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Biomedical subjects

J C Fouron

Publications and source records attributed to J C Fouron.

At least 37 records · Page 2Linked to original sources
PubMed1999

Relationship between flow through the fetal aortic isthmus and cerebral oxygenation during acute placental circulatory insufficiency in ovine fetuses.

OBJECTIVE: We sought to investigate whether the reversal of blood flow through the aortic isthmus, as observed during an increase in placental vascular resistance, could be responsible for a significant fall in oxygen delivered to the fetal brain. STUDY DESIGN: With the appearance of reverse flow in the aortic isthmus, preplacental blood with low oxygen saturation could contaminate the ascending aorta blood destined for the brain. Stepwise compression of the umbilical veins of 8 exteriorized fetal lambs was realized at approximately 140 days of gestation. Four other animals were used as controls. Flows through the aortic isthmus and both carotid and umbilical arteries were measured by Doppler echocardiography in the basal state (hemodynamic class 1) and during moderate (class 2), severe (class 3), and extreme (class 4) increases in resistance to placental flow. Oxygen delivered to the brain was calculated from carotid blood flow and oxygen content. RESULTS: In the control group no change was noted in umbilical and carotid arteries or in the aortic isthmus blood flow. Oxygen delivered to the brain remained stable. In the study group the increase in resistance to placental flow caused a significant fall in umbilical flow and carotid oxygen content, while blood flow in the carotid arteries increased slightly. The values for aortic isthmus flow and oxygen delivered to the brain during the 4 hemodynamic classes were, on average, as follows: class 1, 98.2 and 2.9 mL/(min x kg); class 2, 52.8 and 3.1 mL/(min x kg); class 3, 3.7 and 2.6 mL/(min x kg); and class 4, -29.8 and 0.7 mL/(min x kg), respectively. CONCLUSION: During an acute increase in placental vascular resistance, delivery of oxygen to the brain is preserved despite a significant drop in arterial oxygen content as long as net flow through the isthmus is anterograde.

Acidosis↗
PubMed1999

Prognostic markers in twin pregnancies with an acardiac fetus.

OBJECTIVE: With twin reversed arterial perfusion sequence, the normal cotwin is at risk of heart failure. The purpose of this study was to identify ultrasonographic variables that can help predict prognosis. We hypothesized that variables reflecting the hyperdynamic circulatory condition of the normal fetus and the changes in circulatory impedance in the acardiac mass would correlate with final outcome. METHODS: Ten twin pregnancies with this condition were identified. Follow-up was available for nine. Adverse outcome was defined as death, cardiac failure, or delivery before 30 weeks' gestation for reasons related to the presence of the mass. The following data were collected on the normal fetus: cardiothoracic ratio and left ventricular shortening fraction; and on the mass: maximal length, presence and size of cysts, and presence of a rudimentary heart. The pulsatility index (PI) of the umbilical arteries (UA) of both twins was measured. RESULTS: Four fetuses died, two in utero (22 weeks) and two after cesarean (26 and 31 weeks) for advanced cardiac failure. In the five other cases, the outcome was favorable. The cardiothoracic ratio and presence of cysts or of a rudimentary heart did not correlate with outcome. A PI in the mass' UA significantly lower than that of the normal twin (ratio of 0.71 compared with 1.04 for good outcome, P<.05), an elevated shortening fraction in the second trimester, and a rapid growth rate of the mass were associated with a poor prognosis. CONCLUSION: In pregnancies with twin reversed arterial perfusion sequence, final outcome and treatment decisions can be determined based on hemodynamic criteria.

Adult↗
PubMed1999

Cyclooxygenase-2 plays a significant role in regulating the tone of the fetal lamb ductus arteriosus.

Nonselective cyclooxygenase (COX) inhibitors are potent tocolytic agents but have adverse effects on the fetal ductus arteriosus. We hypothesized that COX-2 inhibitors may not affect the ductus if the predominant COX isoform is COX-1. To examine this hypothesis, we used ductus arteriosus obtained from late-gestation fetal lambs. In contrast to our hypothesis, fetal lamb ductus arteriosus expressed both COX-1- and COX-2-immunoreactive protein (by Western analysis). Although COX-1 was found in both endothelial and smooth muscle cells, COX-2 was found only in the endothelial cells lining the ductus lumen (by immunohistochemistry). The relative contribution of COX-1 and COX-2 to PGE2 synthesis was consistent with the immunohistochemical results: in the intact ductus, PGE2 formation was catalyzed by both COX-1 and COX-2 in equivalent proportions; in the endothelium-denuded ductus, COX-2 no longer played a significant role in PGE2 synthesis. NS-398, a selective inhibitor of COX-2, was 66% as effective as the selective COX-1 inhibitor valeryl salicylate and the nonselective COX inhibitor indomethacin in causing contraction of the ductus in vitro. At this time, caution should be used when recommending COX-2 inhibitors for use in pregnant women.

