Increase In Pulsatility Index Research Articles

Uterine artery blood flow response to correction of amniotic fluid volume

OBJECTIVE: Our purpose was to investigate whether acute alterations of amniotic fluid volume affect uteroplacental perfusion.STUDY DESIGN: Three groups of patients of comparable gestational age were studied in a fetal medicine referral unit: (1) eight pregnancies with severe polyhydramnios because of twin-twin transfusion syndrome undergoing therapeutic amnioreduction, (2) seven with severe oligohydramnios undergoing diagnostic amnioinfusion, and (3) six control women having invasive procedures of similar duration without manipulation of amniotic fluid volume. Color Doppler imaging was used to measure uterine artery impedance index values and quantitative blood flow before and within 15 minutes of the end of the procedure.RESULTS: Quantitative flow measurements increased after amnioreduction (74% median increase of volume flow, range 22% to 329%, p < 0.01) and decreased after amnioinfusion (33% median decrease of volume flow, range 17% to 51%, p < 0.05). Impedance index values increased after amnioinfusion (25% median increase in pulsatility index, range 4% to 71%, p < 0.05) and did not alter with amnioreduction. There were no significant changes in the control group.CONCLUSION: Acute changes in amniotic fluid volume after uteroplacental perfusion. In twin-twin transfusion syndrome amelioration in uterine flow may improve fetal condition and explain in part the success of serial amnioreduction therapy.

Serial assessment of adnexal masses with transvaginal color Doppler sonography

Transvaginal color Doppler sonography (TV-CDS) was performed on 64 women with adnexal masses at 3, 6 and 12 weeks after initial presentation. In 47 (72% of patients studied), the pelvic mass demonstrated a decrease in size and increase in pulsatility index (PI) after 12 weeks. Of the patients undergoing surgery in this group, one had a tubo-ovarian abscess, one diverticular abscess and one hydrosalpinx. In seven patients (10%), there was no change in size or PI. Three in this group had an endometrioma, whereas two had a peritoneal cyst. In five (7%), there was no change in size and an increase in PI. One of these patients had a mucinous cystadenoma. In three (5%), there was a decrease in size and PI. Two of these patients had a tubo-ovarian abscess. In two (3%) patients studied, the mass showed an increase in size and decrease in PI; both had corpora luteum cysts with acute hemorrhage. Seventy-two percent of masses with high impedance underwent regression, whereas only 21% of lesions with low impedance did. Only 20% of masses demonstrating low impedance or morphologically complex structure regressed. Sixtyfive percent of lesions that regressed had a significant drop in PI, whereas all the lesions that showed no change in size or enlargement had either no change or decrease in PI. Probability of regression was the greatest in young women (less than 40 years of age) and in masses < 5 cm. Ninety-three percent of women with persistent masses that underwent progestational suppression demonstrated regression with decrease of PI and peak systolic velocity. Three masses that did not respond included two hemorrhagic tubo-ovarian abscesses and one cystadenoma. Changes in PI were more predictive of regression (92%) than morphology or patient age. Therefore, TV-CDS was a useful parameter in schemes to distinguish masses in those patients whose may spontaneously regress from those that might fail to regress or enlarge.

Haemodynamic consequences of embolizing aneurysms: a transcranial Doppler study

Twenty patients with aneurysms were studied with transcranial Doppler before, during and after endovascular treatment with Guglielmi detachable coils. Catheterization of the anterior circulation decreased middle cerebral artery velocities by 15-20%. Inserting coils into the aneurysms increased pulsatility indices modestly, reflecting a stiffening of the cerebral circulation. Pre- and posttreatment velocities were not significantly different, and there was no evidence of coil embolization precipitating vasospasm. The haemodynamic stability, seen during and after therapy, suggests that coil embolization may prove a safe alternative way of treating acutely ruptured aneurysms.

Duplex Doppler sonographic evaluation of splanchnic and renal effects of single agent and combined therapy with nadolol and isosorbide-5-mononitrate in cirrhotic patients.

