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A Matias

Publications and source records attributed to A Matias.

36 records · Page 2Linked to original sources
PubMed1998

Screening for chromosomal abnormalities at 10-14 weeks: the role of ductus venosus blood flow.

OBJECTIVE: To assess the possible role of Doppler ultrasound assessment of ductus venosus blood flow in screening for chromosomal abnormalities at 10-14 weeks of gestation. METHODS: Ductus venosus flow velocity waveforms were obtained immediately before fetal karyotyping in 486 consecutive singleton pregnancies at 10-14 weeks of gestation. All cases were screened for chromosomal defects by a combination of maternal age and fetal nuchal translucency thickness. The peak systolic and diastolic velocities, the velocity during atrial contraction and the pulsatility index were measured. RESULTS: There were 63 chromosomal defects (38 cases of trisomy 21, 12 cases of trisomy 18, seven cases of trisomy 13, three cases of Turner's syndrome and three cases of triploidy). In 57 (90.5%) cases there was reverse or absent flow during atrial contraction. Abnormal ductus venosus flow was also observed in 13 (3.1%) of the 423 chromosomally normal fetuses. In the chromosomally abnormal group, compared to the normal group, the median heights of the S and D waves were significantly lower and the pulsatility index was significantly higher. However, multivariate regression analysis demonstrated that only the height of the A wave provided a significant independent contribution in distinguishing between the chromosomally normal and abnormal groups. CONCLUSION: These preliminary results suggest that assessment of ductus venous blood flow in pregnancies considered to be at high risk for chromosomal defects may result in a major reduction in the need for invasive testing, with only a small decrease in sensitivity.

Adolescent↗
PubMed1998

Venous return and right ventricular diastolic function in ARED flow fetuses.

The absence or reversal of end-diastolic flow in the umbilical artery (UA) is widely accepted as an ominous sign of fetal compromise. However, in these high-risk pregnancies, the significance of sequentially appearing changes of the venous return is poorly established. Doppler blood flow waveforms were longitudinally assessed in the inferior vena cava (IVC), ductus venosus (DV), umbilical vein (UV) and tricuspid valve, along with the UA, middle cerebral artery and descending aorta. Thirty-two serial Doppler studies were performed in six fetuses with intrauterine growth-retardation (IUGR). In the cases of absent or reversed UA endodiastolic flow, changes in the venous return were found following the same sequence: presence of dicrote pulsations in the UV, increase of retrograde flow in the IVC and reduction or inversion of DV velocity during atrial contraction. Transtricuspid flow patterns changed from normal to a restrictive pattern of ventricular filling. There were two intrauterine deaths and one early neonatal death. Our preliminary results suggest that the evaluation of the venous compartment of hemodynamically disturbed preterms fetuses along with right ventricular filling appears to be a useful model for investigating the physiopathology of fetal deterioration and, therefore, may yield indirect discriminatory signs of severe compromise.

Adult↗
PubMed1997

Ductus venosus revisited: a Doppler blood flow evaluation in the first trimester of pregnancy.

The functional role of the fetal ductus venosus (DV) is still poorly established. Few reports are available in the literature concerning assessment of fetal venous return during the late first trimester of pregnancy. Our objective was to determine the normal Doppler blood velocity waveform in the human fetal DV as early as 10-13 weeks gestation. Adopting strict methodological concerns, 61 Doppler blood flow evaluations of the DV considered technically acceptable were selected. Using transvaginal Doppler ultrasound, several DV haemodynamic parameters were assessed: peak systolic and diastolic velocities, time-averaged velocity, maximum velocity during atrial contraction, pulsatility index and fetal heart rate (FHR). Except for the FHR, no significant variations were observed for the above mentioned parameters during this period, and no correlation could be established between FHR and the different flow velocity parameters. Further knowledge about DV haemodynamics in the early phases of pregnancy may make a valuable contribution to the understanding of fetal venus return to the heart and cardiac function.

Blood Flow Velocity↗
PubMed1997

Increased fetal nuchal translucency: possible involvement of early cardiac failure.

