Measurement of Oxygen Consumption in Children Undergoing Cardiac Catheterization: Comparison Between Mass Spectrometry and the Breath-by-Breath Method

Accurate measurement of oxygen consumption (VO₂) is important to precise calculation of blood flow using the Fick equation. This study aimed to validate the breath-by-breath method (BBBM) of measuring oxygen consumption VO₂ compared with respiratory mass spectroscopy (MS) for intubated children during cardiac catheterization. The study used MS and BBBM to measure VO₂ continuously and simultaneously for 10 min in consecutive anesthetized children undergoing cardiac catheterization who were intubated with a cuffed endotracheal tube, ventilated mechanically, and hemodynamically stable, with normal body temperature. From 26 patients, 520 data points were obtained. The mean VO₂ was 94.5 ml/min (95 % confidence interval [CI] 65.7–123.3 ml/min) as measured by MS and 91.4 ml/min (95 % CI 64.9–117.9 ml/min) as measured by BBBM. The mean difference in VO₂ measurements between MS and BBBM (3.1 ml/min; 95 % CI ?1.7 to +7.9 ml/min) was not significant (p = 0.19). The MS and BBBM VO₂ measurements were highly correlated (R ² = 0.98; P < 0.0001). Bland–Altman analysis showed good correspondence between MS and BBBM, with a mean difference of ?3.01 and 95 % limits of agreement ranging from ?26.2 to +20.0. The mean VO₂ indexed to body surface area did not differ significantly between MS and BBBM (3.4 ml/min m²; 95 % CI ?1.4 to 8.2; p = 0.162). The mean difference and limits of agreement were ?3.8 ml/min m² (range, ?19.9 to 26.7). Both MS and BBBM may be used to measure VO₂ in anesthetized intubated children undergoing cardiac catheterization. The two methods demonstrated excellent agreement. However, BBBM may be more suited to clinical use with children.     

Oxygen consumption in infants and children during heart catheterization

Oxygen consumption was measured in infants, children, and adolescents during diagnostic heart catheterizations. A total of 825 measurements of oxygen consumption (VO₂) was performed in 504 subjects using a semiopen hood system and a paramagnetic oxygen analyzer. In 256 subjects under 3 years of age, body dimensions and heart rate were found to be significant factors for oxygen consumption. The regression equation for both sexes was: VO₂/BSA (ml/min · m²) = 3.42 · height (cm) − 7.83 · weight (kg) + 0.38 · HR − 54.1 (r ²= 0.39, SD = 38.7), where BSA is body surface area and HR is heart rate. VO₂/BSA was significantly lower in infants less than 3 months of age (133 ± 33 ml/min · m²) compared with infants of 3–12 months (171 ± 37 ml/min · m²; p < 0.01). In 272 children aged 3 years and older and adolescents, gender was a significant factor in oxygen consumption together with BSA and HR. The regression line equation for males was VO₂/BSA (ml/min · m²) = 0.79 · HR − 7.4 · BSA(m²) + 108.1 (r ²= 0.45, SD = 34.2). The regression line equation for females is VO₂/BSA (ml/min · m²) = 0.77 · HR − 5.2 · BSA(m²) + 106.8 (r ²= 0.43, SD = 34.4). Hematocrit, systemic oxygen saturation, and blood pressure were not significant factors. The predictive value of nomograms for oxygen consumption is limited because of the large interindividual variations not explained by differences in gender, body size, or simple hemodynamic variables. Preferably, oxygen consumption is measured; but if nomograms for oxygen consumption are used for hemodynamic assessment, the wide confidence intervals should be considered.     

