Cardiopulmonary exercise testing in children following surgery for tetralogy of Fallot

The purpose of this study was to compare the cardiopulmonary responses at rest and during exercise of children following surgical correction of tetralogy of Fallot. The physiologic measurements assessed at rest and during maximal treadmill exercise included diffusing capacity of the lung for carbon monoxide, heart rate, oxygen consumption, minute ventilation, and cardiac output. Twenty children with repaired tetralogy of Fallot served as the study group, and 20 normal boys and girls served as controls. Subjects with tetralogy of Fallot had significantly lower values than those of control subjects for maximal cardiac output and somewhat lower values for diffusing capacity of the lung for carbon monoxide and heart rate. We conclude that the exercise cardiac function of children with surgically corrected tetralogy of Fallot is somewhat diminished compared with that of control children. This information is necessary to establish safe, yet effective exercise guidelines for this select population.     

Cardiopulmonary performance during exercise in patients with repaired tetralogy of Fallot with absent pulmonary valve

In patients with tetralogy of Fallot and absent pulmonary valve, the dilated pulmonary arteries sometimes result in bronchial compression and pulmonary symptoms due to airway obstruction, recurrent pulmonary infection, and development of bronchiectasis. After complete intracardiac repair, residual pulmonary disease may be expected to result in impaired cardiopulmonary performance during exercise. To assess this hypothesis, nine patients with tetralogy of Fallot and absent pulmonary valve underwent exercise testing and were compared to 38 patients with tetralogy of Fallot repaired using a transannular patch. All patients were exercied to maximum volition using a 1 minute incremental treadmill protocol with monitoring of pulmonary functions and expired gases. Maximal heart rate, maximal oxygen consumption, oxygen consumption at anaerobic threshold, and maximal respiratory exchange ratio were similar for the two groups. There was no significant difference for ventilation and gas exchange parameters at rest or at maximal exercise, and values for both groups were below the predicted normal for healthy subjects. Breathing reserve, however, did tend to be some-what lower in the group with tetralogy of Fallot with absent pulmonary valve. In summary, despite significant preoperative symptoms, cardiopulmonary performance during exercise in patients with tetralogy of Fallot and absent pulmonary valve is similar to patients with tetralogy of Fallot repaired with a transannular patch.     

Efficiency of oxygen cost during exercise in patients with symptoms of fatigue during physical activities

BACKGROUND: With growing age, values for oxygen uptake decrease for the same level of exercise. However, some children with normal heart and normal maximal oxygen uptake complain of exertional fatigue. AIM: To evaluate the energy expenditure during submaximal treadmill exercise. SUBJECTS AND METHODS: In 20 children with exertional fatigue (mean age at testing: 7.9 +/- 1.8 years), oxygen uptake and respiratory gas exchange were assessed breath by breath. A graded exercise test was performed until exhaustion. Patients were compared to an age- and gender-matched control group (8.4 +/- 1.9 years, p = 0.45). RESULTS: Maximal oxygen uptake in patients (48.6 +/- 7.1 mL O(2)/min/kg) was similar to normal controls (47.4 +/- 5.2 mL/min/kg, p > 0.25). The inclination of the treadmill at maximal exercise was significantly (p = 0.02) lower in patients (12.6 +/- 4.9%) versus controls (16.0 +/- 3.5%). During submaximal exercise, oxygen uptake (expressed as mL/min/kg or as a percent of maximal oxygen uptake) was significantly higher (p < 0.001) in patients compared to normal controls. CONCLUSION: Children with exertional fatigue as compared to healthy controls, have a higher oxygen uptake for the same level of exercise and therefore perform at each level of exercise closer to their maximal exercise capacity. This may in part explain subjective complaints of poor exercise tolerance.     

转运呼吸机在危重患儿院际转运中的应用研究

目的 探讨转运呼吸机在危重患儿院际转运过程中的应用价值。方法 选择湖南省儿童医院2018年1月—2019年1月未使用转运呼吸机转运和2019年1月—2020年1月使用转运呼吸机转运的危重患儿分别作为对照组(n=120)和观察组(n=122),对两组病例的一般情况,转运途中心率、呼吸、经皮血氧饱和度变化,不良事件发生情况和转归进行对比分析。结果 转运前两组患儿性别、年龄、氧合指数(PaO₂/FiO₂)、小儿危重病例评分、转运前病程、原发疾病、心率、呼吸、经皮血氧饱和度的比较差异均无统计学意义(P>0.05)。转运途中两组患儿心率、呼吸、经皮血氧饱和度的比较差异无统计学意义(P>0.05);观察组气管导管脱管、留置针脱出、心搏骤停发生率低于对照组,差异无统计学意义(P>0.05)。观察组机械通气时间、儿童重症监护病房住院时间较对照组缩短,转运成功率、治愈及好转率较对照组升高,差异有统计学意义(P<0.05)。结论 转运呼吸机在危重患儿院际转运中的应用可在一定程度上协助提高院际转运的成功率,改善危重患儿的预后,值得在院际转运...     

