Artery Blood Flow Velocity Waveforms Research Articles

Cord blood gases and absence of end-diastolic blood velocities in the umbilical artery

Umbilical artery and vein blood gases were compared in three groups of pregnant women delivered by elective caesarean section: group 1 ( n = 21), normal controls; group 2 ( n = 15), complicated pregnancies with normal umbilical artery blood flow velocity waveforms; and group 3 ( n = 14), complicated pregnancies with absent end-diastolic blood velocity in the umbilical artery. Newborns in group 3 were found to be small for gestational age and to have significantly lower oxygen pressure and saturation. These fetuses were thus in a state of chronic hypoxia, which may predispose for development of intra-uterine distress. Doppler ultrasound examination can be useful in identifying this high risk group requiring intensified surveillance.

Relationship between the ovine fetal umbilical artery blood flow waveform and umbilical vascular resistance

Ultrasonic umbilical artery blood flow velocity waveform indexes decrease throughout gestation as umbilical blood flow increases. However, it is not known whether the decrease in indexes such as systolic/diastolic ratio is a direct result of a change in umbilical vascular resistance. Umbilical artery blood flow was measured as vasoactive agents angiotensin II, arginine vasopressin, norepinephrine, serotonin, and the thromboxane A2 sympathomimetic agent U-46619 were infused into the inferior vena cava of chronically instrumented ovine fetuses. Angiotensin II, arginine vasopressin, norepinephrine, serotonin, and U-46619 all significantly increased fetal arterial pressure levels. Angiotensin II, arginine vasopressin, and U-46619 significantly reduced umbilical blood flow and fetal heart rate. All five pressor agents increased umbilical vascular resistance. Systolic/diastolic ratios were obtained from pulsatile umbilical blood flow tracings. Systolic/diastolic ratios before infusions were significantly correlated with baseline values of umbilical blood flow (r = -0.55) and umbilical vascular resistance (r = 0.52). Systolic/diastolic ratios decreased with increasing infusion rates of angiotensin II, arginine vasopressin, norepinephrine, and serotonin, and increased with infusion of U-46619. There was no significant correlation between systolic/diastolic ratio and either umbilical blood flow or umbilical vascular resistance during infusion of angiotensin II, arginine vasopressin, or serotonin. Systolic/diastolic ratio decreased with increasing umbilical vascular resistance during norepinephrine infusion (r = -0.44). Systolic/diastolic ratio changed in the predicted direction only when umbilical vascular resistance was increased by infusion of U-46619 (r = 0.80). We conclude that umbilical artery waveform analysis is not an adequate predictor of acute changes in umbilical blood flow or vascular resistance.

Fetal umbilical and internal carotid artery blood flow velocity waveforms during maternal fenoterol administration

Blood flow velocity waveforms in the fetal umbilical and internal carotid artery were studied during maternal fenoterol treatment in 25 pregnant patients admitted for premature labour between 27 and 35 weeks of gestation. The pulsatility index (PI) from the umbilical artery was significantly reduced (p = 0.02), the PI being situated below the — 2 SD limit of the normal reference curve in 28%. There was no statistically significant difference in PI from the umbilical artery when distinguishing between ruptured and unruptured membranes. The reduced pulsatility index of the umbilical artery suggests a decrease in vascular resistance, hence improved utero-placental perfusion. The pulsatility index of the fetal internal carotid artery followed the normal distribution.

Direct determination of the ovine fetal umbilical artery blood flow waveform

Ultrasonographic umbilical artery blood flow velocity waveform analysis has been proposed as a means of noninvasive assessment of fetal well-being. We computed waveform indices from directly measured umbilical artery blood flow in chronically instrumented ovine fetuses from 109 to 138 days of gestation (term, 145 days). The three waveform indices (systolic/diastolic ratio, pulsatility index, and resistance index) correlated significantly with each other (r = 0.90 to 0.98). These indices progressively decreased with gestation and were significantly correlated with calculated umbilical vascular resistance (r = 0.68 to 0.70, p less than 0.01) and with umbilical blood flow (r = -0.71, p less than 0.01). During the final week of pregnancy, systolic/diastolic ratio could be predicted by the combination of placental size (total cotyledonary mass), fetal size (ponderal index), and either umbilical blood flow or umbilical vascular resistance (multiple linear regression, r2 = 0.94). Fetal heart rate declined from day 109 of gestation to 138 days. Fetal heart rate was significantly correlated with waveform indices only when values exceeded 170 beats/min (r = -0.37 to -0.51). Ovine fetal umbilical artery waveform indices changed at approximately the same rate as those reported for human fetuses in late gestation on the basis of external Doppler ultrasonographic velocity measurements. These results suggest that the sheep is a suitable model for investigations of umbilical artery waveform analysis.