Pulmonary Limitation to Exercise After Repair of D-Transposition of the Great Vessels: Atrial Baffle Versus Arterial Switch

This study evaluated resting pulmonary function and its impact on exercise capacity after atrial baffle (BAFFLE) and arterial switch (SWITCH) repair of D-transposition of the great vessels (DTGV). Previously decreased exercise capacity in DTGV patients has been primarily attributed to cardiovascular limitations, whereas pulmonary limitations have largely been overlooked. Resting flow volume loops were compared for BAFFLE (n = 34) and SWITCH (n = 32) patients. Peak exercise variables were compared for BAFFLE (n = 30) and SWITCH (n = 25). Lung disease (restrictive and/or obstructive) was present in 53% of DTGV patients (BAFFLE 62% and SWITCH 44%; p = 0.14). BAFFLE patients had a normal breathing reserve, whereas that of SWITCH patients was decreased (27.3 ± 28.3 vs. 13.0 ± 19.2; p = 0.04). BAFFLE patients attained a lower percent of predicted peak oxygen pulse (82.7 ± 20.5% vs. 94.7 ± 19.3%; p = 0.04) and peak oxygen consumption (VO_2peak) (26.6 ± 6.7 ml/kg/min vs. 37.3 ± 8.5 ml/kg/min; p < 0.01) than SWITCH patients. Patients after surgical repair for DTGV have an underappreciated occurrence of lung disease, even post-SWITCH. SWITCH patients have diminished breathing reserves, suggesting a pulmonary limitation to VO_2peak. BAFFLE patients have lower VO_2peaks, greater breathing reserves, and lower oxygen pulses than SWITCH patients, suggesting a cardiac limitation to peak aerobic capacity with probable secondary pulmonary limitations. Treating underlying lung disease in symptomatic patients after repair of DTGV may improve functional status.     

Peak Circulatory Power as an Indicator of Clinical Status in Children After Fontan Procedure

Peak circulatory power (CircP), a product of peak exercise oxygen uptake (VO₂) and peak mean or systolic arterial blood pressure, has proved to be a strong predictor of poor outcome in adults with congenital heart disease. This study sought to compare CircP with other cardiopulmonary exercise (CPX) test variables and to assess whether CircP is superior in categorizing patients into well-functioning vs. poorly functioning at-risk groups in the pediatric population after a Fontan procedure. The CPX test reports of 50 patients were retrospectively reviewed after the Fontan procedure. The patients were divided into two groups. The well-functioning group included patients in New York Heart Association (NYHA) classes 1 and 2 (n = 36). The poorly functioning at-risk group included patients in NYHA classes 3 and 4 and those with significant indicators or outcomes of a poor prognosis (n = 14). The patients in the well-functioning group had significantly higher CircP values based on mean blood pressure (MBP) (P < 0.001), higher CircP values based on systolic blood pressure (SBP) (P < 0.001), and higher peak VO₂ (P = 0.004) than those in the poorly functioning at-risk group. At a cutoff value less than 2100.4 mmHg/mlO₂/kg/min, CircP MBP had a sensitivity of 85% in categorizing children to the poorly functioning at-risk group. CircP correlated well with the clinical status of our patients. CircP and peak VO₂ did not differ significantly in ability to identify poorly functioning patients. Further prospective analysis is needed to assess whether CircP can serve as a prognostic marker for the pediatric population after Fontan procedure.     

Recovery kinetics of heart rate and oxygen uptake in long-term survivors of acute leukemia in childhood

Analysis of the recovery period following physical exercise has gained importance in evaluating cardiopulmonary capacity, not only in athletes but also in patients with proven or suspected heart failure. The purpose of this study was to apply these methods to long-term survivors of acute lymphoblastic leukemia (ALL) in childhood, who are at risk of developing anthracycline-induced cardiomyopathy. Nine children (mean age 12 years) and 10 adults (mean age 24 years) were included in the study after treatment for childhood ALL. Recovery of oxygen uptake and heart rate following maximal spiroergometric exercise was compared to that in 29 trained and untrained age-matched controls. The change in oxygen uptake (ΔVO₂) and heart rate (ΔHR) between maximal effort and 60 s of recovery did not differ significantly, either between children after oncological therapy (ΔVO₂: 14.95 ml/kg, ΔHR: 35 bpm) and healthy children (ΔVO₂: 15.85 ml/kg, ΔHR: 37 bpm), or between adult former oncological patients (ΔVO₂: 13.1 ml/kg, ΔHR: 27 bpm) and untrained adults (ΔVO₂: 15.7 ml/kg, ΔHR: 31 bpm). There was, however, a significant difference in ΔVO₂ between trained adults (ΔVO₂: 24.5 ml/kg) and both untrained adult controls (ΔVO₂: 15.7 ml/kg, p = 0.004) and adult patients (ΔVO₂: 13.1 ml/kg, p = 0.0002). This difference was not detected for heart rate. In conclusion, the recovery period did not reveal a discernible difference in cardiopulmonary capacity between former ALL patients and untrained age-matched controls. We did confirm that heart rate and oxygen uptake recovery serve as indicators of physical fitness.     

