Biomedical subjects
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The exercise limitation in a child with asthma is the result of several factors: the lack of ventilatory reserve, muscle deconditioning, and cardiac limitation. The severity of the airway obstruction is a major determinant of physical fitness. Aerobic and anaerobic fitness are equally affected. Both types of fitness can be improved by specific training programs.
Nine allozymic loci in 1,635 individuals of Sardina pilchardus obtained at 33 sites ranging from the North to the South limits of the Bay of Biscay were analyzed to provide a description of the genetic structure of the sardine population. Individual body size and age were also recorded and analyzed. In the study population, weak but significant genetic differences were found, and a cline was observed between multilocus heterozygosity and longitude. The cline was predominantly driven by allelic frequencies of two loci, PGM-1* and PEP-lt*, and using a cline model, we estimated a migration rate of 103.1 km/gen (dispersal distance per generation). In addition, we observed that the cline was linked to biological data such as mean length and mean age of the fish. Two hypotheses may explain this cline: mixing of two different populations in the Bay of Biscay or a selective process. The weak genetic differences, the important dispersal distance per generation, and the link between genetic and biological data suggest that selection is likely to be the primary factor that maintains the cline.
The object of this study was to evaluate the results of anatomical correction of transposition of the great arteries (TGA) in an inter-regional centre. The characteristics of 220 patients operated between 1985 and 2002 were analysed. Prenatal diagnosis of TGA was made in 38 patients (17%) including 36 of the 109 patients operated since 1995 (33%) and leading to earlier atrial septostomy in this situation (p= 0.046). Since 1995, the global early mortality of 12.3% has been significantly reduced to 5.5% (N= 6) including 4.4% (3/68 cases) of simple TGA (p= 0.002). In multivariate analysis, the only independent risk factor for early mortality was the occurrence of a major per-operative complication (p< 0.0001). The average follow-up was 4.8 +/- 4.5 years with an 86% survival at 5, 10 and 15 years and 97% survival at 5 years for patients operated after 1995. There were 22 reoperations including 14 on the right ventricular outflow tract. The non-reoperation rate at 10 years was 80% for simple TGA versus 70% in complex TGA (p= 0.0001). Survivors are asymptomatic with a normal ECG and normal LV function on echocardiography. Five patients have significant pulmonary stenosis and 4 have mild aortic regurgitation. The exercise stress tests performed between the ages of 7 and 10 were all normal. The authors conclude that that modern and reproducible management of TGA is possible in an inter-regional centre with results comparable to those of surgical centres of reference.
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AIM: To compare the haemodynamic status during high-frequency oscillatory ventilation and conventional mechanical ventilation in very preterm infants with respiratory distress syndrome. METHODS: Thirty-two neonates of less than 30 wk gestation randomly assigned to high-frequency oscillatory ventilation (n = 15) or conventional mechanical ventilation (n = 17) had three echocardiographies and one cerebral Doppler-echography under the same ventilation during the first 48 h of life. RESULTS: Mean airway pressure was 2 cm H2O higher in infants ventilated with high-frequency oscillatory ventilation at the different echocardiographies. Comparable right ventricular indexes were observed in the two groups. Reduction of the ductus arteriosus diameter and ductal closure were significant only in neonates ventilated conventionally. Left ventricular performance and left ventricular contractility did not differ between the groups. The high-frequency group had lower end diastolic velocity and a higher resistance index in the anterior cerebral artery. CONCLUSION: Compared with conventional mechanical ventilation, high-frequency oscillatory ventilation was achieved without altering cardiac function. However, the inability of the left ventricle to improve its performance in the presence of a significant ductal shunt suggests a narrow range of optimal pressures under this ventilatory mode.
