Hsia Henry H, Marchlinski Francis E
Electrophysiology Service, Cardiovascular Division, University of Pennsylvania Health System, Philadelphia, Pennsylvania, USA.
Card Electrophysiol Rev. 2002 Dec;6(4):472-81. doi: 10.1023/a:1021109130276.
Dilated cardiomyopathy is a diverse group of heart diseases with variable arrhythmia substrates. The response to programmed stimulation is dependent on spontaneous arrhythmia presentation. In patients with dilated cardiomyopathy, the majority of sustained monomorphic VT is caused by a scar-related reentrant mechanism, similar to that of coronary artery disease. The arrhythmia is uniformly inducible and is often refractory to pharmacologic therapy. Sustained VT is associated with more extensive myocardial fibrosis and non-uniform anisotropy, involving both the endocardium and epicardium, compared to those without sustained reentry. The response to programmed stimulation is more variable in patients presenting with nonsustained arrhythmia, cardiac arrest or syncope. Inducibility of monomorphic VT is much lower compared to those with ischemic heart disease. Other non-reentrant mechanism, such as focal automaticity, can also be observed in patients with monomorphic VT, in the absence of myocardial scar or evidence of slow conduction. The utility of electrophysiology studies to determine prognosis and to guide therapy remains limited in this patient population. The clinical outcome does not correlate with arrhythmia inducibility, and suppression of induced arrhythmia does not predict a good prognosis. The diagnosis of sarcoidosis or Chagas' cardiomyopathy should be considered in patients with dilated cardiomyopathy of unknown etiology, particularly in those with marked regional wall motion abnormalities and inducible VT. Epicardial reentrant circuits may be more prevalent in these cardiomyopathies, especially in those with VT related to chronic Chagas' disease. Although bundle branch reentry VT is a common finding in patients with dilated cardiomyopathy, it can occur in cardiomyopathy of any type and may coexist with other myocardial reentrant VT. It often has a typical bundle branch block QRS pattern during VT and is associated with His-Purkinje conduction delay. Evidence of macroreentry involving the bundle branches can usually be demonstrated, and catheter ablation of the bundle branches provides an effective and specific treatment.
扩张型心肌病是一组病因多样的心脏病，具有可变的心律失常基质。对程序刺激的反应取决于自发心律失常的表现。在扩张型心肌病患者中，大多数持续性单形性室性心动过速（VT）是由瘢痕相关的折返机制引起的，类似于冠状动脉疾病。这种心律失常通常是可诱发的，并且对药物治疗往往耐药。与无持续性折返的患者相比，持续性VT与更广泛的心肌纤维化和非均匀各向异性有关，累及心内膜和心外膜。对于出现非持续性心律失常、心脏骤停或晕厥的患者，对程序刺激的反应更具变异性。与缺血性心脏病患者相比，单形性VT的可诱发性要低得多。在没有心肌瘢痕或缓慢传导证据的单形性VT患者中，也可观察到其他非折返机制，如局灶性自律性。在这一患者群体中，电生理检查用于确定预后和指导治疗的效用仍然有限。临床结果与心律失常的可诱发性无关，诱导性心律失常的抑制并不能预测良好的预后。对于病因不明的扩张型心肌病患者，应考虑结节病或恰加斯心肌病的诊断，特别是那些有明显局部室壁运动异常和可诱发VT的患者。心外膜折返环在这些心肌病中可能更常见，尤其是在与慢性恰加斯病相关的VT患者中。虽然束支折返性VT在扩张型心肌病患者中很常见，但它可发生于任何类型的心肌病，并且可能与其他心肌折返性VT共存。VT发作时通常具有典型的束支阻滞QRS波形态，并与希氏束-浦肯野传导延迟有关。通常可以证明存在涉及束支的大折返证据，束支导管消融提供了一种有效且特异性的治疗方法。
