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Biomedical subjects

G Rizzo

Publications and source records attributed to G Rizzo.

At least 127 records · Page 7Linked to original sources
PubMed1995

Cardiac flow after fetal blood sampling in normally grown and growth-retarded fetuses.

The objective of this study was to evaluate the effect of fetal blood sampling on cardiac flow velocity waveforms. Flow velocity waveforms were measured from the ascending aorta and pulmonary artery immediately before and after fetal blood sampling in 29 normally grown and 12 growth-retarded fetuses. The latter group was characterized by abnormal Doppler indices in the umbilical artery and middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were the peak velocity, the time to peak velocity, and the left and right cardiac output and their ratio. In normally grown fetuses, the peak velocity and right and left cardiac output values increased significantly after fetal blood sampling, while no significant changes were observed in the other indices considered. The gestational age at the time of the procedure was positively related to the amplitude of these changes. In growth-retarded fetuses, fetal blood sampling did not induce any significant increase in cardiac output or peak velocities, while in more than 50 per cent of the fetuses these Doppler indices decreased. The amplitude of the decrease was significantly related to the severity of acidosis in the umbilical vein. In conclusion, the cardiac haemodynamic response to fetal blood sampling differs between normally grown and growth-retarded fetuses. This difference may explain the higher rate of complications occurring in the latter group of fetuses after blood sampling.

Blood Flow Velocity↗
PubMed1995

An elastic computerized brain atlas for the analysis of clinical PET/SPET data.

An elastic computerized brain atlas was developed for the analysis of positron emission tomography/single-photon emission tomography (PET/SPET) data. It consists of a set of digital anatomical contours and a template of regions of interest, schematically describing the brain, derived from a currently used anatomical/functional brain atlas. A warping algorithm, matching equivalent contours, was implemented to elastically fit the atlas to individual brain images. The elastic computerized brain atlas was applied to representative magnetic resonance imaging (MRI)-PET/SPET studies, MRI providing the anatomical information used by the matching procedure. The atlas is suited for clinical use in a nuclear medicine environment.

Brain↗
PubMed1995

Spatial registration of echocardiographic and positron emission tomographic heart studies.

A method has been developed to match corresponding heart regions from functional echocardiographic (Echo) and metabolic fluorine-18-fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography (PET) studies in individual patients. Echo and PET images are spatially correlated by determining homologous anatomical landmarks (the two papillary muscles and the inferior junction of the right ventricle), identifiable in images obtained by both acquisition modalities. Echo-PET image registration is first performed in the plane identified by the three landmarks, using a rigid rotate-translate scale model. The registration parameters are then used to transform the whole PET volume. This allows a consistent Echo-PET regional analysis, according to a segmental subdivision of the heart. The technique was tested on patients. The overlay of Echo and PET registered images proved the reliability of realignment of the three markers and a good spatial correlation of myocardial walls. This approach to image registration could be applied to other acquisition modalities (such as magnetic resonance imaging and single-photon emission tomography), provided that the three anatomical landmarks are visualized.

Deoxyglucose↗
PubMed1995

Cardiac and venous blood flow in fetuses of insulin-dependent diabetic mothers: evidence of abnormal hemodynamics in early gestation.

OBJECTIVE: Our purpose was to determine whether in early gestation cardiac and venous blood flow patterns of fetuses of insulin-dependent diabetic mothers differ from those of normal fetuses. STUDY DESIGN: Serial recordings were obtained at 12, 16, and 20 weeks of gestation in 11 normal fetuses, 16 fetuses of insulin-dependent diabetic mothers with first-trimester glycosylated hemoglobin levels < or = 8.5% (group 1), and 11 fetuses of insulin-dependent diabetic mothers with first-trimester glycosylated hemoglobin levels > 8.5% (group 2). Velocity waveforms at the level of atrioventricular valves, inferior vena cava, and umbilical vein were recorded by means of color and pulsed Doppler equipment by either transvaginal or transabdominal approaches. The following variables were measured: ratio between the peak velocities during early passive ventricular filling and active atrial filling at the level of atrioventricular valves, percent reverse flow during atrial contraction in inferior vena cava, and pulsations in umbilical vein. RESULTS: In all the fetuses the ratios between early and active ventricular filling increased linearly with advancing gestation, whereas the percent reverse flow in the inferior vena cava decreased linearly. However, fetuses of diabetic mothers showed significant differences in the slope of the functions describing the development with gestation of these index values, resulting in lower values of the ratios between early and active ventricular filling at the level of both ventricular valves and higher values of percent reverse flow in inferior vena cava. These differences were more evident in group 2 fetuses of diabetic mothers, and statistically significant differences were found in the slope values compared with group 1 fetuses. In normal fetuses umbilical vein pulsations were present only in two fetuses at 12 weeks of gestation (18.18%) and were never evidenced later in gestation. A significantly higher incidence of pulsations was found at 12 weeks in fetuses of diabetic mothers (group 1, 56.25%; group 2, 81.81%) and pulsations were present until 16 weeks (group 1, 37.5%; group 2, 45.47%). CONCLUSIONS: An impaired development of cardiac and venous blood flow patterns occurs in fetuses in insulin-dependent diabetic mothers. These abnormalities are more evident in pregnancies with poorer glycemic control but still occur in the presence of stricter metabolic control.

