Umbilical artery waveform during bicycle exercise in normal pregnancy.

The use of Doppler umbilical artery waveforms in placental abruption; a report of two cases

Variation and correlation in human fetal umbilical Doppler velocities with fetal breathing: Evidence of the cardiac-placental connection

Placental vascular abnormalities are associated with a host of pregnancy complications including placenta mediated fetal growth restriction (FGR). Umbilical arterial (UA) Doppler ultrasound velocity waveforms are widely used in the diagnosis of underlying placental vascular abnormalities in pregnancies with suspected FGR, which greatly helps to prevent stillbirth via ongoing fetal monitoring and timely delivery. However, the sensitivity of UA Doppler diagnosis diminishes late in gestation. Our goal was to present a generalized wave decomposition method to compute forward and reflected components from UA waveforms. A detailed anatomical based model was also developed to explain observed UA flow waveform and to explore how vascular properties affect the shape of flow wave components. Using data from a previous study of pregnant mice using high frequency ultrasound microscopy, we examined in utero Doppler and M-mode ultrasound measurements in 15 fetuses' UA. Following ultrasound, the placentas had been collected and perfused with contrast agent to obtain high-resolution 3D images of the feto-placental arteries. Model of these specimens indicates the significant role of terminal load impedance (capillary and/or veins) in creating positive or negative reflected flow waveforms. A negative flow reflected waveform is obtained when terminal impedance is elevated. This is consistent with the elongated and non-branching terminal villi that are proposed to cause the highly abnormal UA waveforms found in early-onset FGR. The significance of these findings for the diagnostic utility of UA Doppler in human pregnancy is that the identification and measurement of wave reflections may aid in discriminating between healthy and abnormal placental vasculature in pregnancies with suspected late-onset FGR.

To investigate the effects of antenatal betamethasone on fetal and uteroplacental hemodynamics. The study comprised 33 women with singleton high-risk pregnancies (23-33 weeks; 27 pregnancies < 30 weeks) not in labor, but at risk for preterm delivery based on fetal or maternal indications. They were treated with two doses of 12 mg betamethasone intramuscularly 24 h apart to enhance fetal lung maturity. Flow velocity waveforms were recorded with Doppler ultrasound from the umbilical artery, the fetal middle cerebral artery, the ductus venosus and both maternal uterine arteries, once before and twice after betamethasone administration. Twenty-one (64%) women delivered within 4 days, nine (27%) women within 5-7 days and three (9%) within 8-15 days after the first dose of betamethasone. Two days after betamethasone, a decrease in pulsatility index was found in the umbilical artery (P = 0.0002) and ductus venosus (P = 0.003). Changes in the umbilical artery waveform from reversed to absent, and from absent to positive diastolic flow, were noted in 12 of 15 cases (P < 0.01). After 4 days, umbilical artery and ductus venosus velocity waveforms in the undelivered fetuses either returned to the type of waveform observed before treatment or showed further deterioration. No significant effects of betamethasone were observed in the fetal middle cerebral artery and uteroplacental circulation. Maternal antenatal betamethasone resulted in a significant transient change in the velocity waveform and a decrease in the pulsatility index in the umbilical artery and ductus venosus, but did not influence uteroplacental circulation. These findings indicate a direct effect of betamethasone on fetal circulation.