Animals↗
PubMed1998

Factors affecting the prognosis of Ebstein's anomaly during fetal life.

BACKGROUND: The echocardiographic criteria that have been used to evaluate severity of Ebstein's anomaly in utero are the same as those applied after birth. OBJECTIVE: The objective of this study was to establish prognostic criteria that take into account the peculiarities of the fetal hemodynamics. METHOD: The video recordings of eight fetuses with Ebstein's anomaly were retrospectively reviewed. RESULTS: The following indexes had no prognostic significance either on fetal or neonatal outcome: the ratio of functional tricuspid opening over the diameter of the annulus, the degree of displacement of the tricuspid valve opening, and the degree of tricuspid regurgitation. The index of severity (based on the surfaces of right atrium + atrialized right ventricle) and the cardiothoracic ratio had a significant impact only on neonatal survival. The smallest fossa ovalis were found in two fetuses who had hydrops. Fetuses who reached term without problems had higher left ventricular outputs. A positive linear correlation was found between the z score of the left ventricular output and the size of the fossa ovalis (r = 0.81, p < 0.05). CONCLUSION: The prognosis of Ebstein's anomaly during fetal life is not influenced by criteria described for postnatal life and may be related to factors that control the volume load of the left ventricle.

Ebstein Anomaly↗
PubMed1998

Expression of cyclooxygenases in ductus arteriosus of fetal and newborn pigs.

OBJECTIVE: We studied the ontogeny of the expression of cyclooxygenase-1 and cyclooxygenase-2 in the ductus arteriosus and evaluated their functional significance. STUDY DESIGN: The expression of cyclooxygenase-1 and cyclooxygenase-2 was studied in ductus arteriosus of fetal (at approximately 75% gestation) and term newborn pig. Effects of selective inhibitors of cyclooxygenase-1 and cyclooxygenase-2 on ductal patency were evaluated by Doppler ultrasonography. RESULTS: Ductus arteriosus of the fetus expressed virtually only cyclooxygenase-1 immunoreactive protein and activity. In contrast, the ductus of the term newborn pig (<45 minutes old) contained proteins of both cyclooxygenase-1 and cyclooxygenase-2, but the latter contributed to >90% of prostaglandin E2 formation. The selective cyclooxygenase-2 inhibitor DuP697 reduced prostaglandin E2 levels in the ductus arteriosus, albeit not in plasma, but did not affect ductal patency in the newborn pig (<1(1/2) hours old); in contrast, the cyclooxygenase-1 inhibitor valeryl salicylate, like indomethacin, markedly reduced levels of prostaglandin E2 in the plasma and ductus arteriosus and caused significant constriction of the ductus arteriosus. CONCLUSION: The ductus arteriosus of the term newborn pig, in contrast to that of the fetus, expresses cyclooxygenase-2, but circulating prostaglandins, arising mostly from cyclooxygenase-1, seem to exert the major control on ductal patency in vivo. Our data suggest that cyclooxygenase-2 inhibitors might be better alternatives for the fetus than nonselective cyclooxygenase blockers if indicated for maternal conditions such as inflammation or for tocolysis.

Animals↗
PubMed1998

Myocardial, erythropoietic, and metabolic adaptations to anemia of prematurity in infants with bronchopulmonary dysplasia.

OBJECTIVES: The effects of anemia of prematurity during bronchopulmonary dysplasia (BPD) as well as on the metabolic and erythropoietic functions were determined before and after a transfusion. Fourteen anemic (Hb range: 65-88 gm/L), oxygen dependent (fraction of inspired oxygen < or = 35%), nonventilated, preterm infants with BPD were studied at a postnatal age of 6 +/- 2 weeks. STUDY DESIGN: Cardiac output, heart rate, mean velocity of circumferential fiber shortening, shortening fraction (SF), and stroke volume were assessed by pulsed and continuous wave Doppler echocardiography. Values for resting oxygen consumption, carbon dioxide production, and energy expenditure were obtained by indirect calorimetry. The affinity of oxygenated hemoglobin was determined by a blood oxygen dissociation analyzer. RESULTS: An increased hemoglobin level resulted in a suppression of erythropoietin secretion (p < 0.001), whereas heart rate, cardiac output, stroke volume, and SF decreased (p < 0.05). Weight gain before and after transfusion were similar. Plasma lactate levels decreased from 1.6 +/- 0.3 to 1.2 +/- 0.3. Oxygen consumption, carbon dioxide production, and energy expenditure were not affected. CONCLUSIONS: Anemia of prematurity and BPD increase heart rate, cardiac output, stroke volume, and SF. These hemodynamic compensatory responses are normalized by transfusion.

