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Biomedical subjects

M J Rice

Publications and source records attributed to M J Rice.

At least 37 records · Page 2Linked to original sources
PubMed1996

Reversed shunting across the ductus arteriosus or atrial septum in utero heralds severe congenital heart disease.

OBJECTIVES: This study was performed to define the significance of Doppler color flow mapping in demonstrating reversal of the direction of the normal physiologic flow across the atrial septum and ductus arteriosus in the human fetus. BACKGROUND: Reversal of the physiologic shunting across the ductus arteriosus or atrial septum in utero (i.e., left to right) can be readily identified by Doppler color flow mapping, complemented by pulsed and continuous wave Doppler information. METHODS: We reviewed echocardiograms recorded at our three institutions from 1988 to 1993, which displayed reversal of flow by Doppler color flow in 53 fetuses of gestational age 18 weeks to term. The diagnoses were confirmed by postnatal echocardiography, operation or autopsy. Reversal of shunting was consistently associated with severe heart disease. RESULTS: Reversed atrial shunting was found with severe left heart obstructive lesions, including 19 with hypoplastic left heart syndrome, 3 with critical aortic stenosis, 2 with double-outlet right ventricle and 1 each with an interrupted aortic arch, atrioventricular septal defect and severe left ventricular dysfunction due to dilated cardiomyopathy. Reversed ductus arteriosus shunting was found with severe right heart obstructive lesions, including nine fetuses with pulmonary atresia, six with severe obstructive tricuspid valve abnormalities, five with severe tetralogy of Fallot, four with Ebstein's anomaly and two with single ventricle and pulmonary stenosis. Associated cardiac lesions were common in both groups. Only 3 of the 15 infants who were delivered alive from the reverse ductus arteriosus shunt group and 4 of 12 from the reverse atrial shunt group still survive. CONCLUSIONS: The finding of reversed flow by Doppler color flow mapping during fetal life provides a key to subsequent accurate diagnosis and denotes a spectrum of diseases with a very poor prognosis.

Ductus Arteriosus↗
PubMed1996

Pediatric echocardiography: current role and a review of technical advances.

Advances in echocardiography have enhanced our diagnostic imaging capabilities for congenital heart defects. In addition to improved resolution of two-dimensional images, cardiac hemodynamic assessment is possible with the use of Doppler, color Doppler, and stress echocardiography. Transesophageal echocardiography has allowed intraoperative assessment of cardiac repairs, and fetal echocardiography has allowed development of the field of fetal cardiology. The developing areas of intravascular ultrasonography and three-dimensional echocardiography show promise for the future. Echocardiography continues to revolutionize our ability to diagnose congenital heart defects accurately.

Echocardiography↗
PubMed1995

Comparison of four Doppler echocardiographic methods for calculating pulmonary-to-systemic shunt flow ratios in patients with ventricular septal defect.

Several methods currently exist for quantifying pulmonary (Qp) and systemic (Qs) shunt flow using Doppler echocardiography, although none is widely utilized. In this study, 39 patients (age 2 months to 12 years, mean 2.1 years) underwent an echocardiographic examination within 1 month of Qp:Qs shunt flow determination by oximetry at catheterization. Qp:Qs was determined by 4 methods that utilized: (1) velocity time integrals and luminal areas to estimate volume flow of the pulmonary artery and aorta; (2) the square of the ratios of pulmonary artery to aorta, multiplied by the ratio of pulmonary to aortic peak flow velocities; (3) inclusion of mitral and tricuspid valve volume flow to pulmonary and aortic volume flow; and (4) ventricular septal defect (VSD) diameter and velocity time integral to calculate left-to-right shunt, which, when added to aortic volume flow (Qs), can be used to estimate Qp. Each of the first 3 methods was statistically correlated to the oximetry Qp:Qs, with r values ranging from 0.54 to 0.66 (p < 0.001). However, the fourth method, based on direct computation of flow across the VSD, had the best correlation to catheterization data (r = 0.82), and further improved when 7 patients with a large VSD (> 9 mm/m2), all of whom had bidirectional shunting, were removed (r = 0.90). Thus, we concluded that this latter method demonstrated the best correlation to catheterization-derived shunt flow data, and because this method is somewhat less labor-intensive than the others, should provide clinically useful data well suited for serial evaluation in infants and children with VSD.

Child↗
PubMed1995

In utero pulmonary artery and aortic growth and potential for progression of pulmonary outflow tract obstruction in tetralogy of Fallot.

