Nath S, DiMarco J P, Mounsey J P, Lobban J H, Haines D E
Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville, USA.
Circulation. 1995 Sep 1;92(5):1188-92. doi: 10.1161/01.cir.92.5.1188.
Accelerated junctional rhythms have been observed before the development of AV nodal block during radiofrequency (RF) catheter ablation of the AV junction. However, the time course and temperatures required to induce an accelerated junctional rhythm and AV nodal block during this procedure have not yet been characterized.
Nineteen patients underwent RF ablation of the AV junction with a thermistor ablation catheter. RF energy was initially delivered at 10 W for 9 seconds and then increased by 5-W increments for 9 seconds at each power level up to a maximum power of 50 W. If a junctional rhythm was observed during the power titration, a 30- to 60-second RF application was then delivered at the same power level. The power was then further increased to a maximum of 50 W if AV nodal block was not observed after 20 seconds of RF delivery. The procedure was successful in all 19 patients. A median of one RF application (range, one to eight applications) was required to produce permanent AV nodal block. An accelerated junctional rhythm was observed during 89% of successful attempts versus 70% of unsuccessful deliveries (P = NS). The median time to onset of the junctional rhythm was significantly shorter during successful compared with unsuccessful applications (1.8 versus 7.7 seconds, respectively; P < .001). Similarly, the mean time to appearance of AV nodal block was significantly shorter during successful compared with unsuccessful attempts (19.6 +/- 9.4 versus 36.8 +/- 19.0 seconds, respectively; P < .01). The catheter tip temperatures associated with the development of an accelerated junctional rhythm were significantly lower than those associated with the appearance of AV nodal block (51 +/- 4 degrees C versus 58 +/- 6 degrees C, respectively; P < .001). Mean temperatures in the range of 60 +/- 7 degrees C were required to produce permanent AV nodal block.
The development of an accelerated junctional rhythm within 5 seconds and the appearance of AV nodal block within 30 seconds of RF onset were both highly characteristic of successful target sites during RF ablation of the AV junction. The accelerated junctional rhythm and AV nodal block were both highly temperature dependent. The temperatures associated with the onset of AV nodal block were significantly higher than the temperatures resulting in an accelerated junctional rhythm.
在房室交界区的射频（RF）导管消融过程中，在房室结传导阻滞发生之前已观察到加速性交界性心律。然而，在此过程中诱发加速性交界性心律和房室结传导阻滞所需的时间进程和温度尚未明确。
19例患者使用热敏电阻消融导管进行房室交界区的射频消融。射频能量最初以10W持续9秒，然后在每个功率水平上以5W的增量增加并持续9秒，直至最大功率50W。如果在功率滴定过程中观察到交界性心律，则在相同功率水平下进行30至60秒的射频施加。如果在射频施加20秒后未观察到房室结传导阻滞，则功率进一步增加至最大50W。该手术在所有19例患者中均成功。产生永久性房室结传导阻滞平均需要1次射频施加（范围为1至8次施加）。在89%的成功尝试中观察到加速性交界性心律，而在不成功的施加中这一比例为70%（P=无显著差异）。与不成功的施加相比，成功施加时交界性心律开始的中位时间显著更短（分别为1.8秒和7.7秒；P<.001）。同样，与不成功的尝试相比，成功尝试时房室结传导阻滞出现的平均时间显著更短（分别为19.6±9.4秒和36.8±19.0秒；P<.01）。与加速性交界性心律发生相关的导管尖端温度显著低于与房室结传导阻滞出现相关的温度（分别为51±4℃和58±6℃；P<.001）。产生永久性房室结传导阻滞需要平均温度在60±7℃范围内。
在房室交界区射频消融过程中，射频开始后5秒内出现加速性交界性心律以及30秒内出现房室结传导阻滞均是成功靶点的高度特征。加速性交界性心律和房室结传导阻滞均高度依赖温度。与房室结传导阻滞发生相关的温度显著高于导致加速性交界性心律的温度。