Doppler ultrasound assessment of tumor vascularity in gynecologic disorders.

Real-time two-dimensional and pulsed-wave Doppler ultrasonic examinations were performed on 8 normal volunteers and 97 patients with various gynecologic disorders; the objective was to assess uterine and tumor vascularities. Each arterial blood flow velocity wave-form was classified into two types. The resistance indices of normal and abnormal flows were greater than .7 and less than .7, respectively. In normal volunteers, abnormal flows were nil. In 8 of 44 patients with benign tumors (18.2%), abnormal flows were evident and all proved to be cases of leiomyoma or adenomyosis. Doppler signals were not detected in 18 of 36 patients with cervical carcinoma (50%) and abnormal flows were noted in only 6 (16.7%). In all cases of endometrial carcinoma, ovarian carcinoma, and trophoblastic disease, typically abnormal flows were noted. Moreover, in most subjects a decrease in blood flows was observed after chemotherapy by anticancer drugs or irradiation. Therefore, Doppler ultrasound is a pertinent and noninvasive tool that can be used repeatedly for assessing the tumor vascularity in gynecologic disorders.

Umbilical artery velocity waveforms are not valid indices for assessing growth retardation in utero

Blood flow velocity waveforms from the umbilical artery of 126 normal fetuses with no complications at 20–41 weeks and in 31 growth-retarded fetuses, were recorded using pulsed Doppler ultrasound. A total of 140 examinations were performed on normal fetuses and 49 on growth-retarded fetuses. The resistance index (RI) was used as an index of blood flow resistance. In 30 of the 31 growth-retarded fetuses (96.8%), the values of RI were within the mean ± 2 S.D. of normal fetuses. Placental/fetal weight ratio (P/F ratio) was assessed. All values of P/F ratio of growth-retarded fetuses were within the mean ± 2 S.D. of normal values. Small placentas expressed as a normal P/F ratio almost always associated with normal RI values. Therefore, measurement of RI on umbilical artery blood flow velocity waveform by Doppler ultrasound cannot serve as a valid diagnostic index to predict growth retardation of the fetus in utero.

Uterine and umbilical artery blood flow velocity waveforms and their validity in the prediction of fetal compromise

The maternal and fetal placental circulation was studied by recording of the blood flow velocity waveforms (FVW) of the uterine and umbilical artery (UFVW and UmbFVW) in 99 pregnant women. The FVW was quantitated by the Pulsatility-Index (PI). By analysing the UFVWs as well as the UmbFVWs, it was possible to define four groups of patients, based on normal versus abnormal PI on either side of the placenta. The group with abnormal FVWs on both sides of the placental bed showed the highest percentage of pathological phenomena. Uterine and/or umbilical artery FVW analysis was not sensitive in the prediction of small for gestational age (SGA), whereas it was a sensitive method for the prediction of fetal distress (FD) during pregnancy. For the latter, our data suggested that at a chosen specificity of 95%, FVW analysis on both sides of the placental bed was more sensitive than separate UFVW or UmbFVW analysis.

Cerebral artery blood flow velocity waveforms in normal and small for dates fetuses.

Middle cerebral artery (MCA) blood flow velocity waveforms were recorded by a pulsed Doppler system in normal and small for dates (SFD) fetuses. Eighty four normal growth fetuses and 15 SFD fetuses were studied between the 28th and 40th gestational week. The flow velocity waveforms were analysed to determine the resistance index (RI = peak systolic velocity minus end diastolic velocity/peak systolic velocity). The results obtained were as follows: 1. The mean values of RI in the MCA had a peak of 0.802 +/- 0.049 at 32-33 gestational weeks and decreased gradually to a level of 0.686 +/- 0.087 at 40 gestational weeks. 2. In 8 asymmetrical SFD fetuses, the RI values for the MCA were below the normal range (mean -1.5 SD) in 6 cases and normal in 2 cases. 3. The RI values for MCA in all 7 symmetrical SFD fetuses were in the normal range.

Umbilical artery blood flow velocity waveforms and associations with fetal abnormality.