Adult↗
PubMed1995

The effects of fetal blood sampling on ductus venosus blood flow velocity waveforms.

The objective of this study was to evaluate the effect of fetal blood sampling on ductus venosus hemodynamics. A secondary objective was to establish the relationship between the amplitude of these changes, if any, and different variables related either to the procedure of sampling or to fetal characteristics. The ratio was assessed between the systolic and atrial velocities from the ductus venosus that were measured immediately before and immediately after fetal blood sampling in 32 appropriately grown fetuses and in 12 growth-retarded fetuses. The latter group was characterized by abnormal Doppler indices in the umbilical artery and the middle cerebral artery, suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The systolic/atrial ratio fell significantly after fetal blood sampling, but this decrease was less evident in growth-retarded fetuses. Neither the site of needling (placental cord insertion or intrahepatic vein) nor transplacental puncture during the procedure affected this decline. Similarly, fetal smallness, the volume of fetal blood aspirated and baseline values in Doppler indices from the ductus venosus and middle cerebral artery were unrelated to the observed changes. Stepwise regression analysis indicated that the variables that most significantly and independently affect the decline of the Doppler index were gestational age at the time of the procedure and pO2 values in the umbilical vein. In conclusion, modifications in ductus hemodynamics are induced by fetal blood sampling. These changes are less evident in hypoxemic growth-retarded fetuses and this reduced hemodynamic response may explain the higher rate of complications occurring in such fetuses after blood sampling.

Blood Flow Velocity↗
PubMed1995

Ventricular ejection force in growth-retarded fetuses.

The objective of this study was to determine whether in growth-retarded fetuses secondary to uteroplacental insufficiency the cardiac ventricles exert a force different from that of appropriately grown fetuses. Doppler echocardiographic studies were performed in 156 appropriately grown fetuses (gestational age 18-38 weeks) and in 72 growth-retarded fetuses (gestational age 24-36 weeks) free from structural and chromosomal abnormalities and characterized by Doppler changes in the umbilical artery and middle cerebral artery suggesting uteroplacental insufficiency as the most likely etiology of the growth defect. Right and left ventricular ejection force values were calculated from velocity waveforms recorded at the level of aortic and pulmonary valves, according to Newton's second law of motion. In appropriately grown fetuses, left and right ventricular ejection force values significantly increased with advancing gestation and the two ventricles exerted similar force. In growth-retarded fetuses, the ventricular ejection force was significantly and symmetrically decreased in both ventricles. Among growth-retarded fetuses, a poorer perinatal outcome was observed in those fetuses in which the ejection force of both ventricles was below the 5th centile of the normal limits for gestation. In 12 growth-retarded fetuses followed longitudinally during the last week preceding intrauterine death or Cesarean section due to antepartum heart-rate late decelerations, a significant decrease of ejection force was found in both ventricles. Finally, a significant relationship was found between the severity of acidosis and right and left ventricular ejection force values in 22 fetuses in which Doppler recordings were performed immediately before cordocentesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1995

Effects of thyrotropin releasing hormone on cardiac and extracardiac flows of appropriately grown and growth-retarded fetuses.

