Search PubMed⌕ Search

Biomedical subjects

J S Carvalho

Publications and source records attributed to J S Carvalho.

At least 19 recordsLinked to original sources
PubMed2002

The human ductus venosus between 13 and 17 weeks of gestation: histological and morphometric studies.

BACKGROUND: Doppler studies of the ductus venosus are increasingly being integrated in the assessment of fetal well-being. Establishing the precise morphology and structure of the ductus venosus would provide a better understanding of Doppler findings during fetal adaptation. There is conflicting evidence from previous studies about the structure of the ductus venosus, especially with regard to the presence of a sphincter at the ductus venosus inlet. The aim of this study was to examine the morphology and histological structure of the ductus venosus wall and surrounding tissues at 13-17 weeks' gestation. DESIGN: This was a prospective study on 28 fetuses obtained from medical termination of pregnancies between 13 and 17 weeks' gestation. Scanning electron microscopy and histological and immunohistochemical studies were carried out on ductus venosus sections obtained from different spatial planes. RESULTS: The inlet of the ductus venosus contained a shelf which was rich in elastin, but devoid of any evidence of a smooth muscle sphincter. The isthmus of the ductus venosus above the inlet was narrowed, giving the lumen of the vessel an hourglass appearance. The endothelial surface of the ductus venosus, above the level of the inlet, showed longitudinal corrugations along its entire length. Longitudinally arranged elastin fibers were also seen along the length of the ductus venosus. A single layer of longitudinally arranged smooth muscle cells was present along the entire length of the ductus venosus, with occasional individual nerve cells visible in this layer. CONCLUSIONS: The presence of an elastin-rich shelf and a narrow ductus venosus inlet orifice may act to accelerate flow from the portal sinus into a high-velocity system in the ductus venosus. The abundant elastin fibers in the adventitia of the ductus venosus may help antegrade wave propagation by elastic recoil. This study clearly demonstrates the lack of an anatomical smooth muscle sphincter at the ductus venosus inlet. However, the combination of endothelial corrugations and innervated smooth muscle support the hypothesis that the ductus venosus is an actively regulated vessel with the capacity to rapidly change diameter along its entire length in response to certain stimuli.

Endothelium, Vascular↗
PubMed2001

The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation.

BACKGROUND: Ultrasound imaging of the fetal ductus venosus is becoming increasingly commonplace in clinical practice. The true anatomical relationships of the fetal umbilical and portal venous systems have not been clearly defined due to paucity of published data on the relevant anatomy. This has led to confusing terminology when describing the fetal umbilical, portal and hepatic circulations. The aim of the present study was to examine and document the anatomy of the umbilical, portal and hepatic venous systems and to propose a standardized nomenclature. METHODS: This was a prospective study on 11 fetuses obtained from medical termination of pregnancies between 14 and 19 weeks of gestation. The liver was microdissected to expose the branching pattern and anatomical relations of the umbilical, portal and hepatic venous systems. RESULTS: A wide L-shaped venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified. The portal sinus was connected to the right and left hepatic lobes, by the right and left intrahepatic portal veins, respectively. The extrahepatic portal vein drained into the portal sinus just before the origin of the right intrahepatic portal vein. The ductus venosus, a branchless straight vessel, originated from the portal sinus and ascended steeply in the direction of the diaphragm. Numerous small vessels draining the liver converged into three main hepatic veins, which open into the subdiaphragmatic vestibulum. CONCLUSION: Based on detailed sequential anatomical dissection and clear illustrations, the present study documents the anatomy of the umbilical, portal and hepatic venous systems. Taking into account the embryological origin of the vessels, a new anatomically appropriate and simplified nomenclature of these venous systems is proposed. In clinical practice, the consistent use of the suggested terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.

Dissection↗
PubMed2001

Right and left ventricular long-axis function in the fetus using angular M-mode.