Blood flow velocity waveforms from the umbilical artery of 126 normal fetuses with no evident complications at 20-42 weeks of gestation and 15 fetuses with various abnormalities at 25-42 weeks were recorded using pulsed Doppler ultrasound. The resistance index (RI) was assessed on each blood flow velocity waveform. In 9 fetuses with a slight abnormality, the values of RI were within the mean +/- 2 SD of normal fetuses, and the outcome was good. In 3 of 6 fetuses with a serious abnormality, the values of the RI were high, and 2 of these fetuses died in utero within a few days after the recording. Another fetus with a high RI and 3 with a normal RI died neonatally. Therefore, Doppler ultrasound assessments of the umbilical artery blood flow velocity waveform in utero aid in predicting the outcome for fetuses with major abnormalities.

The uterine artery blood flow velocity waveform in pathological pregnancy

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in 41 women with undisturbed pregnancy as well as in 32 women with complicated pregnancy at 4-week intervals from a gestational age of 18 weeks onwards. Of these women, four did not complete the study. In a second group of 76 patients at least one FVW was recorded after admission to the obstetrical department because of complicated pregnancy. The Pulsatility-Index (PI) for normal pregnancy was based on the results of the 41 women with undisturbed pregnancy (Mulders et al. (1988) Early Hum. Dev., 17, 55–70). The complete study group ( n = 145) was divided in two groups, based on the value of the last measured uterine artery PI before delivery; in the abnormal PI group (PI ⩾ 1.02 before 32 weeks or PI ⩾, 0.91 after 32 weeks, n = 38) hypertension, fetal distress during pregnancy, premature delivery, small for gestational age babies (SGA) and lower placental weight were all significantly increased. In each of the groups of patients with either SGA, fetal distress during pregnancy, pre-existing hypertension with proteinuria and pregnancy-induced hypertension with or without proteinuria the mean PI was significantly increased as compared to the results in normal pregnancy. Sensitivity and specificity of the last uterine artery PI for the detection of SGA and/or fetal distress during pregnancy were 48.8% and 82.7%, respectively. The longitudinally studied women ( n = 73) were divided in two groups, based on uterine artery PI before 32 weeks of gestation; in the abnormal PI group (PI ⩾1.02, n = 12) pregnancy was more complicated by premature delivery and low birth weight. Sensitivity for the early prediction of pathological pregnancies (at least one pathological phenomenon as mentioned above) was 30.4%, whereas specificity was 90.0%.

The uterine artery blood flow velocity waveform: reproducibility and results in normal pregnancy

Uterine artery blood flow velocity waveforms (FVW) were recorded longitudinally in normal pregnancies (n = 41) at 4-week intervals from a gestational age of 18 weeks onwards. Furthermore, reproducibility of the uterine artery FVWs and the relation with maternal heart rate (MHR) was studied. The uterine artery FVW showed a low resistance flow pattern already from 18 weeks onwards, with high diastolic flow velocity relative to systolic flow velocity. Mean values (+/- S.D.) for the Pulsatility-Index (PI) before and after 32 weeks of normal pregnancy were 0.73 (+/- 0.17) and 0.67 (+/- 0.15) respectively; for the A/B ratio these values were 1.98 (+/- 0.30) and 1.85 (+/- 0.25) respectively. Intra- and interobserver reproducibility could be established for uterine artery FVW analysis. A varying time-period between the FVWs (0-4 min), repositioning of the flow probe and different observers did not cause any systematic effect on the PI, although variation increased in case of a longer time-period between the FVWs. Overall variation of the PI in the reproducibility experiments appeared to be caused more by inter- than intrapatient variance. Inter- and intrapatient variance were in the same range for the results of the longitudinal study. A statistically significant, inverse relationship between uterine artery PI and MHR could be established in a majority of cases. The mean regression coefficient for all patients of the reproducibility study was -0.0061; PI decreases with 0.0061 when maternal heart rate increases 1 beats/min.

The effect of epidural anaesthesia for caesarean section on maternal uterine and fetal umbilical artery blood flow velocity waveforms

Summary. The blood flow resistance in the maternal uteroplacental and fetal umbilical artery circulation was studied in eight otherwise normal patients undergoing elective lower segment caesarean section. The systolic/diastolic A/B ratio (the ratio of peak systolic to least diastolic flow velocity) for the uteroplacental and fetal umbilical circulation was determined from the artery blood flow velocity-time waveform and used as an index of blood flow resistance. Each patient received a 1 litre intravenous crystalloid infusion before an epidural bupivicaine injection. Both crystalloid infusion and epidural anaesthesia resulted in a significant decrease in the maternal uteroplacental systolic/diastolic (A/B) ratios, associated with a decrease in fetal umbilical artery A/B ratio. This study suggests a beneficial fetal effect from the improved maternal uterine perfusion after epidural anaesthesia.

