Kim J W, Seo H S, Na J O, Suh S Y, Choi C U, Kim E J, Rha S-W, Park C G, Oh D J
Guro Hospital, Cardiovascular Centre, Korea University, 97 Gurodong-Gil, Guro-gu, Seoul, Republic of Korea 152-703.
Heart. 2008 Jun;94(6):765-9. doi: 10.1136/hrt.2007.115980. Epub 2007 Sep 19.
Myocardial bridge (MB) is characterised by focal compression of a coronary artery in systole by an overlying band of myocardium. Chronic compression and relaxation of the MB may produce endothelial dysfunction by direct stress.
To determine whether MB alters endothelial function, thus influencing the plaque formation.
128 patients (mean (SD) age 54.7 (10.9) years, 56 men) with typical angiographic systolic milking effects and >30% reduction in diameter of the coronary artery during systole after intracoronary nitrate (glyceryl trinitrate, 200 mug) infusion were studied. 231 control patients (mean (SD) age 52.9 (12.1) years, 111 men) without overt coronary artery disease including MB were also studied. Endothelial function was estimated by incremental acetylcholine (Ach) infusion into the left coronary ostium. Intracoronary ultrasound assessments were obtained in 74/128 patients with MB and 81/231 controls.
The mean (SD) vasoconstrictive response to maximal Ach was more pronounced at the bridging segments than at matched segments in controls (-71.9 (14.9) vs -30.3 (22.6), p = 0.009). Coronary vasoconstriction (>50%) to Ach was seen more often in the MB group than in controls (114/128 (89.1%) vs 81/231 (35.1%), p = 0.007). No significant correlation was found between the severity of MB and vasoconstriction in response to Ach. A typical half-moon phenomenon was seen in 71/74 (95.9%) cases of the MB group, but not in controls (p<0.001). Plaques at the bridging segments were absent in 67/74 (90.5%) and mild in 7/74 (9.5%) cases, as compared with those of matched segments of the left anterior descending coronary artery in controls (plaque burden 5.91 (1.37)% vs 24.71 (24.21)%, p = 0.002).
Despite the prominent relationship between MB and endothelial dysfunction, bridging segments are spared from atherosclerotic plaque formation.
心肌桥（MB）的特征是在收缩期冠状动脉被覆盖其上的心肌带局部压迫。MB的慢性压迫和舒张可能通过直接应力导致内皮功能障碍。
确定MB是否会改变内皮功能，从而影响斑块形成。
研究了128例患者（平均（标准差）年龄54.7（10.9）岁，56例男性），这些患者具有典型的血管造影收缩期挤奶效应，且在冠状动脉内注入硝酸盐（硝酸甘油，200μg）后收缩期冠状动脉直径减少>30%。还研究了231例无明显冠状动脉疾病（包括MB）的对照患者（平均（标准差）年龄52.9（12.1）岁，111例男性）。通过向左冠状动脉口递增注入乙酰胆碱（Ach）来评估内皮功能。在128例MB患者中的74例和231例对照中的81例进行了冠状动脉内超声评估。
与对照组匹配节段相比，MB节段对最大Ach的平均（标准差）血管收缩反应更明显（-71.9（14.9）对-30.3（22.6），p = 0.009）。MB组中Ach引起的冠状动脉血管收缩（>50%）比对照组更常见（128例中的114例（89.1%）对231例中的81例（35.1%），p = 0.007）。未发现MB的严重程度与对Ach的血管收缩之间存在显著相关性。MB组74例中的71例（95.9%）出现典型的半月现象，而对照组未出现（p<0.001）。与对照组左前降支冠状动脉的匹配节段相比，MB组74例中的67例（90.5%）桥接节段无斑块，7例（9.5%）有轻度斑块（斑块负荷5.91（1.37）%对24.71（24.21）%，p = 0.0
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