Aerobic fitness related to cardiovascular risk factors in young children

Low aerobic fitness (maximum oxygen uptake (VO_2PEAK)) is predictive for poor health in adults. In a cross-sectional study, we assessed if VO_2PEAK is related to a composite risk factor score for cardiovascular disease (CVD) in 243 children (136 boys and 107 girls) aged 8 to 11 years. VO_2PEAK was assessed by indirect calorimetry during a maximal exercise test and scaled by body mass (milliliters per minute per kilogram). Total body fat mass (TBF) and abdominal fat mass (AFM) were measured by Dual-energy X-ray absorptiometry. Total body fat was expressed as a percentage of total body mass (BF%) and body fat distribution as AFM/TBF. Systolic and diastolic blood pressure (SDP and DBP) and resting heart rate (RHR) were measured. The mean artery pressure (MAP) and pulse pressure (PP) were calculated. Echocardiography, 2D-guided M-mode, was performed. Left atrial diameter (LA) was measured and left ventricular mass (LVM) and relative wall thickness (RWT) were calculated. Z scores (value for the individual − mean value for group)/SD were calculated by sex. The sum of z scores for DBP, SDP, PP, MAP, RHR, LVM, LA, RWT, BF%, AFM and AFM/TBF were calculated in boys and girls, separately, and used as composite risk factor score for CVD. Pearson correlation revealed significant associations between VO_2PEAK and composite risk factor score in both boys (r = −0.48 P < 0.05) and in girls (r = −0.42, P < 0.05). One-way ANOVA analysis indicated significant differences in composite risk factor score between the different quartiles of VO_2PEAK (P < 0.001); thus, higher VO_2PEAK was associated with lower composite risk factor score for CVD. In conclusion, low VO_2PEAK is associated with an elevated composite risk factor score for CVD in both young boys and girls.     

Gas exchange during exercise in obese children

Twenty-three obese children, aged 9 to 14 years, ranging in percentage overweight from 26% to 83% (median 51.6%±16.3%), and 37 normal-weight children, matched for sex, age and height, performed a maximal exercise test on a treadmill. Cardiorespiratory performance was assessed by determination of the ventilatory anaerobic threshold (VAT) expressed in ml O₂/min per kg and as a percent of maximal oxygen uptake (% VO₂max). VAT and VO₂max related to body weight were significantly lower (P<0.01) in the obese than in the normal-weight children. VAT % VO₂max was similar in the two groups. A significant correlation was found between VAT and VO₂max both in the obese (r=0.85) and in the control groups (r=0.79). The habitual level of physical activity was lower in the obese subjects compared to the control subjects (P<0.001). In conclusion our study shows that physical fitness of overweight children is quantitatively lowered and that it can be assessed by VAT. VAT does not require a maximal test and is particularly useful in the ergometric study of subjects with exercise intolerance.Abbreviations AT anaerobic threshold - HR heart rate - VAT ventilatory anaerobic threshold - VCO₂ carbon dioxide output - VE ventilation - VO₂ oxygen uptake - VO₂max maximal oxygen uptake     

Heart rate variability and exercise capacity of patients with repaired tetralogy of Fallot

Heart rate variability (HRV) has been used as a reliable method to detect cardiac autonomic nervous system activity. Peak oxygen uptake (VO₂ peak) has been a predictor of death for adults with repaired tetralogy of Fallot (TOF). This study investigated the correlation between HRV and exercise capacity in 30 patients with TOF after surgery for total correction. The median age of the patients was 14 years (range, 9–25 years), and the median follow-up period was 11.6 months (range, 5.3–20.2 months). Low- and high-frequency-domain HRV significantly correlated with VO₂ peak (r = 0.56, P = 0.001 and r = 0.44, P = 0.02, respectively). After the 1-year follow-up evaluation, VO₂ peak and HRV analysis did not differ from those at entry to the study. However, low- and high-frequency-domain HRV still correlated significantly with VO₂ peak (r = 0.43, P = 0.03 and r = 0.52, P = 0.007, respectively). Left ventricular early diastolic myocardial velocity was most closely correlated with the VO₂ peak (r = 0.51, P = 0.005). Impaired cardiovascular autonomic control and left ventricular diastolic dysfunction may be responsible for exercise intolerance in patients with repaired TOF. Long-term follow-up evaluation with exercise testing and 24-h Holter monitoring are warranted.     

