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Biomedical subjects

J C Fouron

Publications and source records attributed to J C Fouron.

At least 91 records · Page 5Linked to original sources
PubMed1988

The inhibition of the postnatal rise of 2,3-diphosphoglycerate in newborn lambs as a result of glucose perfusion.

Due to the abrupt increase in 2,3-diphosphoglycerate (2,3-DPG) concentration in the newborn lamb, which begins soon after birth, this interval in development was considered an excellent period to test the hypothesis that glucose perfusions could inhibit 2,3-DPG synthesis. Ten newborn lambs were divided into two groups and perfused either with glucose (15 mg/kg/min) or physiologic saline (45% NaCl) for 10 days. Blood gases, electrolytes, glycemia, O2 pressure at 50% Hb saturation, and 2,3-DPG levels were compared in the two groups. Glucose levels remained significantly elevated during the first 3 days in the glucose perfused group. The O2 pressure at 50% Hb saturation increased in both groups but was significantly lower in the glucose perfused group when determined on day 5 and 8. The postnatal increase in 2,3-DPG was significantly diminished in the glucose infused lambs, which suggests that glucose perfusion has an inhibiting effect on erythrocyte 2,3-DPG synthesis.

2,3-Diphosphoglycerate↗
PubMed1987

Cardiovascular status during ketamine anesthesia in the fetal lamb.

To determine the effects of maternal ketamine anesthesia on fetal hemodynamic and cardiac function, a study was carried out on 8 chronically catheterized fetal lambs. Ketamine was administered intravenously to the mother every 15 min during 1 h. The fetal PO2 and pH remained within physiological limits whereas the PCO2 decreased from 44.35 +/- 1.36 to 37.32 +/- 4.75 Torr (p less than 0.05). The following changes of the fetal heart systolic time intervals were observed: a progressive lengthening of the preejection period (PEP) (from 52 +/- 10 to 63 +/- 11 ms, p less than 0.01), a shortening of the ejection time (ET) and a significant increase of the PEP/ET ratio (from 0.32 +/- 0.04 to 0.47 +/- 0.01, p less than 0.01). The two components of PEP, electromechanical delay and the isovolumetric contraction time were both prolonged. A progressive rise of fetal systolic and diastolic pressures was also noted (p less than 0.01). Fetal heart rate increased (145 +/- 33 to 190 +/- 28 beats/min, p less than 0.01) and cardiac beat-to-beat variability decreased (from 0.028 to 0.009, p less than 0.01) during the ketamine anesthesia. This study demonstrates that maternal anesthesia with ketamine can alter indices of fetal myocardial function and other cardiac parameters used in fetal and neonatal monitoring, without affecting tissular oxygenation.

Anesthesia, General↗
PubMed1986

Value of respiratory variations of right ventricular dimension in the identification of small atrial septal defects (secundum type) not requiring surgery: an echocardiographic study.

In search of reliable criteria that could help differentiate insignificant atrial septal defects (ASDs) from those with a large shunt, M-mode echocardiograms of three groups of patients were studied retrospectively: group I = 10 normal children (mean age 5.7 years); group II = 10 patients (mean age 7 years) with small ASD in whom the decision was taken not to proceed to surgical closure, based on hemodynamic and angiographic criteria; and group III = 15 patients (mean age 7 years) with an "operable" shunt, who underwent corrective surgery. The results showed that right ventricular end-diastolic dimensions during expiration (RVDDE) were increased in all patients in group III but were normal in only 3 of the 10 patients in group II. A normal septal movement was found in all patients in groups I and II but also in five patients in group III. The variation in right ventricular diastolic dimension with respiration (RVDVR) was always normal in group II. However, in group III all patients but one had a small RVDVR (less than 6%). It was concluded that a normal RVDDE is very specific (100%) but not sensitive (30%), a normal septal movement is very sensitive (100%) and moderately specific (70.6%), and a normal RVDVR is both very sensitive (100%) and specific (94.4%) as a criterion for identification of small ASDs not requiring surgery.

Adolescent↗
PubMed1986

Wall thickness, cavity dimensions, and myocardial contractility of the left ventricle in patients with simple transposition of the great arteries. A multicenter study of patients from 10 to 20 years of age.