OBJECTIVES: This study was designed to define patterns of pulmonary artery and aortic growth in fetuses with tetralogy of Fallot and to determine the potential for in utero progression of right ventricular outflow tract obstruction. BACKGROUND: Despite an abundance of reports documenting the prenatal diagnosis of tetralogy of Fallot, there is little information about its course in utero. METHODS: Pulmonary artery and ascending aortic diameters were measured from prenatal and postnatal echocardiograms of 16 fetuses with tetralogy of Fallot, initially studied at 23.6 +/- 6.0 (mean +/- SD) weeks of gestation. Fetuses were classified retrospectively as having mild and severe tetralogy of Fallot according to whether the pulmonary artery circulation was (severe, n = 5) or was not (mild, n = 11) ductus arteriosus dependent at birth. RESULTS: Initial main pulmonary artery diameter was small for gestational age in 9 fetuses, large in 2 and normal in 5 compared with data from 57 gestational age-adjusted normal fetal studies; it was significantly smaller in the group with severe tetralogy of Fallot (p = 0.05). The initial main pulmonary artery/aortic diameter ratio was also smaller for the group with severe tetralogy of Fallot (0.50 +/- 0.15 vs. 0.73 +/- 0.14 in the group with mild tetralogy of Fallot, p = 0.01). Initial aortic and branch pulmonary artery diameters tended to be normal or near normal for age. In eight fetuses serially studied, main and branch pulmonary artery growth was normal or reduced during prenatal follow-up. Pulmonary artery growth was most reduced in two fetuses in the group with severe tetralogy of Fallot, resulting in pulmonary artery hypoplasia at birth. Two fetuses with valvular pulmonary atresia at birth had previously shown anterograde pulmonary outflow in midgestation, suggesting progression of pulmonary outflow obstruction. CONCLUSIONS: The postnatal spectrum of pulmonary artery size in tetralogy of Fallot can be attributed to variable patterns of growth in utero. Main pulmonary artery size, main pulmonary artery/aortic diameter ratio and pattern of pulmonary artery growth may be predictive of the severity of postnatal pulmonary outflow obstruction. Pulmonary atresia can develop in utero in some fetuses with tetralogy of Fallot.

Aorta↗
PubMed1995

The use of hope as a coping mechanism in abused women.

The purpose of this study was to identify how abused women use hope and to determine whether hope is a coping mechanism in their relationship with the abusers. Four focus group sessions were conducted with a sample of 24 women using a phenomenological methodology. The data analysis indicated that abused women maintain hope in four major dimensions: hope for change in their partner's behavior, hope for survival, hope as something to cling to, and hope for control of the situation. The subjects stated that hope was used as a coping mechanism to help them keep their sanity; but in this context, the subjects often saw hope as false or unreal. Thus some abused women used hope as a mechanism to attempt to resolve cognitive dissonance between their internal beliefs and the external reality of physical violence.

Adaptation, Psychological↗
PubMed1994

Substituted 2-benzothiazolamines as sodium flux inhibitors: quantitative structure-activity relationships and anticonvulsant activity.

Thirty-two aryl-substituted 2-benzothiazolamines have been tested for their ability to modulate sodium flux in rat cortical slices. A QSAR analysis, applied to these derivatives, showed a trend toward increasing potency as sodium flux inhibitors with increasing lipophilicity, decreasing size, and increasing electron withdrawal of the benzo ring substituents. Additionally, 4- or 5-substitution of the benzo ring was found to decrease potency. The combination of increased lipophilicity, small size, and electron withdrawal severely limited which groups were tolerated on the benzo ring, thus suggesting that the optimal substitution patterns have been prepared within this series. Nine of these compounds were potent inhibitors of veratridine-induced sodium flux (NaFl). These nine compounds also proved to be anticonvulsant in the maximal electroshock (MES) assay. Fourteen additional 2-benzothiazolamines demonstrated activity in the MES screen, yet exhibited no activity in the NaFl assay. These derivatives may be interacting at the sodium channel in a manner not discernible by the flux paradigm, or they may be acting by an alternative mechanism in vivo.

Animals↗
PubMed1993

Effect of patent ductus arteriosus on Doppler-derived right ventricular systolic time intervals.