Nineteen asthmatic boys (aged 13.4 years, 25-75 percentile: 11.5-15.1 years) performed short bouts of maximal exercise (force-velocity test) to test their anaerobic fitness and tolerance of maximal anaerobic exercise. Fourteen healthy boys (aged 13.9 years, 25-75 percentile: 11.6-15.7 years) matched for anthropometric characteristics including lean body mass (LBM), pubertal stage, and weekly physical activity formed a control group. The maximal anaerobic power (W(ana)) was measured during the force-velocity test. The maximal oxygen uptake (V'(O2max)) was assessed during a standard graded exercise test. Pre- and post-exercise pulmonary function was measured by body plethysmography. The asthmatic children exhibited lower W(ana) than the control group (8.2 watt.kg(-1) LBM, 25-75 percentile: 7.55-10.6 vs. 11.3 watt.kg(-1) LBM, 25-75 percentile: 9.46-14.1; P = 0.01). V'(O2max) was also diminished in the asthmatic group (P = 0.01). Multiple stepwise regression models revealed that Tanner's score (P < 0.001) and the diagnosis of asthma (P < 0.01) were the best predictors of W(ana). In conclusion, a diminished anaerobic fitness could contribute to the overall exercise limitation in asthmatic children.
Conventional treatment of pulmonary atresia with ventricular septal defect (VSD), hypoplastic pulmonary arteries (PA) and major aorto-pulmonary collaterals (MAPCAs) is controversial: from symptomatic and palliative treatment for some authors to surgery with unifocalisation of collaterals for others. These treatments never use native pulmonary arteries as only source of pulmonary flow, but create "neo-pulmonary arteries". Nine cases of pulmonary atresia with VSD, hypoplastic PA and MAPCAs were treated by rehabilitation of native PA through a staged approach: 1) surgical neonatal connection between right ventricule (RV) and hypoplastic PA, 2) evaluation and interventionnal catheterism with angioplasty of PA stenosis and closure of collaterals, 3) complete surgical correction with reconstruction of right outflow track and PA and closure of VSD. After first surgical stage of RV-PA connection at the mean age of 4.8 months (+/- 5.6 months), 8 patients were alive and underwent 22 cardiac catheterisms (mean of 2.7 per patient), with angioplasty of PA, and occlusion of MAPCAs in 6 and 2 patients respectively. Seven patients underwent complete anatomical correction at the mean age of 28.8 months (+/- 17.7 months) with one late death. The 6 remaining patients had encouraging hemodynamic status (RV pressure/LV pressure ratio at 0.6 +/- 0.26; mean left and right distal pulmonary pressure at 15.2 mmHg (+/- 9.1 mmHg)), and good functionnal status (3 in NYHA functionnal class 1, and 3 in class 2), for a mean follow-up of 79.5 months (+/- 41.4 months). One patient had reoperation on right outflow track stenosis, 6 years after correction. This small series enhances the feasibility of a staged approach with rehabilitation of small PA, allowing complete surgical correction with the native PA with good hemodynamic and functional results in pulmonary atresia, with VSD, hypoplastic PA and MAPCAs.
UNLABELLED: The prevalence of cardiovascular malformation is high in Turner's syndrome. We report two cases of partial anomalous pulmonary venous drainage associated with a severe bronchial disease. CASE REPORTS: Case 1: a 5-year-old girl with monosomy X presented with acute respiratory failure. The chest X-ray showed an atelectasis of the left lower lobe. The patient improved following bronchoscopic removal of a bronchial cast. During hospitalization, an anomalous pulmonary venous drainage of the right lung was discovered. In spite of complete surgical repair of the cardiac malformation, several episodes of respiratory failure occurred several years after the operation. Case 2: a 9-year-old girl with monosomy X and coarctation of the aorta underwent pre-operative cardiac catheterization. She had a history of bronchiectasis, leading to a lobectomy. Her respiratory condition improved following surgery. A partial anomalous pulmonary venous return was discovered during the cardiac angiography. The coarctation was repaired surgically. The correction of the left-to-right shunt was not necessary. CONCLUSION: The partial anomalous pulmonary venous return is frequently reported in Turner's syndrome. The possible respiratory disease associated with this cardiac malformation is usually described as a consequence of the increase in pulmonary blood flow. Our two cases did not match this hypothesis.
