Hernandez R, Mann D E, Reiter M J
Division of Cardiology, University of Colorado Health Sciences Center, Denver 80262.
Pacing Clin Electrophysiol. 1989 Dec;12(12):1884-9. doi: 10.1111/j.1540-8159.1989.tb01880.x.
Atrioventricular (AV) block occurring in the His-Purkinje system may occur sporadically and can be difficult to document. In this article, we describe two patients with spontaneous episodes of AV block, in whom the use of upright tilt during electrophysiological testing led to a diagnosis of His-Purkinje disease. In both cases, testing in the supine position only uncovered mild or no abnormalities of infra-nodal conduction. In the first case, high grade block distal to the His occurred and the mechanism appeared to be bradycardia-dependent block. In this case, increased sympathetic tone due to upright tilt may have enhanced the slope of phase 4 depolarization in abnormal His-Purkinje cells, leading to block. In the second case, high grade block distal to the His was seen with upright tilt and the mechanism of block appeared to be fatigue phenomenon in the His-Purkinje system. These cases emphasize the elusive nature and varied mechanisms of His-Purkinje block and illustrate the utility of electrophysiological testing in the upright position in patients with suspected conduction system disease.
发生在希氏-浦肯野系统的房室（AV）阻滞可能偶发，且难以记录。在本文中，我们描述了两名患有自发性AV阻滞的患者，在他们的电生理检查中采用直立倾斜试验后确诊为希氏-浦肯野病。在这两个病例中，仅仰卧位检查时未发现明显或仅轻度的结下传导异常。在第一个病例中，希氏束远端出现高度阻滞，其机制似乎是心动过缓依赖性阻滞。在该病例中，直立倾斜导致交感神经张力增加，可能增强了异常希氏-浦肯野细胞的4期去极化斜率，从而导致阻滞。在第二个病例中，直立倾斜时可见希氏束远端高度阻滞，其阻滞机制似乎是希氏-浦肯野系统的疲劳现象。这些病例强调了希氏-浦肯野阻滞难以捉摸的性质和多种机制，并说明了直立位电生理检查对疑似传导系统疾病患者的实用性。