Fifty-one patients with uncomplicated transposition of the great arteries (TGA) and normal pulmonary pressure who were 10 to 20 years old and 69 normal subjects matched for age were studied by M mode echocardiography. Left ventricular internal dimensions and posterior wall thickness showed positive correlation with the body surface area in the TGA as well as in the control groups. Values for these parameters in the TGA group were generally smaller than those in the normal population. Septal thickness of patients with TGA (5.9 +/- 1 mm) was also smaller than that in the control group (6.6 +/- 1 mm) (p less than .01). Septal motion was normal in 11 patients with TGA and paradoxical in 19 patients in this group. In the other 21 patients the septum was flat. The following systolic time intervals of the left ventricle were found for patients with TGA: preejection period (PEP) 64 +/- 11 msec, ejection time (ET) 310 +/- 37 msec, and PEP/ET 0.21 +/- 0.04. These values were significantly different from those of the right ventricle for the normal population: PEP 77 +/- 12 (p less than .01), ET 327 +/- 25 (p less than .05), and PEP/ET 0.24 +/- 0.03 (p less than .01). Shortening fraction and mean velocity of circumferential fiber shortening (49 +/- 7% and 1.6 +/- 0.3 circ/sec, respectively) were also significantly higher (p less than .01) in patients with TGA than in the control group (33 +/- 4% and 1.1 +/- 0.2 circ/sec). These data should help achieve reliable quantitative and qualitative interpretations of echocardiograms of patients with TGA.

Adolescent↗
PubMed1986

Myocardial function and hemoglobin oxygen affinity during hyperglycemia in the fetal lamb.

To determine the effects of maternal hyperglycemia on fetal hemodynamic and cardiac function, a study was carried out on nine chronically catheterized fetal sheep. In six fetuses, glucose was infused intravenously with an initial dose of 5 mg/kg per min. Data were compared with controls. This dose was gradually increased to 16 mg/kg per min by the fifth day. The initial blood glucose was 14.7 +/- 3.0 mg/dl and increased to 54.6 +/- 16.4 mg/dl by the last day of the infusion period (P less than 0.001). The PO2 decreased from a baseline of 20.25 +/- 3.40 to 15.88 +/- 5.24 mmHg (P less than 0.01). Similarly significant decreases were also observed for the blood O2 content and O2 hemoglobin saturation: 8.5 +/- 1.7 to 6.4 +/- 2.2 ml/dl and 62.3 +/- 13.6 to 46.1 +/- 17.6%, respectively, during hyperglycemia (P less than 0.01). The duration of the preejection period (PEP) before the start of the experiment was 45 +/- 4 ms; a final value of 57 +/- 10 ms was obtained (P less than 0.01). However, the electromechanical delay and ejection time (ET) showed no significant variation. The ratio of the PEP/ET increased from 0.31 +/- 0.04 to 0.38 +/- 0.07 (P less than 0.01) during hyperglycemia. The reticulocytes increased from 1.4 +/- 1.8 to 3.1 +/- 2.9% (P less than 0.05) and the 2,3-diphosphoglycerate decreased from 4.4 +/- 1.1 to 2.8 +/- 1.2 mumol/g hemoglobin (P less than 0.005). This study demonstrated that fetal hyperglycemia depresses myocardial function in the fetal lamb. The changes in cardiac function could not be explained by the small drop in O2 saturation.

2,3-Diphosphoglycerate↗
PubMed1985

Effects of maternal alcohol intoxication on fetal circulation and myocardial function: an experimental study in the ovine fetus.

To determine whether acute alcohol ingestion during pregnancy could affect fetal myocardial function, studies were carried in six chronically catheterized fetal sheep during maternal alcohol infusion. Absolute ethyl alcohol (0.8 ml/kg) was administered to the mother over 10 minutes via the jugular vein. These infusions were repeated every 30 minutes during 3 hours, and peak maternal and fetal blood concentrations close to 200 mg/dl alcohol were reached. Fetal PCO2 decreased from a baseline of 43.15 +/- 3.75 to 36.13 +/- 2.6 torr 1 hour after the start of alcohol infusion (P less than 0.05). Similarly, pH rose from 7.37 +/- 0.027 to 7.44 +/- 0.015 (P less than 0.05). Both values returned to baseline level at the end of alcohol infusion. PO2 remained within physiologic limits. The systolic time intervals of the fetal heart showed a rapid and prolonged modification. The pre-ejection period from 58 +/- 8 to 66 +/- 4 msec (P less than 0.05) during the infusion; this change was related to an increase in the isometric contraction period. The ratio of the pre-ejection period over the ejection time was also significantly increased (P less than 0.01), and remained elevated until the end of the experiment (12 hours). A rise in fetal systolic and diastolic pressures was observed at about 2 hours after the start of the alcohol infusion, and lasted 4 hours. This study suggests that an episode of maternal alcohol intoxication causes rapid depression of fetal myocardial contractility that is maintained several hours after cessation of alcohol ingestion.

Alcoholic Intoxication↗
PubMed1985

Physiologic modulations of the systolic time intervals in the fetal lamb.

