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Biomedical subjects

M Gewillig

Publications and source records attributed to M Gewillig.

At least 73 records · Page 4Linked to original sources
PubMed1997

Assessment of cardiorespiratory exercise function in obese children and adolescents by body mass-independent parameters.

The parameters used to assess aerobic exercise function by gas exchange are usually adjusted for body mass and are expressed as millilitres per minute per kilogram. In the case of obese children this could lead to overcorrection with an underestimation of their exercise capacity. The purpose of the present study was to assess cardiorespiratory exercise function in obese subjects using body mass-independent parameters. As both carbon dioxide output (VCO2) and oxygen uptake (VO2) are usually corrected for body mass, the slope of VCO2 versus VO2 can be considered to be independent of body mass. This slope was calculated below the ventilatory threshold (S1) and above the ventilatory threshold (S3). Exercise tests were performed on a treadmill and respiratory gas exchange was measured breath-by-breath. A group of 29 obese children [mean age 11 (SD 2.5) years] were compared to 16 normal controls of the same age range [mean age 10.8 (SD 2.2); P > 0.05]. The patients were overweight by 36 (SD 17.9)% and had a body mass index of 25.0 (SD 3.8). The results showed that S3 in the obese subjects was significantly steeper compared to the normal controls [1.30 (SD 0.20) vs 1.10 (SD 0.20); P < 0.05]. The steepest values for S3 were found in the subjects with the highest degree of obesity. This method has some limitations, since in a large proportion of the patients (48%) no ventilatory threshold could be detected, which is prerequisite for calculation of these slopes. The latter was already suppressed at the onset of exercise in 21% of the sample or could not be detected because of breathing irregularity in 27%. It is suggested from this study that cardiorespiratory exercise function in obese children is reduced, especially when assessed by parameters of aerobic exercise which cancel the confounding effect of body mass.

Adolescent↗
PubMed1997

Management with a staged approach of the premature hydropic fetus due to complete congenital heart block.

UNLABELLED: The management of the preterm fetus with hydrops due to complete congenital heart block is difficult. The outcome is frequently associated with significant morbidity and mortality. Two fetuses presented at the post menstrual age of 29 and 30 weeks respectively with severe hydrops due to complete heart block. The following staged approach was adopted: (1) enhance fetal lung maturation with maternal corticosteroids and thyroid releasing hormone for 48 h; (2) elective Caesarean section; (3) classical neonatal management consisting of intubation and ventilation, drainage of all cavities with effusions; (4) increase neonatal heart rate by administration of i.v. isoprenaline, by bipolar trans-oesophageal pacing or epicutaneo-oesophageal pacing; (5) after the regression of the hydrops, start epicardial pacing after implantation of 2 or 3 temporary epicardial 3/0 pacemaker; (6) implantation of a permanent abdominal pacing system with steroid epicardial tip once the threshold exceeds 20 mA or when the baby weighs more than 1500 g. In these patients a permanent pacing system was implanted at the ages of 8 weeks (2045 g) and 4 weeks (1560 g) respectively. No major complications occurred; the cardiac outcome with 37 and 34 months of follow up is excellent. CONCLUSION: This proposed staged approach with temporary epicardial leads can improve the outcome of hydropic fetuses due to complete congenital AV block.

Adult↗
PubMed1997

Submicroscopic deletion in chromosome 22q11 in trizygous triplet siblings and their father. Clinical variability of 22q11 deletion.

A submicroscopic deletion of chromosome 22q11 was demonstrated in three triplets and in their father. Two children had the typical DiGeorge sequence with at least three of the four cardinal features: conotruncal heart disease, hypoplastic thymus and typical facial features. Hypoparathyroidism was present in one of them. The third child had features of both DiGeorge and velo-cardio-facial syndrome (VCFS). The father presented with features compatible with VCFS. This observation further illustrates the wide variability in expression of a submicroscopic deletion of 22q11, even within one family.

Abnormalities, Multiple↗
PubMed1997

Intelligence and psychosocial adjustment in velocardiofacial syndrome: a study of 37 children and adolescents with VCFS.