Congenital atrioventricular block is defined (Yater) as a documented conduction defect in a young subject with unquestionable bradycardia in the absence of a history of infection which might have caused the condition after birth. It is a rare condition (1 out of 20,000 births) and may be isolated or associated with another congenital malformation. Four cardiac malformations are classically associated: endomyocardial fibrosis, morphological abnormalities close to the conduction system: corrected transposition, left isomerism; patent ductus arteriosus and atrial septal defect apparently unrelated but the most common; the association of mitral regurgitation in adults, although the significance is not very clear. Isolated block is often observed in patients with mothers suffering from autoimmune disease, often clinically latent. Anti Ro/SS-A and La/SS-B antibodies cross into the foetal circulation and cause inflammation of the conduction tissues but the causal mechanism is not known. The diagnosis of the conduction defect is sometimes made during foetal life by echocardiography. After birth, the diagnosis is made by electrocardiography but the block is not always complete or permanent, its degree often increasing with time. In addition, in advanced degrees of block, the escape rhythm tends to slow down. Long-term follow-up studies have revised the previously considered good prognosis of isolated congenital atrioventricular block but advances in cardiac pacing provide satisfactory treatment. In the foetus, isolated atrioventricular block is usually associated with an escape rhythm > 60/min and enables normal vaginal delivery; a low heart rate < 55/min and anasarca carry a poor prognosis. In the neonate, pacing is indicated in babies with cardiac failure and a heart rate < 55/min. Follow-up by Holter monitoring, exercise testing and echocardiography is justified in children and adolescents; the patients may become symptomatic at any age. Pacing is essential in symptomatic cases (malaise, ventricular dysfunction) and useful in cases with long QT intervals, frequent ventricular extrasystoles and wide ventriculogrammes. Pacing is not always easy in children. Epicardial pacing by thoracotomy or an epigastric approach is possible but endocavitary pacing is to be preferred using thin pacing catheters introduced via the subclavian vein and small pacemakers implanted in a sub or prepectoral site. A pacing mode which restores the normal atrioventricular sequence is theoretically superior to single ventricular pacing even if rate responsive frequency.
BACKGROUND: It is well recognized that a right ventricle (RV) may eventually fail if working as systemic. This has led to arterial switch operation for transposition of the great arteries (TGA), but more recently to anatomic correction of 'corrected transposition' or atrio-ventricular discordance (AVD) combining an atrial switch and a ventricular outflow repair (arterial switch or Rastelli type). METHODS: We report here 8 cases of such anatomic correction of AVD in patients from 3 months to 10 years. Of these patients, 6 had situs solitus, and 2 situs inversus; 7 patients had a ventricular septal defect (VSD); 5 had an increased pulmonary flow, and 3 had a decreased pulmonary flow with pulmonary stenosis (PS) or pulmonary atresia (PA). In all, 6 had discordant and 1 had concordant ventriculo-arterial (VA) relations, and 1 had double-outlet RV, 2 had an associated coarctation, and 1 had a cor triatriatum. Of the 8 patients, 5 had pulmonary artery hypertension, 3 a moderate to severe tricuspid insufficiency and 6 had undergone one or more previous operations. Correction was done between 3 months and 10 years of age, with 7 having a Senning procedure (twice left-sided) and 1 a Mustard type operation. VA outflows were repaired with: 4 arterial switches, 1 left ventricle to aorta rerouting, 1 right ventricular outflow tract (RVOT) repair and 2 Rastelli. A tricuspid annuloplasty was done once. RESULTS: All patients survived the operation, but 2 patients needed a reoperation (both successful): late obstruction of pulmonary venous channel after a left-sided Senning, and residual VSD closure. Mean follow-up is 45 months (3-122). Of the 8 patients, 6 patients are in sinus rhythm, 2 have junctional rhythm. A patient with junctional rhythm and occasional tachycardia died suddenly 18 months after surgery 1 week after satisfactory evaluation. All have a normal left ventricle function as evidenced by echocardiography. CONCLUSIONS: Despite a more demanding procedure, the 'anatomic repair' of hearts with AVD is possible, even in infancy, with good early and mid-term result. Despite the potential late rhythmic problems of the Senning operation (somehow more frequent with AVD in our experience), it may become, with increasing experience, the procedure of choice in corrected transposition.
