Rovai Daniele, Di Bella Gianluca, Pingitore Alessandro, Coceani Michele
CNR, Institute of Clinical Physiology, Pisa, Italy.
Ann Noninvasive Electrocardiol. 2015 Mar;20(2):103-7. doi: 10.1111/anec.12242. Epub 2014 Dec 22.
Myocardial bridging (MB) occurs when a segment of an epicardial coronary artery takes an intra- myocardial course, thus leading to systolic compression. Most myocardial bridges involve the left anterior descending artery and are observed in 14-35% of patients. Different pathophysiological mechanisms can induce symptoms secondary to myocardial ischemia: systolic coronary compression, diastolic dysfunction associated with aging and coronary atherosclerosis, LV hypertrophy, vasospasm, microvascular and endothelial dysfunction, plaque development proximal to the bridge.
We performed a literature review of MB, with a particular emphasis on electrocardiographic manifestations.
Stable angina-like chest pain is the usual presentation and MB should be suspected in patients at low risk for coronary atherosclerosis which refer this symptom or which present myocardial ischemia at instrumental examinations. ECG changes are not specific for MB and resting ECG is often normal or presents ST segment anomalies. Exercise stress test often shows non specific signs of ischemia, conduction disturbances or arrhythmias which do not allow the distinction between myocardial bridging and other causes of myocardial ischemia; angina often appears during exercise, even in the absence of ECG changes. Myocardial perfusion deficits at scintigraphy are neither obligatory nor specific. Although the clinical significance of MB is still debated, MB has been associated with acute coronary syndrome, coronary vasospasm, and even sudden cardiac death.
Although MB may lead to myocardial ischemia during stress, its clinical presentation and electrocardiographic findings are not specific.
心肌桥（MB）是指一段心外膜冠状动脉走行于心肌内，从而导致收缩期受压。大多数心肌桥累及左前降支动脉，在14% - 35%的患者中可见。不同的病理生理机制可诱发继发于心肌缺血的症状：收缩期冠状动脉受压、与衰老和冠状动脉粥样硬化相关的舒张功能障碍、左心室肥厚、血管痉挛、微血管和内皮功能障碍、桥近端斑块形成。
我们对心肌桥进行了文献综述，特别强调心电图表现。
稳定型心绞痛样胸痛是常见表现，对于有此症状或在器械检查时出现心肌缺血但冠状动脉粥样硬化风险较低的患者，应怀疑心肌桥。心电图改变对心肌桥不具有特异性，静息心电图通常正常或出现ST段异常。运动负荷试验常显示非特异性缺血、传导障碍或心律失常体征，无法区分心肌桥与其他心肌缺血原因；心绞痛常在运动时出现，即使无心电图改变。心肌灌注显像的缺损既非必然出现也不具有特异性。尽管心肌桥的临床意义仍存在争议，但心肌桥已与急性冠状动脉综合征、冠状动脉痉挛甚至心源性猝死相关。
尽管心肌桥在应激时可能导致心肌缺血，但其临床表现和心电图表现不具有特异性。
