Evaluation of thymic function in patients with congenital heart disease who underwent thymectomy

Abstract

Congenital heart diseases are the malformations with the greatest impact on infant morbidity and mortality and on public health costs in Brazil, accounting for 3 to 5% of deaths in the neonatal period. In more than 50% of cases, invasive surgery is needed to correct the defect. In these patients, partial or total removal of the thymus during cardiac surgery may be necessary to better approach the vessels at the base of the heart. It is important to note that the late immunological consequences of neonatal thymectomy are still poorly understood.BACKGROUND: In recent years, open-heart surgery in neonates has become an increasingly safe and frequently performed procedure, and in the vast majority of patients partial or total removal of the thymus is necessary to access the heart or large blood vessels. In 2009, Sauce and collaborators evaluated patients aged between 18 and 26 years, who underwent thymectomy before 15 days of life and found significant peripheral immunological changes such as: fewer CD4 + and CD8 + T cells; reduced proportion of naive T lymphocytes fresh out of the thymus, less TREC (TCR recombination excision circle); accumulation of populations of oligoclonal memory T cells; inflammation markers increased. These data indicate signs of premature aging of the immune system related to the lack of production of new T lymphocytes by the thymus. There is, therefore, a growing concern in relation to the increased risks of an early senescence process of the immune response and its consequences of later appearance. Thus, this project presents a proposal for conducting a clinical and laboratory study of patients undergoing cardiac surgery with thymectomy, through laboratory tests and the evaluation of the patients' clinical history and prevalence of infectious, autoimmune and neoplastic diseases, and compare them with patients with heart disease who did not need corrective surgery. Methods: Demographic data, cardiological assessment, immunological assessment and assessment of the occurrence of infections, allergies, autoimmune and neoplastic diseases of patients will be assessed through interviews and medical record data. For laboratory tests, peripheral blood will be collected to perform the following analyzes: TRECs, leukogram, lymphocyte immunophenotyping, immunoglobulins, vaccine responses, interleukin profile. The results will be described and compared using chi-square, T-test or other statistical tests deemed appropriate. (AU)