Nutritional status and chronic pulmonary hyperinflation can alter respiratory muscle function in cystic fibrosis (CF). This study investigated: 1) whether inspiratory muscle function is reduced in children with stable CF in comparison with healthy controls; and 2) the mechanisms leading to inspiratory muscle weakness, which probably predispose to respiratory muscle fatigue. We determined the tension-time index of the inspiratory muscles (TTMUS) noninvasively at rest in 16 children with mild to moderate CF (mean age, 11 +/- 2 years) and 10 healthy controls (mean age, 11 +/- 2 years). The TTMUS was determined as follows: TTMUS = TI/TTOT.PI/PIMAX, where PI is the mean inspiratory pressure estimated from the measure of mouth occlusion pressure (P0.1), PIMAX is the maximal inspiratory pressure, and TI/TOT is the duty cycle. The results showed similar nutritional status in both groups, as well as mild to moderate airway obstruction, hyperinflation, and trapped gas in the CF group. In this group only, a significant inverse relationship was found between TI/TOT and PI/PIMAX[TITTOT = 0.482 - (0.388PI/PIMAX), r = -0.53; p < 0.05]. These patients also had greater TTMUS (TTMUS = 0.087 +/- 0.030 in CF vs. 0.056 +/- 0.014 in controls, P < 0.01) that increased with decreasing lean body mass (r = -0.70, P < 0.005), with increasing percent predicted functional residual capacity (r = 0.70, P < 0.05), and increasing volumes of trapped gas (r = 0.77, P < 0.01). The multiple linear regression analysis for these factors was significant (R2 = 0.84, P < 0.01); however, the partial regression coefficient was significant only for lean body mass (r2 = 0.60, P < 0.05). Therefore, muscle mass appeared as the strongest determinant of TTMUS in CF. This study used a noninvasive method to assess the inspiratory muscle performance in children with CF. The results suggest impairment in inspiratory muscle function in these children despite good nutritional status and only mild to moderate alteration in pulmonary function tests. In addition, we were able to investigate some of the determinants of inspiratory muscle weakness, namely, muscle mass, hyperinflation, and trapped gas, and found that muscle mass played a predominant role.
BACKGROUND: Carbamazepine (Tegretol) is frequently prescribed to pregnant epileptic women. Various congenital malformations constitute the most described side-effects in their newborns. CASE REPORTS: Case 1. Esteban was born by caesarean section at 39 weeks of gestation, weighing 3,860 g. His Apgar score was 8, 9, 10 at 1, 3 and 5 minutes. His mother was given phenobarbital until 1.5 months of pregnancy then carbamazepine 400 mg LP x 2/day, raised to 600 mg LP x 2/day at the 25th week of gestation because of epileptic crisis. The newborn was transferred at day 4 for drowsiness, mild jaundice, persistent vomiting and bouts of hypotonia/hypertonia, tremors and hyperexcitability. His plasma Tegretol level was 5.9 micrograms/mL and severe hypocalcemia (1.35 mmol/L) was noted. Hypocalcemia disappeared within 48 hours and gastric and neurologic troubles by day 6. The patient left the hospital at day 14. Case 2. Matheo, Esteban's brother, was born by caesarean section after 39 weeks of gestation, weighing 3,210 g. His Apgar score was 9, 10, 10 at first, third and fifth minutes. The mother's anti-epieptic treatment associated carbamazepine LP 400 mg x 3/day and vigabatrin four tablets of 500 mg/d until the 6th month of pregnancy and five tablets by day thereafter. The newborn presented vomiting from the first feeding; tremors were noted on day 2. His plasma Tegretol level was 5.7 micrograms/mL (N = 4-8 micrograms/mL) and the baby was transferred. Upon arrival, persistent vomiting and succession of hypotonia/hypertonia with intermittent opisthotonos were noted. Blood and urine tests showed: low calcemia (2.19 mmol/L), negative Brand reaction and DNPH test, normal urinary and blood amino acid chromatography. The course was spontaneously favourable and the child went home at day 11. CONCLUSION: Newborns of epileptic mothers treated with carbamazepine and/or vigabatrin during pregnancy should be placed under clinical observation during their first postnatal week. Calcemia monitoring is suggested for infants whose mothers were not supplemented with vitamin D during pregnancy. With a follow up of respectively 26 and 7 months, both brothers have normal milestones, confirming the transitory and benign character of reported side-effects.
