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Biomedical subjects

L Leduc

Publications and source records attributed to L Leduc.

At least 19 recordsLinked to original sources
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↗
PubMed1999

Hypertension in pregnancy: new recommendations for management.

Hypertension in pregnancy is a frequent complication that has substantial adverse perinatal outcomes. Hypertension may be preexisting (chronic) essential or secondary hypertension; a second entity is pregnancy induced (gestational hypertension, preeclampsia). Recent advances have identified newer markers for pregnancy hypertension: several potential candidate genes may explain the apparent family inheritance of preeclampsia, and some thrombophilic markers have been associated with the condition. Management options for mild to moderate hypertension include a short hospital stay to exclude ongoing severe hypertension and to ascertain fetal well-being. Outpatient care with appropriate maternal and fetal surveillance, including umbilical artery doppler velocimetry, is recommended for better perinatal outcomes. Acute care for severe hypertension includes the use of magnesium sulfate to prevent eclampsia and antihypertensive medication. Expeditious delivery is recommended when the maternal or fetal states cannot be stabilized. Follow-up after delivery allows the uncovering of any other coexisting hypertensive or cardiovascular disorder.

Blood Pressure↗
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↗
PubMed1997

Report of the Canadian Hypertension Society Consensus Conference: 3. Pharmacologic treatment of hypertensive disorders in pregnancy.

OBJECTIVE: To provide Canadian physicians with evidence-based guidelines for the pharmacologic treatment of hypertensive disorders in pregnancy. OPTIONS: No medication, or treatment with antihypertensive or anticonvulsant drugs. OUTCOMES: Prevention of maternal complications, and prevention of perinatal complications and death. EVIDENCE: Pertinent articles published from 1962 to September 1996 retrieved from the Pregnancy and Childbirth Module of the Cochrane Database of Systematic Reviews and from MEDLINE; additional articles retrieved through a manual search of bibliographies; and expert opinion. Recommendations were graded according to levels of evidence. VALUES: Maternal and fetal well-being were equally valued, with the belief that treatment side effects should be minimized. BENEFITS, HARMS AND COSTS: Reduction in the rate of adverse perinatal outcomes, including death. Potential side effects of antihypertensive drugs include placental hypoperfusion, intrauterine growth retardation and long-term effects on the infant. RECOMMENDATIONS: A systolic blood pressure greater than 169 mm Hg or a diastolic pressure greater than 109 mm Hg in a pregnant woman should be considered an emergency and pharmacologic treatment with hydralazine, labetalol or nifedipine started. Otherwise, the thresholds at which to start antihypertensive treatment are a systolic pressure of 140 mm Hg or a diastolic pressure of 90 mm Hg in women with gestational hypertension without proteinuria or pre-existing hypertension before 28 weeks' gestation, those with gestational hypertension and proteinuria or symptoms at any time during the pregnancy, those with pre-existing hypertension and underlying conditions or target-organ damage, and those with pre-existing hypertension and superimposed gestational hypertension. The thresholds in other circumstances are a systolic pressure of 150 mm Hg or a diastolic pressure of 95 mm Hg. For nonsevere hypertension, methyldopa is the first-line drug; labetalol, pindolol, oxprenolol and nifedipine are second-line drugs. Fetal distress attributed to placental hypoperfusion is rare, and long-term effects on the infant are unknown. Magnesium sulfate is recommended for the prevention and treatment of seizures. VALIDATION: The guidelines are more precise but compatible with those from the US and Australia.

Antihypertensive Agents↗
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

Placenta percreta: balloon occlusion and embolization of the internal iliac arteries to reduce intraoperative blood losses.

Obstetric hemorrhage is still a potential cause of maternal mortality and morbidity. Angiographic embolization techniques have been described in cases of postcesarean bleeding, vaginal wall hematomas, cervical ectopic pregnancies, and postpartum bleeding to control persistent bleeding from pelvic vessels. We describe two cases of pregnancy complicated with placenta percreta. Balloon occlusion and embolization of the hypogastric arteries were performed during the cesarean section and hysterectomy, resulting in a remarkable reduction in intraoperative blood loss. Balloon occlusion and embolization of the internal iliac arteries significantly reduce intraoperative blood losses.

