实验性甲状腺机能减退犬的心房电生理效应及其对房性心律失常的影响

应用心脏电刺激技术，观察了实验性甲状腺机能减退犬的心房电生理效应及其潜在的抗心律失常作用，２４只犬随机分成正常对照组、胺碘酮组和甲状腺机能减退组。胺碘酮组犬予以胺碘酮口服，每日４００ｍｇ，共４周．以甲状腺全切除术创作甲状腺机能减退模型。电生理实验结果表明，甲状腺机能减退状态与胺碘酮的心电生理效应有很高的一致性，两者均延长心房有效不应期（ＡＥＲＰ）和心房功能传导期（ＡＦＣＰ）。不同的是，甲状腺机能减退状态对心房间传导时间（ＬＡＣＴ）无影响，胺碘酮使之延长。甲状腺机能减退组和胺碘酮组持续性房性快速型心律失常（ＳＡＴ）的诱发率均显著低于正常对照组。

The atrial electrophysiologic properties of hypothyroidism and its potential antiarrhythmic effects in an experimental canine model

The First Military Medical University Department of Cardiology,Sun Yat-sen Memorial Hospital, Sun Yat-sen University of Medical sciences The clinical observations that atrial fibrillation was common in hyperthyroidism,while rare in hy-pothyroidism led to this study on the potential antiarrhythmic effects of hypothyroidism in dogs.The ani-mals were randomly divided into 3 groups.Group 1(n=8)served as normal controls.Group 2(n=9)werethe hypothyroid models by total thyroidectomy.Group 3(n=7)were given amiodarone orally 400mg a dayfor 4 weeks.The results in the cardiac electrophysiologic properties showed similarities between hypothy-roidism and effects of amiodarone,which included prolongation of atrial effective refractory period(ERP)and atrial functional conduction period(FCP),and the atrial tachyarrhythmias induced by burst pacing be-ing less likely sustained.What was different was that hypothyroidism had no effect on interatrial conduc-tion time(IACT),while amiodarone suppressed myocardial conduction velocity characterized by frequencydependence.