Exercise Capacity in Pediatric Heart Transplant Candidates: Is There Any Role for the 14 ml/kg/min Guideline?

A peak oxygen consumption (VO₂) of <14 ml/kg/min has been identified as a predictor of l-year mortality in adults with congestive heart failure (CHF) and is used as a criterion for listing for cardiac transplantation (OHT). The role of VO₂ measurement in children awaiting OHT has not been thoroughly evaluated. We sought to assess the degree of exercise impairment and the clinical applicability of the 14 ml/kg/min rule in children awaiting OHT. Cardiopulmonary exercise test (CPT) and cardiac catheterization data in all patients listed for OHT during the period of 1995–2003 were reviewed. Fourteen patients with a mean age of 15.5 ± 2.9 years underwent CPT with no serious adverse events at an interval of 6.6 ± 5.1 months prior to OHT. The etiology of CHF was multifactorial. Patients had impaired aerobic capacity with a mean peak VO₂ of 20.4 ± 6.8 ml/kg/min. Eleven of 14 patients (79%) had a peak VO₂ higher than the adult cutoff value of 14 ml/kg/min. Pediatric ambulatory patients with CHF can safely undergo CPT. Because of age-related differences in oxygen consumption and varied etiologies of CHF a peak VO₂ of <14 ml/kg/min is not a useful criterion for listing for OHT in this population.     

Reliability of estimation of maximum performance capacity on the basis of submaximum ergometric stress tests in children 10–14 years old

Thirty-three 10-year-old boys repeatedly performed six symptom-limited, spiroergometric exercise tests according to the vita maxima method over an observation period of 4 years. Submaximum and maximum performance parameters were assessed and their correlation was calculated. The correlation of the heart rate at 1, 2 and 3 watts/kg body weight with the values of maximum performance capacity (watt_max and VO₂max) and with the body-weight-related, relative maximum values was statistically significant. The correlation factors for the relative values were about twice as high (r=0.55) as the absolute values (r=0.27). The heart rate at 1, 2 and 3 watts/kg therefore was more characteristic of the relative values, which represent the state of training, and less for the absolute performance capacity, which depends to a great extent on body weight. However, the statistically significant correlation factors were too low to estimate reliably the state of training in an individual case. The correlation of physical working capacity at an HR of 170/min (PWC 170) with the maximum ergometric Watt performance was r=0.80 and therefore appears to be sufficient to estimate the maximum performance capacity in children. This is however only valid for children over the age of 11.Abbreviations PE physical education - kg kilogram of body-weight - watt_max maximum ergometric performance capacity - VO₂max maximum oxygen uptake - HR heart rate - PWC 170 physical working capacity at an HR of 170/min - LBM lean body mass - x arithmetic mean - s standard deviation This work was supported by Fonds zur Förderung der wissenschaftlichen Forschung, Projekt Nr. P5203     

Peak expiratory flow rate of rural school children from Wardha district,Maharashtra in India

Background  Peak expiratory flow rate (PEFR) recording is an essential measure in the management and evaluation of asthmatic children. The PEFR can be measured by a simple instrument—peak expiratory flow meter. The aim of this study was to determine the normal PEFR in rural school children from Wardha district of Maharashtra state, India. Methods  The PEFR was measured in 1078 healthy rural school children, living in Wardha district, Maharashtra using the Mini-Wright peak flow meter. All measurements were obtained in a standing position and the best out of three trials was recorded. Anthropometric measurements, weight, height, and mid-upper-arm circumference (MAC) were recorded, and body surface area (BSA) and body mass index (BMI) were calculated. Results  Positive correlation was seen between age, height, weight and PEFR. The regression equations for PEFR were determined for boys and girls separately. The boys had higher values than the girls at all heights. The prediction equation for PEFR based on height was PEFR = 3.64 height (cm) − 257.86 (R=0.47, R ²=0.22) for female; PEFR = 4.7 height (cm) − 346.51 (R=0.62, R ²=0.38) for male. Conclusion  PEFR is a reliable measurement, which can be used routinely and regularly in rural areas for assessment of airway obstruction and prediction formula derived for use in this population.     

