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Biomedical subjects

J C Fouron

Publications and source records attributed to J C Fouron.

At least 19 recordsLinked to original sources
PubMed2006

[Fetal haemodynamic and left heart dysfunction].

Foetal cardiology is a well established field of paediatric cardiology. It is no longer a simple exercise of prenatal diagnosis of cardiac malformations. It also covers the investigation and treatment of arrhythmias and functional and dynamic cardiocirculatory evaluation of the foetus which does not always have primary organic cardiac disease. It is this aspect which will be described in this article. The interactions of the left heart / foetal haemodynamics are classified in two main groups according to whether the left myocardial dysfunction is primary or secondary to changes of pre- or afterload. The haemodynamics singularities of the normal foetal circulation are and essential basis for the understanding of the phenomena observed.

Arrhythmias, Cardiac↗
PubMed2004

Early intertwin differences in myocardial performance during the twin-to-twin transfusion syndrome.

BACKGROUND: In the twin-to-twin transfusion syndrome (TTTS), pressure rather than volume overload is increasingly considered as a key factor in the pathogenesis of the cardiomyopathy of the recipient twin. If this is the case, cardiac dysfunction should be among the first signs observed with TTTS. The objective of this study was to determine whether intertwin differences in myocardial function are modified early in the course of TTTS and whether they can help to differentiate this condition from intrauterine growth restriction (IUGR). METHODS AND RESULTS: Eight variables were analyzed on the first fetal echocardiography on 21 pairs of twins with TTTS and 11 with IUGR. No difference was found between the 2 groups for the cardiothoracic ratio, pulsatility indices in the umbilical and middle cerebral arteries, and peak velocity of the middle cerebral artery. Significant difference was found for ventricular septal thickness, but with no association with the conditions under study. With TTTS, left ventricular shortening fraction was consistently greater in the donor twins, and myocardial performance indices (MPIs) were elevated in the recipient twins. This increase in MPI was caused by a lengthening of the isovolumic periods compared with those of the donor twin: left ventricular and right ventricular isovolumic periods 0.105+/-0.047 and 0.097+/-0.026 seconds, respectively, for the recipient twins versus 0.0561+/-0.46 and 0.065+/-0.03 seconds, respectively, for the donor twins (P<0.001). These changes in the isovolumic periods were mainly due to significant prolongation of isovolumic relaxation times. A change in left ventricular MPI > or =0.09 combined with a change in right ventricular MPI > or =0.05 would identify a TTTS with a sensitivity of 75% and a false-positive rate of 9%. CONCLUSIONS: The observed diastolic function impairment goes along with the pressure-overload pathogenic concept proposed in TTTS. Assessment of intertwin difference in MPI is a valuable tool for early differential diagnosis between TTTS and isolated IUGR.

Diagnosis, Differential↗
PubMed2004

Immediate and short-term effects of pulmonary artery banding on left ventricular performance in foetal sheep.

AIM: To evaluate foetal left ventricular performance when its preload was increased by banding the pulmonary artery, a study design where a simultaneous change in left ventricular afterload is unlikely. METHODS: Nine ovine foetuses were studied with real-time images and Doppler echocardiography before, 3-4 and 6-8 d after surgery. Seven of these foetuses were also studied during the surgical intervention, immediately before and within 2 min after banding. RESULTS: The immediate effects of a 90-95% reduction of the pulmonary artery cross-sectional area were: a 53 +/- 20% (mean +/- SD) decrease and a 38 +/- 10% increase of right (RvQ) and left ventricular output (LvQ), respectively. Comparing measurements before and 3-4 d after operation, there was a 64 +/- 16% decrease of RvQ and a 64 +/- 25% increase of LvQ. The increase in LvQ was due to an increase in both heart rate (19 +/- 10%) and stroke volume (38 +/- 18%). After an additional 3-4 postoperative days, heart rate remained increased to the same extent, but there was a more pronounced increase of LvQ (93 +/- 19%) and stroke volume (59 +/- 22%). CONCLUSION: The parallel foetal circulation has a capacity to handle a severely increased afterload for the right ventricle by immediately improving and maintaining an increased left ventricular performance. This improvement was in part accomplished by an increase in stroke volume.

Analysis of Variance↗
PubMed2001

Fetal cardiac performance in uncomplicated and well-controlled maternal type I diabetes.