Thirty-eight cirrhotic patients with esophageal varices were investigated by duplex Doppler sonography. In every patient, the portal blood flow mean velocity (cm/sec) and portal blood flow volume (ml/min) were measured. In addition, the pulsatility index [(maximum-minimum)/mean velocity] was measured in the superior mesenteric artery, in the hepatic arteries, in an intrasplenic artery, and in intrarenal arteries. These parameters were measured again 120 to 180 minutes after administration of nadolol (80 mg orally) in 22 patients, 90 minutes after administration of isosorbide-5-mononitrate (20 mg orally) in nine patients, and subsequently after administration of isosorbide 5-mononitrate to 10 of the 22 patients treated earlier with nadolol. Duplex Doppler sonographic parameters also were evaluated in seven patients 120 minutes after administration of a placebo. In five of the 22 patients treated acutely with nadolol, the same parameters were measured again after 60 minutes without any additional drug administration. No hemodynamic changes occurred in response to the placebo. Portal blood flow mean velocity and portal blood flow volume decreased after nadolol and isosorbide-5-mononitrate; mesenteric pulsatility index increased after both nadolol and isosorbide-5-mononitrate. After combined therapy, we observed a further reduction in portal blood flow mean velocity and portal blood flow volume and a significant increase in hepatic, splenic, and mesenteric pulsatility indices. The addition of isosorbide-5-mononitrate to nadolol caused a decrease in portal blood flow mean velocity of more than 17% in all patients. Nadolol caused a slight increase in renal pulsatility index, which was amplified by the addition of isosorbide-5-mononitrate, suggesting a decrease in renal blood flow.

Central and peripheral hemodynamic changes in fetuses with absent end-diastolic velocity in umbilical artery: Correlation with computerized fetal heart rate pattern

OBJECTIVES: Our purpose was to study hemodynamic changes in peripheral and central blood vessels and to correlate these changes with the computerized fetal heart rate pattern in fetuses with absent end-diastolic velocity in the umbilical artery. STUDY DESIGN: Doppler studies of the umbilical artery, the middle cerebral artery, and aortic and pulmonic outflow, together with computerized fetal heart rate monitoring, were performed every 2 to 4 days until delivery in 13 fetuses with absent end-diastolic velocity in the umbilical artery. The pulsatility index was calculated from the flow velocity waveforms obtained from the umbilical and middle cerebral arteries. The velocity time integral (an index of cardiac output) and the heart rate were calculated from the flow velocity waveforms obtained from the aortic and pulmonic outflow. RESULTS: Two fetuses were delivered immediately after the first examination because of repetitive fetal heart rate decelerations. One fetus was excluded from the study because of major malformations. Ten had three to eight tests each. Six had a biphasic change of the middle cerebral artery, which consisted of a decrease (p < 0.001) followed by an increase in the pulsatility index (p < 0.05). When the middle cerebral artery lost its vasodilation, there was an increase in the middle cerebral artery/umbilical artery pulsatility index ratio (p < 0.05). Left cardiac output decreased (p < 0.05), resulting in an increase in the pulmonary/aortic velocity time integral × heart rate ratio (p < 0.05). Reduced fetal heart rate variation (< 30 msec) developed in all six fetuses, and they were delivered because of repetitive fetal heart rate decelerations. Four fetuses with only a decrease in the middle cerebral artery pulsatility index did not have reduced fetal heart rate variation or decelerations, the aortic velocity time integral × heart rate didn't decrease, and the pulmonic/aortic velocity time integral × heart rate ratio didn't increase. These fetuses were delivered for reasons other than fetal distress. The middle cerebral artery pulsatility index correlated with the aortic velocity time integral × heart rate (r = -0.53, p < 0.0001), and the middle cerebral artery/umbilical artery pulsatility index correlated with the pulmonic/aortic velocity time integral × heart rate (r = 0.56, p < 0.0001). CONCLUSION: Abnormal fetal heart rate patterns occur in fetuses with absent end-diastolic velocity in the umbilical artery when the middle cerebral artery begins to lose its compensatory maximal dilation. The increase in the middle cerebral artery pulsatility index is associated with a significant reduction in left ventricular output without significant changes in right ventricular function. Thus it appears that a loss of autonomic reactivity occurs in the brain first and is followed within a few days by a similar response in the heart, as shown by the decreased fetal heart rate variation. (AM J OBSTET GYNECOL 1994;170:509-15.)

Correlation of Doppler and placental immunohistochemical features in normal and intrauterine growth-retarded fetuses.