We report data on a group of 37 VCFS patients with specific reference to their intelligence, behaviour, and social competence. Fifty five percent of the children had a borderline to normal IQ. Mental retardation (defined as IQ < 70 or > -2 SD below the mean) was found in 45%. In the majority, the mental retardation was mild (38%) and only two patients had moderate mental retardation. Severe mental retardation seems to be rare in VCFS. The present study shows also that the incidence of mental retardation is much higher in the familial than the de novo group. Intelligence is not correlated with the presence or absence of a heart defect. Significantly higher verbal IQs than performance IQs (probably related to deficits in visuospatial-perceptual functioning) were found. Problems in social-emotional functioning and attention were also found. Further longitudinal studies are necessary to provide an accurate prognosis and appropriate intervention for VCFS children.

Abnormalities, Multiple↗
PubMed1997

Factors influencing medium-term performance of right-sided cryopreserved homografts.

BACKGROUND OF THE STUDY: Between February 1987 and December 1996, 187 children and young adults underwent right ventricular outflow tract (RVOT) reconstruction with aortic or pulmonary homografts. METHODS: Patients were allocated to four groups according to preoperative diagnosis: RVOT obstructions with ventriculo-arterial (VA) concordance (n = 90), RVOT obstructions with VA discordance (n = 26), truncus arteriosus (n = 19) and RVOT reconstruction after the Ross procedure (n = 52). RVOT reconstruction was a reoperation in 49.7% of cases. A pulmonary homograft was used in preference (87% in concordant, 90% in Ross, 79% in truncus, and 50% in discordant groups). RESULTS: Five patients died after homograft repair (hospital mortality rate 2.7%). Mean follow up was 34 +/- 27 months. Four patients died during subsequent follow up; hence actuarial survival rate was 93 +/- 2% at 60 months. All other patients are currently in NYHA class I or II. Nine patients underwent reoperation because of homograft dysfunction. Overall survival was 90 +/- 3% at 60 months. CONCLUSIONS: Uni- and multivariate analysis identified young age at correction, the use of aortic homografts, corrections in patients with VA discordance, and longer aortic cross-clamp time as independent predictors of homograft failure.

Adolescent↗
PubMed1996

Idiopathic restrictive cardiomyopathy in childhood. A diastolic disorder characterized by delayed relaxation.

Six children with idiopathic restrictive cardiomyopathy were evaluated. Electrocardiographic evaluation disclosed left atrial dilatation and repolarization abnormalities. Echocardiographic examination showed gross left atrial enlargement (182 +/- 29% of predicted values, P < 0.001) in the presence of normal left ventricular cavity dimensions (99 +/- 6%, P: ns). Left ventricular wall thickness varied from normal to mild concentric hypertrophy (septum: 116 +/- 16%, P < 0.05). Global left ventricular systolic function was normal or slightly subnormal; however, the relaxation was significantly delayed throughout diastole. E/A ratio was 4.1 +/- 1.4 and deceleration time 94 +/- 7 ms. Marked ventricular filling occurred in mid-diastole as could be deduced from a prominent mid-diastolic mitral L wave on the Doppler flow tracing. Early filling contributed 56 +/- 6%, mid-diastolic filling 28 +/- 4% and atrial contraction 16 +/- 3% to total ventricular filling as estimated by determining E-area, L-area and A-area, respectively. The left ventricular pressure curve showed a steady decline during mid-diastolic filling. This implies that the driving force for mid-diastolic filling is not the increased left atrial pressure but suction by the ventricle. The restrictive haemodynamics are therefore not caused by increased intrinsic stiffness of the ventricular wall, but most likely result from serious dysfunction and delay of the active relaxation of the ventricle. Progression of the disease was observed in three out of six patients, resulting in death or extreme low cardiac output. The three other patients remained clinically stable during the follow-up period of 6-10 years.

Adolescent↗
PubMed1996

Dynamics of respiratory gas exchange during exercise after correction of congenital heart disease.