Umbilical Artery and Uteroplacental Blood Flow Velocity Waveforms in Normal Pregnancy — A Cross‐Sectional Study

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.

Umbilical Artery and Uteroplacental Blood Flow Velocity Waveforms in Normal Pregnancy– A Cross-Sectional Study

Umbilical Artery and Uteroplacental Blood Flow Velocity Waveforms in Normal Pregnancy– A Cross-Sectional Study

Renal arterial blood flow velocity waveforms in pregnant women

Seventy-two continuous-wave Doppler ultrasonographic examinations were performed on nine nonpregnant and 56 normal pregnant women. The range of gestation was 6 to 40 weeks, and the objective was to record the renal arterial blood flow velocity waveform. Acceleration time and systolic per diastolic ratio of renal arterial blood flow velocity waveforms were assessed. Of 72 examinations, 68 recordings were made of the left renal artery (94.4%) and 28 of the right renal artery (38.9%), respectively. There was no correlation between acceleration time and systolic per diastolic ratio and gestational age, respectively, and no correlation between acceleration time and systolic per diastolic ratio, and caliceal diameter of the renal pelvis, respectively. Acceleration times of the left and right renal arteries were 47 +/- 11 and 40 +/- 8 msec in nonpregnant women and 62 +/- 23 and 62 +/- 23 msec in pregnant women, respectively. The left and right systolic per diastolic ratios were 3.1 +/- 0.7 and 2.9 +/- 0.5 in nonpregnant women and 2.8 +/- 0.6 and 2.6 +/- 0.5 in pregnant women, respectively. Therefore these data provide a foundation for the study of hydronephrosis, which may occur in pregnant women.

The Effect of Epidural Anaesthesia for Caesarean Section on Maternal Uterine and Fetal Umbilical Artery Blood Flow Velocity Waveforms

Summary. The blood flow resistance in the maternal uteroplacental and fetal umbilical artery circulation was studied in eight otherwise normal patients undergoing elective lower segment caesarean section. The systolic/diastolic A/B ratio (the ratio of peak systolic to least diastolic flow velocity) for the uteroplacental and fetal umbilical circulation was determined from the artery blood flow velocity-time waveform and used as an index of blood flow resistance. Each patient received a 1 litre intravenous crystalloid infusion before an epidural bupivicaine injection. Both crystalloid infusion and epidural anaesthesia resulted in a significant decrease in the maternal uteroplacental systolic/diastolic (A/B) ratios, associated with a decrease in fetal umbilical artery A/B ratio. This study suggests a beneficial fetal effect from the improved maternal uterine perfusion after epidural anaesthesia.

The effect of epidural anaesthesia for caesarean section on maternal uterine and fetal umbilical artery blood flow velocity waveforms.

The blood flow resistance in the maternal uteroplacental and fetal umbilical artery circulation was studied in eight otherwise normal patients undergoing elective lower segment caesarean section. The systolic/diastolic A/B ratio (the ratio of peak systolic to least diastolic flow velocity) for the uteroplacental and fetal umbilical circulation was determined from the artery blood flow velocity-time waveform and used as an index of blood flow resistance. Each patient received a 1 litre intravenous crystalloid infusion before an epidural bupivicaine injection. Both crystalloid infusion and epidural anaesthesia resulted in a significant decrease in the maternal uteroplacental systolic/diastolic (A/B) ratios, associated with a decrease in fetal umbilical artery A/B ratio. This study suggests a beneficial fetal effect from the improved maternal uterine perfusion after epidural anaesthesia.

The umbilical artery blood flow velocity waveform in relation to fetal breathing movements, fetal heart rate and fetal behavioural states in normal pregnancy at 37 to 39 weeks

In 19 normal pregnancies between 37 and 39 weeks of gestation, the blood flow velocity waveform (FVW) of the umbilical artery was studied in relation to fetal breathing movements, fetal heart rate (FHR) and the fetal heart rate patterns (FHRPs) A and B. FHRP A is stable, with a narrow oscillation bandwidth, FHRP B shows a wider oscillation bandwidth. Although for state-assessment it is necessary to record three variables simultaneously, the linkage of these variables in the near-term healthy fetus is such, that FHRP A and B may be used for the assignment of behavioural states 1F and 2F. The FVW was characterized by the Pulsatility-Index (PI). Presence of fetal breathing movements strongly disturbed the regularity of the FVW. A significant inverse relationship between FHR and PI was established. A weighted regression coefficient was calculated: PI decreases 0.0075 with an increase of FHR of 1 beat per minute (PI 140 = PI + 0.0075(FHR - 140)). The PI was higher during periods of FHRP A as compared to FHRP B. However, this difference disappeared, when the influence of FHR was taken into account by normalising all PIs to a standard heart rate level of 140 bpm. One should perform the umbilical artery blood flow measurements in absence of fetal breathing - (causing irregularity of the FVW) and body movements (because of accompanying FHR accelerations) and FHR should be taken into account when evaluating the FVWs.

