拡張型心筋症における刺激伝導系の電気生理学的検討

Electrophysiological study of conduction system in dilated cardiomyopathy

　拡張型心筋症（dilated cardiomyopathy,DCM）の予後は明らかに不良で，死亡例の約半数は突然死である^1）。その機序については必ずしも明らかではないが，ほとんどが重篤な不整脈によるものと考えられている。

　本症の心筋には，変性，線維化および肥大などの病変を広範に認めるが，これらの心筋病変の広がりや程度によっては，刺激伝導系にも種々の障害を起こし得る^2）。

Electrophysiological study was performed in 29 cases with dilated cardiomyopathy (DCM). Prolongations of maximum corrected sinus node recovery time and sino-atrial conduction time were found in 7(24.1%) and 8 cases (27.6%), respectively. Prolongations of PA, AH, H, HV interval and QRS duration were found in 4 (13.8%), 8 (27.6%), 16 (57.1%_*), 17 (60.7%^*) and 17 (60.7%), respectively.

The mean value of HRAmax/HRAc in DCM group was higher than in control group significantly (p< 0.001). Atrial fibrillation after rapid atrial pacing (< 250/m) or atrial extrastimulus method appeared in 6 cases (20.7%) in DCM group and none in control group. These results showed the enhanced atrial vulnera-bility in DCM group.

A-V nodal conduction disturbance was found in 12 cases (41.4%) when these disturbances were evaluated by prolongation of AH interval in His bundle electro-gram and latent conduction disturbance judged by atrial pacing

During the follow up period, 8 of 29 cases (27.6%) were suddenly dead, A-V conduction disturbance, espe-cially in His-purkinje system was highly demonstrated in their His bundle electrograms.

_*except a case with complete A-V block