The peak oxygen uptake of healthy Turkish children with reference to age and sex: a pilot study

Maximal oxygen uptake (VO2max) has an important place in the assessment of cardiopulmonary fitness. Currently there is insufficient normative data for Turkish children. With this preliminary study, we aimed to set up a normative data for our lab which may also serve as a basis for future large population based studies in Turkey. We assessed the peak oxygen consumption of 80 healthy Turkish children aged 5-13 years and examined the cardiopulmonary responses to exercise test in relation to their age, sex and body size. Dynamic lung functions were positively and significantly correlated with age. A similar correlation was observed for the peak VO2. A significant positive correlation between peak VO2 and body size was demonstrated only in boys for height. There were no differences in all of the test parameters with reference to sex except in the age group of 13 years. Boys who were 13 years old had higher mean values of maximal voluntary ventilation (MVV), oxygen uptake at anaerobic threshold, peak VO2, and exercise test duration than those of girls of the same age (p < 0.05). VO2 plateau was detected only in 25%, and when two groups with and without VO2 plateau were compared, there were no differences regarding the age, sex, weight, height and exercise test results. Assessment of VO2 by graded exercise stress testing by treadmill is accepted as a safe and effective method of evaluating the physical fitness of children. Current study presents normal data for a limited subpopulation of healthy Turkish children.     

Ergometry procedures independent of body weight in children with special reference to blood pressure behavior in stress

For the purpose of investigating differences in terms of gender and methodology, a group of 80 healthy children engaged in leisure-time sport activities (male: n = 50; 10.9 +/- 1.1 years; female: n = 30; 11.5 +/- 1.1 years) was divided into 3 groups, which were then subjected to different ergometric procedures. In group I, boys and girls were compared in a bicycle ergometry in an upright seated position. In group II, a bicycle ergometry in upright seated position was compared with a bicycle ergometry in a supine position. In group III, a bicycle ergometry in upright seated position was compared with a treadmill exercise. Bicycle ergometry was started at 25 W; workload was increased in steps of 25 W every 3 min until the children felt exhausted. Results: No differences with respect to gender were found for maximum oxygen uptake, maximum heart rate and maximum lactate. The relevant parameters were also similar on submaximal levels of exercise intensity. All children reached a degree of thorough physical exhaustion at heart rates close to 200 X min-1. As in adults, maximum oxygen uptake decreased in the following order: treadmill exercise greater than bicycle ergometry in upright seated position greater than bicycle in supine position. Systolic and diastolic blood pressure on the various levels of exercise were lower than among adults.(ABSTRACT TRUNCATED AT 250 WORDS)     

Restrictive Ventilatory Impairment and Arterial Oxygenation Characterize Rest and Exercise Ventilation in Patients After Fontan Operation

The objective of this study was evaluate the relationships between abnormal pulmonary circulation, lung function, and respiratory response during exercise in Fontan patients. Pulmonary function and cardiopulmonary exercise tests were performed in 101 Fontan patients and 122 controls. A small vital capacity (VC) with a high residual volume-to-total lung capacity ratio and a slight but significant low arterial saturation with hypocapnia were observed in Fontan patients. The number of surgical procedures determined VC. Total cavopulmonary connection, fenestration, higher pulmonary arterial wedge pressure, and smaller VC were independent determinants of low arterial saturation, which was the only determinant of hypocapnia. Arterial saturation decreased during exercise and resting arterial saturation correlated with that at peak exercise. Improvement in dead space ventilation was less in Fontan patients and was independently determined by resting arterial saturation. A steeper minute ventilation–carbon dioxide production slope was determined by resting arterial saturation, arterial carbon dioxide tension, and peak oxygen uptake. In Fontan patients, in addition to dead space ventilation, surgery-related reduced VC, the type of repair, and high pulmonary arterial wedge pressure cause arterial desaturation with subsequent hypocapnia, resulting in accelerated inefficient ventilation at rest and during exercise.     