To investigate the anaerobic capacity in children with bronchial asthma, eight male children with atopic asthma (age: 12 +/- 1.7 yr) and seven healthy control subjects (age: 12 +/- 1 yr) performed a 30-s all-out exercise test: the Wingate anaerobic test (WanT). Post-exercise plasma epinephrine (E), norepinephrine (NE), venous blood lactate (La), and blood pH levels were determined. Peak power (Ppeak), mean power (Pm), and total energy expenditure (Wtot) during the WanT were assessed. The relative importance of aerobic (WO2) and anaerobic (Wana) energy release during the WanT was also evaluated. In comparison with control subjects, the children with asthma exhibited lower Ppeak (W.kg-1): 6 +/- 1.14 vs 7.3 +/- 0.5, P < 0.05; lower Pm (W.kg-1): 4.7 +/- 0.8 vs 5.9 +/- 0.5, P < 0.05; and lower Wtot (Jg-1): 140.3 +/- 25 vs 176.9 +/- 19, P < 0.05. The relative contribution of WO2 (26%) and Wana (74%) to the Wtot was identical in both groups. Blood lactate and pH kinetics revealed significantly lower La values and less acidosis in the asthmatic group (P < 0.001). Lastly, E (pg.ml-1) concentrations were lower in the asthmatic group: 274.96 +/- 84.58 vs 901.28 +/- 604.76, P < 0.05. These results suggest a reduced anaerobic capacity in children with asthma. A diminished adrenergic response to exhausting exercise, leading to a decreased anaerobic glycolysis, could partly account for this phenomenon.
An acute wheezing episode is the most common feature of severe lower respiratory tract infection during infancy. Respiratory syncytial virus (RSV) is the major causative agent. In order to study inflammation during acute wheezing episodes in infants, we wanted to assess the feasibility and contribution of induction of pharyngeal secretions. We therefore compared inflammatory markers in the pharyngeal secretions of 27 infants suffering from acute wheezing episodes with an RSV infection (RSV+) and 18 infants suffering with acute wheezing episodes without RSV infection (RSV-). Pharyngeal secretions were recovered by physiotherapy using isotonic saline. The safety of the procedure was carefully checked. Pharyngeal secretions were homogenized with dithiothreitol. Total cells and eosinophils were counted and levels of eosinophil cationic protein (ECP) and histamine were measured. Induction of pharyngeal secretion was always well tolerated. Eosinophils were present in five RSV+ and seven RSV- patients. ECP levels were not significantly different between the groups. Histamine levels after protein adjustment were significantly increased in RSV+ patients (p<0.01) in comparison to RSV- patients. In this study, we have shown, that pharyngeal secretion can be safely recovered from infants suffering from acute wheezing episodes, and that it can be analysed for enumeration of inflammatory cells and measurement of inflammatory mediators.
Molecular studies have shown microdeletions in region q11 of chromosome 22 in nearly all patients with DiGeorge, velocardiofacial and conotruncal anomaly face syndromes (DGS, VCFS and CTAFS, respectively) and in a high percentage of non-syndromic familial cases of conotruncal defects (CTD). CTD account for roughly a fourth to a third of all non-syndromic congenital heart defects (CHD), thus, 22q11 could harbor a major genetic factor of CHD. We searched for a 22q11 microdeletion in familial cases of non-syndromic CTD. Thirty-six cases of various isolated CTD, that is without history of hypocalcemia, immune deficiency, absent thymus, and dysmorphic appearance, were selected. With 48F8, a cosmid probe localized in the smallest deleted region of the DiGeorge critical region (DGCR), we found no deletions by fluorescence in situ hybridization in these 36 affected individuals of 16 families with recurrent CTD. Moreover, D22S264, a microsatellite localized at the distal part of the largest deleted region, was used to genotype the patients. Thirty-two patients out of 37 were heterozygous and hence not deleted at this locus, whereas 5 were uninformative. In conclusion, there are no large deletions in familial cases of various CTD, whether these defects are identical or not within a family. This result does not rule out other minor anomalies in this chromosomal region.