The aim of this study was to correlate and compare Doppler and anatomical placental findings obtained from 48 normal and 35 intrauterine growth-retarded (IUGR) fetuses. The IUGR group consisted of 19 fetuses from pregnancies complicated by pre-eclampsia and 16 from healthy mothers. Color Doppler evaluation of umbilical, spiral and uterine arteries was performed. Placental specimens from both normal and growth-retarded fetuses were obtained at the time of delivery. Placental specimens were evaluated using histochemical and immunohistochemical techniques. A progressive decrease in the pulsatility index was observed in umbilical, spiral and uterine arteries throughout pregnancy in the normal-growth fetuses. High umbilical artery pulsatility index values were obtained in 29 out of the 35 growth-retarded fetuses, six of them showing absent or reversed end-diastolic umbilical artery flow pattern. A total of 13 IUGR fetuses showed high resistance uterine artery flow velocity waveforms. Increased pulsatility index values were obtained from the spiral arteries of 16 growth-retarded fetuses. Abnormal histological and histochemical placental patterns were observed in all the growth-retarded fetuses with umbilical artery Doppler abnormalities. The presence of a peculiar dendritic cell subpopulation, strongly resembling the Langerhans cells, expressing the HLA-DR+/CD1+ phenotype, was detected in all growth-retarded fetuses, whether there was maternal pathology or not. Our data show uterine and spiral artery data as being ineffective in the monitoring of IUGR fetuses. The placental extracellular matrix seems to play an important role in the regulation of the umbilical circulation. The presence of CD1+ cells as a sign of a possible immunological mechanism in the pathogenesis of the intrauterine growth retardation is discussed.

Head-upright tilt-table testing: a useful tool in the evaluation and management of recurrent vertigo of unknown origin associated with near-syncope or syncope.

Recurrent idiopathic vertigo associated with near-syncope and syncope is a common perplexing problem, some cases of which are considered autonomically mediated (vasovagal). Upright-tilt-table testing has emerged as a potential method to test for vasovagal episodes. This study evaluated the use of this technique in the evaluation and management of patients with recurrent idiopathic vertigo associated with near-syncope or syncope. Twenty-one patients with recurrent unexplained vertigo and syncope/near-syncope and 11 control subjects were evaluated by use of an upright-tilt-table test for 30 minutes, with or without a graded isoproterenol infusion (1 to 4 micrograms/min given intravenously), in an attempt to provoke hypotension, bradycardia, or both, which reproduced the patient's symptoms. The patients included 10 men and 11 women (mean age, 51 +/- 16 years). Eleven controls with no history of vertigo were also studied. Transcranial Doppler sonography was used to assess cerebral arteriolar blood flow during tilt. All tilt-positive patients were placed on therapy with either beta-blockers, disopyramide, or transdermal scopolamine, the effectiveness of which was determined with another tilt-table study. Symptoms occurred in seven patients (33%) during the baseline tilt and in eight patients (38%) during isoproterenol infusion (total positives, 71%). Transcranial Doppler sonography demonstrated a 225% +/- 192% increase in pulsatility index and a 70% +/- 29% increase in resistance index (indicative of cerebral arteriolar vasoconstriction) at the time of vertigo. No control subject experienced syncope during this test. Each tilt-positive patient eventually became tilt-negative with therapy, and over a mean follow-up period of 26 months, no further episodes have occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

In Vivo Effect of Calcitonin Gene Related Peptide on Middle Cerebral Artery Blood Flow Velocity In Humans

A double blind, placebo controlled, escalating dose study was undertaken in five healthy, conscious volunteers to investigate the effects of human synthetic alpha calcitonin gene-related peptide (CGRP) on middle cerebral artery (MCA) blood flow velocity using transcranial Doppler sonography. During placebo infusion, there was no significant change in any of the parameters studied. During CGRP infusion, all subjects showed flushing of the face and neck. Infusion of CGRP caused a significant increase in arterial pulse pressure and heart rate and a fall in diastolic and mean arterial blood pressure when compared to baseline. Peak and mean MCA velocity did not change significantly. There was a significant increase in pulsatility index though interpretation of this was confounded by the central systemic effects of CGRP. The observed haemodynamic changes may be explained by a prompt sympathetic nervous system response in order to maintain mean arterial blood pressure. Our data suggest that if cerebral vasodilatation had occurred, it was not associated with increased blood flow as an increase in MCA velocity might have been expected. An alternative explanation is that, at the doses employed, CGRP did not cause dilatation of normal cerebral vessels in healthy subjects. This does not however exclude the fact that CGRP may cause dilatation of a spastic artery as seen in cerebral vasospasm following subarachnoid haemorrhage.