OBJECTIVE: Long-axis function is determined by the longitudinally oriented myocardial fibers. Postnatally, conventional M-mode is used to assess tricuspid and mitral valve ring movements in relation to the cardiac apex. During fetal life, this is precluded by variable fetal position. We assessed the feasibility of determining right and left ventricular long-axis function in the fetus. METHODS: A prospective, pilot study. The four-chamber view obtained during routine fetal echocardiography was recorded in a cineloop to which B-mode guided M-mode echocardiography was applied using angular M-mode. This allowed retrospective and correct placement of the cursor line from cardiac apex to tricuspid or mitral valve rings. M-mode tracings of the valve ring movements in relation to the apex were derived from the originally stored loop. Data from 18 fetuses (17-29 weeks of gestation) were available for analysis. Total excursion of the valve rings was measured offline. A second cursor line was simultaneously placed in the left ventricular outflow tract during color flow mapping for timing purposes (n = 6). RESULTS: Right and left ventricular long-axis recordings were obtained in 18 and 14 cases, respectively. Total right ventricular excursion was 5.2 mm (SD, 0.9 mm) (range, 3.9-7.2 mm). Total left ventricular free wall excursion was 4.5 mm (SD, 1.1 mm) (range, 3.0-6.8 mm). For paired data, the mean of differences (right ventricle-left ventricle) was 0.8 mm (95% confidence interval 0.5-1.2). The valve rings moved towards the apex during systole (shortening) and away from it during diastole (lengthening). Peak downward movement coincided with cessation of aortic flow and diastolic lengthening with flow through the atrioventricular valves. CONCLUSION: Long-axis function in the fetus is feasible if M-mode angle correction is used. There was no clinically significant difference between tricuspid and mitral valve excursions. The pattern of atrioventricular valve movement is coordinate and similar to that of adults. Long-axis function offers a new avenue to study systolic and diastolic function in the fetus.

Echocardiography↗
PubMed2001

Congenital absence of portal vein in the fetus: a case report.

Congenital absence of portal vein (CAPV) is a rare abnormality, which may be associated with other abnormalities. We report a case of prenatal diagnosis of absent portal vein confirmed on postnatal ultrasonography and computed tomography scan. The ultrasound features of CAPV include dilated intra-abdominal segment of umbilical vein, dilated inferior vena cava and the presence of hyperechogenic areas in the liver. Blood coming from the umbilical vein directly drains into the inferior vena cava. The dilated intra-abdominal segment of the umbilical vein shows high velocity pulsatile flow, resembling that of ductus venosus. These findings should prompt a careful search for the portal vein and any associated anomalies.

Adult↗
PubMed2001

Limitations of using first-trimester nuchal translucency measurement in routine screening for major congenital heart defects.

OBJECTIVE: To evaluate the effectiveness of nuchal translucency (NT) measurement in screening for major congenital heart disease (CHD) in chromosomally normal fetuses. DESIGN: A population based cohort study of all women having fetal NT measurement at 10-14 weeks of gestation in an unselected population over a 3-year period. The outcome measure was the identification of major CHD in chromosomally normal pregnancies either antenatally or postnatally. RESULTS: Major defects of the heart and great arteries were identified in 26 out of 7339 pregnancies (prevalence 3.5 per 1000 pregnancies). Out of 26 cases, only four (sensitivity 15.4%, 95% CI 4-35) were in the group of 258 pregnancies (3.5%) with increased NT of > or = 2.5 mm. The prevalence of major CHD increased from 3.1 per 1000 for NT < 2.5 mm to 50 per 1000 for NT > or = 3.5 mm (likelihood ratio of 14.1, 95% CI 4.2-47.9). The positive and negative predictive values for NT > or = 2.5 mm were 1.6% and 99.7%, respectively. CONCLUSIONS: The prevalence of major CHD in this study was 3.5 per 1000, suggesting that ascertainment of CHD in our study population was thorough. Fetuses with NT measurements > or = 3.5 mm have a significantly increased risk of major CHD, and this identifies a subgroup of high-risk patients in whom early fetal echocardiography would be advocated. The low sensitivity of NT for major CHD in the general population, however, indicates that NT cannot be relied on as the sole or major screening tool for this condition as previously reported.

Adult↗
PubMed2001

Prenatal diagnosis of mosaic trisomy 8 in a fetus with normal nuchal translucency thickness and reversed end-diastolic ductus venosus flow.

We report a case of the prenatal diagnosis of trisomy 8 in a fetus presenting with normal nuchal translucency of 0.8 mm and reversed end-diastolic ductus venosus blood flow at a routine first-trimester scan at 11 weeks of gestation. No structural abnormalities were detected by the ultrasound scan. Karyotyping by chorionic villus sampling led to the diagnosis of mosaic trisomy 8, which was confirmed by fluorescent in-situ hybridization on fetal tissue samples.

