Early left ventricular abnormality/dysfunction in obese children affected by NAFLD.

BACKGROUND AND AIMS: Although it is generally accepted that non alcoholic fatty liver disease (NAFLD) is linked to increased risk of cardiovascular disease, the presence of abnormalities in cardiac function among NAFLD children is limited and controversial. Aim of the study was to detect cardiac abnormalities/dysfunction in a paediatric population of NAFLD. METHODS AND RESULTS: Anthropometric, laboratory, cardiovascular fitness, 24 h blood pressure monitoring and Doppler echocardiography parameters were obtained in 50 untreated children (37 males; mean age 12.2 + 2.5) with biopsy-proven NAFLD. Abnormalities in both cardiac function and geometry could be identified in the whole study population: prevalence of about 35% in left ventricular hypertrophy, 14% of concentric remodelling and 16% of left atrial dilatation. Furthermore children with NAFLD (NAS score <5) showed lower cardiac alterations compared to NASH patients (NAS score >5). After adjusting for age, sex and BMI, a positive correlation was found only between LV mass and NAS score (p < 0.001). CONCLUSION: Our results suggest that cardiac dysfunction can be detectable early in NAFLD children and this is not linked to cardiovascular and metabolic alteration, other than to liver damage. Although as a preliminary stage, we can speculate a possible direct relationship between liver and heart steatosis, already occurring during childhood.

Impaired energy expenditure despite normal cardiovascular capacity in children with type 1 diabetes.

BACKGROUND: Benefit of fitness on children with type 1 diabetes mellitus (T1DM) is still debated. AIM: To evaluate the influence of physical activity on metabolic balance and exercise tolerance in prepubertal children affected by T1DM. METHODS: We analyzed 35 pre-/peripubertal T1DM children and 31 matched controls using an activity monitor (SenseWear Armbad) and physical activity questionnaire (PAQ) to assess energy expenditure (EE), total and active, sedentary and physical activities (h/day and Mets = metabolic equivalents). The maximal cardiopulmonary exercise test (CPET) was also performed. RESULTS: Total physical activities and total and active EE (>3 Mets) resulted higher in controls than in T1DM patients and self-reported perception of physical and sedentary activities was altered in T1DM children as well in controls and were different from the measured data. No differences were found in CPET parameters with the exception of a higher maximal blood pressure in T1DM children. In multivariate analysis HbA1c negatively correlated with VO(2). CONCLUSION: Prepubertal T1DM children seem to have a lower level of physical activity and EE and a probable altered feeling of physical and sedentary activities. On the other hand, T1DM children do not show any alteration of cardiovascular performance, although glycemic control (HbA1c) may play a role in cardiovascular performance.

Energy expenditure and insulin sensitivity evaluation in obese children affected by hepatosteatosis.

OBJECTIVES: The aim of our study was to evaluate the physical and sedentary activities and energy expenditure (EE) in a group of children affected by non-alcoholic fatty liver disease (NAFLD), compared with normal and obese subjects, using a physical activity questionnaire (PAQ) and a SenseWear armband (SWA). METHODS: Forty NAFLD (10 females), 41 lean (NRM; 11 females) and 30 obese (OB; 10 females), age- and pubertal stage-matched, children were included. RESULTS: Sedentary activity (PAQ) was similar in NAFLD and NRM but less in OB, while SWA showed that NAFLD spent less time in physical activity and more in sedentary activities compared with NRM, but not with OB. Insulin sensitivity index result is related to active EE (cal kg(-1) d(-1) ) in NAFLD, while homeostatic model assessment index result was negatively related to total EE in OB. CONCLUSIONS: Regular physical activity must be encouraged in all obese children affected by NAFLD or not, and SWA might be a possible valid tool for evaluating actual EE.

A pilot trial on safety and efficacy of erythrocyte-mediated steroid treatment in CF patients.