In pediatric exercise testing, conventional measures of aerobic exercise function such as maximal O2 uptake or the ventilatory anaerobic threshold (VAT) use only one value for the assessment of exercise capacity. We studied a more comprehensive approach to evaluate aerobic exercise function by analyzing the steepness of the slope of CO2 production (VCO2) vs. VO2 above the VAT (S3). This was calculated in 32 patients operated on for congenital heart disease [16 for transposition of the great arteries (TGA) and 16 for tetralogy of Fallot (TF)] and was compared with 16 age-matched controls (nl). The results show that the reproducibility of this new assessment method was excellent (coefficient of variation for S3: 8.6%). S3 was significantly steeper (P<0.05) in the patients (1.31 +/- 0.22 for TGA and 1.28 +/- 0.16 for TF) compared with the nl (1.10 +/- 0.22). Also, the difference between S3 and the slope of VCO2 vs. VO2 below the VAT was significantly higher in the patients (0.37 +/- 0.22 for TGA and 0.31 +/- 0.10 for TF) than in controls (0.22 +/- 0.06). The steeper slopes were associated with lower than normal values for VAT and O2 during exercise. It is concluded that the analysis of the steepness of the slope of CO2 is a sensitive, reproducible, and objective approach to evaluate the integrative cardiopulmonary response to exercise. It complements the assessment of a subnormal VAT by reflecting the extent of anaerobic metabolism.

Aerobiosis↗
PubMed1996

Congenitally absent pulmonary veins--diagnostic pitfalls. Two case reports.

Two patients with partial absence of the right and left pulmonary veins respectively are described. Congenitally absent pulmonary veins are a rare phenomenon and the diagnosis is often missed or delayed. When children present with haemoptysis and/or recurrent respiratory infections with no obvious underlying cause, absence of the pulmonary veins must be part of the differential diagnosis. Special investigations to be done in these patients are chest roentgenograph to compare the lung volumes, radio-isotope scan, echocardiography and cardiac catheterisation. Magnetic resonance imaging may be helpful in defining the cause and site of obstruction of the pulmonary veins. Depending on the cause, surgery might be considered.

Child↗
PubMed1995

Comparison by computerized numeric modeling of energy losses in different Fontan connections.

BACKGROUND: Different surgical techniques for creating a Fontan circulation can be used. The option of including an atrium in the circuit, or the technique used for connecting the caval veins to the pulmonary artery in a total cavopulmonary connection, frequently is empirical and is based on personal experience and preference. The hemodynamic and energetic differences between the different circuits are small, and short-term results are comparable. However, small, energetic differences may have significant implications for the long-term follow-up. The finite element method allows a computer-based modeling of the flow dynamics and pressure losses. It permits comparison of different Fontan connections in a single patient with identical geometry and functional conditions. METHODS AND RESULTS: We compared the atriopulmonary connection with different types of cavopulmonary connections, which differed in the degree of symmetry of implantation of both caval veins into the right pulmonary artery. Based on anatomic models and physiological flow dynamics, three-dimensional geometries and finite element meshes were created with PATRAN; flows were calculated with POLYFLOW (B), and results were visualized with DATA VISUALIZER. CONCLUSIONS: The atriopulmonary connection produces higher energy losses than the cavopulmonary connection (+/- 1 mm Hg at rest). The cavopulmonary connection is more efficient when the connection of the caval veins to the pulmonary artery is asymmetrical.

Blood Flow Velocity↗
PubMed1995

Serial cardiorespiratory exercise testing in patients with congenital heart disease.

Aerobic capacity of patients with different forms of congenital heart disease was serially evaluated in 79 patients and the evolution was correlated with the lesion and the level of daily activity. The patients were divided into six groups: patients with a small ventricular septal defect (VSD) with mini shunt (n = 14), mild pulmonary valve stenosis with gradient < 40 mm Hg (PS) (n = 12), mild to moderate aortic valve stenosis (gradient 36 +/- 17 mmHg) (AS) (n = 12), patients 4.7 +/- 2.1 years after repair of tetralogy of Fallot (PO-TF) (n = 16), patients 2.2 +/- 2.9 years after closure of a high flow/high gradient VSD (PO-VSD) (n = 13), and patients 2.6 +/- 1.7 years after Fontan repair (Fontan-PO) (n = 12). Aerobic capacity was assessed by determination of the ventilatory anaerobic threshold (VAT). VAT reflects the highest aerobic exercise level prior to a disproportionate increase of CO2 and ventilation relative to O2 uptake; it is independent of patient motivation. Data are expressed as percentage of normal O2 uptake at VAT, determined in 234 age/gender matched controls. The habitual level of physical activity was assessed by a standardised questionnaire. Aerobic capacity in all subgroups of patients, even with very mild defects, was at or below the lower limit of normal. Children left unrestricted from physical exercise (VSD, PS, PO-VSD) had no change over the study period. However, aerobic capacity of patients with medically imposed physical restrictions (AS) and significant residual haemodynamic lesions (PO-TF, Fontan) decreased with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Transverse arch hypoplasia predisposes to aneurysm formation at the repair site after patch angioplasty for coarctation of the aorta.