Adaptation, Physiological↗
PubMed1998

Fetal atrial flutter: diagnosis, clinical features, treatment, and outcome.

OBJECTIVES: To assess clinical features, treatment efficacy, and outcome of fetal atrial flutter. STUDY DESIGN: All atrial flutter cases seen in our unit between 1988 and 1995 were reviewed retrospectively and compared with the pooled data of 37 echocardiographically documented and published cases. RESULTS: Atrial flutter was found in 15 of 49 (30.6%) fetuses who had been referred because of clinically relevant tachyarrhythmia. Mean age at detection was 34+/-4 weeks' gestation. Atrial flutter was incessant in 11 and intermittent in 4, with a mean atrial rate of 442+/-65 beats/min and a mean ventricular rate of 216+/-28 beats/min. A predominance of 2:1 atrioventricular conduction was observed. In 5 of 15 cases another form of arrhythmia (supraventricular tachycardia, chaotic atrial rhythm, ventricular extrasystoles) coexisted with atrial flutter. Eleven fetuses were treated with maternal digoxin, and five subsequently converted to sinus rhythm. Four fetuses received no medication; of these four, two showed brief self-limited episodes of atrial flutter and two were delivered after detection of the arrhythmia. Only one fetus (6.7%), who did not respond to drug therapy, was delivered prematurely because of mild congestive heart failure. Seven neonates were in atrial flutter at birth; rhythm control could be easily achieved with sotalol or digoxin (n = 5), flecainide (n = 1), or electroconversion (n = 1) within the first 2 days of life without any relapse. CONCLUSION: Fetal atrial flutter accounts for approximately one third of all clinically relevant tachyarrhythmia. Although the suppression rate of incessant atrial flutter with digoxin is only 50%, this therapy may be useful for its positive inotropic and negative chronotropic properties. In our experience most fetuses with therapy-resistant atrial flutter and absence of 1:1 atrioventricular conduction do not experience congestive heart failure and do not need to be delivered prematurely. After birth, conversion to sinus rhythm was easily achieved in all neonates.

Anti-Arrhythmia Agents↗
PubMed1998

Foetal supraventricular tachycardia treated with sotalol.

This retrospective study (1991-95) presents our experience with sotalol in the treatment of 14 foetuses with supraventricular tachycardia (SVT). SVT was diagnosed in a structurally normal heart at a gestational age of 24-35 (median 28) weeks. In eight foetuses, hydrops was evident at presentation. In all patients pharmacological conversion with digoxin was tried before sotalol treatment was started. Sotalol was given orally to the mothers in a dose of 80-160 mg x 2. Cardioversion was obtained in 10 foetuses. In seven of these patients re-entry tachycardia and in five pre-excitation could be documented after birth. In two foetuses not responding to sotalol a long RP tachycardia was demonstrated; even when using digoxin, sotalol, flecainide and/or propafenone in different combinations after birth complete suppression of the arrhythmia was not obtained. Two severely hydropic foetuses died 1 and 10 d, respectively, after starting with sotalol. The 12 surviving infants were doing well except for one infant, with a cerebral lesion probably related to the arrhythmia. These findings demonstrate that sotalol can be useful in the treatment of foetal SVT.

Adrenergic beta-Antagonists↗
PubMed1998

Circulatory changes induced by isovolumic increase in red cell mass in fetal lambs.

AIM: To verify whether extra uterine changes in total peripheral vascular resistance and cardiac output, caused by raised haematocrit, occur in fetal life and if they can be documented using conventional ultrasound techniques. METHODS: An exchange transfusion with packed red cells was performed on five fetal lambs at 140 days of gestation (weight 3.44, SD 0.48 kg); three others were used as controls. The haematocrit was raised from 44 +/- 3 to 64 (SD2)%. RESULTS: Body temperature, blood gas, and pH remained within normal limits. Blood viscosity increased from 5.3 (0.3) to 9.6 (1.6) cps. Combined cardiac output fell to 30% of its initial value. The pulsatility index (PI) remained unchanged in the umbilical artery (0.66, SD 0.1) and descending aorta (1.3, SD 0.3). A significant positive correlation was found between haematocrit and PI only in the carotid artery (r = 0.67, p < 0.01). CONCLUSION: In the fetus, as in adults, an increase in blood viscosity is associated with a fall in cardiac output. However, the low resistance and the relative inertia of the placental vascular bed blunt the velocimetric changes that could be induced in the lower body vascular system by an increase in resistance. Such changes were observed only in the carotid artery. These results could be of interest in the Doppler monitoring of human fetuses at risk of an abnormal increase in their haematocrit.