Adult↗
PubMed2001

Significance of chromosome 22q11 analysis after detection of an increased first-trimester nuchal translucency.

OBJECTIVE: To determine the value of performing routine fluorescent in situ hybridization (FISH) for microdeletions of chromosome 22q11 when karyotyping fetuses with increased nuchal translucency. DESIGN: This was a prospective observational study carried out over an 18-month period. Fetal karyotyping by chorionic villus sampling was offered to 5429 women attending for a routine booking scan in the first trimester when their nuchal translucency adjusted risk for Down syndrome was > or = 1 in 300. Cytogenetic samples were routinely tested for the 22q11 microdeletion when the nuchal translucency was > or = 3 mm. RESULTS: The prevalence of increased nuchal translucency > or = 2.5 mm was 180 (3.3%) and > or = 3.5 mm was 42 (0.8%). None of 75 fetuses with an increased nuchal translucency and normal karyotype demonstrated a 22q11 microdeletion on FISH analysis. In the same cohort, 3 of 20 (15%) cases of major congenital heart defects in which nuchal translucency was measured, had a nuchal translucency measurement > or = 2.5 mm. CONCLUSIONS: Routine FISH analysis for chromosome 22q11 microdeletions at the time of chorionic villus sampling for increased first-trimester nuchal translucency is of limited value. As a significant proportion of fetuses with increased nuchal translucency will be found to have congenital heart defects later in the pregnancy, FISH analysis for chromosome 22q11 microdeletions can be targeted to fetuses with specific congenital heart defects. Tissue from the chorionic villus sampling should therefore be stored for subsequent analysis, until after detailed echocardiography is performed.

Adolescent↗
PubMed2001

Isolated echogenic foci in the fetal heart: do they increase the risk of trisomy 21 in a population previously screened by nuchal translucency?

OBJECTIVES: To confirm the hypothesis that isolated cardiac echogenic foci at the second-trimester anomaly scan do not influence our current calculation of risk of trisomy 21 in individual pregnancies, which is based on maternal age and nuchal translucency thickness at 11-14 weeks. DESIGN: Observational study in a fetal medicine unit. METHODS: In a general pregnant population undergoing first-trimester nuchal translucency screening, data from 239 singleton pregnancies with isolated cardiac echogenic foci at the second-trimester anomaly scan were compared with those of a control group of 7449 pregnancies with normal anomaly scans. Prevalence of trisomy 21 was determined in both groups. Following the anomaly scan, the individual risks of trisomy 21 were calculated by adjusting the previous risk based on maternal age and first-trimester nuchal translucency. We assumed that echogenic foci did not alter each individual risk calculation. The expected number of cases of Down syndrome in both groups was then calculated from the sum of probabilities of each individual affected fetus. The observed number of cases was compared with the expected number in both study and control populations. RESULTS: There was no statistically significant difference between the prevalence of trisomy 21 in the study group (no cases) and in the control population (three cases). From individual risk calculations, observing no cases of trisomy 21 in the study group was the most likely event if echogenic foci did not increase the risk of this chromosomal abnormality (P = 0.62). CONCLUSION: The finding of isolated echogenic foci at the time of the 20 week-scan does not significantly change the risks of trisomy 21 if background risk and previous nuchal translucency measurements are taken into account in the individual risk calculation. We suggest that no further adjustments to risk should be used.

Adult↗
PubMed2001

Early prenatal diagnosis of major congenital heart defects.

Specialized fetal echocardiography at 18 to 22 weeks for high-risk groups is well established as being sensitive and specific for most cardiac abnormalities. Early fetal echocardiography (< 16(+0) weeks, i.e. 16 weeks and 0 days) is a feasible alternative to mid second trimester scanning for families at risk of congenital heart disease. Two main areas have contributed to the increasing interest in first and early second trimester fetal echo. The recognition of the association between increased nuchal translucency and structural heart abnormalities has led to the identification of an important high-risk group at 11 to 14 weeks. Furthermore, the use of modern ultrasound technology has allowed greater utilization of transabdominal scanning in addition to the transvaginal route. Most major structural heart defects can accurately be diagnosed from the late first trimester of pregnancy and many families at-risk can be reassured of 'normality' of cardiac connections at an early stage. Some lesions may evolve throughout pregnancy and therefore early scans should not replace mid trimester fetal echocardiography.

