|Year : 2016 | Volume
| Issue : 1 | Page : 148-149
The cause and effects of neonatal/infantile thymectomy
Hasan Ekim1, Meral Ekim2
1 Departments of Cardiovascular Surgery, Bozok University School of Medicine, Yozgat, Turkey
2 Department of Biochemistry, Bozok University, School of Health, Yozgat, Turkey
|Date of Web Publication||22-Dec-2015|
Department of Cardiovascular Surgery,Bozok University School of Medicine, Yozgat
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Ekim H, Ekim M. The cause and effects of neonatal/infantile thymectomy
. Med J DY Patil Univ 2016;9:148-9
The thymus, primary source of circulating T-lymphocytes, is located in the superior portion of the anterior mediastinum behind the sternum and in front of the major vessels.  Congenital open heart operations are required aortic arterial cannulation. During these operations, a thymectomy is preferred in order to avoid innominate vein injury and for a safe aortic cannulation, especially in patients in the 1 st year of life due to the large volume of the thymus.
The development of thymus is almost complete at birth, and reaches sufficient size and weight in the first 6 months following birth. In course of time, it becomes a structure composed of fatty tissues due to degeneration. This natural process (involution) occurs relatively early period of life. However, importance of the thymopoiesis beyond the initial production of Treg cells still remains a matter of debate. 
In neonates, removal of the thymus results in a loss of thymus-derived Treg cells and a reduced number of circulating Treg cells.  Turan et al.  revealed the significant differences in mean lymphocyte numbers, and CD2, CD4, CD5, CD8, CD16 ratios between the patients who had neonatal thymectomy and age-matched healthy controls. Also, a significant decrease in T-lymphocytes and Treg cell receptor excision circles were found in children who underwent neonatal thymectomy, consistent with cessation of thymopoiesis.  It is expected that neonatal thymectomy might lead to adverse consequences on immune system.  Therefore, total thymectomy should not be performed to avoid early immunosenescence, as reported in an article (The immune system in infants thymectomized during surgical correction of congenital heart defects) published in this issue of the journal.
Although thymectomy is tolerated in patients older than 6 months without any known adverse consequences,  the long-term effects of total thymectomy under certain conditions such as malignancies or infections still have not been proven.  Congenital cardiac operations have been routinely performed over 30-40 years. For the moment, thymectomized individuals are still not in older age groups. Therefore, to obtain invaluable data, all patients undergoing neonatal thymectomy should be followed up throughout the whole life.
In conclusion, considering the possible adverse consequences of total thymectomy in the aging process, we suggest that partial thymectomy should be preferred instead of total thymectomy in neonates/infants undergoing open heart surgery.
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