BACKGROUND: Chronic neutrophil inflammation of the respiratory tract tissues plays a key role in the pathogenesis and in prognosis of cystic fibrosis (CF). It is evident that an anti-inflammatory therapy represents an important step in the treatment of CF patients. Corticosteroids and ibuprofen have been proven to slow down the impairment of the pulmonary function in CF patients but their use is limited by the frequency of adverse events. A novel strategy for delivering low doses of steroids for long periods through the infusion of autologous erythrocytes loaded with dexamethasone has been recently set up. A recent study suggested the feasibility of therapy with low doses of corticosteroids delivered through engineered erythrocytes in CF patients. This study presents a further analysis of safety and efficacy of this therapy. METHODS: The treatment group was not randomised and the assignment was based on the patient's consent. Patients entered the study if they had a forced expiratory volume in 1 second (FEV1) <70%, puberty development completed, pancreatic insufficiency, and chronic pulmonary infection requiring frequent cycles of intravenous antibiotic therapy. Patients were excluded if they underwent systemic corticosteriod therapy in the three months preceding the experimental treatment or were on therapy with non-steroidal anti inflammatory drugs (NASDs), or if they had liver CF disease, allergic bronchopulmonary aspergillosis, or positive tuberculin test. Controls were patients who followed a standard treatment, who fulfilled the enrollment criteria, and who were matched to the experimental group by gender, age, and severity of the disease. RESULTS: Nine patients in the experimental group received the treatment once a month for a period of 24 month. Patients did not develop diabetes, cataract, or hypertension, or other typical side effects of steroid treatment during the follow up period. There was a constant improvement of FEV1 in patients undergoing the experimental treatment compared to a gradual decrease of the same parameter in the standard therapy group (P = 0.04). The average of clinic and radiological indexes did not vary. The number of infective relapses that have required antibiotic intravenous therapy was not different in the two groups, although the average of these episodes was slightly higher in the experimental therapy group. CONCLUSION: Intraerythrocyte corticosteroid treatment may stabilize the respiratory function in CF patients but is often considered too invasive by patients. The results obtained by our study may help planning an experimental, controlled, randomised study. A sample size of 150 patients per group would be sufficient for demonstrating such a difference with a 95% confidence interval and a power of 90%.

Cardiovascular hemodynamics: relationships with insulin resistance in obese children.

We investigated blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR) and their relationships with insulin and glucose blood levels in a group of 24 obese children (mean age, 11.9 +/- 2.1 years; 19 males). The data were compared to those obtained from a group of 19 healthy controls of the same age (12.4 +/- 2.1 years; p = NS; 13 males). BP at rest was measured and all subjects underwent an exercise testing on the treadmill (Bruce Prot.), time of exercise, maximal heart rate, maximum systolic blood pressure, CO, and SVR at rest and at peak exercise were considered. Only in the OC group were an oral glucose tolerance test were performed to calculate insulin sensitivity index (ISI) and echocardiography performed to determine the left ventricular mass (LVM). The relationships between cardiovascular and metabolic parameters were investigated. Student's t-test and linear regression analysis were used when appropriate. OC had a significant reduction in TE and higher BP, and linear regression analysis showed significant correlations between BP, ISI, and LVM. We speculate that OC need a regular cardiovascular and metabolic screening to prevent the development of early cardiovascular damage.

Cardiopulmonary performances in young children and adolescents born with large abdominal wall defects.

BACKGROUND/PURPOSE: As long as the survival rate of patients with abdominal wall defects (AWD) increases, information about long-term follow-up is becoming necessary. Even though quality of life in these patients, in absence of associated anomalies, appears to be unaffected, respiratory impairment soon after birth has been documented; therefore, participation in sports rarely is addressed. METHODS: Eighteen patients, ranging in age from 7 to 18 years, operated on at birth for large abdominal wall defects (> 4 cm for gastroschisis; >6 cm for omphalocele) were asked to come for a stress test on a treadmill, with measurements of time of exercise (TE), maximal oxygen consumption (VO2 max) and continuous recording of vital parameters. Respiratory function also was assessed by Forced Vital Capacity (FVC). RESULTS: Ergometric data were compared with those of a normal pediatric population. All patients were able to perform the stress test with no cardiovascular abnormalities detected at rest or on exertion. Maximum heart rate was reached after a significantly shorter TE, and VO2 max was significantly reduced when comparing normal subjects with AWD subjects and AWD subjects in sports with those sedentary. FVC was only slightly reduced in AWD patients without reaching statistical significance. CONCLUSIONS: These findings indicate that patients operated on for AWD at birth exhibit a normal cardiorespiratory function; decreased TE and VO2 max are likely to reflect a lack of physical activity with a lower degree of fitness. Therefore, no limitations to motor performances should exist for these patients. Well-being may be greatly improved by regular exercise.

Does chronic pacing affect exercise capacity after Mustard operation for transposition of the great arteries?