Echocardiography↗
PubMed1999

Screening for fetal aneuploidies and fetal cardiac abnormalities by nuchal translucency thickness measurement at 10-14 weeks of gestation as part of routine antenatal care in an unselected population.

OBJECTIVES: To evaluate first trimester pregnancy screening for fetal aneuploidy and congenital heart defects by maternal age and nuchal translucency measurement and screening for fetal aneuploidies and congenital heart defects by ultrasound in an unselected population. DESIGN: A prospective study. SETTING: Fetal medicine unit, St George's Hospital, London. SAMPLE: 4523 consecutive viable fetuses at 10-14 weeks with a crown-rump length between 38 and 80 mm were scanned transabdominally (93%) or transvaginally (7%). METHODS: Screening was performed by calculating the background risk from maternal age, gestational age and obstetric history, which was then adjusted with the nuchal translucency measurement in relation to crown-rump length (adjusted risk). MAIN OUTCOME MEASURES: Measurements of crown-rump length and nuchal translucency thickness. An adjusted risk of > 1:270 was considered as a positive screening test. Pregnancy outcome was obtained through karyotyping, outcome questionnaires and examination of the newborn infants. RESULTS: Mean maternal age was 29-4 years and mean gestational age 12.2 weeks. Screening was positive in 230/4523 fetuses (5.1%), when the adjusted risk (mean 1:2649) was > 1:270. Fetal karyotype was abnormal in 23 (0.51%) cases, including twelve with trisomy 21, five trisomy 18, one trisomy 13, one trisomy 10, one monosomy X and two triploidies. For a false positive rate of 4.7%, the sensitivity of this test was 78% in detecting any fetal aneuploidy. Only one out of nine major congenital heart defects in this population was found within the 110 euploid fetuses with increased nuchal translucency thickness (> 2.5 mm). CONCLUSION: Screening for fetal aneuploidy by maternal age and nuchal translucency measurement can be effective in an unselected population. However, our results do not support its effectiveness in the detection of cardiac abnormalities.

Adolescent↗
PubMed1999

Anomalous origin of the left coronary artery from the pulmonary trunk. Clinical features and midterm results after surgical treatment.

OBJECTIVE: To report the authors' experience with the anomalous origin of the left coronary artery (AOLCA) from the pulmonary trunk, emphasizing preoperative data, surgical aspects and midterm results of the follow-up. METHODS: Retrospective analysis of 11 patients operated upon at the Royal Brompton Hospital from October, 84 to April, 97. RESULTS: Nine infants had heart failure (HF) and two other children presented with dyspnea and chest pain. All had ECG changes. The echocardio-gram identified the anomalous origin of the coronary artery in 7 (64%) patients and hemodynamic studies were performed in 7 patients. All infants were operated upon between the 2nd and 10th month of life. Six patients were treated with aortic reimplantation of the left coronary artery, whereas five were operated upon according to the Takeuchi technique. All patients are alive, with clear improvement of the ECG changes and ventricular function, as evaluated by echocardiography. Two patients operated upon according to the Takeuchi technique required additional surgery due to severe supravalvular pulmonary stenosis. CONCLUSION: AOLCA is a rare disease. Most patients show early signs of severe HF associated with ECG findings. Surgical therapy must be instituted early in the disease, preferentially through aortic implantation of the anomalous coronary artery, with a high possibility of success. Shortly after surgery, clinical and ECG improvement, as well as normalization of left ventricular function, should be expected.

Adolescent↗
PubMed1998

First-trimester transabdominal fetal echocardiography.