Exercise Performance Following Repair of Hypoplastic Left Heart Syndrome: A Comparison with Other Types of Fontan Patients

Reports of exercise performance after Fontan surgery for hypoplastic left heart syndrome (HLHS) are lacking. We compared the exercise performance of total cavopulmonary connection type (TCPC) of Fontan subjects with HLHS (group 1, n= 7) to those not requiring a Norwood procedure having a systemic right ventricle (group 2, n= 6) or a systemic left ventricle (group 3, n= 8). The subjects underwent assessment of resting pulmonary mechanics followed by maximal exercise testing with a bicycle or treadmill protocol. ECG, oxygen consumption, and carbon dioxide production were measured continuously. There was not a significant difference seen between HLHS and the comparison groups for the following parameters: maximum heart rate, maximum oxygen consumption, respiratory exchange ratio, breathing reserve, and arterial oxygen saturation at rest or exercise. Exercise performance in the TCPC type of Fontan patients was comparable regardless of ventricular morphology or surgical approach.     

Pulmonary function and oxygen uptake during exercise in 11-year-old patients with cystic fibrosis

Ten patients with cystic fibrosis (CF), 5 girls and 5 boys, 11 years of age, underwent pulmonary function and bicycle exercise testing. The material includes all but 2 CF patients in this age group in southern and eastern Norway. The CF children had a moderately reduced pulmonary function, the girls more pronounced than the boys. The mean maximal oxygen uptake (max VO2) in the CF boys was 55 ml/kg/min (94% of age predicted value; range 79-105%), and the CF girls 42 ml/kg/min (79% of age predicted value; range 67-89%). The mean maximal peak heart rate was 195 beats/min. Only one CF girl showed apparent pulmonary limitation during exercise. Increased ventilatory equivalent for oxygen was found during both rest and exercise for the CF girls, but only during rest for the CF boys. Max VO2 was fairly well related to the habitudinal physical activity of the children (r = 0.79).     

Functional state of the cardiorespiratory system in healthy children at rest and during the bicycle ergometry test

Altogether 25 healthy untrained children aged 9 to 12 years were examined. There were 11 boys and 14 girls. The following parameters were measured at rest and during bicycle ergometry: the heart rate, oxygen consumption, pulmonary ventilation, metabolic units, the ratio of oxygen consumption increment, oxygen pulse, stroke and cardiac indices, index of the Q-Z interval and work fitness. The ECG was recorded as well. During exercise, adequate reaction of the cardiorespiratory system was characterized by linear growth of the heart rate, cardiac index and oxygen consumption together with a proportional shortening of the Q-Z interval. At all levels of exercise the girls manifested more pronounced chronotropic stimulation, leading to the attainment of the submaximal heart rate (1.5 Watt/kg). On chronotropic delay overtension of inotropic function was demonstrable in children exposed to high loads, which was accompanied by restriction of the cardiac index growth.     

Maximal voluntary work and cardiorespiratory fitness in patients who have had Kawasaki syndrome.

To assess the natural history of Kawasaki syndrome and its effect on maximal voluntary work and cardiorespiratory fitness, we performed cycle ergometry testing in 47 patients who had had the syndrome. Forty-one patients performed maximal effort as judged by achievement of 95% predicted heart rate response. Oxygen consumption, carbon dioxide production, and minute ventilation were performed in 23 patients. There was no difference in maximal voluntary work (total work, mean power) or maximal oxygen consumption between case subjects and control subjects. There were no differences between patients with and those without aneurysms. Serial exercise studies were performed in 10 patients; of these, two with initially normal exercise study findings had decreased maximal voluntary work and oxygen consumption with ischemic changes, and both were at high risk for the development of stenotic or occlusive coronary arteries. The other eight patients had normal cardiorespiratory reserve and no ischemic changes with serial studies. These results suggest that patients have normal cardiorespiratory fitness after Kawasaki syndrome. With the development of ischemic heart disease, they may have decreased cardiorespiratory reserve. Serial evaluation of cardiorespiratory fitness may demonstrate ischemic heart disease.     

