Kinoshita S
Am Heart J. 1978 Jul;96(1):54-61. doi: 10.1016/0002-8703(78)90126-6.
In five patients with tachycardic RDBBB (rate dependent bundle branch block), variations in the critical CL (cycle length) inducing RDBBB were investigated. In one patient, independent of changes in the preceding CL, the critical CL inducing RDBBB was invariable, extending over two years. In the other patients, the critical CL inducing RDBBB varied within a comparatively short period. However, when RDBBB was maintained for only a few cycles, the critical CL allowing reversion to normal conduction was always longer than the critical CL inducing RDBBB here, in all patients except one. In one patient such a distinct difference in CL could not be disclosed because the critical CL inducing RDBBB varied from cycle to cycle. These observations suggest that independent of variations in the refractory period of the blocked bundle branch, the critical CL allowing reversion to normal conduction was considerably longer than this refractory period in all patients. The possible mechanisms by which RDBBB could be maintained are discussed. The most probable mechanism appears to be "true" unidirectional block in the affected bundle branch, in which the refractory period for the retrogradely conducted impulse is shorter than that for the anterogradely conducted impulse.
在5例心动过速性RDBBB（心率依赖性束支传导阻滞）患者中，研究了诱发RDBBB的临界CL（周期长度）的变化。在1例患者中，与前一个CL的变化无关，诱发RDBBB的临界CL在两年多的时间里保持不变。在其他患者中，诱发RDBBB的临界CL在相对较短的时间内有所变化。然而，当RDBBB仅持续几个周期时，除1例患者外，所有患者中允许恢复正常传导的临界CL总是长于在此诱发RDBBB的临界CL。在1例患者中，由于诱发RDBBB的临界CL在不同周期之间变化，无法揭示CL的这种明显差异。这些观察结果表明，在所有患者中，与阻滞束支不应期的变化无关，允许恢复正常传导的临界CL比该不应期长得多。讨论了RDBBB得以维持的可能机制。最可能的机制似乎是受累束支中的“真正”单向阻滞，其中逆向传导冲动的不应期短于正向传导冲动的不应期。
