29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果

目的报道29例房束型和短房室型Mahaim纤维的电生理特点与射频消融结果。方法对29例Mahaim纤维患者（房束型10例，短房室型19例）进行心内电生理检查和射频导管消融治疗。结果29例患者Mahaim纤维只存在递减性前向传导功能，其中2例合并隐匿性房室旁路（左侧游离壁和右侧中间隔各1例），2例合并三尖瓣峡部依赖型心房扑动，3例合并房室结双径路（均为慢快型）。经Mahaim纤维前传的逆向性房室折返性心动过速时，房束型心室最早激动点在右心室心尖部，短房室型心室最早激动点在三尖瓣环消融靶点处。于三尖瓣环的心房侧成功消融所有Mahaim纤维，其中28例于三尖瓣环游离壁的心房侧消融成功，1例于右心房中间隔消融成功。13例标测到明显的Mahaim纤维电位，25例（房束型9例，短房室型16例）有效消融时出现加速性Mahaim纤维的自主心律。合并房室结双径路、隐匿性房室旁路和三尖瓣峡部依赖型心房扑动者，分别给予以慢径改良、旁路消融和右心房峡部线性消融。随访（17＋8）个月，无1例心动过速复发。结论Mahaim纤维多位于三尖瓣环游离壁。导管消融是Mahaim纤维介导的心动过速安全、有效的治疗方法。消融中出现加速性Mahaim纤维自主心律可以作为判定有效消融的预测指标。消融术前和术后应进行详尽的电生理检查以明确是否合并其他的心动过速。

Electrophysiological features and radiofrequency ablation of Mahaim fibers-29 cases report

Objective The purpose of this study was to evaluate the electrophysiological features and the effect of radiofrequency ablation of Mahaim fiber. Methods Twenty-nine patients having Mahaim fiber tachycardia ( including ten atriofascicular and nineteen atrioventricular accessory pathways) underwent electrophysiological study. Results All Mabaim fibers in twenty-nine patiems were found to have only in the anterograde direction with decremental conduction properties. Two patients had coexistence of concealed atrioventricular accessory pathway, three had inducible atrioventricular nodal reentrant tachycardia. Typical atrial flutter was induced in two patients. In atriofascicular accessory pathway, the earliest ventricular activation was at the apex of the right ventricle. But in atrioventricular accessory pathway, the earliest ventricular activation was at the successful ablation site at the tricuspid annulus. Mahaim fiber was localized at right atrial free wall of tricuspid annulus in twenty-eight patients, at midseptal area in one patient. All Mabaim fibers were successfully ablated at the tricuspid annulus. The "M" potential was recorded in thirteen patients. The heat-induced automaticity occurred in twenty-five patients. Other types of tachyarrhythmia except AF were successfully ablated. Tachycardia did not recur during a mean follow-up period of ( 17±8 )months. Conclusion Mahaim fiber is commonly located at right atrial free wall of tricuspid annulus. Radiofrequency current applied to tricuspid annulus can safely eliminate Mahaim fiber conduction. The accelerated automatic beats of Mahaim fiber during radiofrequency catheter ablation can be considered as a marker of successful result. Before and after successful ablation, programmed electrical stimulation to exclude the presence of other arrhymias is a must.