Osman Faizel, Stafford Peter J, Ng G Andre
University Hospital Coventry, Department of Cardiology, Clifford Bridge Rd, Coventry CV22DX.
Indian Pacing Electrophysiol J. 2009;9(2):112-8. Epub 2009 Mar 15.
It was long believed that Mahaim pathways represented nodo-fascicular or nodo-ventricular connections. However, this misconception was challenged when patients underwent surgical or catheter ablation of the AV node but remained pre-excited. Electrophysiology (EP) studies showed these pathways to be right sided decrementally conducting atrio-fascicular accessory pathways with the atrium forming a part of the antidromic tachycardia circuit. Mahaim pathways are usually reported to occur on the right side. We report a patient who presented with a broad complex tachycardia thought to be ventricular tachycardia; however during EP study this was shown to be an antidromic atrioventricular tachycardia utilising a left free wall pathway that demonstrated 'Mahaim-like' properties and was successfully ablated. The pathway was shown to have long conduction times with no retrograde conduction, had an effective refractory period longer than the AV node and its conduction was only evident during antidromic AVRT. It also had a decremental antegrade property and was responsive to intravenous adenosine. These 'Mahaim-like' features are very unusual and rarely reported on the left side.
长期以来，人们一直认为Mahaim纤维束代表结-束或结-室连接。然而，当患者接受房室结的手术或导管消融但仍存在预激时，这一误解受到了挑战。电生理（EP）研究表明，这些纤维束是右侧递减传导的房室束旁道，心房构成了逆向性心动过速环路的一部分。Mahaim纤维束通常报道发生在右侧。我们报告了一名表现为宽QRS波心动过速的患者，最初认为是室性心动过速；然而，在电生理研究中发现这是一种利用左游离壁旁道的逆向性房室折返性心动过速，该旁道具有“类Mahaim”特性并成功消融。该旁道显示出长传导时间且无逆向传导，有效不应期长于房室结，其传导仅在逆向性房室折返性心动过速期间明显。它还具有递减性前向传导特性且对静脉注射腺苷有反应。这些“类Mahaim”特征非常罕见，左侧报道更少。