Late survival after Mustard repair of transposition of the great arteries is generally good but is often characterized by progressive deterioration of ventricular function and by late postsurgical arrhythmias, thus imposing the need for permanent pacing. To evaluate how chronic pacing affects long-term exercise capacity, we compared two groups of these patients: group 1, comprising 12 patients, aged 9.0 +/- 2.6 years, without pacemaker; and group 2, comprising 18 patients, aged 9.3 +/- 2.0 years, with pacemaker. Patient evaluation included history, physical examination electrocardiograph, Holter monitoring, and echocardiography. Pacing modes were as follows: AAI (6 patients), AAIR (9 patients), VVI (2 patients), and VVIR (1 patient). At exercise test we evaluated exercise tolerance, maximum heart rate, blood pressure, oxygen consumption, and cardiac output at rest and at peak exercise. The two groups were comparable for all variables examinated. All pacemakers showed normal function. During the exercise, 11 of 12 patients in group 1 showed sinus rhythm, and in group 2, 11 patients showed sinus rhythm, 5 junctional rhythm, and 2 continuous pacing. There were no significant differences between groups. Chronically paced Mustard patients but with restoration of spontaneous rhythm during the exercise test do not show reduced exercise tolerance in comparison with nonpaced Mustard patients.

Cardiorespiratory functional assessment after pediatric heart transplantation.

Limited data are available on the exercise capacity of young heart transplant recipients. The aim of this study was therefore to assess cardiorespiratory responses to exercise in this group of patients. Fourteen consecutive heart transplant recipients (six girls and eight boys, age-range 5-15 yr) and 14 healthy matched controls underwent a Bruce treadmill test to determine: duration of test; resting and maximum heart rates; maximum systolic blood pressure; peak oxygen consumption (VO2 peak); and cardiac output. Duration of test and heart rate increase were then compared with: time since transplantation, rejections per year, and immunosuppressive drugs received. The recipients also underwent the following lung function tests: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). When compared with healthy controls, transplant recipients had tachycardia at rest (126 +/- 3.7 beats/min; p < 0.001); significantly reduced tolerance (9.3 +/- 0.4 min; p < 0.001), a maximum heart rate of 169 +/- 5.4 beats/min (p < 0.05); a cardiac output of 5.65 +/- 0.6 L/min (p < 0.05); and a lower heart-rate increase from rest to peak exercise (p < 0.001) but a similar VO2 peak. The heart-rate increase correlated significantly with time post-transplant (r = 0.55; p < 0.05), number of rejection episodes per year (r = - 0.63; p < 0.05), and number of immunosuppressive drugs (r = - 0.60; p < 0.05). The recipients had normal FVC and FEV1 values. After surgery, few heart transplant recipients undertake physical activity, possibly owing to over-protective parents and teachers and to a lack of suitable supervised facilities. The authors stress the importance of a cardiorespiratory functional evaluation for assessment of health status and to encourage recipients, if possible, to undertake regular physical activity.

Exercise and sports participation after surgery for congenital heart disease: the European perspective.

The success of surgery for congenital heart disease which has been performed since many years has created a population of patients who require careful follow-up in order to determine their clinical progress and to establish the type and intensity of physical activity which they can safely perform. The authors illustrate the opinion of the European Community regarding children, sport and organizational aspects and also problems concerning the management of pediatric cardiac patients in Europe and Italy. Cardiological and surgical aspects are considered together with the practice of physical activity, with emphasis upon the differences between the various countries. Particular attention is paid to the Italian legislation regarding the certification to participate in competitive or non-competitive sport in such a population of patients. Great importance is given to pediatric cardiac rehabilitation programs which aim at improving the aerobic fitness of patients operated upon for complex congenital heart disease and at illustrating their own cardiovascular limitations so that they can perform physical exercise with the utmost safety.

Exercise testing and 24-hour ambulatory blood pressure monitoring in children with Williams syndrome.

The aim of the study was to assess workload capacity and blood pressure (BP) response to treadmill exercise and 24-hour BP monitoring in children with Williams syndrome. Seventeen children were examined (8 males and 9 females) whose mean age was 13.8 +/- 3.6 years. Six patients were on antihypertensive therapy. Each patient underwent clinical examination and measurement of BP at rest, during exercise, and during 24-hour monitoring. Two-dimensional echocardiogram and echo-Doppler of renal arteries were performed. The test was stopped for muscular fatigue or reduced cooperation. The patients, when compared to a population of healthy children, had reduced total time of exercise (7.3 +/- 1.9 vs 14.3 +/- 2.6 min, p < 0.001) and, at the same workload, increased heart rate (167 +/- 19 vs 145 +/- 16 beats/min, p < 0.001) and increased maximum systolic BP (146 +/- 27 vs 128 +/- 12 mmHg, p = 0.01). Ambulatory blood pressure measurement values showed higher systolic blood pressure both during daytime and nighttime. Our study confirms that children and adolescents with Williams syndrome are at high risk for hypertension, probably related to the alterations of large arteries. The data relating to the synthesis of elastin may have a direct relationship to the compliance of the arterial system, leading to hypertension.