INTRODUCTION: Doppler velocimetry is a rapid noninvasive test that provides valuable information about haemodynamic situation of the foetus and is an efficient diagnostic test of foetal jeopardy which helps in timely intervention and management of high risk pregnancy for better perinatal outcome. OBJECTIVES: To evaluate middle cerebral artery and umbilical arterial velocity waveforms and their various indices during third trimester of pregnancy. METHODOLOGY: Prospective study including 50 women with normal singleton pregnancy and 50 women with intrauterine growth restricted pregnancy booked for regular antenatal checkups in our hospital. RESULTS: Foetal biometery i. e. EFW(estimated foetal weight) , BPD (bi parietal diameter), HC(head circumference), AC(abdominal circumference) and FL( femur length) all the values were significantly reduced in IUGR pregnancy. Mean amniotic fluid index was significantly reduced for IUGR pregnancy. Umbilical artery indices were significantly raised in IUGR pregnancy. Mean Pulsatility index (PI) for study group was 1.03±0.22 as compared to control group of 0.87±0.17, P value being < 0.0003. Mean Resistance index (RI) for study group was 0.65±0.14 as compared to 0.58±0.06 for control group, P value being 0.0015. Mean Systolic diastolic ratio (S/D) for study group was 2.96±0.78 as compared to 2.43±0.32 for control group, P value being < 0.0001. Reduced mean middle cerebral artery indices in IUGR pregnancy. Cerebro umbilical ratio was significantly reduced in study group. AEDV was present in 12% of women in study group and REDV in 8% women of study group. IUGR pregnancies deliver early as in comparison to normal pregnancies. Significant numbers of babies having IUGR were delivery by LSCS. Mean birth weight is significantly reduced in control for study group. Similarly, significant number of babies in IUGR pregnancies requires NICU admission .Significant number of patients in study group has associated PIH. CONCLUSIONS: In normal pregnancy there is gestational age related fall in impedance in umbilical and middle cerebral arteries. Doppler study of umbilical and middle cerebral artery is highly sensitive in the detection of IUGR and prediction of adverse perinatal outcome in small for gestational age.

This study was set to investigate the hemodynamics of the feto-placental circulation in normal and pre-ecclamptic pregnancies using the biomagnetometer SQUID. Thirteen women with pre-eclampsia and 26 healthy women were studied. All were "near term". Biomagnetic signals (waveforms) were recorded from the umbilical arteries. After statistical Fourier analysis, the findings were assigned arbitrarily in terms of spectral amplitudes as high (200-300 fT/ root of Hz), low (80-150 fT/ root of Hz) and borderline (151-199 fT/ root of Hz). In all cases the frequencies considered were distributed in the range 2-7 Hz. Interestingly, the umbilical artery waveforms and the corresponding spectral densities were of high amplitudes in most (88%) normal pregnancies of low amplitudes in most (84.6%) pregnancies complicated with pre-eclampsia. These findings were of statistical significance and were correlated with fetal heart rate (FHR) monitoring, pH and Apgar score at 1 and 5 minutes; high amplitude cases were related with normal FHR monitoring, pH > 7.25 and Apgar score > 7, while low amplitude recordings were connected with abnormal FHR patterns, pH < 7.25 and Apgar score < 7. It is suggested that biomagnetic measurements of the umbilical artery flow, which is an entirely new application of SQUID technology, is a promising procedure in assessing fetal health, especially in high risk pregnancies.

The primary function of the cardiopulmonary system is to provide blood flow (and oxygen) in quantities sufficient to support the metabolic needs of the body. The capacity of the cardiopulmonary system to fulfill this function is maximally stressed when an individual's metabolic rate is increased, a condition that occurs most commonly during physical activity/exercise. A number of physiological changes accompany and facilitate the accommodation of the circulatory system to the hemodynamic demands of exercise (Figure 1). In normal individuals, these changes (which during upright exercise include a tripling of the resting heart rate, a >60% reduction in systemic and pulmonary vascular resistance, and a >50% increase in stroke volume) can ultimately produce a >5-fold increase in cardiac output. The increase in cardiac output is accompanied by enhanced ventricular preload (as the ventricles move up their Starling curves to accommodate the increased workload), a doubling of systolic and mean pulmonary artery pressures (most of the increase in pulmonary artery pressures is due to the concomitant rise in left-sided filling pressures; the increase in transpulmonary pressure gradient is relatively small), and a more modest increase in systemic arterial pressures.1,–,4 Figure 1. Some of the physiological changes that accompany and facilitate the accommodation of the circulatory system to the hemodynamic demands of exercise. RAp indicates right atrial pressure; LAp, left atrial pressure; PVR, pulmonary vascular resistance; SVR, systemic vascular resistance; PAp, pulmonary artery pressure; and AOp, aortic pressure. Congenital heart disease (CHD) may, in a variety of ways and to a variable extent, adversely affect these hemodynamic adaptations. For instance, patients with a Fontan procedure lack a pulmonary ventricle. They therefore cannot increase their pulmonary blood flow and pressures normally (and consequently cannot maintain their ventricular preload and systemic blood flow) during exercise.5 Patients with tetralogy of Fallot and …

