[Clinical heterogeneity of the chromosome 22q11 microdeletion syndrome]. / Heterogeneidad de la presentación clínica del síndrome de microdeleción del cromosoma 22, región q11.

BACKGROUND: DiGeorge anomaly, velocardiofacial syndrome and conotruncal anomaly face syndrome are part of a group of congenital malformations of the chromosome 22q11 microdeletion syndrome, since they share certain phenotypic features as well as a common genetic abnormality. The malformations include mild facial dysmorphic features, conotruncal heart defects, thymic and parathyroid hypoplasia or aplasia and cleft palate. AIM: To describe the initial clinical presentation of children with clinical and molecular diagnosis of 22q11 microdeletion. PATIENTS AND METHODS: Ten children (seven male) with the phenotypic features of 22q11 microdeletion syndrome are reported. Microdeletion was detected in peripheral lymphocytes by fluorescent in situ hybridisation (FISH) with the TUPLE-1 DNA probe. RESULTS: Two children had abnormal karyotypes, one of them had a visible deletion and another child had an unbalanced translocation inherited from his mother who had a balanced translocation between chromosomes 14 and 22. Two of the 10 patients had an anterior laryngeal web, a malformation infrequently described in this syndrome. Five patients had the diagnosis of DiGeorge anomaly, had a more serious clinical presentation and a higher early mortality. CONCLUSIONS: The high frequency of the 22q11 microdeletion syndrome, estimated at 1:5.000 newborns, and its variable presentations requires a high level of awareness for its early diagnosis and appropriate management of associated complications.

[Radiofrequency fulguration for supraventricular tachycardia in pediatrics]. / Fulguración por radiofrecuencia de las taquicardias supraventriculares en pediatría.

Supraventricular tachycardias (SVT) are the most frequent cause of tachycardia in children. Its pharmacological treatment has adverse effects, is not curative, and is not always effective. During the last few years radiofrequency ablation (RF-A) has changed the treatment. The purpose of this study is to evaluate our experience in RF-A in children with SVT. Between 1990 and 1995, 92 patients (1 month to 17 years old) underwent electrophysiological study after the diagnosis of SVT. RF-A was attempted in 55 patients with accessory pathways (AP), slow-pathway of the atrioventricular node, or ectopic focus. The site of ablation was decided according to the electrical signals and the catheter position. The success of the RF-A was confirmed by the interruption of the tachycardia, the change in the sequence of activation of the intracardiac signals, the regression of the preexcitation, and the inability to reinduce tachycardia. RF-A was successful in 81% of the patients; 88% in those with a left AP, 56% in those with a right AP, and 100% in those with nodal reentry. Complications were seen in 7% of the patients: 3 with arterial obstruction, one with a minimal pneumothorax, and one with cardiac tamponade. During a follow up of 16.6 months there was no relapse nor late complications. We conclude that RF-A is a safe and effective procedure in pediatric patients with SVT.

[Di George syndrome]. / Síndrome de Di George.

Two patients with Di George syndrome are presented. Diagnosis was done at ages 4 months and 16 days respectively. Their main clinical symptoms were hypocalcemic convulsions, unusual facies (hyperthelorism, low set prominent ears, micrognathia, short philtrum) and cardiac malformations (vascular ring with right aortic arc, aberrant left innominated artery and ligamentum arteriosus in one of them and Tetralogy of Fallot with pulmonary valve atresia in the other). The first patient is now a 3.5 year old boy, his vascular ring was repaired and he has hypoparathyroidism but no clinical nor laboratory evidence of cellular immunodeficiency. The other patient had evidence of heart failure at her second week of life, she died at age sixteen days and, at necropsy, Fallot's tetralogy with pulmonary valve atresia, closed ductus arteriosus, histologically normal ectopic thymus and absent parathyroid glands were demonstrated. We postulate that these cases correspond to partial forms of Di George syndrome.

[Nonimmune fetal hydrops secondary to fetal tachycardia: their intrauterine diagnosis and treatment]. / Hidrops fetal no immune secundario a taquicardia fetal: diagnóstico y tratamiento intrauterino.

A case of nonimmune hydrops fetalis (NIHF) secondary to fetal supraventricular tachycardia (SVT) diagnosed at 33 weeks gestation is presented. Administration of digoxin to the mother yielded normal fetal heart rhythm and frequency as well as progressive resolution of hydrops after 24 hours of initiation of therapy. Causes of NIHF and diagnostic approach are mentioned. Diagnosis and management of fetal arrhythmias are discussed. The successful perinatal outcome obtained in this case and the literature review, recommend the use of antiarrhythmic drugs therapy in cases of NIHF secondary to SVT.