Right ventricular systolic time intervals (RVSTI) and noninvasive Doppler-derived pulmonary blood flow were measured before and after surgical ductus ligation in 18 otherwise healthy infants and children who were older than 3 months of age. Right ventricular preejection period (PEP) and the ratio of preejection period and right ventricular ejection time (PEP/RVET), both corrected or uncorrected for heart rate, decreased significantly following surgery (PEP 71 +/- 14 vs. 50 +/- 13, p < 0.001 and PEP/RVET 0.29 +/- 0.06 vs. 0.21 +/- 0.05, p < 0.001). The volume of pulmonary blood flow correlated with PEP/RVET (r = 0.48, p = 0.003). The magnitude of the change in pulmonary blood flow correlated with the change in PEP/RVET (r divided by 0.56, p = 0.016). The velocity of circumferential fiber shortening (VCFc) increased after surgery, but not significantly. We speculate that patent ductus arteriosus has a similar effect on right ventricular performance when other congenital heart defects are present.

Blood Flow Velocity↗
PubMed1993

Review of studies evaluating ductal patency in the premature infant.

A series of investigations has been performed to assess the timing of physiologic closure of the ductus arteriosus in premature infants with and without respiratory distress syndrome. The data from these studies emphasize the concept of physiologic ductal patency and give normative data for expected closure rates through the fourth day of life. On the basis of these data, patency on or beyond the fourth day of life is abnormal irrespective of gestational age, and prematurity, in the absence of respiratory distress syndrome, is not a risk factor for persistent patent ductus arteriosus. We also found that persistent patent ductus arteriosus in larger premature infants (> or = 30 weeks of gestation) with respiratory distress syndrome is relatively uncommon. Last, ductal patency was evaluated in a group of low birth weight infants with severe respiratory distress syndrome in a randomized, double-blind trial of exogenous surfactant administration. We concluded that the beneficial effects of exogenous surfactant are not associated with either a greater clinical need for indomethacin or any increased risk of delayed closure of the ductus arteriosus.

Ductus Arteriosus, Patent↗
PubMed1993

Contributions of color Doppler to the evaluation of cardiovascular abnormalities in the fetus.

The applications of color Doppler sonography are reviewed in this article. Color Doppler is an efficient and time-saving means of assessing normal and abnormal flow in the fetus, making it an essential part of the echocardiographic examination for fetal congenital heart disease. In survey mode, color Doppler can be used to quickly evaluate whether flow channels are normal and to detect abnormal flow patterns. These abnormal flow patterns can then be examined further by pulsed or continuous wave Doppler, if needed. Color Doppler, which is subject to less rib shadowing than other Doppler techniques, also can help in assessing the fetal heart when there is less-than-adequate gray scale imaging.

Blood Flow Velocity↗
PubMed1993

Progressive pulmonary stenosis in the fetus: two case reports.

Fetal echocardiography is a helpful tool in diagnosing and following the natural history of fetuses with congenital heart disease. This report describes two fetuses with complex congenital heart disease that developed progressive pulmonary stenosis in utero. On fetal echocardiogram, one of the fetuses had tetralogy of Fallot and the other had a single ventricle. Both fetuses, when followed serially by fetal echocardiography, showed pulmonary stenosis that progressed in severity. These findings confirm that certain cardiac defects progress in severity in utero.

Adult↗
PubMed1991

Ductal patency in neonates with respiratory distress syndrome. A randomized surfactant trial.

The purpose of this study was to evaluate in a controlled study the effect of exogenous surfactant on various manifestations of ductal patency. Premature infants with respiratory distress syndrome were randomized to receive surfactant (Survanta) (n = 22) or air (n = 14). In neonates receiving surfactant, there was a greater tendency for an audible murmur to develop (13 of 22 vs four of 14). In spite of this, the clinical use of indomethacin was similar for the two groups, 10 (45%) of 22 vs six (43%) of 14. Excluding neonates given indomethacin early, a comparable number of surfactant-treated neonates (9/17 [53%]) vs control neonates (6/12 [50%]) demonstrated spontaneous closure of the ductus within a physiologic time frame (on or before day 4). For the gestational ages studied, the beneficial effects of exogenous surfactant were not associated with either an increased risk for delayed closure of the ductus arteriosus or a greater incidence of indomethacin usage. Utilization of exogenous surfactant does not appear to have an adverse impact on ductal patency.

Ductus Arteriosus, Patent↗
PubMed1991

Truncus arteriosus associated with mitral atresia and a hypoplastic left ventricle.

The association of truncus arteriosus with congenital left heart abnormalities is rare. We describe a case of truncus arteriosus associated with mitral atresia and a hypoplastic left ventricle. In 11 other patients diagnosed with truncus arteriosus, none had left heart hypoplasia. Despite the truncal root being primarily or entirely committed to the right ventricle, more right than left heart abnormalities have been found. This is in contrast to double-outlet right ventricle in which left heart abnormalities are more often associated.

Female↗