缺血预处理对心脏瓣膜置换手术围术期甲状腺激素代谢的影响及临床意义

Significance and effects of ischemic preconditioning on perioperative thyroid hormone metabolism in patients with cardiac valve replacement

目的 :了解缺血预处理对心脏瓣膜置换手术围术期甲状腺激素 (TH)代谢的影响及临床意义。方法 :选取 16例风湿性心脏病 (风心病 )瓣膜置换手术患者 ,随机均分为实验组 (IP组 )及对照组 (C组 ) ,IP组采取缺血预处理方案 ,对照组不采取预处理 ,其余同IP组。分别于术前、转流中 (最低温 )、再灌注后 5min ,停机、术后 2 ,2 4 ,4 8h采取血样 ,测定血清总三磺甲状腺原氨酸 (TT3 )、总四碘甲状腺原氨酸 (TT4)、游离三磺甲状腺原氨酸 (FT3 )、游离四碘甲状腺原氨酸 (FT4)、促甲状腺激素 (TSH)浓度 ,组内各时点与术前 ,两组之间各时点进行配对比较。结果 :TT3 和FT3 水平在转流最低温时降至最低点 ,术后 4 8h仍低于术前 ,但IP组术后 2 4～ 4 8h二者水平明显高于对照组 (均P <0 .0 5 ) ,两组T4,FT4水平术后 2 4h已恢复术至前水平 ,各时点间无明显差异 ;TSH水平术后 4 8h两组均低于术前 ;IP组无严重并发症发生 ,对照组有 2例发生低心排。结论 :风心病瓣膜置换手术围术期呈现低T3 综合征 ;缺血预处理可以减轻瓣膜置换手术围术期低T3 综合征的严重程度 。

Objective To explore the significance and effects of ischemic preconditioning on perioperative thyroid hormone metabolism in patients with cardiac valve replacement.Methods Sixteen patients undergoing cardiac valve replacement were randomly divided into 2 gruops:the ischemic preconditioning group (IP group) and the control group (C group). The aorta was clamped for 2 minutes and declamped for 3 minutes with 2 cycles in the IP group.Blood samples were taken before the operation, at the time of the lowest hypothermia, 5 minutes after aortic declamping, the termination of cardiopulmonary bypass (CPB), and at 2, 24, 48 hours after the operation. Then the concentrations of T 3,FT 3,T 4,FI 4 and TSH were measured.Results All levels of thyroid hormone decreased apparently during and after the CPB. Serum T 3,FT 3 declined to the lowest hypothermia during CPB and declined continuously after the operation.Serum T 4 and FT 4 levels in the 2 groups returned to the levels before the operation.TSH level in 48 hours after the operation in the 2 groups were lower than those in the preoperation.Serum T 3 level in the IP group was significantly higher than that in the C group at 24, and 48 hours after the operation.Conclusion Euthyroid sick syndrome exists during and after the CPB in patients with cardiac valve replacement,which can be ameliorated via ischemic preconditioning with less traumatic to the body function.