[Fetal echocardiography I: Foundations]. / Ecocardiografía fetal I: Fundamentos.

Fundamentals of fetal echocardiography are stated, describing a detailed identification of the fetal heart and the echographic, visualization of the great vessels. The importance of prenatal diagnose of congenital fetal cardiac malformations is emphasized.

[Fetal echocardiography II: Prenatal diagnosis of congenital heart defects. Preliminary experience]. / Ecocardiografía fetal II: Diagnóstico prenatal de cardiopatías congénitas. Experiencia preliminar.

A preliminary experience of 28 selective patients is related by authors in the prenatal diagnose of fetal congenital cardiopathy. Echocardiographic findings are evaluated as well as neonatal outcome and the obstetrics approach.

Effect of hemoglobin concentration on critical cardiac output and oxygen transport.

We previously found limited tolerance to acute reduction in cardiac output in lambs at the nadir of their physiological anemia [Am. J. Physiol. 253 (Heart Cir. Physiol. 12): H100-H106, 1987]. To determine the effect of hemoglobin concentration [Hb] on critical cardiac output, critical systemic O2 transport, and peripheral O2 extraction, we performed 31 experiments in 12 one-mo-old lambs at four [Hb] (means +/- SD in g/dl): 7.4 +/- 0.6, 10.5 +/- 0.5, 14.5 +/- 0.5, and 16.5 +/- 0.6. Desired [Hb] was obtained by exchange transfusion with packed red cells or plasma. Cardiac output was reduced by inflation of a balloon-tipped catheter in the right atrium, and critical levels were defined at the point where O2 consumption decreased and/or arterial blood lactate concentration increased in response. With lower [Hb], cardiac output was unchanged, systemic O2 transport was reduced, and fractional O2 extraction was increased, keeping O2 consumption constant at base line. As [Hb] was reduced, critical cardiac output was significantly higher, whereas critical systemic O2 transport was independent of [Hb], as were fractional O2 extraction and mixed venous PO2 at the critical point. Thus peripheral O2 extraction was not affected by changes in [Hb] during progressive decreases in cardiac output. We conclude that 4-wk-old lambs have decreased tolerance to reductions in cardiac output and systemic O2 transport because their relative anemia provides them with a base-line cardiac output and systemic O2 transport close to the critical level.

Late closure of the ductus arteriosus using indomethacin in the preterm infant.

Several studies have shown a lack of effect of indomethacin therapy for the closure of a patent ductus arteriosus (PDA) in premature infants over 14 days of postnatal age. In this report we describe two cases in which a hemodynamically significant PDA was closed with indomethacin in preterm infants over 20 days of age. The response to indomethacin may be more related to postconceptual age than to actual postnatal age. We suggest that intravenous indomethacin therapy should be attempted before surgical ligation is performed in those premature infants under 34 weeks postconceptual age who have a hemodynamically significant patent ductus arteriosus.

Response of the maternal, fetal, and neonatal pituitary-thyroid axis to thyrotropin-releasing hormone.

Thyrotropin releasing hormone (TRH) readily crosses the placenta and stimulates the fetal pituitary. We studied the response of the maternal and fetal pituitary-thyroid axes to TRH and the influence of prenatal exposure to TRH on the physiological postnatal increase in thyrotropin (TSH) and triiodothyronine (T3) in the neonate. Twenty-six pregnant women received TRH (400 or 600 micrograms) intravenous or saline (controls) either 2 or 12 h before elective cesarean section at term. Administration of 400 micrograms of TRH resulted in significant elevations of maternal TSH (15.7 +/- 2.9 versus 3.2 +/- 0.4 microU/ml, p less than 0.01) and prolactin (416 +/- 94 versus 223 +/- 41 ng/ml, p less than 0.05) 2 h later. Maternal T3 remained unchanged. A higher dose of TRH (600 micrograms) produced comparable results. Maternal administration of TRH (400 micrograms) 2 h before delivery resulted in significant increases in fetal TSH and T3 over controls (21.1 +/- 3.7 versus 4.8 +/- 1.0 microU/ml, and 132 +/- 12 versus 64 +/- 9 ng/dl, p less than 0.01, respectively). Cord blood hormone levels 12 hours after TRH administration were similar to controls. Higher doses of TRH did not produce further increases in fetal TSH or T3. Control and treated neonates demonstrated similar physiological postnatal increases in TSH and T3, suggesting that prior exposure to TRH did not blunt this response. These data suggest that maternal administration of TRH is an effective way of increasing fetal T3 levels, and that this treatment does not inhibit the postnatal surge in TSH and T3.