Uteroplacental Doppler velocimetry during Braxton Hicks' contractions.

Pulsed-wave Doppler ultrasound was used to evaluate the influence of Braxton Hicks' contractions on flow velocity waveforms in the uterine arteries. Flow velocity waveforms were obtained from a standardized site, at the crossing of the uterine artery with the external iliac artery near the uterine wall. Doppler signals were recorded in 16 healthy near-term nulliparous pregnant women. During Braxton Hicks' contractions, a considerable increase in pulsatility index (PI) was found in the uterine arteries increasing from 0.71 +/- 0.21 (mean +/- SD) to 1.14 +/- 0.67 (p < 0.005). Maternal heart rate decreased slightly but significantly during contractions. Despite the high PI values that were found during Braxton Hicks' contractions, a diastolic notch in the flow velocity waveform was never noticed. The findings indicate that during Braxton Hicks' contractions, resistance to blood flow in the uteroplacental circulation is considerably increased.

Cerebral vasoconstriction during head-upright tilt-induced vasovagal syncope. A paradoxic and unexpected response.

To determine the effect of vasovagally mediated syncope on the cerebral circulation, transcranial Doppler sonography was used to assess changes in cerebral blood flow velocity during head-upright tilt-induced syncope. Thirty patients (17 men and 13 women; mean age, 43 +/- 22 years) with recurrent unexplained syncope were evaluated by use of an upright tilt-table test for 30 minutes, with or without an infusion of intravenous isoproterenol (1-4 micrograms/min), in an attempt to provoke bradycardia, hypotension, or both. Transcranial Doppler sonography was used to assess middle cerebral artery systolic velocity (Vs), diastolic velocity (Vd), ratio of systolic to diastolic velocities, pulsatility index (PI = Vs-Vd/Vmean), and resistance index (RI = Vs-Vd/Vs) before, during, and after tilt. Syncope occurred in six patients (20%) during the baseline tilt and 14 (46%) during isoproterenol infusion (total positives, 66%). In the tilt-positive patients, concomitant with the development of hypotension and bradycardia, transcranial Doppler sonography showed a 75 +/- 17% decrease in diastolic velocity, unchanged systolic velocity, a 46 +/- 17% decrease in mean velocity, a 295 +/- 227% increase in pulsatility index, and a 73 +/- 34% increase in resistance index. These findings reflect increased cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the insonation point of the middle cerebral artery. This is paradoxic because the expected response of the cerebral circulation to hypotension is vasodilation. We conclude that abnormal baroreceptor responses triggered during vasovagal syncope result in a derangement of cerebral autoregulation with paradoxic vasoconstriction in the face of increasing hypotension.

Umbilical artery velocimetry and non-stress test in monitoring high-risk pregnancies. A comparative longitudinal study.

In a longitudinal comparative study, umbilical artery velocimetry and the non-stress test were used in parallel for surveillance of 153 hospitalized high-risk pregnancies. The occurrence of abnormal flow velocity waveforms of the umbilical artery, with increased pulsatility index but maintained diastolic flow velocity, was an inconsistent finding and often related to pregnancy complications other than intrauterine growth retardation. Among patients with small-for-gestational age fetuses or pre-eclampsia with a small-for-gestational age fetus, there was a significantly higher frequency of abnormal umbilical flow velocity waveforms. This was a consistent finding and was often associated with an absence of diastolic flow velocity and operative delivery for fetal distress. An abnormal non-stress test had a significant relationship with intrauterine growth retardation, but a lower predictive capacity for this condition than the abnormal umbilical artery flow velocity waveform. In patients with small-for-gestational age fetuses and no other complication of pregnancy, umbilical artery velocimetry can be used as a reliable tool for identifying those fetuses that need intensified surveillance. In cases with additional complications, a combined use of blood velocimetry and the non-stress test is advocated.