OBJECTIVES: This study used magnetic resonance imaging (MRI) to evaluate the morphology and pathophysiology of aneurysm formation after patch angioplasty for coarctation of the aorta. BACKGROUND: Late aneurysm formation at the repair site is a well known and frequent complication after patch angioplasty. However, because the underlying mechanisms remain unresolved, postoperative outcome is unpredictable and adequate follow-up difficult. METHODS: Seventy-three of 85 patients with patch angioplasty for coarctation of the aorta were screened for aneurysm formation. Magnetic resonance imaging was performed in all 33 patients with an aneurysm, and results were compared with those for 13 control patients and 10 normal subjects. Mean (+/- SD) time between operation and MRI was 12.0 +/- 2.0 years. Aneurysm was defined as the ratio of the diameter of the aorta at the repair site to the diaphragmatic aorta > or = 1.5. Hypoplasia of the transverse arch and recoarctation at the repair site were defined as a ratio < 0.9. Transverse arch ratios on MRI were compared with those on preoperative cineangiography and the pressure gradient between the patient's right and left arm. RESULTS: All 33 patients with an aneurysm had a hypoplastic transverse arch. The 13 patients with a normal ratio at the repair site had a normal transverse arch ratio (chi square, p < 0.0001). Logarithmic regression showed a significant negative correlation (r = 0.62) between the repair site and transverse arch ratios. A significant pressure difference between the patient's right and left arm was found in patients with versus those without aneurysm (p = 0.0009). No significant difference was found between transverse arch ratios on preoperative cineangiography and postoperative MRI (mean 0.014 +/- 0.1, p = 0.4). CONCLUSIONS: Aneurysm formation at the repair site is highly related to hypoplasia of the transverse arch. Sufficient catch-up growth of a hypoplastic transverse arch is rare after late patch angioplasty. Dynamic phenomena, such as flow acceleration and turbulence, originating in a narrow transverse arch, may contribute to aneurysm formation at the repair site after patch angioplasty.

Adolescent↗
PubMed1995

Right ventricular outflow reconstruction with homografts.

Ninety children and young adults underwent right ventricular outflow tract (RVOT) reconstruction with aortic or pulmonary homografts from May, 1989 to May, 1994. The patients were divided into three groups according to preoperative diagnosis: RVOT obstructions with ventriculo-arterial (VA) concordance (61), RVOT obstructions with VA discordance (18) and truncus arteriosus (11). Of the reconstructions, 52% were reoperations. A pulmonary homograft was used by preference (85% in the concordant group and 33% in the discordant group). One patient died after homograft correction (hospital mortality 1.1%). The mean follow-up was 32 +/- 22 months. One patient died after 10 months due to congestive heart failure and obstructive pulmonary hypertension. All other patients were in NYHA classes I-II. Three patients (two discordant and one truncus correction) underwent reoperation because of aortic homograft dysfunction and calcification. The incidence of significant (> or = 40 mmHg) gradient across the reconstruction found at the last echocardiographic control was 4% in the concordant, 28% in the discordant, and 18% in the truncus, group. Echocardiographic evidence of moderate (grade 2-3/4) pulmonary regurgitation (PR) was noticed in 24 and 13% of the concordant and discordant groups, respectively. From this medium-term experience it is concluded that (1) the medium-term performance of cryopreserved homografts is excellent, even in young patients, (2) corrections in patients with VA discordance need close follow-up, (3) the use of pulmonary homografts, especially in VA concordant lesions, should be encouraged, (4) longer-term follow-up is necessary to confirm the superiority of the cryopreserved homograft when compared to the porcine xenograft in the RVOT.

Adolescent↗