To examine the modulation of fetal systolic time intervals of the ovine fetus in relation to fetal maturation, heart rate, respiratory activity, and circadian rhythm, studies were carried out on 13 fetal-maternal sheep preparations. The data obtained showed that there was a significant correlation between the ejection time (ET) and the RR intervals of the electrocardiogram. The pre-ejection period (PEP) and PEP/ET increased in relation to the fetal maturation (38 ms and 0.25 at 120 days to 52 ms and 0.33 at 145 days of gestation, respectively). When the circadian rhythmicity was analyzed, a relative tachycardia was in evidence during the 21- to 03-h period but systolic time intervals remained unchanged. Except for some tachycardia and cardiac rhythm variability, respiratory activity also had no influence on the systolic time intervals.

Animals↗
PubMed1985

[Respiratory variations in the right ventricular diameter: an echocardiographic element in the diagnosis of partial isolated pulmonary venous return anomaly].

Isolated partial anomalous pulmonary venous drainage (PAPVD), in contrast to atrial septal defect (ASD), does not cancel out the effects of respiration on blood flow in the right ventricle. The aim of this study was to see whether this difference could contribute to the diagnosis of PAPVD without ASD on M mode echocardiography. The diastolic dimensions of the right ventricle on expiration and inspiration were compared in 4 groups of patients aged 2 to 17 years. Group 1 comprised 6 children with PAPVD without ASD; Group 2: 10 children with PAPVD and ASD; Group 3: 11 children with isolated non-restrictive ASD, and Group 4: 10 normal children. Groups 1 and 4 were comparable with a respiratory variation of RV dimension of 10 to 29%. On the other hand, in Groups 2 and 3 the percentage variation was less than 6%. The finding of isolated RV dilatation with normal respiratory variation of its internal dimension should therefore alert the operator to the possible diagnosis of PAPVD without ASD.

Adolescent↗
PubMed1985

[Kawasaki's disease. Epidemiological aspects and cardiovascular manifestations. Apropos of 106 cases].

One hundred and six patients fulfilling accepted diagnostic criteria for Kawasaki disease (90 p. 100 of French-Canadian origin) were evaluated with serial electrocardiograms and echocardiograms (M mode and two-dimensional). Half of the patients (53) had cardiovascular manifestations at one time during their illness. Thirty-one had abnormal electrocardiograms: non specific ST and T wave changes inferiorly (27), prolonged QT intervals (6), first degree AV block (3). M mode echo was abnormal in 31 cases showing: slight pericardial effusion (17), flat septal movement (11), left ventricular dilatation (4), decrease of shortening fraction (2). Seven patients (6.4 p. 100) presented fusiform coronary aneurysm detected in 6 by two-dimensional echography (with angiographic confirmation) and at autopsy in another. M mode echo and electrocardiogram abnormalities were transient in the great majority of patients disappearing during an average follow-up period of 10 months. Coronary aneurysm had disappeared at the end of follow-up in two patients, regressed in three and remained identical in another. There were no relations between severity of clinical symptoms, electrocardiographic or echocardiographic (M mode) abnormalities and the development of coronary aneurysm. Serial studies with two-dimensional echo should be done in every patient with this disease for early detection and follow-up of coronary aneurysm.

Adolescent↗
PubMed1985

[Plain films in supero-inferior ventricles].

Chest radiographs of 11 patients with supero-inferior ventricles proven by echocardiography and angiocardiography are presented. The main feature is the modified configuration of the left heart contour. Even if not specific, this sign is encountered frequently (72%) and may suggest the diagnosis.

Abnormalities, Multiple↗
PubMed1985

Circulatory changes in newborn lambs with experimental polycythemia: comparison between fetal and adult type blood.

Hemodynamic effects of increased hematocrit were compared in two groups of newborn lambs. In the first group (fetal type blood), exchange transfusions were carried out using packed red blood cells obtained from newborn lambs within one to two hours after birth. In the second group (adult type blood), the same procedure was carried out using adult sheep blood. In both groups, hematocrit values ranging between 70% and 80% were reached. The increase in hematocrit caused a decrease in cardiac output due to an increase in peripheral resistance. Pulmonary resistance increased more than systemic resistance. However, the increase in pulmonary resistance was significantly greater in the polycythemic newborn lambs with adult blood. A right-to-left shunt through a patent ductus or a foramen ovale was noted in six of the eight lambs included in this group. On the other hand, none of the seven polycythemic newborn lambs with fetal blood developed signs of right-to-left shunting. It is concluded that during neonatal polycythemia, the level of hematocrit is not the sole factor responsible for the hemodynamic changes observed. Other unknown influences related either to the red cells or the plasma must impinge upon the pulmonary circulation to alter vascular resistance.

Animals↗
PubMed1984

The difference between the systolic time intervals of the left and right ventricles during fetal life.

In order to determine if the two ventricles of the fetal heart contract synchronously the systolic time intervals of both ventricles were compared. Eight experiments were carried out on fetal lambs. The studies demonstrated that while the ejection times of both ventricles were the same, the mean pre-ejection period of the right ventricle was significantly greater than that of the left (57 +/- 8 versus 48 +/- 8 msec, p less than 0.005). These findings were further substantiated in serial studies during a 7-day period on the same fetal lamb. If changes in the systolic time intervals are to be useful in evaluating fetal myocardial function, the values should be obtained from the same ventricle.