A microcomputer-based real-time system for measurement and analysis of umbilical flow velocity waveforms obtained by Doppler ultrasound.

A microcomputer-based system for real-time acquisition and analysis of umbilical arterial blood flow velocity waveforms is described. The spatial peak umbilical flow velocity is transduced by a pulsed Doppler flowmeter and digitized by the microcomputer. The computer allows for coherent averaging of flow velocity over several heart cycles in order to minimize noise that is uncorrelated with the fetal heart beats. In addition, it can compute flow velocity indices that do not require knowledge of the angle of beam incidence or umbilical arterial cross-sectional area. The averaged waveform as well as the computed indices may be displayed in real time. Further, these results may be saved on disk along with other relevant clinical information to be subsequently merged into a relational data base covering all patients monitored. Not only does the system facilitate accurate measurement of umbilical flow velocity waveforms, but the relational data base may also be used to evaluate the clinical significance of these measurements in a patient population.

Effect of arterial counterpulsation on left ventricular volume and pressure.

ARTICLESEffect of arterial counterpulsation on left ventricular volume and pressureCB Mullins, WL Sugg, BM Kennelly, DC Jones, and JH MitchellCB Mullins, WL Sugg, BM Kennelly, DC Jones, and JH MitchellPublished Online:01 Mar 1971https://doi.org/10.1152/ajplegacy.1971.220.3.694MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByMechanical Circulatory Support20 May 2022 | Clinical Journal of the American Society of Nephrology, Vol. 17, No. 6Advances in temporary mechanical support for treatment of cardiogenic shock7 September 2015 | Expert Review of Medical Devices, Vol. 12, No. 6Management of Intra-Aortic Balloon Pumps27 October 2014 | Seminars in Cardiothoracic and Vascular Anesthesia, Vol. 19, No. 2Percutaneous circulatory support during percutaneous coronary interventionInterventional Cardiology, Vol. 4, No. 4The role of percutaneous circulatory assist devices in acute myocardial infarction and high-risk percutaneous coronary intervention in the 21st centuryCardiovascular Revascularization Medicine, Vol. 12, No. 4Intra-Aortic Balloon Counterpulsation for the Treatment of Myocardial Infarction Complicated by Acute Severe Heart FailureCongestive Heart Failure, Vol. 15, No. 1Intraaortic Balloon Pump in the Management of Acute Heart Failure SyndromesEffects of intraaortic balloon pumping on septal arterial blood flow velocity waveform during severe left main coronary artery stenosisJournal of the American College of Cardiology, Vol. 27, No. 4Experimental and Clinical Evaluation of a Counterpulsation Device1 July 2016 | Journal of Biomaterials Applications, Vol. 4, No. 4Principles and Techniques of Intra-aortic Balloon Pump CounterpulsationThe Effect of IABP Ventricular Contractility of the Normal and Ischemic Canine Heart Assessed in Situ by T-EmaxEffect of intraaortic balloon counterpulsation on regional myocardial blood flow and oxygen consumption in the presence of coronary artery stenosis: Observations in an awake animal modelThe American Journal of Cardiology, Vol. 50, No. 4Left ventricular afterload and systemic hydraulic power during in-series cardiac assistance: Studies using intraaortic balloon pumping in dogsAnnals of Biomedical Engineering, Vol. 5, No. 2The response of mechanical performance, coronary blood flow and myocardial oxygen consumption of the normal and failing dog heart to intraaortic balloon pulsation1 July 1974 | Basic Research in Cardiology, Vol. 69, No. 4An Adaptive Model of Ventricular Function Applied to the Study of Assist Device PumpingIFAC Proceedings Volumes, Vol. 6, No. 4The effect of intermittently applied external pressure on the haemodynamics of the lower limb in manBritish Journal of Surgery, Vol. 59, No. 3 More from this issue > Volume 220Issue 3March 1971Pages 694-698 Copyright & PermissionsCopyright © 1971 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1971.220.3.694PubMed5545678History Published online 1 March 1971 Published in print 1 March 1971 Metrics