Range-gated pulsed Doppler has permitted the study of umbilical artery flow velocity waveforms (FVWs) in human fetuses and is becoming part of the antepartum fetal evaluation. No uniform method of describing such velocity waveforms and no significant body of normal values using pulsed Doppler can be found in the literature. The present study reports on a cohort of 268 patients who had pulsed Doppler umbilical artery FVWs performed during their pregnancy. The gestational age at the time of the study ranged between 16th and 42nd weeks of gestation in normal pregnancies. The systolic to diastolic (S/D) ratio was found progressively to decrease as gestation advanced; however, the range of normal values in this study was found to be quite large at all gestational ages. The present data represent normative data of the umbilical artery FVWs S/D ratio in a large number of normal pregnancies as shown by the follow-up of all the patients to delivery. Before umbilical artery waveform becomes part of the antenatal armamentarium, we advise caution before adopting rigid values that are derived from small groups. Lack of standard values for the 95th percentile may result in a premature delivery of an otherwise normal fetus.

The objectives of this study were to characterize spiral artery flow velocity waveforms in normal pregnancies and pregnancies complicated by pregnancy-induced hypertension and/or intrauterine growth retardation, and to examine the diagnostic potential for predicting adverse perinatal outcomes in complicated pregnancies compared with uterine and umbilical artery flow velocity waveforms. In this cross-sectional study, 160 normal and 43 complicated pregnancies were assessed by color and pulsed Doppler during 18-41 weeks of gestation. Flow velocity waveforms were obtained from the spiral, uterine and fetal umbilical arteries. In normal pregnancies, the resistance index of spiral artery flow velocity waveforms decreased significantly with advancing gestation (r = -0.256, p < 0.001). In abnormal pregnancies complicated by pregnancy-induced hypertension and/or intrauterine growth retardation, the incidence of adverse perinatal outcome was significantly higher in patients with abnormal spiral artery resistance indices than in patients with normal spiral artery resistance indices (p < 0.001). An abnormal spiral artery resistance index had a better diagnostic accuracy for adverse perinatal outcome (sensitivity 85.0%, specificity 91.3%, positive predictive value 89.5%, negative predictive value 87.5%, accuracy 88.4%) when compared with the resistance index of uterine and umbilical artery waveforms and presence of a diastolic notch of the uterine artery waveform. Color flow imaging facilitates the precise analysis of spiral artery flow velocity waveforms and provides more accurate information about the uteroplacental circulation in the evaluation of placental function.

Umbilical and arcuate artery blood flow velocity waveforms (FVW) were recorded in 125 normal singleton pregnancies from 20 to 42 weeks of gestation. The FVW were analysed for pulsatility index (PI), peak systolic velocity/minimum diastolic velocity ratio (S/D ratio), rising slope (RS) and descending slope (DS). Both in the umbilical and arcuate arteries, values for all variables declined with advancing gestation, indicating decreasing placental vascular resistance. The umbilical artery PI was unaffected by the fetal heart rate, but the arcuate artery PI was negatively correlated to the maternal heart rate (r = -0.40). The arcuate artery PI decreased by 0.00394 with each beat per minute increase in maternal heart rate. Normal limits (mean +/- 2 SD) were established for umbilical artery PI corrected for gestational age, and arcuate artery PI corrected for gestational age and maternal heart rate.

Objective: The aim of this study was to evaluate the association between umbilical arterial pH and fetal vertebral artery Doppler velocimetry waveforms measured at the beginning of the second stage of labor in physiological term pregnancies.Methods: This was a prospective cohort study of 250 pregnancies. The resistance index, pulsatility index, and peak systolic velocity were measured. The relationship between the fetal Doppler and the umbilical arterial pH was evaluated. A simple linear regression and a general linear model were used to explore possible correlations of Doppler parameters with fetal and neonatal outcome adjusted for confundents.Results: Umbilical arterial pH values were directly associated with vertebral artery pulsatility index. Fetuses with lower pulsatility index values were at increased risk of a subsequent diagnosis of pathological fetal heart rate tracing patterns (presence of decelerations or reduced variability according to FIGO criteria during the second stage of labor). We estimated a decrease in pulsatility index of 10% in those fetuses destined to show a pathological fetal heart rate tracing.Conclusion: Vertebral artery Doppler waveforms correlates with umbilical pH in normal pregnancies and is also a function of fetal heart rate patterns. If this proportional association would be demonstrated also for abnormal pH values, vertebral artery pulsatility index might be useful to evaluate fetal wellbeing in those cases of suspected hypoxia/academia.