The aim of this study was to assess cardiac adaptation to muscular exercise in children operated for tetralogy of Fallot. Eight children with a history of tetralogy of Fallot were studied and compared with ten control children. The basal evaluation consisted of an electrocardiogram, spirometry in all cases. Chest X-ray and echocardiography in all operated children. A muscular exercise stress test with incremental load on a bicycle ergometer was carried out with measurement of the cardiac output by CO2 rebreathing (experimental method). Under resting conditions, the two groups were comparable with respect to anthropometrical parameters and respiratory function. The cardiovascular data confirmed the good postoperative results of the children with a history of tetralogy of Fallot; cardiothoracic index of 0.49 to 0.55; sinus rhythm on the electrocardiogram; right ventricular pressures within normal limits; residual instantaneous right ventricular-pulmonary artery pressure gradient less than 25 mmH. On exercise, there was no significant difference with respect to VO2max, maximal heart rate, maximal cardiac output and maximal ventilation. The relationship between cardiac output and oxygen consumption was linear in two groups: y = 8.17x + 1.95 in the control group, y = 8.57x + 2.82 in the operated children. The change in cardiac output on exercise was comparable in the two groups. These observations seemed to be related to the good postoperative haemodynamic result: absence of pulmonary sequellae and right ventricular dysfunction. Despite the normality of the results obtained in this series, exercise stress testing with analysis of cardiac and respiratory adaptation would seem to be necessary in the follow-up of children operated for tetralogy of Fallot to exclude a ventilatory or circulatory limitation.
Ventricular tachycardia (VT) in children is different to that observed in the adult because ischemic heart disease is exceptionally rare in this age group. The arrhythmia sometimes presents with cardiac failure or loss of consciousness. VT complicates the outcome of operated Tetralogy of Fallot, arrhythmogenic right ventricular dysplasia and some cardiac tumours. Cardiomyopathies are also a cause of VT but it must be noted that ventricular dysfunction may be the result of a prolonged arrhythmia and will disappear after return to sinus rhythm. Many cases of childhood VT occur without any patent cardiac disease even after extensive investigations. Some are benign with a good prognosis, such as salvoes of VT or sustained attacks of so-called ventricular Bouveret. Others carry a more reserved prognosis and require active treatment. Incessant tachycardia of the newborn is difficult to stop may be cured without sequellae. Torsades de pointes is sometimes iatrogenic complicating congenitally long QT syndromes with or without deafness or familial nature, and which may be likened to adrenergic VT. Amiodarone and betablockers are the best antiarrhythmic agents. Investigations with a diagnostic or therapeutic objective are easier in older children but these techniques, whilst not being systematic, do not exclude the very young children. Ablation techniques progress and the limited indications of surgery and implantable defibrillators have to be considered case by case.
The authors report the case of a tetralogy of Fallot associated with a neuroblastoma secreting large quantities of noradrenaline. Anoxic decompensation of the tetralogy of Fallot occurred early at the age of 4 months with cyanotic crises associated with an impression of abdominal pain. A systemic-pulmonary anastomosis was performed and the cyanosis regressed but the crises persisted and investigations showed the presence of a neuroblastoma. The tumour was treated by surgery and chemotherapy and has not recurred after 2 years' follow-up. Complete repair of the tetralogy of Fallot was performed secondarily at the age of 2. In this case, the high concentration of circulating catecholamines was probably a factor of early decompensation of the tetralogy of Fallot by infundibular spasm. A review of the literature revealed 26 cases of cardiac disease with a peripheral neurogenic tumour. Two pathogenic mechanisms are suggested: an embryological abnormality of cardiac cell migration from the neural crest and chronic stimulation of neuroblastic cells by chronic hypoxia.