Pulmonary Function and Oxygen Uptake during Exercise in 11-Year-Old Patients with Cystic Fibrosis

ABSTRACT. Ten patients with cystic fibrosis (CF), 5 girls and 5 boys, 11 years of age, underwent pulmonary function and bicycle exercise testing. The material includes all but 2 CF patients in this age group in southern and eastern Norway. The CF children had a moderately reduced pulmonary function, the girls more pronounced than the boys. The mean maximal oxygen uptake (max VO₂) in the CF boys was 55 ml/kg/min (94% of age predicted value; range 79-105%), and the CF girls 42 ml/kg/min (79% of age predicted value; range 67-89%). The mean maximal peak heart rate was 195 beats/min. Only one CF girl showed apparent pulmonary limitation during exercise. Increased ventilatory equivalent for oxygen was found during both rest and exercise for the CF girls, but only during rest for the CF boys. Max VO₂ was fairly well related to the habitudinal physical activity of the children ( r =0.79).     

Noninvasive Measurement of Cardiac Output During Exercise in Children with Tetralogy of Fallot

In patients with surgically repaired tetralogy of Fallot (TOF), reported peak oxygen consumption (VO(2)) is decreased compared with control subjects. The measurement of exercise cardiac output (CO) could be a useful adjunct for assessing cardiovascular fitness. There are few data assessing noninvasive CO, cardiac index (CI), and stroke volume (SV) during exercise for these patients. This study sought to measure noninvasive CI and SV during rest and exercise in children with repaired TOF. The authors compared 21 asymptomatic children with repaired TOF ages 11-17?years during rest and exercise and 42 gender- and age-matched healthy control children without structural heart disease. Using a Bruce exercise protocol, exercise data were measured noninvasively by a novel inert gas rebreathing technique including peak duration and heart rate, as well as VO(2), CO, CI, and SV measured at 90?% of peak predicted theoretical heart rate (90 % ppHR). Statistical correlation between peak VO(2) and CI was performed. At baseline, there was no statistically significant difference in any of the measures between the groups. At 90 % ppHR, there was an increase in CI during exercise of 140 % in the TOF children and 180 % in the control children. During exercise, SV changed minimally in the patient group, whereas it increased more than 30 % in the control children. At 90 % ppHR, the patient group showed an increase in VO(2) during exercise similar to that of their healthy peers. The patients had a significantly shorter peak exercise duration than normal control subjects. The patients had a lower CI during exercise because they were less able to increase SV. Therefore, at similar heart rates, patients who have had TOF repair must rely on increased peripheral muscle extraction, with a higher arteriovenous oxygen difference (SaO(2)-MvO(2)) during exercise, which may limit peak exercise capacity. In this cohort of TOF patients, noninvasive CI measurement was feasible, and correlation with VO(2) was good.     

Afterload reduction therapy in patients following intraatrial baffle operation for transposition of the great arteries

Patients with intraatrial baffle procedure for transposition of the great arteries (TGA) have diastolic dysfunction, decreased exercise capacity, stroke volume response and elevated systemic vascular resistance (SVR) during exercise. Angiotensin-converting enzyme (ACE) inhibitors improve exercise capacity in adults with congestive heart failure by improving diastolic function and decreasing SVR. We tested the hypothesis that ACE inhibitors decrease SVR and improve exercise capacity in patients after intraatrial baffle procedure for TGA. We studied the effects of enalapril in nine patients with TGA s/p intraatrial switch (mean age, 13.8 ± 3 years) 7 to 21 years (mean, 12 ± 4 years) after intraatrial baffle procedure. Enalapril (0.5 mg/kg/day, maximum dosage 20 mg bid) was administered for 12 months. Patients exercised using a cycle ergometer ramp protocol (0.25 W/kg/min) before enalapril (baseline), 1 month, 6 months, and 12 months after treatment initiation. Heart rate, blood pressure, cardiac output, respiratory rate, minute ventilation, oxygen consumption (VO2), total exercise time, work, and power were measured. SVR, cardiac index, and stroke volume index (SVI) were calculated. Two-tailed paired Student's t-test was used to compare data to those of normal control patients and the patients' baseline data. Patients had lower resting heart rate, cardiac index, maximum heart rate, cardiac index (CI), SVI, VO2, exercise time, work, and power and higher maximal SVR at baseline compared to normal control patients. There was no significant difference in total exercise time, work, power, VO2 (rest/peak), SVR, SVI, and CI after 12 months of therapy compared to patients' baseline values. We conclude that short-term (<1 year) use of enalapril does not improve exercise performance in patients with TGA in whom the intraatrial baffle procedure has been performed.     