The objective of this study was to establish the effect of thyrotropin releasing hormone on the fetal circulation of appropriately grown and growth-retarded fetuses. Doppler recordings were performed immediately before and 15 min after maternal administration of 400 micrograms of thyrotropin releasing hormone in 14 women with appropriately grown and 19 with growth-retarded fetuses. Furthermore, in six women with growth-retarded fetuses, serial recordings were performed at 2-hourly intervals for 8 h until a second thyrotropin releasing hormone dose was administered. Velocity waveforms were recorded from the outflow tracts, inferior vena cava, umbilical artery, middle cerebral artery and descending aorta, and different Doppler indices calculated. In appropriately grown fetuses, thyrotropin releasing hormone induced a significant increase of peak systolic velocity values in the aorta and pulmonary artery and an increase of Doppler-estimated cardiac output. In growth-retarded fetuses, these changes were more evident and associated with a significant decrease in reverse flow in the inferior vena cava during atrial contraction. No changes were observed in fetal heart rate or in the other fetal vessels investigated. In the growth-retarded fetuses followed longitudinally, these changes were evident for the following 8 h and were potentiated by the second thyrotropin releasing hormone administration. In conclusion, thyrotropin releasing hormone induces significant hemodynamic effects on the fetal heart that may temporarily improve the impaired cardiac function of growth-retarded fetuses.

Adult↗
PubMed1995

Prenatal diagnosis of gastroesophageal reflux by color and pulsed Doppler ultrasonography in a case of congenital pyloric atresia.

A case of pyloric atresia diagnosed in the third trimester is described. Real-time ultrasonographic examination revealed polyhydramnios, enlarged stomach, evident gastric peristalsis and esophageal dilatation. Color and pulsed Doppler studies of the gastroesophageal junction revealed the presence of a biphasic flow pattern that was consistent with gastroesophageal reflux.

Adult↗
PubMed1995

Application of a surface matching image registration technique to the correlation of cardiac studies in positron emission tomography (PET) by transmission images.

The aim of this work is to assess the accuracy of a surface matching registration (SMR) technique for the correlation of cardiac studies in positron emission tomography (PET). Registration parameters were estimated by matching corresponding body surfaces, extracted from transmission studies, aligned to the PET emission images to be correlated. The accuracy of the SMR technique in this specific application was assessed by computer simulations, phantom experiments and on clinical PET data. Registration accuracy was evaluated in relation to the body surfaces (external, internal and the combination of the two) used by the SMR method. Better results were found when matching shaped and irregular surfaces such as internal lung contours. The robustness of the method was verified for different counting statistics recorded in transmission images. A clinical validation of the SMR method was performed on fluorine-18-deoxyglucose PET cardiac studies.

Computer Simulation↗
PubMed1995

The value of fetal arterial, cardiac and venous flows in predicting pH and blood gases measured in umbilical blood at cordocentesis in growth retarded fetuses.

OBJECTIVE: To assess the value of Doppler indices, calculated from fetal arterial peripheral vessels, cardiac outflow tracts and venous vessels, in the identification of acidaemia, hypercapnia and hypoxaemia as determined by pH and gas analysis of fetal blood obtained by cordocentesis in growth retarded fetuses. DESIGN: Doppler measurements were taken from umbilical artery, thoracic descending aorta, renal artery, middle cerebral artery, cardiac outflow tracts, inferior vena cava and ductus venosus immediately before cordocentesis. Logistic regression and receiver-operator characteristic curve analysis were performed to examine the relation between Doppler indices and acid-base status. SETTING: Tertiary centre for fetal medicine. SUBJECTS: Forty-eight growth retarded fetuses fulfilling these criteria for inclusion: 1. absence of chromosomal and structural anomalies; 2. an abdominal circumference or ultrasonographic estimated fetal weight less than the 5th centile; 3. presence of abnormal velocity waveforms in umbilical artery; and 4. postnatal confirmation of a birthweight below the 5th centile and absence of structural anomalies. RESULTS: The percentage of reverse flow in inferior vena cava was a more closely related variable for acidaemia (chi 2 = 29.69; P < or = 0.001) and hypercapnia (chi 2 = 12.86; P < or = 0.001) than the other Doppler indices. Hypoxaemia was better predicted by the pulsatility index from middle cerebral artery (chi 2 = 15.31; P < or = 0.001). CONCLUSION: The analysis of velocity waveforms from inferior vena cava and middle cerebral artery can be used to predict acid-base status in growth retarded fetuses secondary to placental insufficiency. This may lead to a more accurate antepartum monitoring of such fetuses.

