Determination of thyroid profile in infants who have undergone surgical correction of congenital heart defects with cardiopulmonary bypass and had hypothermia

Thyroid hormones are of a particular interest as a support for patients who have undergone cardiac surgical interventions. According to the bibliographical findings, artificial blood circulation with CPB, hypothermia and the use of dopamine reduce the level of thyroid hormones. The purpose of this research was to determine the thyroid hormone levels in infants with “acyanotic” and “cyanotic” congenital heart defects at different stages of hospitalization, comparison of the results between groups. Materials and methods used: a single-center prospective cohort study of 54 cases of surgical treatment of children with congenital heart defects (CHDs) was conducted. Correction of congenital heart disease was carried out with CPB in accordance with the approved clinical protocols. To assess the thyroid profile, thyroid-stimulating hormone (TSH), thyroxine (free T4) and triiodothyronine (free T3) were examined. The algorithm for diagnosing hormone levels included three stages - it was measured prior to, one day after and 7 to 10 days after the surgical correction of congenital heart disease. The influence of clinical (hemodynamic) manifestations during surgical intervention on the level of thyroid hormones and TSH in the early and late postoperative period was assessed. Results: the majority of pediatric patients with “acyanotic” and “cyanotic” defects had a thyroid profile within normal limits upon admission to the hospital. In the early postoperative period, a decrease in the level of thyroid hormones and TSH was noted. By the end of hospitalization, a tendency towards independent normalization was revealed in the majority of patients. Children with free T3 level one day after the surgery below normal had longer CPB application (p=0.022), longer clamping of the aorta (p=0.019) and a higher inotropic index (p=0.005) in contrast with those who had free T3 within normal values. Conclusion: the results obtained would be of help in assessing the risk for the transient decrease in the level of thyroid hormones development among children in the first year of life who underwent CHD surgical correction with CPB as well as the need for hormone replacement therapy during the early postoperative period.