OBJECTIVE: To study the impact of well-controlled, uncomplicated maternal diabetes on fetal cardiac development and performance. METHODS: The following variables were studied in 45 fetuses of type I diabetic women by means of mid- and late-trimester echocardiography: interventricular septal thickness; aortic and pulmonary valve diameters; peak and time-to-peak flow velocity of the great arteries; the ratio between peak velocities during early (E) and late (A) ventricular filling at the level of the atrioventricular values; ventricular fractional shortenings; and output. The findings were compared to age-matched control groups of normal fetuses. RESULTS: A significant augmentation of interventricular septal thickness was demonstrated for mid-trimester fetuses of diabetic women, which progressed further towards the end of pregnancy. However, the indices of diastolic and systolic function remained comparable between the gestational age-matched groups. CONCLUSION: Progressive myocardial thickening occurs commonly in mid- and late-trimester fetuses of uncomplicated and well-controlled diabetic pregnancies. The observed degree of hypertrophy is generally mild and does not affect age-related changes in fetal cardiac function.

Adult↗
PubMed2001

Characterization of PGE2 receptors in fetal and newborn ductus arteriosus in the pig.

We compared the total density and the relative expression of EP receptor (EP) subtypes in ductus arteriosus (DA) of the newborn with that of the fetal piglet. Saturation binding experiments showed 3-fold less PGE2 receptors in the newborn than in the fetus because of loss of EP3 and EP4 receptors thus explaining, at least partly, the reduced responsiveness to PGE2 of the newborn DA. Displacement experiments showed that the relative proportions of EP2, EP3, and EP4 were similar in the fetal DA but only EP2 was detected in the DA of the newborn pig. Hence, PGE2 effects in the newborn DA seem to be exclusively mediated by EP2 receptors both in vitro and in vivo. These findings may help to propose more specific therapies for regulation of DA's tone in certain newborns for whom conventional therapy is contraindicated.

Animals↗
PubMed2001

Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years.

OBJECTIVE: Experimental studies on fetal lambs have shown that during an increase in the resistance to placental flow the delivery of oxygen to the brain is preserved as long as net flow through the aortic isthmus is antegrade. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome. STUDY DESIGN: Forty-four fetuses were retrospectively included in this study on the basis of an abnormal Doppler velocity in the umbilical artery. Mean gestational age at delivery was 33.0 +/- 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5). RESULTS: Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth. CONCLUSION: Measuring the ratio of antegrade to retrograde velocity integrals in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.

Aorta↗
PubMed2001

Characterization of PGE2 receptors in fetal and newborn lamb ductus arteriosus.

Although the role of PGE2 in maintaining ductus arteriosus (DA) patency is well established, the specific PGE2 receptor subtype(s) (EP) involved have not been clearly identified. We used late gestation fetal and neonatal lambs to study developmental regulation of EP receptors. In the fetal DA, radioligand binding and RT-PCR assays virtually failed to detect EP1 but detected EP2, EP3D, and EP4 receptors in equivalent proportions. In the newborn lamb, DA total density was one-third of that found in the fetus and only EP2 was detected. Stimulation of EP2 and EP4 increased cAMP formation and was associated with DA relaxation. Though stimulation of EP3 inhibited cAMP formation, it surprisingly relaxed the fetal DA both in vitro and in vivo. This EP3-induced relaxation was specifically diminished by the ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide. In conclusion, PGE2 dilates the late gestation fetal DA through pathways that involve either cAMP (EP2 and EP4) or K(ATP) channels (EP3). The loss of EP3 and EP4 receptors in the newborn DA is consistent with its decreased responsiveness to PGE2.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

Prostanoid receptors: ontogeny and implications in vascular physiology.