BACKGROUND: Fetal echocardiography is usually done during the second trimester of pregnancy, but waiting until that time can lead to anxiety for the parents if the fetus is at high risk of having cardiac abnormalities. We report the feasibility of transabdominal first-trimester fetal echocardiography for early reassurance of normality or a prenatal diagnosis of a cardiac malformation. METHODS: We did first-trimester fetal echocardiography and colour-flow mapping with a 5 MHz curvilinear transducer at 13 weeks' gestation (range 12-13+6 days) in 15 fetuses at risk of cardiac defects. The fetus was judged to be normal if the investigation showed normal visceral situs, four-chamber view, and two normally related great arteries of similar size. We did second-trimester scans and neonatal follow-up for the women who continued with their pregnancies; necropsy was done in two cases of pregnancy termination. FINDINGS: Ten fetuses had normal hearts at the time of the first scan, which was confirmed during second-trimester assessment. In one fetus, the four-chamber view was asymmetrical and a moderate-sized apical muscular ventricular septal defect (VSD) was diagnosed after birth. In another two fetuses we diagnosed small muscular VSD on the second-trimester scans. A complex cardiac malformation was correctly diagnosed in one fetus at 12 weeks of gestation. Thus, in 11 fetuses, the imaging was of sufficient quality to reassure the family or to diagnose an abnormality. In the other four fetuses, the investigation was judged to be incomplete, but no definite cardiac abnormality was identified. INTERPRETATION: Transabdominal fetal echocardiography in the first trimester of pregnancy is feasible. In most patients the resolution of images is sufficient to allow assessment of basic cardiac anatomy, when normal, or detection of complex malformations, when present.

Echocardiography, Doppler, Color↗
PubMed1998

The cobweb syndrome: first trimester sonographic diagnosis of multiple amniotic bands confirmed by fetoscopy and pathological examination.

Amniotic band syndrome is a well described clinical entity presenting with deformities of the limbs, thorax, craniofacial skeleton, soft tissues and umbilical cord, but it still lacks a precise definition and a coherent hypothesis for its pathogenesis. We report on a case of first trimester diagnosis of amniotic band syndrome by sonography and fetoscopy. This revealed multiple abnormalities including facial cleft, brain and limb deformities; the appearance of the amniotic cavity was that of a cobweb containing the fetus. Post-mortem examination and histopathological studies confirmed the diagnosis of amniotic band syndrome. These results may enhance the knowledge of its natural course. In addition, based on histological and newly identified ultrastructural features, we present a hypothesis which could help to explain the aetiopathogenesis of the amniotic band syndrome.

Adult↗
PubMed1998

Coronary arterial anatomy in tetralogy of Fallot: morphological and clinical correlations.

OBJECTIVE: To clarify the problems in angiographic diagnosis of major coronary arteries crossing the right ventricular outflow tract. DESIGN: A retrospective study with clinicomorphological correlations to ascertain any aberrant coronary arteries and variations in distribution of the normal right coronary arterial branches. SETTING: Tertiary referral centre. SUBJECTS: 36 necropsy specimens together with the aortograms and surgical reports from 130 patients with tetralogy of Fallot. RESULTS: A preventricular branch was found in 19% of cases with tetralogy of Fallot, but in none of 13 normal hearts. Aberrant origin of the anterior interventricular coronary artery was found in 14% of the specimens. The combination of "laid back" and straight lateral views, when reviewed retrospectively, identified this anomaly correctly in nine of 16 patients, with these findings confirmed at surgery in seven patients. A major branch initially thought to cross the outflow tract was shown retrospectively to be an infundibular artery in six, with surgical confirmation in four. It was a preventricular branch in another patient. CONCLUSIONS: Using the laid back view alone, infundibular and preventricular branches may be mistaken for a major aberrant artery. A combination of laid back and straight lateral views is needed to avoid false positive diagnosis.

Child↗
PubMed1998

Normal relationships between cardiovascular variables in active orthostatism and clinostatism in postural change.

OBJECTIVE: Autonomic modulation of hemodynamics, essential for the preservation of homeostasis, is well tested by the abrupt postural change from clinostatism to active orthostatism. The aim of this work was to study normal relationships between the cardiovascular variables in active orthostatism and those in clinostatism. METHODS: Hemodynamic parameters in clinostatism and orthostatism were easily measured in 20 healthy subjects of both sexes, aged between 33 and 78 years, without treatment, using the non-invasive thoracic electric bioimpedance method. RESULTS: Cardiovascular variables values in orthostatism are linearly related with their values in clinostatism. CONCLUSIONS: Results show that cardiovascular variables in active orthostatism are linearly related with their values in clinostatism, each variable being specially regulated. A clinostatism and orthostatism intraindividual correlation was obtained, which provides an easily accessible method of detection and interpretation of autonomic dysfunctions, without deleterious consequences for the subjects, which can be very useful for research on physiopathologic mechanisms.

Adult↗