Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction.
(73/963)
OBJECTIVE: The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR). METHODS: Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded. RESULTS: Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in fetuses with abnormal venous flows. The only statistically significant relation between Doppler indices and outcome was the association between abnormal ductus venosus flow and fetal death (r2 = 0.24, P < 0.05). CONCLUSION: Growth restricted fetuses with abnormal venous flow have worse perinatal outcome compared to those where flow abnormality is confined to the umbilical or middle cerebral artery. In fetuses with low middle cerebral artery pulsatility, venous Doppler allows detection of further deterioration. While abnormal venous flows can be significantly associated with fetal demise, gestational age at delivery significantly impacts on all short-term outcomes. (+info)
Fetal adrenal and middle cerebral artery Doppler velocimetry in high-risk pregnancy.
(74/963)
OBJECTIVES: Animal studies have shown that hypoxic fetuses redistribute their blood flow, giving preferential supply to the brain, heart and adrenal glands. The aim of this study was to establish whether blood velocity waveforms in the human fetal adrenal artery and middle cerebral artery showed signs of redistribution of fetal circulation in high-risk pregnancy, and to analyze the relationship between signs of such redistribution and the outcome of pregnancy. METHODS: Fetal middle adrenal artery and middle cerebral artery waveforms were recorded between 27 and 41 weeks of gestation in 102 pregnancies complicated by pregnancy-induced hypertension. Signs of fetal adrenal-sparing were deemed present when the pulsatility index (PI) fell below the fifth percentile of the normal range. Signs of fetal brain-sparing were deemed present when the cerebral artery PI was below the mean -2 SD of the normal range and the cerebroplacental PI ratio was < 1.08. RESULTS: Signs of adrenal sparing were found in 64 cases and brain sparing in 32 cases. Fetal adrenal sparing was strongly associated with adverse perinatal outcome; all perinatal mortality cases showed signs of adrenal sparing. There was a significant positive correlation between the fetal adrenal artery PI and umbilical arterial and venous pH. CONCLUSIONS: Signs of adrenal sparing are frequent in high-risk pregnancies. Adrenal artery velocimetry may be a useful procedure for fetuses at risk for hypoxemia. (+info)
Cerebrovascular reactivity and hypercapnic respiratory drive in diabetic autonomic neuropathy.
(75/963)
Because abnormalities in cerebrovascular reactivity (CVR) in subjects with long-term diabetes could partly be ascribed to autonomic neuropathy and related to central chemosensitivity, CVR and the respiratory drive output during progressive hypercapnia were studied in 15 diabetic patients without (DAN-) and 30 with autonomic neuropathy (DAN+), of whom 15 had postural hypotension (PH) (DAN+PH+) and 15 did not (DAN+PH-), and in 15 control (C) subjects. During CO(2) rebreathing, changes in occlusion pressure and minute ventilation were assessed, and seven subjects in each group had simultaneous measurements of the middle cerebral artery mean blood velocity (MCAV) by transcranial Doppler. The respiratory output to CO(2) was greater in DAN+PH+ than in DAN+PH- and DAN- (P < 0.01), whereas a reduced chemosensitivity was found in DAN+PH- (P < 0.05 vs. C). MCAV increased linearly with the end-tidal PCO(2) (PET(CO(2))) in DAN+PH- but less than in C and DAN- (P < 0.01). In contrast, DAN+PH+ showed an exponential increment in MCAV with PET(CO(2)) mainly >55 Torr. Thus CVR was lower in DAN+ than in C at PET(CO(2)) <55 Torr (P < 0.01), whereas it was greater in DAN+PH+ than in DAN+PH- (P < 0.01) and DAN- (P < 0.05) at PET(CO(2)) >55 Torr. CVR and occlusion pressure during hypercapnia were correlated only in DAN+ (r = 0.91, P < 0.001). We conclude that, in diabetic patients with autonomic neuropathy, CVR to CO(2) is reduced or increased according to the severity of dysautonomy and intensity of stimulus and appears to modulate the hypercapnic respiratory drive. (+info)
Umbilical and middle cerebral artery blood velocimetry: relationship with placental volume.
(76/963)
OBJECTIVE OF THE STUDY: To investigate the relationship between placental volume and the resistance of fetal arteries: umbilical and middle cerebral. MATERIAL AND METHODS: In 82 pregnant women with unaffected pregnancy between 14 and 40 weeks of gestation measurements of placental volume were made according to the parallel planimetric technique. Doppler examinations of umbilical and middle cerebral arteries were performed by means of a duplex system. RESULTS AND CONCLUSION: PI in the umbilical artery (PIUA) correlated significantly negatively with placental volume, whereas no significant correlation was found for the PI in the middle cerebral artery (PIMCA) and placental volume. Middle cerebral artery to umbilical artery PI ratio (PIMCA/PIUA ratio) showed significant positive correlation with placental volume. PIUA showed significant negative correlation with the relative volume of placenta (expressed as multiple of median for the actual gestational age) before 25 weeks of gestation and weak positive correlation with the relative volume of placenta after 25 weeks of gestation. PIMCA showed weak negative correlation with the relative volume of the placenta after 25 weeks of gestation and no correlation before 25 weeks. PIMCA/PIUA ratio showed significant positive correlation with relative placental volume before 25 weeks and significant negative correlation with relative placental volume after 25 weeks. (+info)
Severely impaired cerebrovascular reactivity predicts stroke and TIA risk in patients with carotid artery stenosis and occlusion.