Adult↗
PubMed1995

Hemolytic anemias in pregnancy.

Polymorphism exists and complicates the diagnosis of inherited hemolytic anemias. However, with linkage DNA analysis and, on occasion, with characterization of the mutant gene, it is possible to make a diagnosis on the DNA level. This technique increases our understanding of the enzymatic defect and the relationship with clinical findings. In acquired hemolytic anemias, pregnancy is one of the most commonly associated conditions. The physiology is not yet entirely understood and, therefore, does not allow specific treatment. Supportive therapy is usually the rule in these cases.

Anemia, Hemolytic↗
PubMed1992

Successful treatment with the Smith-Hodge pessary of cervical incompetence due to defective connective tissue in Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders with at least ten distinct types. We report a case of EDS complicated by cervical incompetence. Treatment was undertaken after confirmation that the patient's EDS was not type IV, hence not associated with potentially serious vascular complications. Because of concern about stretching or tearing of the hyperextensible connective tissue associated with EDS, cerclage was not performed. The cervical incompetence due to defective connective tissue was treated with a Smith-Hodge pessary.

Adult↗
PubMed1992

Coagulation profile in severe preeclampsia.

One hundred women with severe preeclampsia or chronic hypertension with superimposed preeclampsia were seen during a 2-year period. We sought to determine whether a normal platelet count assures that no other clinically significant clotting abnormalities are present, and what level of thrombocytopenia predicts a risk of abnormalities in other coagulation indices. Fifty women had platelet counts below 150,000/microL, of whom 13 had a fibrinogen level below 300 mg/dL and two had a prolonged prothrombin time (PT) or partial thromboplastin time (PTT). The admission platelet count was an excellent predictor of subsequent thrombocytopenia (r = 0.829, P less than .001). No subject had an abnormal fibrinogen level or prolonged PT or PTT in the absence of thrombocytopenia. When monitoring intrapartum coagulation indices in preeclampsia, one can safely follow only the platelet count at admission and subsequently, reserving PT and PTT and fibrinogen levels for those cases complicated by counts less than 100,000/microL.

Adult↗
PubMed1991

Baroreflex function in normal pregnancy.

The sinoaortic baroreflex is one of the primary mechanisms that regulates blood pressure. Decreased baroreflex sensitivity has been reported in preeclampsia. We sought to determine whether pregnancy altered baroreflex sensitivity. From a radial artery catheter, heart rate and mean arterial pressure were recorded continuously onto a polygraph. The ratio of change in heart rate produced per unit of change in mean arterial pressure was calculated as an index of baroreflex sensitivity. Mean arterial pressure responses to incremental infusions of phenylephrine (0.4 to 2.0 micrograms/kg/min) were measured in the same patients at term (n = 9, 38.0 +/- 0.3 weeks) and again 6 to 8 weeks postpartum (n = 7). The results indicated (1) higher baroreflex sensitivity in pregnancy than in the postpartum period (0.9 vs 0.5 beats/min/mm Hg) (p less than 0.007); (2) attenuated vascular responsiveness to alpha-adrenergic stimulation in pregnancy (p less than 0.05); (3) a relationship between vascular responsiveness and baroreflex sensitivity. We conclude that pregnancy is associated with an increase in baroreflex sensitivity and that the attenuated response to phenylephrine is, at least in part, a result of increased baroreflex sensitivity.

Adolescent↗
PubMed1991

The hemodynamic effects of intubation during nitroglycerin infusion in severe preeclampsia.

