Raj Satish R, Gillis Anne M, Mitchell Brent, Wyse D George, Sheldon Robert S, Exner Derek V, Morck Margaret, Duff Henry J
Division of Cardiology, Foothills Medical Center and the Cardiovascular Disease Research Group, University of Calgary, Calgary, Alberta, Canada.
Pacing Clin Electrophysiol. 2003 Mar;26(3):662-8. doi: 10.1046/j.1460-9592.2003.00115.x.
Catheter ablation of the atrioventricular junction (AVJ) is a widely accepted treatment for drug refractory atrial fibrillation. Unfortunately, there have been some reports of pause dependent ventricular arrhythmias associated with QT interval prolongation, mainly in patients with reduced LV function. The present investigation evaluates the association of LV function with QT dispersion in response to a sudden rate drop. ECGs were' recorded on 20 patients (13 with normal LV function) on the day following AVJ ablation while paced at a range of ventricular rates (40-120 beats/min), and during a sudden drop from 80 to 40 beats/min. The maximum QT interval (QTmax), minimum QT interval (QTmin), and QT interval dispersion (QTdisp) were compared. In both groups, the QTmax and QTmin increased at slower paced heart rates while the QTdisp did not change. In response to a sudden rate drop from 80 to 40 beats/min, the QTmax increased in both groups of LV function (trend), while the QTmin increased in those with normal LV function (24 +/- 22 ms), but not in those with reduced LV function (0 +/- 14 ms; P = 0.01). Consequently, the QTdisp increased significantly in those with reduced LV function (31 +/- 23 ms) but not in normal LV function (-5 +/- 29 ms; P = 0.01). Morphological QTU changes developed following the sudden rate drop in 67% of the reduced LV versus 8% of the normal LV (P = 0.02) function groups. Following AVJ ablation, QTdisp increased during a sudden rate drop in patients with reduced LV function, but not in patients with normal LV function.
房室结（AVJ）导管消融术是药物难治性心房颤动广泛接受的一种治疗方法。不幸的是，已有一些关于与QT间期延长相关的长间歇依赖性室性心律失常的报道，主要见于左心室功能减退的患者。本研究评估左心室功能与突然心率下降时QT离散度之间的关系。在20例患者（13例左心室功能正常）进行AVJ消融术后次日，在一系列心室率（40 - 120次/分钟）起搏时以及从80次/分钟突然降至40次/分钟期间记录心电图。比较最大QT间期（QTmax）、最小QT间期（QTmin）和QT间期离散度（QTdisp）。在两组中，较慢起搏心率时QTmax和QTmin增加，而QTdisp不变。在从80次/分钟突然降至40次/分钟时，两组左心室功能患者的QTmax均增加（呈趋势），而左心室功能正常者的QTmin增加（24±22毫秒），左心室功能减退者则未增加（0±14毫秒；P = 0.01）。因此，左心室功能减退者的QTdisp显著增加（31±23毫秒），而左心室功能正常者未增加（-5±29毫秒；P = 0.01）。左心室功能减退组67%的患者在突然心率下降后出现QTU形态改变，而左心室功能正常组为8%（P = 0.02）。AVJ消融术后，左心室功能减退患者在突然心率下降时QTdisp增加，而左心室功能正常患者则未增加。