The ultrasonographic measurement of nuchal translucency thickness at 10-13 weeks of gestation is accepted as an efficient method of screening for chromosomal abnormalities. However, the underlying mechanism producing increased nuchal translucency thickness is still poorly understood. The purpose of this study was to investigate the possible contribution of impaired cardiac function to such an increase, by studying the venous return in the ductus venosus, using Doppler ultrasound. In a total of 65 fetuses, nuchal translucency thickness was measured at 10-13 weeks of gestation by means of a transvaginal probe. Color-coded and pulsed Doppler ultrasound were also used to evaluate different hemodynamic parameters in the ductus venosus: maximum systolic and diastolic velocities, pulsatility index, lowest forward velocity during atrial contraction and fetal heart rate. Fetal nuchal translucency thickness of > or = 3 mm was found in 17 cases; in five of them there were chromosomal anomalies: four trisomy 21 and one trisomy 18. Of interest is the finding that in the five chromosomally abnormal fetuses with increased nuchal translucency thickness, the forward velocity during atrial contraction was consistently less than 2 cm/s (p < 0.001). This impairment of atrial contraction may well implicate cardiac failure and/or heart defects in the pathogenesis of increased nuchal translucency thickness in the first trimester of pregnancy. Furthermore, nuchal translucency may prove to be a sensitive marker for the early identification of fetal cardiac anomalies.

Blood Flow Velocity↗
PubMed1995

Constriction of the fetal ductus arteriosus during prenatal betamethasone therapy.

BACKGROUND: Constriction of the fetal ductus arteriosus occurs with maternal indomethacin treatment and has been suggested with corticosteroid therapy as well. CASE: Fetal ductal constriction was diagnosed by Doppler echocardiography at 29 weeks' gestation after a third and fourth course of betamethasone was administered to a pregnant woman with placenta previa. Doppler echocardiography showed a patent ductus arteriosus 3 days after the treatment. CONCLUSION: The risk-benefit ratio of betamethasone should be assessed by large-scale studies when repeated courses or chronic maternal administration of betamethasone are required.

Adult↗
PubMed1993

Affinity of central adenosine A1 receptors is decreased in spontaneously hypertensive rats.

Functional defects in purinergic neurotransmission have been related to the development of arterial hypertension in spontaneously hypertensive rats. In order to elucidate the molecular basis of this perturbation, we have directly characterized adenosine A1 receptors using radioligand binding to rat brain membranes of Wistar Kyoto (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). Saturation studies with [3H]1,3-dipropylcyclopentylxanthine ([3H]DPCPX) showed a lower affinity in both 5- and 48-week-old SHRSP in comparison with age-matched WKY. Similarly, competition experiments with [3H]DPCPX showed lower affinity of R-N6-phenylisopropyladenosine for the low-affinity binding site in 5- and 48-week-old SHRSP in comparison with WKY. In both studies, the difference in KD values was abolished by guanosine-5'-triphosphate in 5-week-old rats and mitigated in 48-week-old animals. No differences in Bmax values were observed in 5-week-old rats, whereas in 48-week-old SHRSP the number of receptors was significantly higher in comparison with age-matched WKY. Saturation experiments with the A1-selective agonist [3H]2-chloro-N6-cyclopentyladenosine ([3H]CCPA) demonstrated a higher affinity in 5-week-old SHRSP, whereas in 48-week-old hypertensive animals it was lower than in control WKY rats. No difference in receptor number was detected in comparison with age-matched WKY. In conclusion, our data demonstrated a diminished affinity of central adenosine A1 receptors for antagonists and for the low affinity state of the agonist binding site in genetically hypertensive rats. This might be due to structural changes of the receptor protein, to an altered G protein or defective receptor-G protein coupling in arterial hypertension.

Adenosine↗
PubMed1993

Neurotoxicity and induction of fibroblast proliferation by acetaldehyde in the rabbit liver.

1. Acetaldehyde may, directly or through the formation of condensation products with biogenic amines, be involved in the pathogeny of alcoholic disease. 2. Rabbits were treated acutely (200 mg kg-1, i.p., 1 h before sacrifice) or subacutely (200 mg kg-1 per day, during 5 days; sacrificed 2 days after end of treatment) with acetaldehyde. Another group was administered 6-OHDA (2 x 50 mg kg-1 on day 0 and on day 1, killed on day 5). 3. Acetaldehyde induced a depletion of hepatic noradrenaline. Both in the acute experiments and 2 days after the subacute treatment with acetaldehyde the levels of hepatic noradrenaline were 25% of control. These effects were similar to, but less intense than those induced by 6-OHDA. 4. Both subacute acetaldehyde and 6-OHDA led to a significant increase in the density of fibroblasts in the portal tract spaces of the rabbit liver. 5. The neurotoxic effects of acetaldehyde and the subsequent increase in liver fibroblast density may play a role in the pathogenesis of alcoholic disease.

