Thymus Matters: Immune and Infectious Consequences of Thymectomy Extent in Neonatal Cardiac Surgery
Aldana Rojas1, Muhammad Faateh1, Grant Chappell2, Andrew Potter1, Muhammad Abdullah Shaikh1, David Morales1, Tara Karamlou3, Carolina Moore1
1Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 2University of Cincinnati College of Medicine, Cincinnati, OH, 3Akron Children's Hospital, Akron, OH
Background: Neonatal thymectomy, though often necessary for exposure during congenital heart surgery, may have unintended immunologic sequelae. Given the thymus's essential role in T-cell maturation, we examined whether the extent of thymic resection impacts postoperative immune recovery and infection risk.
Methods: Institutional data from 105 neonates who underwent complex cardiac surgery (27 partial, 78 total thymectomy) were retrospectively reviewed under IRB approval. Postoperative infections occurring ≥90 days were recorded and hematologic parameters compared between baseline and six months postoperatively. Multiple infection was defined as ≥2 distinct postoperative infections.
Results: Multiple infections occurred more frequently after total compared with partial thymectomy (29.5% vs. 7.4%, p=0.020). Total thymectomy was associated with higher odds of multiple infection (OR 5.3, 95% CI 1.4-33.3, p=0.033), a relationship that remained borderline after adjustment for bypass time (adjusted OR 4.5, 95% CI 1.1-29.7, p=0.063). At six months, total thymectomy was associated with a greater decline in absolute lymphocyte count (ΔALC −0.8 [-2.4-0.2] vs. +0.9 [-0.2-2.6], p=0.011), whereas neutrophil, monocyte, and eosinophil changes were comparable. Postoperative length of stay was also longer following total thymectomy (median 26 [19-49] vs. 21 [16-28] days, p=0.050).
Conclusions: Total thymectomy was associated with higher rates of recurrent infection, impaired lymphocyte recovery, and a trend toward longer hospitalization, independent of bypass duration. These findings highlight an immunologic cost to complete thymic removal and underscore the need for larger studies to confirm this association and define its clinical relevance. Future approaches, including thymic tissue preservation and autologous reimplantation, may help mitigate the immune impact of neonatal thymectomy.
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