Acidosis↗
PubMed1995

Umbilical vein pulsations and acid-base status at cordocentesis in growth-retarded fetuses with absent end-diastolic velocity in umbilical artery.

The objective of this study was to examine the acid-base status in blood obtained at cordocentesis in growth-retarded fetuses with absent end-diastolic velocity in the umbilical artery and divided according to the presence or absence of pulsations in the umbilical vein. Twenty-six growth-retarded fetuses free from structural and chromosomal abnormalities were considered for this study. All the fetuses had absent end-diastolic velocity in the umbilical artery associated in 11 cases (42.3%) with pulsations in the umbilical vein. Gas analysis of fetal blood obtained by cordocentesis was performed immediately after the Doppler recordings. Hypoxemia, acidemia and hypercapnia were defined respectively as the presence of pH or pO2 values 2 standard deviations below the normal mean for gestation and of pCO2 values 2 standard deviations above the normal mean for gestation. Fetuses with umbilical vein pulsations had lower values of pH (p < or = 0.001) and pO2 (p < or = 0.05) and higher values of pCO2 (p < or = 0.001) when compared to those without pulsations. All fetuses with pulsations were hypoxemic and hypercapnic and the incidence of acidemia was 90.9%. Fetuses with continuous blood flow in the umbilical vein, although frequently hypoxemic (80%), have pCO2 and pH values within the normal range in 40 and 52.3% of the cases, respectively. In conclusion, in fetuses with absent end-diastolic velocity in the umbilical artery the presence of umbilical vein pulsations identifies a subgroup of fetuses with a more severe compromise of acid-base status. This may be useful in the selection of the timing of delivery of such fetuses.

Blood Flow Velocity↗
PubMed1995

Performance of Doppler ultrasonography as a screening test in low risk pregnancies: results of a multicentric study.

To assess the efficacy of the Doppler velocimetry of the uterine and umbilical arteries as a screening test for preeclampsia and fetal growth retardation, we studied 916 low risk pregnancies. The S/D ratios of the uterine and umbilical arteries were obtained at 19 to 24 weeks and at 26 to 31 weeks of gestational age. Mean values, receiver operator curves, and the diagnostic accuracy of the tests were calculated for the following end-points: (1) pregnancy-induced hypertension, (2) low birth weight for gestational age, (3) small for gestational age with abnormal outcome, (4) pregnancy-induced hypertension needing preterm delivery. The prevalences for these outcomes were 3.4%, 4.6%, 1%, and 0.7%, respectively. The study was blinded. The umbilical and uterine artery S/D ratios were significantly higher in the abnormal than in the normal outcome group. When uterine arteries were studied at 19 to 24 weeks, sensitivity was 59% in the detection of pregnancy-induced hypertension, 11% in the detection of small for gestational age fetuses, 33% in the detection of small for gestational age fetuses with abnormal outcome, and 83% in the detection of pregnancy induced hypertension needing preterm delivery; the corresponding values for specificity were 69%, 94%, 94%, and 68%. At 26 to 31 weeks the sensitivity values were respectively, 69%, 58%, 75%, and 100% and specificity values were 80%, 59%, 39%, and 79%. When umbilical arteries were studied at 19 to 24 weeks, sensitivity was 38% in the detection of pregnancy-induced hypertension, 46% in the detection of small for gestational age fetuses, 78% in the detection of small for gestational age fetuses with abnormal outcome, and 67% in the detection of pregnancy-induced hypertension needing preterm delivery. The corresponding values of specificity were 74% for all four groups. At 26 to 31 weeks the sensitivity values were 38%, 43%, 87%, and 67%, respectively, and specificity values were 80% for all four groups. We concluded that Doppler examinations of the uterine and umbilical arteries can detect, at midpregnancy, the severe forms of pregnancy-induced hypertension and small for gestational age fetuses but they cannot be used to screen a low risk population in which the prevalence of the disease is low, and hence the positive predictive value is low.

Adult↗
PubMed1994

Ductus venosus velocity waveforms in appropriate and small for gestational age fetuses.