The effectiveness of intravenous nitroglycerin infusion in lowering maternal blood pressure and in blunting the hemodynamic responses to endotracheal intubation was evaluated in six primigravid women with severe preeclampsia. Monitoring consisted of continuous electrocardiogram monitoring, arterial cannulation, and flow-directed pulmonary arterial catheterization in each patient. All patients underwent oxytocin induction of labor and crystalloid and/or colloid expansion to produce a pulmonary capillary wedge pressure of 10 to 15 mm Hg and a colloid osmotic pressure of greater than 17 mm Hg. Intravenous nitroglycerin was administered before induction of general anesthesia. The hemodynamic effects associated with endotracheal intubation revealed a change in the heart rate from 104 +/- 10 to 133 +/- 17 beats/min, an increase in mean arterial pressure from 134 +/- 12 to 164 +/- 32 mm Hg, and an increase in systemic vascular resistance from 1262 +/- 342 to 1351 +/- 259 dynes-sec-cm-5 that was accompanied by a small change in the cardiac index from 4.5 +/- 1.2 to 4.5 +/- 0.9 L.min-1.m-2.

Acute Disease↗
PubMed1991

Urinary sediment changes in severe preeclampsia.

We analyzed the urinary sediment of 30 patients with severe preeclampsia every 4 hours during early labor, delivery, and the postpartum period. Fifteen normal control patients were also followed in a similar fashion. No casts were noticed in the urine samples of the control group. However, the urinary sediment of preeclamptic patients revealed the same uniform pattern regardless of the state of coagulation, or the presence or absence of oliguria or eclamptic seizures. Numerous granular and hyaline casts, red-cell, and tubular cell casts were identified during microscopic evaluation. These data reflect both glomerular and tubular damage in preeclampsia. We conclude that urinary sediment analysis in severe preeclampsia uniformly reflects renal parenchymal damage and does not correlate with or predict the clinical course of the disease.

Adult↗
PubMed1990

Neurokinin inhibition of cholinergic myenteric neurons in canine antrum.

Neurokinins regulate gastrointestinal motility by interacting with receptors on both muscle layers and on myenteric plexus neurons. To determine if specific neurokinin (NK) receptor agonists can mediate inhibitory effects on myenteric neurons, we studied the effect of the NK-1 agonist substance P methylester (SPME) and the putative endogenous NK-2 receptor ligand neurokinin A (NKA) on [3H]acetylcholine [( 3H]ACh) release induced by electrical field stimulation from muscle strips cut from the canine gastric antrum. SPME but not NKA caused a dose-dependent inhibition of stimulated [3H]ACh release in tissues containing the myenteric plexus. The inhibition was not seen in longitudinal muscle without myenteric plexus. Pretreatment of tissues with indomethacin or antiserum to vasoactive intestinal polypeptide (VIP) but not naloxone or adrenergic or cholingergic blockade abolished the SPME-induced inhibition. Exogenous VIP stimulated the release of prostaglandin E2 (PGE2) from full thickness strips, and both VIP and PGE2 inhibited [3H]ACh release induced by electrical depolarization. These findings suggest that NK-1 receptor agonists can selectively inhibit stimulated [3H]ACh release and that this inhibition may involve the release of VIP and PGE2 from neurons within the myenteric plexus.

Acetylcholine↗
PubMed1990

Fetoplacental blood volume estimation in pregnancies with Rh alloimmunization.

Direct intravascular fetal transfusion under ultrasound guidance has become an important method of treating fetal anemia secondary to maternal red cell alloimmunization. An estimate of normal circulating volume would be useful in selecting the volume of donor blood to be transfused to achieve a desired final hematocrit. Thirty-five fetuses between 21 and 35 weeks of gestation underwent 67 direct intravascular transfusions. The fetoplacental volume relative to fetal weight estimated by ultrasound was found to be relatively constant throughout gestation at approximately 100 cm3/kg. The severity of fetal hemolytic disease and its treatment with intrauterine transfusions did not appear to alter the fetoplacental volume. A nomogram for fetoplacental blood volume versus gestational age is described.

Blood Transfusion, Intrauterine↗