Serum immunoreactive erythropoietin of children in health and disease

Serum immunoreactive erythropoietin (siEPO) was determined in cord serum from neonates (n=97, gestational age 36–43 weeks), in healthy children from birth to adolescence (n=260) and in children with haematological (n=30), renal (n=10) and congenital heart diseases (n=70). In healthy children siEPO levels decreased after birth (geometric mean cord siEPO 35.6 mU/ml with 95% range of 17–56 mU/ml in eutrophic, nondistressed fetuses) and reached lowest values during the first 2 months (geometric mean siEPO 11.5 mU/ml). Thereafter siEPO levels increased slightly and were constant between 2 months and adolescence. The geometric mean siEPO for healthy children after birth was 18.8 mU/ml with 95% range of 7–47 mU/ml. These estimates were not significantly different from normal adult values. In newborns with fetal distress (n=15) cord siEPO was significantly elevated (geometric mean 63.0 mU/ml;P<0.001). In children with haematological disease, siEPO and Hb concentration were inversely correlated (log siEPO (mU/ml)=4.1–0.20×Hb (g/dl);r=–0.62;P<0.0005). This relationship was significantly different in children with chronic renal failure (log siEPO (mU/ml)=0.67+0.035×Hb (g/dl);r=0.50;P=0.1). In children with heart disease the geometric mean siEPO was 19.2 mU/ml with 95% range 8–65 mU/ml for cyanotic (SaO₂<94%) and 17.7 mU/ml with 95% range of 12–36 mU/ml for acyanotic patients. In this group siEPO values were inversely correlated to the arterial oxygen content (log siEPO (mU/ml) =1.61–2.04×oxygen content (l/l);r=–0.28;P<0.02).     

Use of near-infrared spectroscopy for estimation of renal oxygenation in children with heart disease

We evaluated whether near-infrared spectroscopy (NIRS) measurement from the flank correlates with renal vein saturation in children undergoing cardiac catheterization. Thirty-seven patients <18 years of age were studied. A NIRS sensor was placed on the flank, and venous oxygen saturations were measured from the renal vein and the inferior vena cava (IVC). There was a strong correlation between flank NIRS values (rSO₂) and renal vein saturation (r = 0.821, p = 0.002) and IVC saturation (r = 0.638, p = 0.004) in children weighing ≤ 10 kg. In children weighing > 10 kg, there was no correlation between rSO₂ and renal vein saturation (r = 0.158, p = 0.57) or IVC saturation (r = –0.107, p = 0.67). Regional tissue oxygenation as measured by flank NIRS correlates well with both renal vein and IVC oxygen saturations in children weighing <10 kg undergoing cardiac catheterization, but not in larger children.     

Physical activity and aerobic fitness in children after liver transplantation

To determine physical activity (PA), aerobic fitness, muscle strength, health‐related quality of life (HRQOL), fatigue, and participation in children after liver transplantation. Children, 6‐12 years, at least one year after liver transplantation, participated in this cross‐sectional study. Measurements: Time spent in moderate to vigorous PA (MVPA) was measured using an accelerometer, and aerobic fitness (VO_{2 peak}) was measured by cardiopulmonary exercise testing. Muscle strength was measured by hand‐held dynamometry. Fatigue was measured using the multidimensional fatigue scale, and HRQOL with the Pediatric Quality of life Core scales and leisure activities was measured using the Children's Assessment of Participation and Enjoyment. Outcomes (medians and interquartile range (IQR)) were compared to norm values. Twenty‐six children participated in this study (14 boys, age 9.7 years, IQR 7.7;11.4). Children spent 0.8 hours/d (IQR 0.6;1.1) on MVPA. One child met the recommendation of at least 1 hour of MVPA every day of the week. Aerobic fitness was similar to norms (VO_{2 peak} 1.4 _L/min, IQR 1.1;1.7, Z‐score ?0.3). Z‐scores of muscle strength ranged between ?1.4 and ?0.4 and HRQOL and fatigue between ?2.3 and ?0.4. Participation was similar to published norms (Z‐scores between ?0.6 and 0.6). Young children after liver transplantation have similar MVPA patterns and aerobic fitness compared to published norms. Despite lower HRQOL, more fatigue, and less muscle strength, these children have similar participation in daily activities. Although children do well, it remains important to stimulate PA in children after liver transplantation in the context of long‐term management.     