Prostanoids exert significant effects on circulatory beds. They play a role in the response of the vasculature to adjustments in perfusion pressure and oxygen and carbon dioxide tension, and they mediate the actions of numerous factors. The role of prostanoids in governing circulation of the perinate is suggested to surpass that in the adult. Prostanoids are abundantly generated in the perinate. They have been implicated in autoregulation of blood flow as studied in brain and eyes. Prostaglandins are also dominant regulators of ductus arteriosus tone. The effects of these autacoids are mediated through specific G protein-coupled receptors. In addition to the pharmacological characterization of the prostanoid receptors, important advances in understanding the biology of these receptors have been made in the last decade. Their cloning and the development of animals with disrupted genes of these receptors have been very informative. The involvement of prostanoid receptors in the developing subject, especially on brain and ocular vasculature and on ductus arteriosus, has also begun to be investigated; the expression of these receptors changes with development. Some but not all of the ontogenic changes in these receptors are attributed to homologous regulation. Interestingly, in the process of elucidating their effects, functional perinuclear prostaglandin E2 receptors have been uncovered. This article reviews prostanoid receptors and addresses implications on the developing subject with attention to vascular physiology.

Animals↗
PubMed2001

[Investigation of fetal arrhythmias by simultaneous recording of ascending aortic and superior vena caval blood flow].

In a period of 18 consecutive months, all the foetus referred to our Foetal Cardiology Unit for investigation of arrhythmia were systematically assessed by M mode echocardiography and simultaneous recording of blood flow in the superior vena cava and the aorta (SVC/Ao). This study was undertaken to compare the performance of these two approaches. The foetus were classified into three groups according to the arrhythmia diagnosed: Group 1: irregular arrhythmias, Group 2: bradycardias, Group 3: tachycardias. A surface ECG was recorded in all the neonates in whom the arrhythmias persisted. In Group 1, including 50 cases of extrasystoles (49 atrial and 1 ventricular), M mode echo and the Doppler provided the diagnosis in 42 and 47 cases respectively. This difference was not statistically significant. Group 2 comprised four cases of bradycardia (2 blocked atrial bigeminy, 2 complete atrioventricular blocks); the two methods provided the diagnosis in all 4 cases. Group 3 comprised 11 cases including 7 supraventricular tachycardias (SVT), 2 flutter, 1 chaotic atrial rhythm and 1 ectopic junctional rhythm. Complete analysis of these arrhythmias was possible by M mode in 4 cases and by Doppler in all cases. This difference was significant. The distribution of the 7 cases of SVT with respect to the duration of the ventriculoatrial interval was possible by M mode in 2 cases and in all cases by Doppler. This was a decisive factor in the choice of antiarrhythmic therapy. The authors conclude that Doppler and M mode are two echocardiographic approaches which are equally effective in the investigation of foetal atrial extrasystoles and probably of sustained foetal bradycardia. However, Doppler recording of SVC/Ao gives a more detailed and precise diagnosis of more complex foetal arrhythmias.

Aorta↗
PubMed2000

Doppler and M-mode ultrasonography to time fetal atrial and ventricular contractions.

OBJECTIVE: To compare ease of recording and reliability of ultrasonographic approaches used to time fetal heart atrial and ventricular contractions. METHODS: Seventeen consecutive fetuses seen at our fetal cardiology unit for possible fetal cardiac arrhythmia were included in this study. The same ultrasonographer obtained M-mode tracings of atrial and ventricular free walls, atrial wall and opening of the aortic valves, a peak of the mitral valve, and the opening of the aortic valves; and Doppler signals of flow-velocity waveforms in the outflow tract of the left ventricle and simultaneous flow-velocity waveforms in the aorta and superior vena cava. The outcome measures were rate of successful attempts and intra- and interobserver reliability coefficients. RESULTS: Valid recordings were made for all patients with one M-mode (atrial and ventricular free walls) and two Doppler (intraventricular, superior vena cava, and ascending aorta) approaches. Atrioventricular intervals were significantly longer with M-mode compared with Doppler ultrasonography. Reliability coefficients were excellent (at least 0.89) for all intraobserver measurements. Comparisons of atrioventricular and ventriculoatrial interval measurements made by two observers gave the following intraclass correlation coefficients (95% confidence interval): atrioventricular = M-mode: 0.87 (0.79, 0. 91), left ventricular outflow: 0.93 (0.89, 0.96), superior vena cava-aorta: 0.98 (0.97, 0.99); ventriculoatrial = M-mode: 0.79 (0.67, 0.87), left ventricular outflow: 0.97 (0.95, 0.98); superior vena cava-aorta: 0.99 (0.98, 0.99). CONCLUSION: Fetal atrioventricular intervals measured indirectly from M-mode or Doppler tracings were equally reliable when measured by the same observer; the Doppler approaches had better correlation between measurements made by two different observers.