Animals↗
PubMed1984

Value of systolic time intervals in the diagnosis of large patent ductus arteriosus in fluid-restricted and mechanically ventilated preterm infants.

M-mode echocardiographic features suggesting a patent ductus arteriosus are based on two groups of indirect criteria: dilation of the left cardiac cavities and changes of systolic time intervals. The reliability of the first group of criteria has been questioned in fluid-limited, mechanically ventilated preterm infants. The sensitivity of the systolic time intervals in the same circumstances is investigated. Twenty-three patients with a large patent ductus arteriosus were selected. Review of their echocardiograms shows that the sensitivity of the various criteria (expressed as percentage of positivity) was as follows: inversion of the ratio of left ventricular preejection period to right ventricular preejection period, 91.3%; left ventricular preejection period to left ventricular ejection time over right ventricular preejection period to right ventricular ejection time less than 1,83%; left atrium dilation, 74%; shortening of left ventricular preejection period, 70%; dilation of left ventricular internal dimensions in diastole, 65%; increase in left atrium/aorta, 52%; and decrease of left ventricular preejection period to left ventricular ejection time, 48%. Three criteria involving time intervals (left ventricular preejection period to right ventricular preejection period, left ventricular preejection period, and left ventricular preejection period to left ventricular ejection time) had 100% specificity. The lowest specificity was found with criteria involving the left atrium (left atrial to aortic root ratio 75% and left atrium 63%). It is concluded that study of systolic time intervals is a reliable means of detecting preterm infants with hemodynamically significant left-to-right shunt through a patent ductus arteriosus even if the infants are mechanically ventilated and fluid restricted.

Ductus Arteriosus, Patent↗
PubMed1984

Low levels of blood alcohol and fetal myocardial function.

In ten experiments carried out on five chronically catheterized pregnant ewes (130 to 140 gestational days), 0.8 ml/kg absolute ethyl alcohol was injected into the mothers over a ten-minute period. Peak maternal and fetal alcoholemia levels were 1.1 +/- 0.1 and 0.9 +/- 0.04 g/L, respectively. Blood gases (arterial PO2, PCO2, pH, and arterial O2 content), cardiovascular parameters (heart rate, arterial pressures), and fetal myocardial function (systolic time intervals) were studied at basal state and during the four hours after injection. To observe changes in fetal O2 affinity, 2-3 diphosphoglycerate concentration and P50 were assessed before and at the peak of blood alcohol level. Maternal and fetal blood ethyl alcohol levels correlated closely (r2 = 0.9512) during all experiments. A small increase in the fetal arterial pH and a decrease in maternal PCO2 was observed just after the injection. This low level of fetal blood alcohol caused a moderate but significant decrease in myocardial contractility as judged by the changes in systolic time intervals. There was no alteration of other cardiovascular parameters and of hemoglobin oxygen affinity.

Animals↗
PubMed1983

Changes in the systolic time intervals of the fetal heart after surgical manipulation of the fetus.

The fetal cardiac systolic time intervals are potentially an important indicator of fetal well-being. Because experimental studies with the use of animal models are being carried out to evaluate the effects of abnormal antenatal factors on fetal myocardial function, it is important to establish the changes in the systolic time intervals that can occur as a result of the surgical preparation of the animal model and also to determine the time required for the recovery of myocardial function. After the appropriate catheters have been placed in fetal sheep, the ratio of preejection time to ejection time was followed in six maternal-fetal sheep models for 3 days postoperatively. The mean values obtained from the animals were then compared to the data obtained and were considered to be normal on the eighth postoperative day. In spite of acid-base data within the physiologic limits, the ratio of preejection period/ejection time was elevated postoperatively and reached normal values between 2 to 3 days postoperatively. The study demonstrates that 3 days are required for the recovery of fetal myocardial function before baseline preexperimental conditions are reached.

Animals↗
PubMed1983

Subxiphoid two-dimensional echocardiographic diagnosis of double-chambered right ventricle.

The echocardiographic features of 14 patients with double-chambered right ventricle are presented. Diagnosis was confirmed in 13 patients at cardiac catheterization and in one at necropsy. The ultrasonic diagnosis was based on the visualization in subxiphoid short-axis view of an anomalous muscle bundle at the lower margin of the right ventricular infundibulum; this structure was present in diastole and systole and the distal portion of infundibulum was wide and free of obstruction. Associated lesions were very frequent (especially ventricular septal defects, present in 13 patients). Subxiphoid two-dimensional echocardiography is an easy, reliable, noninvasive means of assessing this disease in infants and children.

Cardiac Catheterization↗