Wright K N, Bright J M, Cox J W, McCracken M D
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville 37901, USA.
Am J Vet Res. 1996 Feb;57(2):229-35.
To develop a protocol for reliably inducing atrioventricular (AV) block (ideally first- or second-degree), using radiofrequency energy.
An electrosurgical unit was coupled to an ammeter, which was connected to the distal pole of an electrode catheter positioned at the AV node. Control settings had previously been calibrated to the power output in a circuit with a 100-ohm resistance.
10 clinically normal dogs.
Transcatheter AV nodal modification was attempted, using progressive power applications of 10 to 20 W for progressive durations of 10 to 30 seconds. Atrioventricular nodal conduction and refractivity were measured before and 20 minutes and 1 month after ablation. Electrocardiograms were monitored throughout the 1-month period.
Eight of the 10 dogs developed complete AV block, I developed stable 2:1 AV block, and another had no long-term change in AV nodal conduction. Four dogs attained their maximal degree of AV block in 2 to 5 days. Three of these had no AV nodal conduction changes until 2 to 4 days after ablation.
An electrosurgical unit can be economically modified for radiofrequency transcatheter ablation. Stable, incomplete AV block was rarely induced using this protocol, whereas complete AV block often developed. A major finding was frequent delay between energy delivery to the AV nodal region and induction of AV block.
Induction of complete AV block using this technique, followed by permanent pacemaker placement, is an effective alternative to long-term antiarrhythmic treatment in animals with chronic atrial arrhythmias. Transcatheter ablation could be used to treat other forms of tachycardia, as it is in human medicine.
制定一种使用射频能量可靠诱发房室（AV）阻滞（理想情况下为一度或二度）的方案。
将一个电外科设备与一个安培计相连，该安培计连接到位于房室结处的电极导管的远端电极。先前已将控制设置校准到具有100欧姆电阻的电路中的功率输出。
10只临床健康的犬。
尝试经导管进行房室结改良，逐步施加10至20瓦的功率，持续10至30秒。在消融前、消融后20分钟和1个月测量房室结传导和不应期。在整个1个月期间监测心电图。
10只犬中有8只发生了完全性房室阻滞，1只发生了稳定的2:1房室阻滞，另一只房室结传导无长期变化。4只犬在2至5天内达到了最大程度的房室阻滞。其中3只在消融后2至4天之前房室结传导无变化。
电外科设备可经济地改装用于射频经导管消融。使用该方案很少能诱发稳定的不完全性房室阻滞，而完全性房室阻滞经常发生。一个主要发现是向房室结区域输送能量与诱发房室阻滞之间经常存在延迟。
使用该技术诱发完全性房室阻滞，随后植入永久性起搏器，是慢性房性心律失常动物长期抗心律失常治疗的一种有效替代方法。经导管消融可用于治疗其他形式的心动过速，就像在人类医学中一样。