Clinical and cardiorespiratory assessment in children with Down syndrome without congenital heart disease.

OBJECTIVE: To assess the clinical and functional status of a young Down syndrome (DS) population without congenital heart disease. DESIGN: Prospective study of children with DS and control subjects. SETTING: Bambino Gesù Children's Hospital, Rome, Italy. PARTICIPANTS AND METHODS: Forty-two children with DS (mean +/- SD age, 9.8 +/- 3.6 years) underwent genetic, clinical, neuropsychological (IQ), and cardiorespiratory evaluation. Cardiorespiratory fitness was assessed with a treadmill test and a lung function test to determine forced vital capacity, first-second forced expiratory volume, and peak expiratory flow. Data were expressed as a percentage of the predicted values for control children. To assess cooperation during exercise testing, we devised a compliance scale assigning a score according to the subjects' ability to understand instructions, ability to walk and run as required, and need for vocal encouragement. RESULTS: Eighteen (43%) of 42 children with DS were obese, 10 (24%) were short, and 17 (40%) had microcephaly. On the Leiter International Performance Scale, 2 of 35 subjects had a normal IQ score (80-120); all others had low IQ scores (79 to <40). Five subjects did not undergo cardiorespiratory assessment. Eighteen of 37 subjects completed lung function tests: the results for 10 were unremarkable, and results from 8 revealed reduced forced vital capacity because of poor compliance. The subjects tested had low exercise tolerance (mean +/- SD tolerance percentage, 61% +/- 12%), mild tachycardia (maximal heart rate, 91% +/- 4%), and a mild hypertensive response (maximal blood pressure, 89% +/- 8%). Compliance scores correlated significantly with exercise time and age but not with IQ. CONCLUSIONS: Clinical and cardiorespiratory assessment is feasible in subjects with DS without congenital heart disease and should be useful in gauging their fitness level for safe physical activity.

Neuroregulation of growth hormone during exercise in children.

Physical exercise is an important physiological stimulus to growth hormone (GH) release in man. Many neurotransmitters are involved in GH regulation. We studied the effect of the cholinergic pathway on GH secretion induced by physical exercise. Particularly, we studied the effect of a cholinergic muscarinic agonist on GH-induced physical exercise, both in children and adults. Moreover, we investigated the refractoriness of GH secretion after a second physical exercise stimulus. Three different protocols were performed: 1) GH response to physical exercise in children and adults; 2) effect of pyridostigmine on exercise-induced GH secretion in children and adults; 3) GH response to two consecutive exercises in children and adults. Our data show that in children GH peak after physical exercise is higher than in adults. Pyridostigmine enhances GH release in children and in adults. Exercise stimulus was able to release GH in the second test only in children, while the refractory phase did not permit a new GH release in adults. The shift to a modality of neural control of GH secretion peculiar of adults is likely due to neuroregulatory mechanisms which may be partly dependent on long-term variation in hormonal milieu.

Ambulatory blood pressure monitoring in children with aortic coarctation and kidney transplantation.

BACKGROUND: Ambulatory blood pressure monitoring (ABPM) has been found to be of significant importance in clinical practice because numerous blood pressure (BP) measurements may be made throughout the 24-hour period. OBJECTIVE: To assess the clinical utility of ABPM in children with secondary hypertension. METHODS: We studied 37 patients (21 boys and 16 girls), with a mean age of 16.4 +/- 4.1 years, after kidney transplantation and 38 patients (27 boys and 11 girls), with a mean age of 10.2 +/- 2.1 years, after surgical correction of aortic coarctation. Data, expressed as mean +/- SD, were analyzed after dividing the patients into 4 groups. Group A consisted of 25 patients receiving antihypertensive therapy; group B included 12 patients not receiving antihypertensive therapy. Group C included 25 patients operated on before 3 years of age (8 +/- 7 months of age); group D included 13 patients operated on after 3 years of age (74 +/- 29 months of age). RESULTS: In groups A and B, casual BP measurement showed that 16 of 37 patients (43%) were hypertensive; 24-hour ABPM detected a larger number of patients who were hypertensive (23 of 37, 62%); there were 18 in group A and 5 in group B. In groups C and D, casual BP measurement identified 6 of 38 (15%) patients as hypertensive, whereas 24-hour ABPM again identified a higher number (13 of 38, 34%). CONCLUSIONS: Our findings confirm that 24-hour ABPM is more sensitive than casual BP in detecting abnormal BP in patients at high risk for secondary hypertension.