Heart rate and oxygen uptake response to exercise in children with low peak exercise heart rate

Normal children achieve the same increase of oxygen uptake (VO₂) in response to exercise even though resting and submaximal exercise heart rates vary greatly as a function of age, body size and physical conditioning. To determine whether the VO₂ response to exercise is altered when heart rate is significantly reduced by heart disease, we compared 78 children who achieved a peak exercise heart rate of 150 beats/min to 201 controls of similar body size and normal peak exercise heart rates of 180 beats/min. All performed incremental (16.4 Watts/min) maximal cycle exercise. Separate analysis of males and females included heart rate, power (kg-m/min, Watts/kg), VO₂ (ml/min, ml/min per kg), O₂ pulse (VO₂/heart beat), V_E (l/min) and R (VCO₂/VO₂) at rest and during the 1st, 4th and last minute of exercise. Patients with low peak exercise heart rates had also lower resting submaximal exercise heart rates than controls. VO₂ at comparable exercise levels did not differ from controls and consequently O₂ pulse was greater in the patients than controls at rest and at all levels of exercise. A consistent gender difference was only found in controls where males achieved a higher VO₂ and lower heart rates at comparable levels of exercise. The data show a normal exercise VO₂ despite significantly lower heart rates. These findings cannot be explained by an increased arteriovenous difference alone and suggest that the patients retained the ability to effectively modulate stroke volume.     

Recovery Kinetics of Oxygen Uptake Is Abnormally Prolonged in Patients with Mustard/Senning Repair for Transposition of the Great Arteries

The aim of this study was to evaluate the ability to recover from exercise in patients with a Mustard/Senning (M/S) repair for transposition of the great arteries and to identify the major determinants. A total of 40 consecutive patients with a M/S repair at a mean age of 10.0 ± 9.8 months underwent maximal cardiopulmonary exercise testing at 19.5 ± 11.3 years of age. Results were compared to those of a cohort of 153 healthy individuals. Decay of oxygen uptake (VO₂), CO₂ (VCO₂), minute ventilation (VE), heart rate (HR) was calculated for the first minute of recovery. M/S patients had reduced peak VO₂ (22.9 ± 7.2 vs 34.2 ± 9.5 ml O₂/kg/min, p < 0.0001) and VO₂ slope (0.27 ± 0.10 vs 0.47 ± 0.2 L O₂/min, p < 0.0001), Peak O₂ pulse (p < 0.0001) and peak HR (p = 0.001) were reduced. VCO₂ and VE slopes were reduced (p < 0.0001 for both), whereas HR slope was similar (p = 0.38). In M/S patients, the only independent determinants of VO₂ slope during recovery were pulse O₂ slope (p < 0.0001) and VCO₂ slope (p < 0.0001). In M/S patients, a limited cardiopulmonary reserve affects not only maximal exercise responses but also the recovery phase. A prolonged recovery of O₂ pulse and a prolonged CO₂ retention with subsequent prolonged hyperpnea are the main determinants of the delayed recovery.     