(77/963)
Cross-sectional studies suggest that impaired cerebral haemodynamics is associated with symptomatic status in patients with carotid stenosis and occlusion, but there is relatively little prospective data confirming this association. Transcranial Doppler ultrasonography was used to determine the reactivity of the middle cerebral artery to 8% carbon dioxide in air in 107 patients with either carotid occlusion (n = 48) or asymptomatic carotid stenosis (n = 59). Subjects were followed prospectively until stroke, transient ischaemic attack (TIA), death or study end. Mean duration of follow-up was 635 days. No patients dropped out due to operation before an end-point was reached, or were lost to follow-up. There were 11 ipsilateral ischaemic events during follow-up (six strokes, five TIAs). Exhausted ipsilateral middle cerebral artery reactivity (>20% increase in ipsilateral middle cerebral flow velocity in response to 8% carbon dioxide) predicted ipsilateral stroke and TIA risk in the whole group (P: < 0.00001) and in the carotid occlusion (P: = 0.019) and carotid stenosis (P: = 0.015) groups alone. It also predicted the risk of ipsilateral stroke alone in all three groups. Cox regression was performed, controlling for age, gender, hypertension, diabetes, smoking, ipsilateral CT infarct, degree of contralateral stenosis and the presence of ipsilateral stenosis versus occlusion. Exhausted reactivity remained an independent predictor of ipsilateral stroke and TIA (odds ratio 14.4, 95% confidence interval 2.63-78.74, P: = 0.0021). In contrast, the pulsatility index of the middle cerebral artery was a poor predictor of the risk of stroke. Reactivity to 6% carbon dioxide also predicted the risk of stroke and TIA, but slightly less effectively than reactivity to 8% carbon dioxide. Severely reduced cerebrovascular reactivity predicts the risk of ipsilateral stroke and TIA in patients with carotid occlusion, and to a lesser extent in asymptomatic carotid stenosis. Particularly in the former group, a study is required to determine whether revascularization reduces the risk of stroke in patients with exhausted reactivity. (+info)
Reference values of fetal peak systolic blood flow velocity in the middle cerebral artery at 19-40 weeks of gestation.
(78/963)
OBJECTIVES: The objectives of this prospective study were (i) to establish new reference values of peak systolic blood flow velocity measurement in the fetal middle cerebral artery (MCA-PSV) following validated methodological guidelines and (ii) to develop a method to calculate Z-scores of MCA-PSV. PATIENTS AND METHODS: Cross-sectional data were obtained from 331 pregnant women between 19 and 40 weeks' gestation. Reference ranges for MCA-PSV were constructed and for each measurement linear regression models were fitted separately to the mean and standard deviations (SD) as a function of gestational age. An application to calculate Z-scores was developed. A comparison was made between the reference ranges produced in our study and those of a previous one. RESULTS: A new chart, table of centiles and regression equations of MCA-PSV are presented. Comparison of our reference ranges with ones produced in a previous study showed similar 5th centile values. However, the values for the 50th and 95th centiles between 19 and 28 gestational weeks were lower in our study. CONCLUSIONS: We have constructed reference ranges for MCA-PSV which, because they are derived from a larger number of examinations in the 15-20-week period and because the methodological flaws of the previously published study have been eliminated, we consider to be more accurate and therefore more useful for clinical practice. (+info)
Growth of occult arteriovenous malformation after cerebral hemorrhage demonstrated by serial magnetic resonance imaging--case report.
(79/963)
A 19-year-old male presented with sudden onset of right hemiparesis caused by left cerebral hemorrhage. Cerebral angiography demonstrated no vascular abnormality, and the hematoma was removed surgically. At operation, no abnormal vascular lesion was found in the brain adjoining the hematoma. Two years later, magnetic resonance (MR) imaging demonstrated a few foci of flow voids adjacent to the hematoma cavity. Four years after the hemorrhage, MR imaging showed more extensive flow-void abnormalities that indicated growth of an occult arteriovenous malformation (AVM). Cerebral angiography indicated a definite AVM supplied mainly by branches of the middle cerebral artery. Total resection of this lesion was performed. The histological diagnosis was typical AVM. Immunohistochemistry with vascular endothelial growth factor showed staining in the walls of the abnormal vessels. Serial MR imaging is very useful for the diagnosis and management of occult AVMs. (+info)
Direct, longitudinal comparison of (1)H and (23)Na MRI after transient focal cerebral ischemia.
(80/963)
BACKGROUND AND PURPOSE: (23)Na MRI may offer new insight into the evaluation of tissue injury. We performed a direct, longitudinal, morphological comparison of (1)H T2 relaxation, (1)H apparent diffusion coefficient (ADC), (23)Na content, and histopathology after cerebral ischemia to address the hypotheses that (a) (23)Na MRI is unique in comparison to (1)H MRI, and (b) accumulation of (23)Na is an unambiguous marker for dead tissue. METHODS: Rats underwent 30 minutes of focal ischemia. MRIs of (1)H T2, (1)H ADC, and (23)Na content were acquired from 12 hours up to 1, 2, or 14 days after reperfusion. On excision, brains were stained with triphenyltetrazolium chloride (TTC). RESULTS: In all cases, the region of abnormality increased in size for 2 days. On day 5, both (1)H T2 and ADC temporarily appeared normal despite the presence of TTC-defined infarction. By comparison, the volume of tissue exhibiting abnormally intense (23)Na signal mirrored the TTC-defined infarct at all time points. CONCLUSIONS: Regions of high (23)Na content correlate well with the TTC-defined infarct and may be a quantitative in vivo marker for dead tissue. In contrast, the dynamics of the (1)H T2 and ADC make it difficult to interpret these images without additional information because they may appear normal despite infarction. Neither type of (1)H image delineates dead tissue, and none of these methods predicts the potential infarct size at early time points. (+info)