Umbilical Artery Doppler Velocimetry in a Sheep Model of Fetal Growth Restriction

Analysis of umbilical artery flow velocity waveforms, especially systolic-diastolic (S-D) ratio, can predict some pregnancy abnormalities. Most of the earlier studies did not specify the exact segment of umbilical artery sampled. We studied 53 normal singleton pregnancies between 18-41 weeks' gestation to compare S-D ratio measurements of the umbilical artery at different sites: 1) abdominal insertion site, 2) placental insertion site, 3) mid-cord, and 4) an undetermined site. The mean S-D ratio was significantly different (P less than .01) at various segments of the umbilical artery--higher near the abdominal insertion site when compared with the mid-cord, near-placental, and undetermined sites. The S-D ratio at mid-cord was higher than at the undetermined site and the placental insertion site. The near-placental-site S-D ratio was not different from the undetermined site. A lower S-D ratio at the undetermined site may not adequately reflect the true physiologic status of the fetus. Specifying the site of measurement should be an integral part of any report, in order to describe accurately the pathophysiology of fetoplacental circulatory diseases.

Aim: The aim of this study was to compare the effects of bicycle and arm ergometer exercises on physical and psychosocial functions in patients who underwent Coronary Artery Bypass Surgery. Methods: A total of 107 cases (64 males, 43 females) were included in the study, with 23 participants aged between 52 and 65 using bicycle ergometers and a group of 58 people who performed arm ergometers opposite. After the demographic data were recorded, physical functions of all individuals participating in the study were evaluated with a 6-minute walk test, bioimpedance analysis, HDL, LDL, Triglyceride and Total cholesterol values, and psychosocial functions were evaluated with the Beck depression scale, modified borg scale and SF 36 questionnaires before and after the training. All participants were given bicycle or arm ergometer exercises for 6 weeks, 5 sessions per week, for a total of 30 sessions. Result: When the results were examined, it was observed that there was a statistically significant increase in walking distance of the people in the bicycle ergometer group compared to the arm ergometer group (p general health parameter, which is one of the sub-parameters of SF 36, in the arm ergometer group compared to the bicycle ergometer group (p Conclusion: When we look at the results of this study, it is important in terms of revealing that bicycle and arm ergometer exercises similarly improve the physical and psychosocial functions of patients who have undergone Coronary Artery Bypass Surgery. However, it has been shown that cycling exercises are much more advantageous in improving functional capacity. Summary Statement: What is already known about this topic? 1) Walking and arm exercises are good for heart diseases. What this paper adds? 2) Demonstrated that cycling and arm ergometer exercises have curative aspects for patients undergoing Coronary Artery Bypass Surgery. As a result of our study, it has emerged that leg and arm ergometry techniques are good imagers in individuals who have undergone coronary artery bypass surgery.

Antenatal fetal heart rate monitoring was compared with the study of umbilical artery flow velocity waveforms for the recognition of fetal compromise in 170 patients considered at high fetal risk. In 53 patients the infant had a 5-min Apgar score of less than 7 and/or a birthweight less than 10th centile of weight for gestation. Fetal heart rate traces were classified as reactive or non-reactive and also assessed with a modified Fischer score. The systolic/diastolic A/B ratio was measured in the umbilical artery waveform. Fetal compromise was more efficiently recognized by study of the umbilical artery waveforms. The sensitivity of assessment by umbilical artery waveforms was 60% compared with 17% and 36% respectively, for the two methods of scoring fetal heart rate traces. This was not associated with an increase in false-positive results as the predictive value of both positive (64% compared with 69 and 58%) and negative (83% compared with 72 and 75%) results was similar when umbilical artery waveform analysis was compared with the two methods of scoring fetal heart rate traces. Specificity was also similar (85% compared with 97 and 88%).