Left ventricular hypertrophy, treadmill tests, and 24-hour blood pressure in pediatric transplant patients.

BACKGROUND: Hypertension and left ventricular hypertrophy (LVH) are possible complications in pediatric patients after renal transplantation. METHODS: We performed left ventricular echocardiography, 24-hour ambulatory blood pressure monitoring (24-hr ABPM), and treadmill tests in 28 pediatric renal transplant patients (mean age 16.1 +/- 3.7; time since transplantation 36 +/- 23 months). Left ventricular mass (LVM) was indexed for height 2.7. RESULTS: LVH was found in 82% of the patients. Seven of these patients were normotensive by 24-hour ABPM, but five patients showed a hypertensive systolic BP response during the treadmill test. LVM/height 2.7 correlated significantly with the mean 24-hour systolic BP (P = 0.002) and with the maximal exercise systolic BP (P = 0.002). CONCLUSION: LVH is frequent in pediatric renal transplant patients. More information is needed with respect to the risk for LVH, including data from 24-hour ABPM and treadmill testing.

Exercise tolerance and blood pressure response to exercise testing in children and adolescents after renal transplantation.

The aim of the study was to assess exercise tolerance and blood pressure (BP) response to treadmill exercise in children after renal transplantation. Forty-five children were selected (29 males and 16 females) whose mean age was 14.3 +/- 4.2 years. All children had Hb >/= 10 g/dl and creatinine clearance >/=40 ml/min/1.73 m2. They were at least 6 months posttransplantation and were on triple immunosuppressive therapy. Twenty-seven were also on various antihypertensive medications. Each underwent clinical examination and measurement of BP, both at rest and during exercise testing on treadmill. The test was stopped on muscular fatigue or exhaustion. The patients were divided into two groups: those off (A) or on (B) antihypertensive therapy. When compared to a population of healthy children the patients had reduced exercise tolerance (10.1 +/- 2.1 vs 15.1 +/- 1.7 min, p < 0.001) (67 +/- 16%), increased heart rate (174 +/- 19 vs 161 +/- 19 beats/min, p < 0.001) (109 +/- 15%), and increased maximum systolic BP (150 +/- 26 vs 134 +/- 13 mmHg, p < 0. 001) (113 +/- 19%) at comparable workloads. Within the two patient groups, significant differences were observed during exercise testing for maximum heart rate, which was lower in group B (p = 0.03), and maximum systolic BP, which was higher in group A (p = 0.04). Our study confirms that children and adolescents on immunosuppressive therapy after renal transplantation have a hypertensive response during exercise, probably related to medication-induced peripheral vascular tone.

Hypertension in young patients after renal transplantation: ambulatory blood pressure monitoring versus casual blood pressure.

The results of ambulatory blood pressure monitoring (ABPM) in children after kidney transplant were analyzed to ascertain any alteration in circadian BP profile, degree of hypertension, and efficacy of therapy. The data were also compared with casual BP data and left ventricular mass index (LVMI). We have examined 30 patients (17 male, 13 female), mean age 16.1+/-3.6 years after kidney transplant. All patients were receiving triple immune-suppressive therapy and 20 of them were also taking antihypertensive therapy. They underwent clinical examination with measurement of BP at rest, echocardiogram mono-2D, and ABPM. The following ABPM parameters were recorded: systolic (S) and diastolic (D) BP at rest; mean 24-h SBP and DBP; mean daytime SBP and DBP; mean nighttime SBP and DBP; nocturnal fall in SBP and DBP; and mean daytime and nighttime heart rate (HR). The patients were divided in two groups. Group A consisted of 20 patients taking antihypertensive treatment; group B consisted of 10 patients not taking antihypertensive treatment. Casual and ABPM data for the two groups were compared using the Student t test for unpaired data. Blood pressure at rest and LVMI were not statistically different between the two patient groups. The ABPM data showed statistical differences between the two groups for mean 24-h SBP and DBP, daytime and nighttime SBP, nighttime DBP, fall in nocturnal DBP, and nighttime HR. Mean 24-h SBP and DBP, mean daytime SBP and DBP, and mean nighttime SBP and DBP were significantly correlated to LVMI (respectively, P = .009, P = .005, P = .008, P = .007, P = .05, and P = .01). Twenty-four-hour ABPM was more useful in the diagnosis and management of hypertension than was casual BP at rest.

