Maruyama Toru, Fujita Kazumasa, Irie Kei, Moriyama Shouhei, Fukata Mitsuhiro
Department of Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Higashi-ku, Maidashi 3-1-1, Fukuoka 812-8582, Japan.
J Arrhythm. 2017 Oct;33(5):424-429. doi: 10.1016/j.joa.2016.12.005. Epub 2017 Feb 6.
Acetylcholine is widely used for a diagnostic provocation test of coronary spasm in patients with vasospastic angina. Acetylcholine usually induces coronary vasodilatation mediated by muscarinic receptor activation, but sometimes it evokes vasoconstriction of coronary arteries where the endothelium is damaged. Early repolarization syndrome is characterized by a J wave observed at the end of the QRS complex in a surface electrocardiogram. The J wave is attributed to the transmural voltage gradient at the early repolarization phase across the ventricular wall, which stems mainly from prominent transient outward current in the epicardium, but not in the endocardium. Transient high-dose application of acetylcholine into the epicardial coronary arteries provides a unique opportunity to augment net outward current, selectively, in the ventricular epicardium and unmask the J wave, irrespective of the cardiac ischemia based on coronary spasm. Acetylcholine augments cardiac membrane potassium conductance by enhancing acetylcholine-activated potassium current directly and by activating adenosine triphosphate-sensitive potassium current, in addition to the reduced sodium and calcium currents in the setting of severe ischemia due to vasospasm. However, the role of acetylcholine as an arrhythmogenic probe of the J wave induction in patients with suspected early repolarization syndrome warrants future prospective study.
乙酰胆碱广泛用于变异性心绞痛患者冠状动脉痉挛的诊断激发试验。乙酰胆碱通常通过毒蕈碱受体激活介导冠状动脉扩张，但有时会引起内皮受损部位冠状动脉的血管收缩。早期复极综合征的特征是体表心电图QRS波群终末出现J波。J波归因于早期复极阶段跨心室壁的跨壁电压梯度，其主要源于心外膜而非心内膜的显著瞬时外向电流。在心外膜冠状动脉内瞬时高剂量应用乙酰胆碱提供了一个独特的机会，可选择性地增加心室心外膜的净外向电流并显露J波，而与基于冠状动脉痉挛的心肌缺血无关。除了在血管痉挛导致严重缺血的情况下钠电流和钙电流减少外，乙酰胆碱还通过直接增强乙酰胆碱激活的钾电流和激活三磷酸腺苷敏感性钾电流来增加心肌膜钾电导。然而，乙酰胆碱作为疑似早期复极综合征患者J波诱发的致心律失常探针的作用值得未来进行前瞻性研究。
