal Findings

This prospective study was conducted at The Homerton University Hospital, London between January 2006 and March 2007. Using applanation tonometry, the radial artery pulse waveform was recorded and the aortic waveform derived. Augmentation pressure (AP) and Augmentation Index at heart rate 75/min (AIx-75), measures of arterial stiffness, were calculated.

We recruited 665 women with singleton pregnancies. Women who developed pre-eclampsia (n = 24, 3.6%) or gestational hypertension (n = 36, 5.4%) were excluded. We also excluded 47 women with other pregnancy complications or incomplete follow-up, leaving 541 healthy normotensive pregnant women for subsequent analysis. In the overall group of 541 women, there were no significant changes in AP or AIx-75 as pregnancy progressed. In 45 women followed longitudinally, AP and AIx-75 fell significantly from the first to the second trimester, then rose again in the third (P<0.001). The two main ethnic groups represented were Caucasian (n = 229) and Afrocaribbean (n = 216). There were no significant differences in AP or AIx-75 in any trimester between these two ethnic groups.

Conclusions

This study is the largest to date of pulse wave analysis in normal pregnancy, the first to report on a subset of women studied longitudinally, and the first to investigate the effect of ethnicity. These data provide the foundation for further investigation into the potential role of this technique in vascular disorders in pregnancy.

Influence of the Menstrual Cycle, Pregnancy, and Preeclampsia on Arterial Stiffness

Arterial stiffness and compliance are major predictors of adverse cardiovascular events and are influenced by female sex hormones, including estrogen and progesterone. The aim of this longitudinal study was to evaluate the effect of the menstrual cycle, normal pregnancy, and preeclampsia on central and systemic arterial stiffness. Ten healthy nulliparous women with regular menses were studied in the early and midfollicular, periovulatory, and luteal phases of a single menstrual cycle. Twenty-two primigravida pregnant women were studied throughout pregnancy at 16, 24, 32, and 37 weeks gestation and at 7 weeks postpartum. Fifteen primigravida women with preeclampsia were studied at diagnosis and 7 weeks postpartum. Augmentation index and carotid-radial and carotid-femoral pulse wave velocities were measured using applanation tonometry. Augmentation index fell during the luteal phase of the menstrual cycle (luteal phase versus periovulatory phase; P <0.05). In normal pregnancy, pulse wave velocity and augmentation index increased from 24 weeks over the third trimester ( P ≤0.01 for both). All of the measures were increased in women with preeclampsia ( P ≤0.01), with augmentation index and carotid-femoral pulse wave velocity remaining elevated 7 weeks postpartum ( P ≤0.02). We conclude that systemic arterial stiffness undergoes major changes during the menstrual cycle and pregnancy and that preeclampsia is associated with greater and more prolonged increases in arterial stiffness. These effects may contribute to adverse cardiovascular outcomes of pregnancy and preeclampsia.

Antihypertensive therapy and central hemodynamics in women with hypertensive disorders in pregnancy

OBJECTIVE

To estimate the changes in central hemodynamics features of pregnant women presenting with hypertensive disorders and to analyze the effects of standard antihypertensive treatment on maternal central hemodynamics.

METHODS

Applanation tonometry was used to record the radial artery pulse waveform in 80 women presenting with preeclampsia or gestational hypertension and 80 normotensive controls matched for gestational age. In each case, an averaged aortic waveform was derived and analyzed to calculate augmentation pressure and augmentation index at heart rate 75 beats per minute (bpm).

RESULTS

In women with preeclampsia and gestational hypertension, both augmentation pressure (P<.001 and P<.05, respectively) and augmentation index at heart rate 75 bpm (P<.001 and P<.001, respectively) were significantly higher than in controls. Augmentation pressure and augmentation index at heart rate 75 bpm were significantly higher in early- compared with late-onset preeclampsia (P<.001) and in severe compared with mild preeclampsia (P<.001). Antihypertensive therapy with alpha methyldopa resulted in a significant fall in both augmentation pressure and augmentation index at heart rate 75 bpm in preeclampsia (P<.001) but not in gestational hypertension.

CONCLUSION

Arterial stiffness is increased in women with hypertensive disorders of pregnancy compared with normotensive controls. In preeclampsia, vascular stiffness was significantly improved by antihypertensive treatment with alpha methyldopa, but remained higher than in normotensive controls.