Lane G K, Kennelly B M
Eur J Cardiol. 1979 Jul;10(1):71-5.
This report concerns a patient with complete heart block, in whom electrophysiological studies showed at times an escape rhythm with narrow QRS complexes preceded by His potentials with normal HV intervals (35--40 msec) and at other times an escape rhythm of similar rate, having wide QRS complexes of left bundle branch block configuration with no preceding His bundle activity. Complexes intermediate in width and configuration and preceded by His potentials with an HV interval inversely proportional to QRS width were also recorded. These observations are explained by a site of block proximal to the His bundle and competition between two pacemaker foci having similar discharge rates, one situated in the junctional region below the site of block and the other more distally in the right bundle branch or right ventricle. It is proposed that the combination of a proximal site of block and a distally situated dominant pacemaker may be a common reason for failure to record a His potential in patients with complete heart block.
本报告涉及一名完全性心脏传导阻滞患者，其电生理研究有时显示逸搏心律，QRS波群狭窄，希氏束电位之前有正常的HV间期（35 - 40毫秒），其他时候显示类似速率的逸搏心律，QRS波群宽大，呈左束支传导阻滞图形，之前无希氏束活动。还记录到宽度和形态介于两者之间且之前有希氏束电位、HV间期与QRS宽度成反比的波群。这些观察结果可通过希氏束近端的阻滞部位以及两个放电速率相似的起搏点之间的竞争来解释，一个位于阻滞部位下方的交界区，另一个更靠远端，位于右束支或右心室。有人提出，近端阻滞部位和远端占主导地位的起搏点相结合可能是完全性心脏传导阻滞患者未能记录到希氏束电位的常见原因。
