Mahaim纤维的电生理特征和导管射频消融

探讨Mahaim纤维的电生理特征和导管射频消融的可行性。 1996年 5月至 1999年 4月对 4例拟诊为Mahaim纤维引起的逆向型房室折返性心动过速的病人进行了电生理检查和射频导管消融。男 3例、女 1例 ,年龄 31± 19岁 ,心动过速发作史 15± 14年 ,频率 2 0 1± 17(180～ 2 2 0 )次 /分 ,发作时均有明显的心悸症状。 4例窦性心律时心电图除 1例轻微预激外均正常。心房程序电刺激可以诱发心动过速。心室起搏时从房室结逆传 ,静脉注射ATP 2 0mg室房分离。 4例Mahaim心动过速均只有前传并呈递减传导特性。 1例同时合并房室结折返性心动过速。 2例导管操作发生心房颤动并经过Mahaim纤维前传 ,1例持续发作、1例短暂发作。 4例分别在心房起搏、心动过速和心房颤动时三尖瓣心房侧标测和消融。心室预激较体表V1导联QRS波起始处提前 40± 6 (34～ 46 )ms处消融均获成功 ,1例靶点位于右前侧壁、3例位于右后侧壁。能量 35± 5W ,消融 5± 3次 ,X线透视时间 38± 2 1min。无手术相关的并发症。合并房室结折返性心动过速 1例同时作了慢径改良。分别随访 3个月～ 3年无 1例心动过速复发。临床研究证实 ,导管射频消融是治疗Mahaim介导的心动过速的有效、可行和安全的方法

Electrophysiological Characteristics and Radiofrequency Catheter Ablation of Mahaim Fibers.

To study electrophysiological characteristics and the feasibility of radiofrequency catheter ablaton of Mahaim fibers.From May 1996 to April 1999,four patients (three male,one female) with tachycardia of left bundle branch block pattern were considered to have antidromic atrioventricular reciprocating tachycardia produced by Mahaim fibers.The mean age was 31±19 years.All patients had symptomatic episodes of tachycardia with histories of a mean of 15 ±14 years.The mean heart rate was 201 ±17 beats per minute during tachycardia.Their ECG was normal during sinus rhythm except that one patient had minal ventricular preexcitation.The Mahaim tachycardia was induced by atrial programmed stimulation in all patients.The QRS configuration was the same as tachycardia during atrial pacing.Electrophysiologic characteristics of these unique accessory pathways were that they only had anterograde conduction with decremental property.Ventricular atrial conduction was via atrioventricual node during ventricular pacing,and was blocked by 20 mg ATP injection.Atrial fibrillation (AF) with anterograde conduction via Mahaim fiber was induced by catheter manipulation in two patients and was persistent in one,transient in the other.One patient also had atrioventricular nodal reentrant tachycardia(AVNRT).The accessory pathways were mapped and ablated in atrial side of the tricuspid annulus,two in atrial pacing,one in tachycardia,and one in AF.Earliest ventricular activation preceded the onset of the QRS complex by mean of 40±6(34～46) ms in successful ablated target sites.Three accessory pathways were located in posterolateral right atrium near tricuspid annulus,one in anterolateral.A mean of 5±3 radiofrequency pulses were delivered at a mean of 35±5 W.The slow pathway modification was successfully acomplished in the patient with AVNRT during the same procedure.The mean X fluoroscopy exposure time for the procedure was 38±21 minutes.The accessory pathways were eliminated in all patients with no complications occurred.Tachycardia did not recur after follow up of 3 to 36 months.Conclusion:Tachycardia mediated by Mahaim fibers can be eliminated effectively,safely and feasibily by radiofrequency catheter ablation.