Transkranielle Doppler-Sonographie: Normwerte und physiologische Veränderungen

In 100 normal subjects mean flow velocity in the middle (MCA), anterior (ACA), and posterior (PCA) cerebral arteries and mean pulsatility index were examined by transcranial Doppler ultrasound. Age-dependent normal reference values were assessed. The measured parameters showed a large variation increasing with age. The highest flow velocities were found in the MCA, the lowest in the PCA. The highest mean side difference in flow velocity was observed in the ACA. An increase of pulsatility index and a decrease of flow velocities in all examined vessels were found with increasing age. The influence of ventilation and heart function on flow velocity and pulsatility index was demonstrated by the investigation of 10 normal subjects in different phases of ventilation and 1 patient with aortic valve insufficiency.

Influence of raising maternal blood pressure with angiotensin II on utero-placental and feto-placental blood velocity indices in the human

1. The effect of doubling doses of angiotensin II on maternal systemic blood pressure and arcuate and fetal umbilical artery Doppler velocity profiles has been investigated in 10 women in first- and 10 in second-trimester pregnancy. Ten non-pregnant women were also studied. 2. A progressive decrease in the pressor response to angiotensin II in early pregnancy as previously described was confirmed. 3. Angiotensin II induced a significant dose-dependent increase in the pulsatility index (a measure of downstream resistance) in the umbilical artery in both first- and second-trimester patients. There was an apparent increase in the threshold response of the pulsatility index to angiotensin II in the umbilical artery as pregnancy progressed. There was also a significant correlation between changes in maternal systolic or diastolic pressure and change in umbilical artery pulsatility index, but this did not differ between the two trimesters. This suggests that the increase in pulsatility index is related to blood pressure rather than angiotensin II. This is consistent with reports that angiotensin II does not cross the haemomonochorial placenta. 4. Basal pulsatility index in the arcuate artery fell with increasing gestation. There was a significant inverse association between the evoked change in maternal systemic blood pressure and the change in arcuate artery pulsatility index, suggesting local vasodilatation. 5. We conclude that acutely increasing maternal blood pressure leads to increased vascular resistance on the fetal side of the circulation.

Transcranial Doppler and real-time cranial sonography in neonatal hydrocephalus.

Nine hydrocephalic infants who were less than 1 year old and 7 age-matched control subjects were examined by real-time and transcranial Doppler sonography to evaluate cerebral blood flow and to correlate it to ventricular size. These 16 infants were placed in one of three groups: infants in group 1 (n = 7) had a normal ventricular size, infants in group 2 (n = 3) had a progressively increasing ventricular size, and infants in group 3 (n = 6) had ventriculomegaly with either stable or decreasing ventricular size or a functioning ventriculoperitoneal shunt. All scans performed on group-2 infants showed markedly increased ventricular size and increased pulsatility index, while those on group-1 infants showed a normal ventricular size and pulsatility index. However, the scans of group-3 infants revealed increased ventricular size and pulsatility index for all groups. Regression analysis of the data showed rather weak correlations between ventricular size and pulsatility index for all groups. The regression data suggest that ventricular size is not the main determinant of cerebral blood flow in the neonate with hydrocephalus and that intracranial pressure may be a more critical factor. These data suggest that pulsatility index, as measured by transcranial Doppler, can be clinically more important than just the anatomical data alone in the evaluation of hydrocephaly. This points to a possible use of transcranial Doppler sonography in the evaluation of hydrocephalic patients for placement of ventriculoperitoneal shunts.

The correlation of biochemical monitoring versus umbilical flow velocity measurements of the human fetus

The pulsatility index of the fetal umbilical arteries was evaluated in 14 high-risk pregnant patients delivered by cesarean section between 30 and 35 weeks of gestation. Transabdominal cord sampling by ultrasonic guidance was performed on 10 of these patients. Umbilical arterial and venous blood was obtained in all patients from the doubly clamped cord at the time of cesarean section. The blood samples were analyzed for respiratory gases, acid-base balance, and lactate concentrations. A significant relationship was found between the pulsatility index and pH, PCO2, and lactate concentrations measured on umbilical venous blood sampled in utero. The pulsatility index also correlated with the same variables measured on venous and arterial blood sampled at cesarean section. Umbilical venous blood obtained transabdominally had a significantly higher oxygen content than blood obtained at cesarean section. No significant correlation was found between umbilical venous oxygen content obtained at transabdominal cord sampling and the pulsatility index. At a pulsatility index > 1.5, lactate concentrations in umbilical venous blood increased sharply. There would appear to be a curvilinear relationship between umbilical blood flow and these indices of fetal oxygenation, such that moderate increases in pulsatility index were not associated with a significant increase in fetal lactate concentrations.

