2.1. Subjects

The approval of the experimental protocols was obtained from the Committee for Ethics in Research. Since humans were included in this study, a National Institute of Health (NIH) for protecting human research participants certificate was obtained. The potential risks of the study were explained to each child and their parents. The written informed consent was obtained from the parents, following the guidelines established by the institutional review board ethics committee. The experimental procedures complied with the ethical standards of the 1975 Helsinki Declaration.

A total of 13 children with congenital heart disease who had undergone surgical correction for congenital heart impairment (7 males and 6 females) and 14 healthy control children (8 males and 6 females) aged 13 ± 2 years were tested at the Cardio Pediatric department. All cardiac patient groups had undergone cardiac surgery reconstruction during infancy for congenital heart disease (before 2 years of age). Table 1 shows the characteristics of the patients and controls children. Seven subjects had pulmonary valve atresia, four had a transposition of great arteries, and two had tricuspid atresia. Throughout the research, the medication was not modified. Children that were infected did not take part in the study. No surgery or changes in heart function occurred in any of the people during the prior 24 months. Participants with unstable angina, aortic stenosis, acute myocardial infarction, obstructive cardiomyopathy, hypertension above 220/120 mmHg, or locomotor or mental disorders that could limit muscle performance were excluded from the study. Healthy subjects practicing sport for more than 3 h per week were excluded from the present study.

Characteristics of children with congenital heart disease (CHD) and control subjects.

Definition of abbreviations: values are mean ± standard deviation. PVA = pulmonary valve atresia, TGA= transposition of great arteries, and TA = Tricuspid atresia.

Weight was measured to the nearest 0.1 kg with a multi-frequency bioelectrical impedance analyzer (TBF-410GS, Tanita Co., Tokyo, Japan), and height was measured to the nearest 0.1 cm with a Harpenden stadiometer 602VR, with the child standing and wearing no shoes or heavy clothing.

The nutritional status was determined using the body mass index (BMI), which was then classified using the WHO Anthro and AnthroPlus software (Geneva, Switzerland).

The cardiac participants had undergone cardiac reconstruction surgery for congenital heart disease and expressed exercise limitations. They had the following specifications:

Dyspnea with moderate exercises and belongs to class II of the functional categorization system of the New York Heart Association (NYHA);

Absence of other disabling diseases;

Ability to perform an exercise without an adverse cardiovascular disorder, such as arrhythmia. Subjects suffering from angina, aortic stenosis, a history of myocardial infarction, obstructive cardiomyopathy, or hypertension were not included in the study.

Medications were unchanged throughout the study, including converting the enzyme inhibitors, diuretics, cardiotonic, anticoagulant, and immunosuppressive drugs. Only, 2 (out of the 13) subjects were without drug treatment. Infected children were excluded from the research.