The Effects Of Oral Thyroxine Pre-operation In Children On Thyroid And Cardiac Function For Congenital Heart Disease After Cardiopulmonary Bypass

Objective The study was to aim at that whether oral thyroxine pre-operation could prevent the decline of thyroid hormone levels and improve cardiac function for congenital heart disease(CHD)after cardiopulmonary bypass(CPB).The secondary purpose was to observe the safety of oral thyroxine supplementation.Methods 40 congenital heart disease children were randomly assigned to a control group(group A,n = 10),and three treatment groups(group B,group C,and group D,n =10).Group A didn’ t receive any Interventions;Group B,group C and group D respectively received oral L-T4 at a dose of 0.5ug/(kg · d),1 ug/(kg · d)and 2ug/(kg · d)for 3 days before surgeries.The primary measurements were thyroid hormone levels including total tri-iodothyronine and thyroxine(TT3,TT4),free tri-iodothyronine and thyroxine(FT3,FT4),and thyroid stimulating hormone(TSH)at predetermined time points.The other measurements were serum CK-MB and cTnI levels at 24 hours after surgery.And clinical outcomes included the potential side effects indicating hyperthyroidism in peri-operation,length of ICU stay,time of intubation,postoperative hemodynamic changes,and left ventricular ejection fraction(LVEF).Results The serum thyroid hormone levels showed a different decline after surgery in all groups.TT3,FT3,TT4 and FT4 levels at 12 hours after surgery were not only statistically higher in group D compared to group A(p<0.01,p<0.01,p<0.01,p<0.01),but also higher comparing with group C(p<0.05,p<0.01,p<0.05,p<0.01)and group B(p<0.01,p<0.05,p<0.05,p<0.01).The serum CK-MB and cTnI levels at 24 hours after surgery in group D and C were lower than that in group A(p<0.01,p<0.05).Besides,CK-MB and cTnI levels in group D were both lower than that in group B(p<0.05,p<0.01);however,cTnI level in group C was lower than that in group B,while CK-MB level had no statistically significant differences in the two groups(p>0.05);and neither CK-MB level nor cTnI level had statistically significant differences between group D and C.There was no adverse effects and evidences of hyperthyroidism in peri-operation among treatment groups.Early postoperative hemodynamics,length of stay in ICU and intubation time had no statistically significant differences in all groups.Conclusion Preoperative oral L-T4 can ameliorate low thyroid hormone syndrome and myocardial injury after open-heart surgery using CPB.And oral L-T4 at small doses is safe and won’t lead to adverse effects.