常见的J波与J波综合征.ppt

发生机制 T波记忆发生新机制 定义： 束支阻滞、心室预激、心室起搏、室速、单次室早等心室异常激动后，出现持续的T波改变。 机制： 离子通道的改变：Ito电流在T波记忆发生中，起到一定作用，但目前单细胞的例子通道改变不能解释整体心室的复极变化。 发生率及分类： 1.发生率：5%~15% 2.分类：短期和长期 有人认为与心室异常激动存在时间长短相关 危害 心室复极改变 跨室壁复极离散度升高，进而增加恶性室性心律失常发生的风险 2008年文献认为： 机制—电反馈机制 1.心室起搏中 A：起搏，停止 B:起搏—链霉素—停止 结果：T波偏移角：70± 4.3度， 减少为17 ±10度 结论： 牵张敏感性受体在心肌分布广泛，阻断后可预防心脏记忆现象，证明机械电反馈机制在T波电交替发生中有重要作用 谢谢 * Before discussing ST segment elevation in each individual clinical entity, I would like to to briefly review the cellular mechanisms for ST segment elevation and related Repolarization waves on the ECG. Based on biophysical principles of ECG recording, any wave on the body surface ECG represents a coincident voltage gradient generated by cellular electrical activity within the heart. The ST segment is the tracing immediately succeeding the QRS complex that extends until the beginning of the T wave. Normally, the ST segment stays at the same level as the T-P segment. In the two ends of the ST segment, QRS represents ventricular activation, whereas the T wave is the symbol of ventricular repolarization. Ventricular activation normally starts with endocardial depolarization and propagates to the epicardium, generating a large voltage gradient that manifests as the QRS complex on the surface ECG. Because the epicardium normally depolarizes last, the epicardial action potential notch may produce a J wave immediately following the QRS on the surface ECG. Sometimes, the J wave is partially buried inside of the QRS that manifests as J point elevation. It should be emphasized that the J wave generated by the the right ventricle is completely buried inside of the QRS as seen in right precordial leads V1 to V3 under normal condition. When action potentials at all of myocardial layers reach a plateau phase, generating little voltage gradient that is correspondent to an isoelectric ST segment. Therefore, any potential difference across the ventricular wall during plateau phase may cause the disp