Exercise capacity and blood pressure response in children and adolescents after renal transplantation

Physical working capacity and cardiovascular response to graded exercise on a bicycle ergometer were investigated in 70 children and adolescents (33F, 37M) after renal transplantation. Results of static and dynamic lung function tests were within the normal range in all patients. Systolic blood pressure, heart rate, pulmonary ventilation and oxygen uptake increased with workload and returned to pre-exercise levels after 5 m of rest. During exercise, blood pressure values were within the normal range in almost all patients. The increase in heart rate and respiratory frequency was blunted in patients receiving beta blocking agents. Maximum workloads (Wmax) were 2.00 × 0.48 W/kg in females and 2.38 × 0.54 W/ kg in males, which are 78 × 18% and 84 × 18% of the normal values predicted for age. Maximum oxygen consumption (VO₂max) was 23.2 × 5.8 ml/min/kg in females and 28.3 × 5.8 ml/min/kg in males. Half of the patients had height below the third percentile. For this reason exercise capacity in relation to height is probably a more relevant parameter than age. Using actual height, Wmax was 102 f 20% and 102 f 29%, and VO₂max 74 f 14% and 80 f 18% of predicted values, respectively. We conclude that the adaption of the cardiovascular and respiratory system to graded exercise was influenced by beta blocking agents. Wmax and VO₂max were significantly reduced for age in pediatric patients after renal transplantation. Wmax was normal, but VO₂max was still reduced if corrected for height.     

成比例辅助通气在呼吸机依赖极低出生体重儿中的临床应用

目的：比较成比例辅助通气模式（PAV）和传统辅/控通气模式（A/C）对呼吸机依赖极低出生体重儿的生理学和呼吸力学影响。方法：46例呼吸机依赖极低出生体重儿随机分为PAV组和A/C组（每组23例）。PAV组以脱逸法设置阻力卸载增益,A/C组按常规通气方法调节,连续通气治疗3 d。每日在早、中、晚3个时间段分别连续监测观察30 min,比较两组患儿动脉血气分析结果、血氧饱和度（SPO2）、心率、血压、呼吸频率（RR）、平均气道压（MAP）、吸气峰压（PIP）、呼吸末正压（PEEP）、潮气量（VT）、每分通气量（MV）及氧合指数（OI）等指标。结果：血气分析指标中,PAV组PaO2、OI高于A/C组（均P0.05）;呼吸力学指标中,PAV组PIP、MAP低于A/C组（均P0.05）;血流动力学指标中,PAV组收缩压、舒张压变异度均低于A/C组（均P0.05）。结论：对呼吸机依赖极低出生体重儿,较之A/C模式,PAV模式能以更低的气道压维持机体气体交换正常,改善氧合,人机协同性更好。     

Noninvasive Cardiac Output Measurement at Rest and During Exercise in Pediatric Patients After Interventional or Surgical Atrial Septal Defect Closure

In the majority of patients, secundum atrial septal defects (ASDs) are treated interventionally or surgically, before the onset of clinical symptoms, between 3 and 6?years of age. Because right-ventricular dimensions usually normalize after ASD closure, it has been assumed that cardiac function and exercise performance also normalize at long-term follow-up. The aim of our study was to determine cardiac index (CI) at rest and during exercise at medium-term follow-up of children who had undergone surgical or interventional closure of ASD because no such reports have been published thus far. Seventeen patients (age range 8.8-17.3?years) who underwent surgical correction were included together with 17 subjects who received an interventional procedure with Amplatzer and Helex occluders (age range 12.2-17.3?years). The study was performed after a median interval of 8.6?years (range 6.5-11.6) after the procedure. Twelve healthy children of comparable age served as controls. CI measurements were performed based on the inert gas-rebreathing method with the Innocor system. For exercise testing, the standard treadmill protocol of the German Society of Pediatric Cardiology was used. CI, stroke volume (SV), and heart rate (HR) were determined at rest and at two standardized submaximal exercise levels (levels 3 and 6). CI increased in all subjects under exercise conditions. Neither SV nor HR displayed significant differences between the three groups either at rest or under exercise conditions. Although HR increased continuously, no increase of indexed SV occurred beyond level 3. Noninvasive determination of CI at rest and during exercise with the IGR method is feasible in the pediatric age group. At medium-term follow-up, we found no significant differences between patients who underwent surgical or interventional ASD closure compared with normal controls.     