Animals↗
PubMed1998

Ventriculo-atrial time interval measured on M mode echocardiography: a determining element in diagnosis, treatment, and prognosis of fetal supraventricular tachycardia.

OBJECTIVE: To determine whether M mode echocardiography can differentiate fetal supraventricular tachycardia according to the ventriculo-atrial (VA) time interval, and if the resulting division into short and long VA intervals holds any relation with clinical presentation, management, and fetal outcome. DESIGN: Retrospective case series. SUBJECTS: 23 fetuses with supraventricular tachycardia. MAIN OUTCOME MEASURES: A systematic review of the M mode echocardiograms (for VA and atrioventricular (AV) interval measurements), clinical profile, and final outcome. RESULTS: 19 fetuses (82.6%) had supraventricular tachycardia of the short VA type (mean (SD) VA/AV ratio 0.34 (0.16); heart rate 231 (29) beats/min). Tachycardia was sustained in six and intermittent in 13. Hydrops was present in three (15.7%). Digoxin, the first drug given in 14, failed to control tachycardia in five. Three of these then received sotalol and converted to sinus rhythm. All fetuses of this group survived. Postnatally, supraventricular tachycardia recurred in three, two having Wolff-Parkinson-White syndrome. Four fetuses (17.4%) had long VA tachycardia (VA/AV ratio 3.89 (0.82); heart rate 226 (10) beats/min). Initial treatment with digoxin was ineffective in all, but sotalol was effective in two. Heart failure caused fetal death in one and premature delivery in one. All three surviving fetuses had recurrences of supraventricular tachycardia after birth: two had the permanent form of junctional reciprocating tachycardia and one had atrial ectopic tachycardia. CONCLUSIONS: Careful measurement of ventriculo-atrial intervals on fetal M mode echocardiography can be used to distinguish short from long VA supraventricular tachycardia and may be helpful in optimising management. Digoxin, when indicated, may remain the drug of choice in the short VA type but appears ineffective in the long VA type.

Anti-Arrhythmia Agents↗
PubMed1997

Doppler velocimetric indices from the abdominal and placental ends of the umbilical artery of growth-restricted fetuses.

PURPOSE: In normal pregnancies, as gestation advances, a progressive decrease is observed in the differences between Doppler indices recorded at the 2 extremities of the umbilical cord. The purpose of this study was to determine whether the same pattern is observed in pregnancies complicated by intrauterine growth restriction (IUGR). METHODS: Forty-seven fetuses with sonographic diagnosis of IUGR underwent investigation by Doppler sonography. Blood flow velocities were measured at the abdominal and placental ends of the umbilical cord. The systolic-diastolic ratio, pulsatility index, and resistance index were calculated for each site. The differences in values between the 2 ends of the cord were calculated (abdominal end minus placental end) and then compared with the differences calculated for normal fetuses. RESULTS: In contrast to normal fetuses, IUGR fetuses with abnormal Doppler measurements had significant differences in the pulsatility and resistance indices between the 2 ends of the cord after 28 weeks of gestation. In addition, when compared with normal fetuses, the IUGR fetuses had a significantly greater difference in the values for the 2 ends of the cord for all indices. CONCLUSIONS: These results emphasize the importance of identifying the sampling site for serial Doppler investigations in IUGR-complicated pregnancies.

Abdomen↗
PubMed1997

Potential value of fetal echocardiography in the differential diagnosis of twin pregnancy with presence of polyhydramnios-oligohydramnios syndrome.