Adult↗
PubMed2000

Isolated ductus arteriosus aneurysm in the fetus and infant: a multi-institutional experience.

OBJECTIVES: The purpose of this study was to describe the clinical characteristics and outcome and to elucidate the pathogenesis of ductus arteriosus aneurysm (DAA). BACKGROUND: Ductus arteriosus aneurysm is a rare lesion that can be associated with severe complications including thromboembolism, rupture and death. METHOD: We reviewed the clinical records, diagnostic imaging studies and available histology of 24 cases of DAA, diagnosed postnatally (PD) in 15 and antenatally (AD) in 9 encountered in five institutions. RESULTS: Of PD cases, 13 presented at <2 months, and all AD cases were detected incidentally after 33 weeks of gestation during a late trimester fetal ultrasound study. Of the 24, only 4 had DAA-related symptoms and 6 had associated syndromes: Marfan, Smith-Lemli-Opitz, trisomies 21 and 13 and one possible Ehlers-Danlos. Three had complications related to the DAA: thrombus extension into the pulmonary artery, spontaneous rupture, and asymptomatic cerebral infarction. Six underwent uncomplicated DAA resection for ductal patency, DAA size or extension of thrombus. In the four examined, there was histologic evidence of reduced intimal cushions in two and abnormal elastin expression in two. Five of the 24 died, with only one death due to DAA. Of 19 survivors, all but one remain clinically asymptomatic at a median follow-up of 35 months; however, two have developed other cardiac lesions that suggest Marfan syndrome. A review of 200 consecutive third trimester fetal ultrasounds suggests an incidence of DAA of 1.5%. CONCLUSIONS: Ductus arteriosus aneurysm likely develops in the third trimester perhaps due to abnormal intimal cushion formation or elastin expression. Although it can be associated with syndromes and severe complications, many affected infants have a benign course. Given the potential for development of other cardiac lesions associated with connective tissue disease, follow-up is warranted.

Aneurysm↗
PubMed2000

Reference values for differences between cardio-circulatory variables of normal twin fetuses.

BACKGROUND: No reference values exist concerning the differences between cardio-circulatory variables of normal twin fetuses. The normal data could be useful in the identification of conditions causing opposite hemodynamic effects on each twin. OBJECTIVE: To establish the normal differences among cardio-circulatory parameters of twin fetuses during the second and third trimesters of gestation. MATERIALS AND METHODS: Twenty-seven normal twin pregnancies were used in this longitudinal and prospective study. Doppler-echocardiographic investigations were performed every 2-3 weeks starting at an average of 23.11 +/- 3.13 (mean +/- standard deviation) weeks' gestation. At each visit, the following cardio-circulatory variables were evaluated: the cardio-thoracic ratio, the ventricular wall and septal thicknesses, end-diastolic and systolic diameters, ventricular fractional shortenings, velocity of circumferential fibre shortenings and left and right ventricular outputs. In addition the following measurements were made from Doppler recordings: through both aortic and pulmonary valve the acceleration and ejection times, the peak systolic velocities and the velocity time integrals; and through both mitral and tricuspid valves peak velocities of E and A waves and the E/A ratios. Finally the pulsatility index of the umbilical artery was also evaluated. RESULTS: There was no single variable where the intertwin difference changed with gestational age. No systematic difference between the smaller and larger twin could be demonstrated for any variables except for the cardio-thoracic ratio. CONCLUSION: Reference tables should permit a comparative approach between the two twins in the investigation of life threatening complications such as twin-to-twin transfusion syndrome.

Blood Flow Velocity↗
PubMed2000

Correlation between electrocardiographic and ultrasonographic time-interval measurements in fetal lamb heart.