Are obese children truly unfit? Minimizing the confounding effect of body size on the exercise response

To test the hypothesis that obese children are unfit (i.e., have abnormal responses to exercise testing consistent with reduced levels of habitual physical activity), we used new analytic strategies in studies of 18 obese children performing cycle ergometry. The subject's weight (mean +/- SD) was 168 +/- 24% that predicted by height, and the age range was 9 to 17 years. Size-independent measures of exercise (e.g., the ratio of oxygen uptake (VO2) to work rate during progressive exercise and the temporal response of VO2, carbon dioxide output (VCO2), and minute ventilation (VE) at the onset of exercise) were used. The ability to perform external mechanical work was corrected for VO2 at unloaded pedaling (change in maximum oxygen uptake (delta VO2max) and in anaerobic threshold (delta AT). On average, obese children's responses were in the normal range: delta VO2max, 104 +/- 41% (+/- SD) predicted (by age); delta AT, 85 +/- 51%; ratio of change in VE to change in VCO2, 111 +/- 21% and ratio of change in VO2 to change in work rate, 100 +/- 24%, but six of the obese children had values of delta VO2max or delta AT that were more than 2 SD below normal. In addition, obese children did not have increased delta VO2max or delta AT with age as observed in nonobese children. Although the response time of VO2 was normal (99 +/- 32% of predicted), those for both VCO2 and VE were prolonged. We conclude that the finding of obesity in a child is not a reliable indicator of poor fitness but that testing cardiorespiratory responses to exercise can be used to identify subjects with serious impairment and to individualize therapy.     

Heart rate recovery after exercise and cardiac autonomic nervous activity in children

To investigate the difference in heart rate (HR) recovery after exercise between children and young adults, we administered a constant load of light exercise intensity and progressive treadmill exercise tests to nine children (aged 9 to 12 y, group A) and eight young adults (six male and two female, aged 17 to 21 y, group B) who had a history of Kawasaki disease without significant coronary arterial lesions. HR after both exercise protocols was analyzed. The low-frequency (LF) and high-frequency (HF) components of HR variability were measured, and LF/HF was calculated (log LF, log HF, log L/H). Arterial baroreflex sensitivity was assessed by the phenylephrine method. There were no differences between groups A and B in resting HR, peak HR, peak oxygen uptake, and decreases in systolic blood pressure during the recovery period. HR 1 and 2 min after peak exercise and 1 min after constant-load exercise was significantly lower in group A than in group B (p < 0.05), and the changes in HR from peak values after both exercise tests were also greater in group A than in group B (p < 0.05-0.01). Although no difference in arterial baroreflex sensitivity was observed, log HF was significantly higher in group A than in group B (p < 0.01), and log L/H was significantly lower in group A than in group B (p < 0.05). The value of log HF correlated inversely with the decrease in HR immediately after both exercise protocols (p < 0.05-0.01). Although log L/H correlated with the decrease in HR after peak exercise (p < 0.05-0.0005), the early decline in HR after constant-load exercise did not correlate with log L/H. Arterial baroreflex sensitivity did not correlate with the decrease in HR at any recovery time. These data suggest that the early phase of HR recovery after light to severe exercise is influenced by the cardiac parasympathetic nervous activity at rest and that the greater central cholinergic modulation of HR in children than in young adults may be responsible in part for children's faster HR recovery after exercise.     

甲状腺功能亢进症儿童的甲状腺激素与心率减速力及心率变异性的相关性

目的 对甲状腺功能亢进症（简称“甲亢”）儿童的心率减速力（DC）、心率加速力（AC）、心率变异性（HRV）进行分析,并探讨甲亢儿童的血清甲状腺激素水平与DC、AC及HRV的关系。方法 选取甲亢儿童47例,另选取50例健康儿童为对照组,对所有受试者行24 h动态心电图检查,将甲亢组与对照组的DC、AC、心率（HR）及HRV各指标[RR间期总体标准差（SDNN）、RR间期平均值的标准差（SDANN）、相邻RR间期差值的均方根（RMSSD）、低频功率（LF）、高频功率（HF）]进行比较,并将甲亢儿童的甲状腺激素指标[游离三碘甲状腺原氨酸（FT3）、游离甲状腺素（FT4）]与DC、AC及HRV各指标进行相关性分析。结果 甲亢组的DC、SDNN、SDANN、RMSSD、LF、HF均低于对照组;AC和HR均高于对照组（P < 0.05）。甲亢儿童的血清FT3、FT4与DC、SDNN、SDANN、RMSSD、LF、HF均呈负相关（P < 0.05）;与AC和HR呈正相关（P < 0.05）。结论 甲亢儿童的心脏自主神经功能受损,表现为迷走神经张力降低。血清甲状腺激素水平越高,迷走神经张力越低,提示发生心血管疾病的危险性越大。