OBJECTIVE: Our purpose was to establish whether index values of cardiac performance could discriminate between the twin-twin transfusion syndrome and placental insufficiency as the etiology of the polyhydramnios-oligohydramnios sequence in monochorionic diamniotic twins. STUDY DESIGN: Thirteen monochorionic diamniotic twin pregnancies with ultrasonographic evidence of polyhydramnios-oligohydramnios sequence had a complete echocardiography. The etiology was confirmed postnatally: placental insufficiency in eight pairs and the twin-twin transfusion syndrome in five. Intertwin comparisons were made for the following cardiac parameters: cardiothoracic index, end-diastolic thickness of the ventricular walls and septum, aortic and pulmonary artery Doppler peak velocities, ejection and acceleration times, left ventricular shortening fraction, and combined cardiac output and output indexed to fetal weight. RESULTS: All five recipient twins had thickened ventricular walls. The left ventricular shortening fractions and outputs were significantly increased in the donor twin with twin-twin transfusion syndrome and normal in placental insufficiency. CONCLUSION: In twin-twin transfusion syndrome the donor twin shows evidence of a hyperdynamic cardiac state. Intertwin comparison of cardiac parameters, especially the left ventricular shortening fraction, can be considered a useful tool in diagnosing the different etiologies of the polyhydramnios-oligohydraminos sequence.

Adult↗
PubMed1997

Doppler velocimetry of the aortic isthmus in human fetuses with abnormal velocity waveforms in the umbilical artery.

Experimental studies in animals using Doppler ultrasound suggest that hemodynamic disturbances during fetoplacental circulatory insufficiency will be detected at an earlier and less severe stage in the aortic isthmus compared to the umbilical artery. In cases in which more severe impairment of the placental circulation was achieved, reverse flow was recorded in the aortic isthmus before its appearance in the umbilical artery. The present study was undertaken to investigate whether the same findings could be demonstrated in the aortic isthmus of the human fetus. The video recordings of 100 fetuses with abnormal umbilical artery pulsatility index were reviewed. Qualitative abnormalities of the Doppler waveform, i.e., absence or reversal of end-diastolic velocities, were more frequently found in the aortic isthmus (absent 28%, reversed 41%) compared to the fetal end of the umbilical artery (absent 20%, reversed 19%; p < 0.0001) and also more frequently found in the fetal end compared to the placental end (absent 13%, reversed 2%; p < 0.0001). This study confirms our previous observations of the aortic isthmus as a site for early detection of fetoplacental hemodynamic disturbances. Reverse diastolic flow in the isthmus could direct poorly oxygenated blood from the descending aorta towards the carotid arteries and the brain. Further prospective studies are needed to establish the clinical value of these findings in terms of perinatal morbidity and, more importantly, of long-term neurological impairment.

Adult↗
PubMed1996

Comparison of effects of 95% and 90% oxygen saturations in respiratory distress syndrome.

AIMS: To determine if decreasing arterial blood saturation from 95% to 90% could cause vasoconstriction of the pulmonary vasculature and dilatation of a patent ductus arteriosus in preterm newborn infants with respiratory distress syndrome (RDS). METHODS: Doppler echocardiographic studies were compared at 95% and 90% pulse oxygen saturation (SpO2) in 13 preterm infants aged 61.7 (4.3) hours with RDS and Doppler echocardiographic evidence of tricuspid regurgitation. RESULTS: The mean (SD)Doppler echocardiographic indices determined at 95% were heart rate (146 (3.60) beats per minute), acceleration time of the velocity wave forms of the pulmonary artery (PAAT) (51.8 (2.5) milliseconds), ratio of PAAT to right ventricular ejection time (ET) (0.26 (0.02)), diameter of the ductus arteriosus (2.6 (0.6) mm), pulmonary blood flow (0.33 (0.03) l/minute) and the left ventricular shortening fraction (SF)(0.4 (0.02)%). The ascending aorta flow velocity wave form was used for the calculation of pulmonary blood flow. The right ventricular to right atrial systolic pressure gradient calculated using the peak velocity of the tricuspid regurgitation jet was 26.7 (7.4) mm Hg. CONCLUSIONS: A decrease from 95% to 90% SpO2 did not have any effect on the pulmonary circulatory haemodynamics nor the ductus arteriosus.

Carbon Dioxide↗
PubMed1996

[Importance of intrauterine diagnosis of rudimentary autonomic circulation in an acardiac twin].

Foetal acardia is a major complication of twin pregnancies which endangers the life of the healthy twin. The authors report the case of a twin pregnancy with an acardiac twin followed up by repeated echocardiography from the 20th week of pregnancy until delivery at the 36th week. Despite the presence of a parasitic mass, the healthy twin showed no sign of heart failure. Attentive ultrasonography of this mass showed a certain degree of autonomic circulation ensured by a rudimentary cardiac pump. This case confirms the favorable effect of this finding on the healthy twin, moreover, it clarifies some haemodynamic features of the parasitic mass: to-and-fro circulation, characteristic of a cardiac pump without a valve, anastomoses and competitive flow between the two circulatory systems.

Abnormalities, Multiple↗