Assessment of Coronary Flow Reserve in the Coronary Sinus by Cine 3T-Magnetic Resonance Imaging in Young Adults after Surgery for Tetralogy of Fallot

This study aimed to evaluate CFR by assessing blood flow in the coronary sinus and systemic endothelial function measured by FMD of the brachial artery in an open prospective study of 10 control subjects and 10 patients (ages, 15–25 years) who have undergone surgical TOF repair. Reduced ventricular function, impaired exercise capacity, and ventricular arrhythmia have been proposed as risk factors for sudden cardiac death after surgical repair of TOF. Some of this may be related to impaired myocardial perfusion. A 3.0T GE Signa Excite scanner was used to achieve phase-contrast, velocity-encoding cine magnetic resonance imaging in the coronary sinus before and during infusion with adenosine (0.14 mg/kg/min). FMD was measured in the brachial artery before arterial occlusion and 5 min afterward. The TOF group demonstrated significantly higher volumetric blood flow in the coronary sinus (282 ± 63 ml/min) than the normal control subjects at rest (184 ± 57 ml/min) (P = 0.006). During adenosine infusion, this difference disappeared. The CFR was 2.00 ± 0.43 in the control group and 1.19 ± 0.34 in the TOF group (P = 0.002). No correlation between FMD and CFR was observed in the study group (r _s = 0.61, n = 8, P = 0.15). This study showed a reduced CFR due to a higher blood flow of the subject at rest in the TOF group. This reduced CFR may disable a normal adaptation to increased oxygen demand during exercise and increase myocardial vulnerability to reduced blood supply postoperatively for TOF patients with coronary heart disease.     

Aerobic fitness in prepubertal children according to level of body fat

Aim: The purpose of this study was to investigate the relationship between maximum oxygen uptake (VO_2PEAK) and body fat in young children on a population‐based level. Methods: Participants were 586 children (311 boys and 275 girls) aged 6.8 ± 0.4 years, recruited from a population‐based cohort. VO_2PEAK was measured by indirect calorimetry during a maximal exercise test. Percent body fat (BF%) was estimated from skinfold measurements. Results: Significant relationships existed between BF% and absolute values of VO_2PEAK (mL/min), VO_2PEAK scaled by body weight (mL/min/kg) and VO_2PEAK by allometric scaling (mL/min/kg^0.71), whereas no relationships were detected for VO_2PEAK scaled to fat‐free mass (FFM) (mL/min/FFM). Person correlation coefficients for boys were 0.26, ?0.38, ?0.19 and ?0.01 NS and for girls 0.33, ?0.42, ?0.21 and ?0.03 NS, respectively. Significant differences in VO_2PEAK existed between different quartiles of BF%, with the exception when VO_2PEAK was scaled to FFM. Conclusion: Our findings document the coexistence of two known risk factors for disease at a young age on a population‐base and confirms that VO_2PEAK was scaled to FFM represents a body fat independent way of expressing fitness.     

Relationship of brain natriuretic peptide concentrations to left ventricular function and adverse outcomes in children with end-stage renal disease undergoing hemodialysis

B-type natriuretic peptide (BNP) is a biomarker of cardiovascular disease that is common in adults with chronic kidney disease (CKD). However, in children with CKD, the range and predictive power of BNP concentrations are not known. We aimed to determine the effect of HD on BNP, as well as the prognostic impact of BNP, in end-stage renal disease (ESRD) children undergoing hemodialysis (HD). Thirty-five children with chronic renal failure (16 boys age 12.1 ± 3.7 years) on maintenance HD were included. BNP level was measured, and Doppler echocardiography was performed 30 min before (pre-HD BNP) and 30 min after (post-HD BNP) HD in each patient. An adverse event was defined as all-cause death and heart failure hospitalization. The median pre-HD BNP, the post-HD BNP, and the change in BNP were, respectively, 240 pg/ml (72 to 3346), 318 pg/ml (79 to 3788), and 9 pg/ml (−442 to 1889). Pre-HD BNP concentration was negatively correlated with left ventricular (LV) ejection fraction (r = −0.41, P = 0.018). During a mean follow-up of 39 ± 14 months, 6 patients died, and 3 were hospitalized for heart failure. Using univariate analysis, BNP before and after HD as well as Doppler tissue imaging velocities had a strong graded relationship with adverse events. Cox proportional hazards model demonstrated that pre-HD body weight (P = 0.008), pre-HD BNP (P = 0.011), and post-HD BNP (P = 0.038) remained independent predictors of adverse outcome. Even in case of ESRD, BNP still strongly correlated with LV systolic and diastolic dysfunction and was associated with mortality in HD children.