256层CT冠状动脉成像在心肌桥与心肌缺血相关性研究中的应用

Application of 256 layer CT coronary angiography in the study of relationship between myocardial bridge and myocardial ischemia

目的应用256层CT冠状动脉成像（CTCA）探讨心肌桥（MB）与心肌缺血的关系。方法回顾性分析经256层CTCA检查诊断的120例单纯MB患者的影像学资料，根据MB类型分为浅表型与深在型，测量不同时相MB长度；计算壁冠状动脉（MCA）收缩期狭窄率，并比较不同Noble分级中MB类型的差异。结果浅表型与深在型MB舒张期长度分别为（19.48±8.20）、（22.25±8.21）mm，差异未见统计学意义（t＝1.81，P〉0.05）；收缩期长度分别为（19.56±7.37）、（22.63±9.82）mm，差异未见统计学意义（t＝1.96，P〉0.05）；MCA收缩期狭窄率分别为（32.06±11.89）、（44.11±12.15）%，差异有统计学意义（t＝5.38，P〈0.01）。MCA收缩期狭窄Noble分级中2、3级深在型MB（17/23、1/1）比例明显高于1级（29/96），Noble 1级与2级、1级与2、3级总和MB类型比较差异有统计学意义（χ2＝14.946，P〈0.01；χ2＝16.167，P〈0.01）。结论MB好发于前降支中段，MB类型、厚度及MCA收缩期狭窄程度均与心肌缺血有着密切关系，MCA收缩期狭窄程度为2、3级的患者更易发生心肌缺血；MB长度与心肌缺血无明显相关性。

Objective To investigate the relationship between myocardial bridge （MB） and my- ocardial ischemia by 256-slice CT coronary angiography （CTCA）. Methods The images of 120 cases of simple MB diagnosed by 256-slice CTCA were retrospectively analyzed . They were divided into superfi- cial type and deep type. The length of MB in different phase was measured, and the stenosis degree of MCA in systole was calcuated, and the differences of MB type in different Noble grade were compared. Results The length of superficial and deep type MB in diastole were respectively （ 19.48 ±8.20） mm and （22.25 ± 8.21 ）mm, there was no significant difference between the two groups （t = 1.81, P 〉 0. 05） ; the length in systole were respectively （19.56 ±7.37）mm and （22. 63 ±9. 82） mm, there was no significant difference between the two groups （ t = 1.96, P 〉 0. 05 ） ; the stenosis degree of MCA in systole were respectively （ 32.06± 11.89 ） % and （ 44. 11 ± 12. 15 ） %, there was significant difference between the two groups（t =5.38 ,P 〈0. 01 ）. The deep type of MB in grade 2 and 3 （ 17/23, 1/1 ） was significantly higher than that in grade 1 （29/96）. The difference between grade 1 and 2 （X2 = 14. 946, P〈0.01）, grade 1 and grade2 ＋ grade 3 was significant （X2 =16. 167,P〈0.01）. Conclusions MB preferentially occurs in the middle segment of anterior descending branch. The thickness and type of MB, the stenosis degree of MCA in systolic are closely correlated with myocardial ischemia, the grade 2 and 3 of MCA in systolic were more likely to occur myocardial isehemia, but the length of MB has no significant correlation with myocardial ischemia.