Acetaldehyde↗
PubMed1991

Long-term administration of 1,3-dipropyl-8-sulfophenylxanthine causes arterial hypertension.

Adenosine has been shown recently to be the main factor responsible for the trophic effects of sympathetic innervation. As sympathetic denervation causes hypertrophic and hyperplastic changes reminiscent of those occurring in blood vessels of spontaneously hypertensive rats, we decided to study the effect of a continuous blockade of adenosine receptors on both blood vessel structure and blood pressure. A continuous infusion of 1,3-dipropyl-8-sulfophenylxanthine (DPSPX; 30 micrograms/kg per h for 7 days) to Wistar rats caused hyperplastic changes in peritoneal fibroblasts and mesenteric arterioles, hypertrophic changes in the smooth muscle of the tail artery and significant increase in the size of left ventricle myocardial cell nuclei. Both diastolic and systolic blood pressure increased significantly above control values. The results confirmed the trophic effects of adenosine and showed that chronic blockade of adenosine receptors causes arterial hypertension.

Adenosine↗
PubMed1990

Effects of sympathetic denervation on liver fibroblasts: prevention by adenosine.

1. The effect of chemical denervation with 6-hydroxydopamine (6-OHDA) upon portal tract fibroblasts of dogs and rabbits was studied. 2. Denervation led to a significant increase in the density of portal tract fibroblasts both in the dog and in the rabbit. 3. Mast cells, present in the dog but not in the rabbit liver, were also significantly increased by denervation. 4. Noradrenaline depletion induced by reserpine did not increase the density of fibroblasts in the liver portal spaces of the dog. Mast cell density, however, was actually decreased when compared with control. 5. Continuous i.v. infusions of adenosine (10 micrograms kg-1h-1) to dogs totally prevented the effects of 6-OHDA-induced denervation upon fibroblast and mast cell densities in the portal space connective tissue. 6. It is concluded that the sympathetic nervous system is exerting a repressive effect on liver fibroblasts, as was found to occur in various other mammalian tissues. Mast cells, which are known to be activated in various pathological processes of fibrosis, appear to share with fibroblasts a modulating effect from the sympathetic nervous system. 7. The results strongly support the hypothesis of adenosine being the sympathetic trophic factor involved in the control of fibroblasts in the connective tissue of dog liver. A similar role for adenosine had previously been found in the dog saphenous vein.

Adenosine↗
PubMedDate not supplied

Haemodynamic evaluation of the first trimester fetus with special emphasis on venous return.

Knowledge of the fetal circulation is a prerequisite for understanding the physiological behaviour of the developing fetus. In this overview dealing with Colour and Power Doppler ultrasound findings in the first trimester of pregnancy and its pathophysiological background, we aim to report on the methodological aspects, normal blood flow waveform patterns, normal reference values for haemodynamic parameters and potential clinical applications for both arterial and venous flow information (umbilical artery, descending aorta, middle cerebral artery, umbilical vein, inferior vena cava, ductus venosus) and atrioventricular valves. Particular emphasis is devoted to the venous return to the heart. Alterations in venous waveforms, particularly in the ductus venosus, are correlated with the pathophysiology of some fetal diseases and are suggested as a promising tool for the screening of cardiac impairment and as an alternative method for fetal biophysical surveillance.

Arteries↗
PubMedDate not supplied

Early antenatal diagnosis of cardiac defects using transvaginal Doppler ultrasound: new perspectives?

OBJECTIVE: Cardiac defects are the most prevalent congenital anomalies. Screening policies have adopted an 18- to 22-week ultrasound scan to detect such anomalies. However, diagnosis may be feasible early in pregnancy using transvaginal Doppler ultrasound. METHODS: Transvaginal ultrasound, including nuchal translucency (NT) measurement, is routinely performed at 10-13 weeks of gestation at our department. Complementary arterial and venous blood flow Doppler evaluation is also performed in cases of increased NT as a part of an ongoing research project. RESULTS: Ultrasound revealed complete atrioventricular septal defects in 2 trisomic fetuses (trisomy 18 and 21) at 12 and 13 weeks of gestation, respectively, with increased NT and abnormal venous blood flow velocity. CONCLUSIONS: Increased NT has been associated with major chromosomal anomalies and is being increasingly related to cardiac defects. Considering that venous blood flow patterns may provide additional clues to the cardiac function, it may be useful as a complementary tool for the earlier diagnosis of structural cardiac anomalies.

Adult↗