The objective of this study was to evaluate differences in ductus venosus velocity waveforms between appropriate and small for gestational age fetuses by using a new index based on the ratio between systolic and atrial peak velocities. Ductus venosus velocity waveforms were cross-sectionally recorded in 164 appropriate for gestational age fetuses at 16-42 weeks of gestation and in 97 small for gestational age fetuses free from structural and chromosomal abnormalities between 24-36 weeks of gestation. Small for gestational age fetuses were divided according to the Doppler findings in arterial peripheral vessels: group A (n = 33), normal ratio between umbilical artery and middle cerebral artery Pulsatility Indices; group B (n = 41), umbilical artery/middle cerebral artery ratio > 95th centile but presence of end diastolic flow in umbilical artery; group C (n = 23), umbilical artery/middle cerebral artery ratio > 95th centile and absence of end diastolic flow in umbilical artery. Eighteen small for gestational age fetuses (10 from group B and 8 from group C) were also serially studied until delivery due to fetal distress. Ductus venosus velocity waveforms were recorded at the level of its origin from umbilical vein and the ratio between systolic and atrial peak velocities (systolic/atrial ratio) calculated. In appropriate for gestational age fetuses, systolic/atrial ratio values significantly decrease with gestation. No significant differences were found in systolic/atrial ratio between appropriate for gestational age fetuses and group A small for gestational age fetuses while, after correction for gestational age, significantly higher values were found in group B (P < or = 0.01) and group C (P < or = 0.001) fetuses. Among these fetuses, those with systolic/atrial ratio above the 95th confidence interval showed a poorer perinatal outcome. No relationships were found between systolic/atrial ratio and Pulsatility Index values from fetal arterial peripheral vessels, while a positive relationship was found with the percentage reverse flow in inferior vena cava. In fetuses serially followed, the systolic/atrial ratio progressively increased approaching the onset of abnormal fetal heart rate patterns. The systolic/atrial ratio allows the evaluation of ductus venosus hemodynamics in small for gestational age fetuses and this index may be useful in the monitoring of such fetuses.

Aorta, Thoracic↗
PubMed1994

Does measurement of amniotic fluid index detect changes in amniotic fluid volume after second-trimester amniocentesis?

The objective of this study was to establish whether variations of amniotic fluid volume induced by second-trimester amniocentesis could be detected by serial measurements of amniotic fluid index. A total of 130 singleton pregnancies undergoing second-trimester amniocentesis for genetic indications were considered. Amniotic fluid index was measured at three different time intervals: 30-60 min before amniocentesis, immediately after the procedure, and 60 min after the procedure. Serial measurements were obtained either by a single operator (n = 55) or by the three independent operators (n = 75). Significantly lower amniotic fluid index values were demonstrated immediately after amniocentesis when compared with the pre-amniocentesis and subsequent measurements in the study design with both the single and multiple operators. No statistically significant changes were found between the first amniotic fluid index measurements and those obtained 1 h after amniocentesis. These results suggest that second-trimester amniocentesis induces a temporary decrease of amniotic fluid volume detectable by serial amniotic fluid index measurements, no longer evident 1 h after the procedure.

Journal Article↗
PubMed1994

Transverse cerebellar diameter in small-for-gestational-age fetuses: pregnancy dating is possible only when growth retardation is secondary to uteroplacental insufficiency.

The objective of this study was to establish whether measurement of the transverse cerebellar diameter to determine gestational age differs in small-for-gestational-age fetuses with normal or abnormal Doppler velocity waveforms. Our secondary objective was to compare the efficacy of measurement of transverse cerebellar diameter with that of femur length in pregnancy dating among small-for-gestational-age fetuses. A total of 107 small-for-gestational-age fetuses with established dates and free from structural and chromosomal abnormalities were considered for this study. According to the Doppler results, fetuses were divided into two groups: group A (n = 64), with normal Doppler values as expressed by a ratio of pulsatility indices between the umbilical artery and middle cerebral artery of 95th centile. Measurements of transverse cerebellar diameter and femur length were compared to previously established 95th centile prediction intervals. In both groups of small-for-gestational-age fetuses, the values for transverse cerebellar diameter were lower than in normally grown fetuses after normalization for gestational age. The difference was more evident in group A (p <or= 0.001) than in group B (p <or= 0.05). Only 68.7% of transverse cerebellar diameter values of group A fetuses fell within the normal limits for gestation, while this occurred in 90.6% of group B fetuses. When compared to the femur length, the transverse cerebellar diameter measurement appeared to be better for predicting gestational age in both groups of small-for-gestational-age fetuses (p <or= 0.001). However, this measurement may be used to estimate gestational age only in small-for-gestational-age fetuses with abnormal Doppler findings.

Journal Article↗