The objective of this study was to establish the echocardiographic modality that best correlates with electrical events in the fetal heart. No documentation on the relationship between electrical events recorded with a surface ECG and fetal M-mode or Doppler echocardiographic measurements is available. The following ultrasound tracings were recorded simultaneously with a surface ECG on six exteriorized near-term fetal lambs: 1) M-mode echocardiography of atrial and ventricular contractions; and 2) Doppler flow velocity waveforms in the right superior vena cava (SVC) either alone or 3) in association with those of the ascending aorta. In the SVC, the onset of the retrograde A wave and the beginning of the forward wave during ventricular systole were used as markers for the start of the P wave and QRS complex, respectively. For the simultaneous SVC and ascending aorta tracings, the beginnings of the A and of the aortic ejection waves were used as markers. On average, the atrioventricular interval was 84 ms longer than the PR interval with the M-mode, corresponding to an increase of 107%. A similar observation was made for the simultaneous Doppler signals from SVC and ascending aorta, but the difference between the atrioventricular and PR intervals was smaller, averaging 35 ms. When the SVC Doppler was taken alone, no significant difference was found between atrioventricular and ventriculoatrial compared with PR and RP intervals, respectively, and a strong correlation was found between the two methods of measurement, both for the atrioventricular (r = 0.91) and ventriculoatrial (r = 0.89) intervals. Doppler interrogation of the SVC alone and, to a lesser degree, of the SVC and ascending aorta are reliable indirect markers for the timing of electrical events of the fetal lamb heart in sinus rhythm.

Animals↗
PubMed1999

Developmental changes in prostaglandin E(2) receptor subtypes in porcine ductus arteriosus. Possible contribution in altered responsiveness to prostaglandin E(2).

BACKGROUND: Prostaglandin E(2) (PGE(2)) is important in ductus arteriosus (DA) patency, but the types of functional PGE(2) receptors (EP) in the developing DA are not known. We postulated that age-dependent alterations in EP and/or their subtypes may possibly contribute to the reduced responsiveness of the newborn DA to PGE(2). METHODS AND RESULTS: We determined PGE(2) receptor subtypes by competition binding and immunoblot studies on the DA of fetal ( approximately 75% and 90% gestation) and newborn (<45 minutes old) pigs. We studied the effects of EP receptor stimulation on cAMP signaling in vitro and on term newborn (<3 hours old) DA patency in vivo. Fetal pig DA expressed EP(2), EP(3), and EP(4) receptors equivalently, but not EP(1). In neonatal DA, EP(1), EP(3), and EP(4) were undetectable, whereas EP(2) density was similar in fetus and newborn. Prostaglandin-induced changes in cAMP mirrored binding data. 16,16-Dimethyl PGE(2) and 11-deoxy PGE(1) (EP(2)/EP(3)/EP(4) agonist) produced more cAMP in fetus than newborn, but butaprost (selective EP(2) agonist) caused similar cAMP increases in both; EP(3) and EP(4) ligands (M&B28767 and AH23848B, respectively) affected cAMP production only in fetus. After birth, administration of butaprost alone was as effective as 11-deoxy PGE(1) and 16,16-dimethyl PGE(2) in dilating DA in vivo. CONCLUSIONS: The data reveal fewer PGE(2) receptors in the DA of the newborn than in that of the fetus; this may contribute to the decreased responsiveness of the DA to PGE(2) in newborn. Because EP(2) receptors seem to mediate the effects of PGE(2) on the newborn DA, one may propose that a selective EP(2) agonist may be preferred as a pharmacological agent to maintain DA patency in infants with certain congenital heart diseases.

Animals↗
PubMed1999

Outcome of children with atrial septal defect considered too small for surgical closure.

There are few studies providing information on the natural course of hemodynamically insignificant atrial septal defect (ASD). To review the outcome of patients with secundum ASD, we retrospectively reviewed the charts of patients who had initially not been considered for surgical closure after age 1 year, and who had either a follow-up of at least 10 years or documented closure. Thirty patients, 22 females and 8 males, fulfilled our inclusion criteria. Mean age at diagnosis was 1.3 year and mean follow-up duration was 11.5 years. Seventeen patients had spontaneous closure of the ASD at a mean age of 8.4 years. There were 7 asymptomatic patients whose ASD was still patent at the last visit (mean age 14.1 years, mean follow-up 13.2), with defect dimensions on echocardiography ranging from 1 to 6 mm. The remaining 6 patients were considered to require surgical closure on the basis of an apparent increase in size of the ASD and secondary clinical and hemodynamic manifestations. These results (1) confirm that not all secundum ASDs need to be treated surgically because they can still spontaneously close past the age of 5, and (2) suggest that in a minority of cases the size of the defect could increase.

Cardiac Surgical Procedures↗