Digital and radial artery blood flow in patients with Raynaud's phenomenon in response to nifedipine

The effect of nifedipine on haemodynamic changes in the hand after cooling in 10 patients with Raynaud's phenomenon is assessed. Nifedipine reduced the fall in digit blood flow induced by cooling and limited the increase in pulsatility index (a measure of peripheral resistance). There was good correlation between digital arterial inflow (measured by strain gauge plethysmography) and radial artery pulsatility index (measured by Doppler waveform analysis).

Fetal blood flow velocity waveforms in relation to changing peripheral vascular resistance

In an acute experiment in Texel ewes, Doppler flow velocity waveforms from the fetal descending aorta were related to peripheral vascular resistance as calculated from perfusion pressure divided by electromagnetically measured volume flow in the descending aorta. Vascular resistance was increased by stepwise embolization of the peripheral circulation via repeated bolus administration of Sephadex G-25 microspheres. A rise in peripheral vascular resistance was associated with a reduction in peak and end-diastolic flow velocity and an increase in Pulsatility Index. Clinically, if similar changes are observed in growth retarded fetuses, the findings are usually interpreted to represent ‘uteroplacental insufficiency’. Present data provide direct evidence that raised peripheral vascular resistance does indeed produce such waveform changes.

THE USE OF CEREBRAL ARTERY PULSATILITY INDEX TO PREDICT NEUROLOGIC OUTCOME

Decreased blood flow velocity (increased pulsatility index, PI) in the anterior cerebral arteries (ACA) has been reported in preterm infants with intraventricular hemorrhage. From Feb. 1982 to Aug. 1983, we prospectively evaluated PI, cranial ultrasound and neurologic status (Sarnat Score), in 60 infants ⩽32 weeks gestation on days 1, 3 and 7 and then weekly until discharge, to determine their correlation with PI. PI was calculated from the tracings obtained by doppler ultrasound by the method described by Bada et al. Survival, neurologic status (Sarnat Score), cranial ultrasound, occurrence of seizures, and discharge neurologic examination (Parmalee exam) were assessed.Mean B.Wt. was 1151 grams (640-1750) and mean GA was 30.1 weeks (26-32). There were 31 males and 29 females. Mean Apgar Score at 1 minute was 4.7 and at 5 minutes was 6.6. Forty-two of the infants were inborn.The maximum PI recorded on day 1 correlated negatively with B.Wt. (p<0.05) and positively with mortality (p<0.06), occurrence of seizures (p<0.05) and development of hydrocephalus (p<0.06). There was no correlation between PI done at any time and GA, neurologic status (Sarnat Score), cranial ultrasound or discharge neurologic examination.Decreased cerebral blood flow velocity (high PI) is correlated with mortality, occurrence of seizures and later development of hydrocephalus. Follow-up of these infants is pending.

Intracranial pressure and cerebral arterial pulsatile flow measurements in neonatal intraventricular hemorrhage

We examined the clinical significance of noninvasive intracranial pressure measurements and pulsatility indices in 74 infants with confirmed IC-IVh. The intracranial pressure measurements were obtained using the applanation principle, and the pulsatility indices were calculated from the Doppler flow velocity tracings of the anterior cerebral artery. Fifty-three infants (71.6%) who died had a significantly lower birth weight and gestational age than those who survived. Survival rate decreased significantly with increased intracranial pressure (P less than 0.0002) and increased pulsatility indices (P less than 0.0001). We found no significant relationship between outcome and the size of IC-IVH demonstrated by CT scan. Birth weight, intracranial pressure measurements, and cerebral arterial pulsatile flow changes appear to be major prognostic indicators in neonatal IC-IVH.