Hegbom Finn, Orning Otto M, Gjesdal Knut
Heart & Lung Center, Ullevål University Hospital, Oslo, Norway.
Scand Cardiovasc J. 2003 Sep;37(4):199-204. doi: 10.1080/14017430310002257.
AV node modification reduces ventricular rate during atrial fibrillation (AF). We induced AF in patients with dual AV nodal pathways before and after radiofrequency ablation (RFA) of AV nodal reentry tachycardia (AVNRT) and examined the role of the two pathways in the transmission of impulses during AF.
AF was induced in 30 patients before and after slow pathway ablation. Before RFA mean (AF CLmean) and shortest (AF CLshort) ventricular cycle lengths correlated significantly to ERPf, ERPs, and antegrade Wenckebach block (r = 0.53-0.67). Ablation eliminated slow pathway conduction completely in 10 patients (group A), whereas in 20 patients some slow pathway conduction was still present (group B). After RFA there was a 10% increase in AF CLmean (20%, p < 0.05 in A and 5%, p = NS in B) and 7% in AF CLshort (11%, p = NS in A and 6%, p = NS in B). During isoproterenol infusion after RFA AF CLmean increased 8% (p < 0.05) (14% in A and 6% in B; p < 0.05 in both groups). The effects of RFA were mainly confined to patients with ERPs less than the median value (13% vs 3% in those above median, respectively; p < 0.05).
The refractory periods of the AV nodal pathways are the main determinants of ventricular rate during induced AF. Slow pathway ablation reduces ventricular rate during AF. This effect was greatest when slow pathway conduction was completely eliminated. A short ERPs predicted a greater reduction in ventricular rate.
房室结改良可降低心房颤动（AF）时的心室率。我们在房室结折返性心动过速（AVNRT）患者行射频消融（RFA）前后，诱发其发生AF，并研究两条通路在AF冲动传导中的作用。
30例患者在慢径路消融前后均诱发了AF。RFA前，平均（AF CLmean）和最短（AF CLshort）心室周期长度与功能性不应期（ERPf）、有效不应期（ERPs）及前传文氏阻滞显著相关（r = 0.53 - 0.67）。消融使10例患者（A组）的慢径路传导完全消失，而20例患者（B组）仍存在部分慢径路传导。RFA后，AF CLmean增加了10%（A组增加20%，p < 0.05；B组增加5%，p = 无显著性差异），AF CLshort增加了7%（A组增加11%，p = 无显著性差异；B组增加6%，p = 无显著性差异）。RFA后静脉滴注异丙肾上腺素时，AF CLmean增加了8%（p < 0.05）（A组增加14%，B组增加6%；两组p均< 0.05）。RFA的作用主要局限于ERPs小于中位数的患者（分别为中位数以上患者的13%对3%；p < 0.05）。
房室结通路的不应期是诱发AF时心室率的主要决定因素。慢径路消融可降低AF时的心室率。当慢径路传导完全消除时，这种效应最大。较短的ERPs预示着心室率降低幅度更大。
