Differential electrophysiologic properties of decremental retrograde pathways in long RP' tachycardia.
Differential electrophysiologic properties of decremental retrograde pathways in long RP' tachycardia.
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长 RP 心动过速递减逆行通路的差异电生理特性。
DOI：
10.1161/01.cir.76.1.21
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发表时间：
1987
期刊：
影响因子：
37.8
通讯作者：
DiMarco,JP
中科院分区：
文献类型：
--
作者：
Lerman,BB;Greenberg,M;Overholt,ED;Swerdlow,CD;SmithJr,RT;Sellers,TD;DiMarco,JP
长 RP' 室上性心动过速 (SVT) 通常在折返回路的逆行通路中表现出缓慢和递减的传导特性。人们对这些通路的电生理特性知之甚少。我们研究了 10 名患有长 RP' SVT 的患者（RP'/RR，0.52 至 0.71）； 5 名患者存在不寻常形式的房室结折返（快-慢），5 名患者的旁路 AV 通路具有缓慢、递减的逆行传导特性。在 SVT 期间，评估了静脉内腺苷（37.5 至 150 微克/千克）的作用，其增加室上组织中的钾电流 (iK) 并使膜电位超极化至 Ek (-90 mV)，以及维拉帕米 (0.10 至 0.20 毫克/千克 iv) 缓慢内向通道阻断的反应。腺苷和维拉帕米在快慢房室结折返时具有相似的作用，因为这两种药物都通过阻断逆行慢房室结通路来终止 SVT。相比之下，腺苷和维拉帕米对递减旁路逆行传导具有不同的影响。腺苷终止了逆行递减途径中所有 SVT 发作，而维拉帕米仅对五名患者中的两名患者的该组织产生直接影响。因此，递减逆行旁路可以表现出至少两种类型的电生理反应。仅对腺苷诱导的超极化 K+ 电流作出反应的通路可能包括抑制的快 Na+ 通道组织，即部分去极化（大于 -60 至 -70 mV）的心房组织。相反，对缓慢内向钙电流和 K+ 电导的调节做出反应的递减旁路具有与房室结类似的药理学特性，并且可能代表更完全去极化的心房纤维，静息膜电位为 -60 mV 或更小。
Long RP' supraventricular tachycardias (SVT) often demonstrate both slow and decremental conduction properties in the retrograde pathway of the reentrant circuit. The electrophysiologic properties of these pathways are poorly understood. We studied 10 patients with long RP' SVT (RP'/RR, 0.52 to 0.71); five had the unusual form of atrioventricular nodal reentry (fast-slow) and five patients had accessory AV pathways with slow, decremental retrograde conduction properties. During SVT, the effects of intravenous adenosine (37.5 to 150 micrograms/kg), which increases potassium current (iK) in supraventricular tissue and hyperpolarizes membrane potential toward Ek (-90 mV), and the response to slow-inward channel blockade with verapamil (0.10 to 0.20 mg/kg iv) were evaluated. Adenosine and verapamil has similar effects in the presence of fast-slow AV nodal reentry since both agents terminated SVT by producing block in the retrograde slow AV nodal pathway. In contrast, adenosine and verapamil had differential effects on retrograde conduction in decremental accessory pathways. Adenosine terminated all episodes of SVT in the retrograde decremental pathway, whereas verapamil had a direct effect on this tissue in only two of five patients. Decremental retrograde accessory pathways can therefore demonstrate at least two types of electrophysiologic responses. Pathways that respond only to adenosine-induced hyperpolarizing K+ current likely comprise depressed fast-Na+ channel tissue, i.e., partially depolarized (greater than -60 to -70 mV) atrial tissue. In contrast, decremental accessory pathways that respond to both modulation of the slow-inward calcium current and K+ conductance have pharmacologic properties similar to those of the AV node and may represent more completely depolarized atrial fibers with resting membrane potentials of -60 mV or less.