Exercise tolerance and behavior of blood pressure in children and adolescents after renal transplant.

OBJECTIVE: The purpose of the study was to evaluate the exercise tolerance and the behaviour of blood pressure during a maximal exercise testing on treadmill for a group of patients with renal transplant carried out at least 6 months earlier. EXPERIMENTAL DESIGN, SETTING AND PATIENTS: In a retrospective study, nineteen patients were examined in our laboratory: 13 boys and 6 girls, mean age 15.8 years (range 10.5-22). INTERVENTIONS: All patients were given a clinical examination, an ECG at rest, a maximal exercise testing on treadmill (Bruce protocol), a mono-2D echo, a lung function test and 24-hour Holter monitoring. The results of the exercise test were compared with those of two control groups of same age and body surface area. RESULTS: The clinical examination of their cardiovascular apparatus gave normal results. The echo revealed anatomical and heart function anomalies related to the original disease. Exercise testing on treadmill showed a reduction in exercise tolerance (p < 0.001) and the maximal heart rate showed a statistically significant difference (p < 0.001) in comparison to control groups. Maximal systolic blood pressure was higher than in patients with same body surface area (p < 0.001) and higher than in peers (p = 0.133). CONCLUSIONS: In view of this hypertensive response, strenuous physical activity should be undertaken with caution and indeed submaximal aerobic activity is more suitable for this population of patients.

Maximal oxygen consumption and stress performance in children operated on for congenital diaphragmatic hernia.

The long-term follow-up of patients operated on for congenital diaphragmatic hernia (CDH) at birth has been extensively evaluated, both clinically and with respect to respiratory function. However, little is known about the sports practice and stress performance of these subjects. Fifteen of 107 patients operated on for CDH underwent exercise stress testing with a stepwise increase in workload. A questionnaire was provided, which requested information on sports practice and lifestyle. Maximal oxygen consumption [Vo2 max] was measured along with dynamic lung volumes. Clinical examination included a whole-body assessment (height, weight, skinfolds) and vital parameters (heart rate and blood pressure). Fifteen healthy children who practiced regular physical activity (2 to 4 hours/week) served as controls. All the CDH patients experienced a good lifestyle, but only 8 of them were participating in sports. Exercise duration and Vo2 max were significantly lower for the CDH patients, and were lowest for the sedentary patients. Therefore, the reduced Vo2 max of these otherwise healthy children most likely represents a lower degree of physical fitness rather than decreased respiratory function. Fitness is an expression of well-being; thus, there is evidence that these patients could safely participate in competitive motor activities.

Reciprocating supraventricular tachycardia in children: low rate at rest as a major factor related to propensity to syncope during exercise.

Reciprocating supraventricular tachycardia may have several clinical presentations, with symptoms often more severe during exercise or emotional stress. This study shows by using transesophageal atrial pacing, the factors related to syncope during exercise. Between May 1989 and June 1994, transesophageal atrial pacing was performed at rest and during exercise in 75 children aged > 6 years with suspected or documented episodes of paroxysmal supraventricular tachycardia. Reciprocating supraventricular tachycardia could be induced both at rest and during exercise in 22 patients (8 girls, 14 boys; mean age 10.6 +/- 2.7 years, range 7 to 15 years) with ventriculoatrial interval < 70 msec in 11 patients and > 70 msec in 11. At rest, all patients had palpitations caused by the induction of tachycardia. After conversion to sinus rhythm, when tachycardia was induced during exercise, symptoms did not change in 14 patients (group A), whereas symptoms worsened (presyncope) in eight (group B). The statistical analysis showed a significant difference of mean reciprocating supraventricular tachycardia rate at rest between the two groups (group A, 211 +/- 23 beats/min; group B, 173 +/- 33 beats/min; p = 0.0057) and reciprocating supraventricular tachycardia rate variation from rest to exercise (group A, 62 +/- 18 beats/min; group B, 105 +/- 24 beats/min; p = 0.0001). These data suggest that children with low tachycardia rate during normal activities may have syncope more frequently, independently of the tachycardia rate during exercise or emotional stress.