Mehdirad A A, Clem K L, Love C J, Nelson S D, Schaal S F
Department of Internal Medicine, Ohio State University Medical Center, Columbus, USA.
Pacing Clin Electrophysiol. 1999 Jan;22(1 Pt 2):233-7. doi: 10.1111/j.1540-8159.1999.tb00339.x.
Despite using different electrode positions, "conventional" external DC cardioversion in patients with atrial fibrillation is ineffective in 6%-50% of cases. An alternative when DC cardioversion is not successful is low energy internal cardioversion, which is performed at increased risk. We tested the hypothesis that optimization of electrode pad position under fluoroscopy to encompass as much atrial muscle as possible might improve the success rate of external cardioversion and thus minimize the need for internal cardioversion.
Fifteen (9 males, 6 females) patients (age: 54 +/- 15 years, weight: 124 +/- 35 kg) with chronic atrial fibrillation (> 8 weeks) who had undergone unsuccessful conventional external cardioversion entered the study. Repeat conventional external cardioversion with electrodes in standard (right anterior and left posterior) positions was followed by "optimized" external cardioversion by positioning electrodes under fluoroscopy (using metallic markers). In case of failure, internal cardioversion was performed.
All 15 patients had undergone unsuccessful conventional external cardioversion with 360-J shocks. Eight patients (group A) reverted to sinus rhythm with one or two 360-J shocks using fluoroscopy-guided pad placement (53%). Six of the remaining 7 (86%) patients (group B) had successful internal cardioversion with biphasic shocks (12 +/- 3 J). The body weight and body mass index were statistically lower in group A vs group B (106 +/- 27 vs 145 +/- 33 kg, p = 0.03 and 35 +/- 8 vs 45 +/- 8 kg/m2, P = 0.48, respectively). There was no statistically significant in age, height, body surface area, duration of atrial fibrillation, amiodarone therapy, ejection fraction, or underlying heart disease.
Unsuccessful external DC cardioversion, in some patients, is in part due to suboptimal conventional positioning of electrode pads that can be improved under fluoroscopic guidance by achieving the best possible vector encompassing the right and left atria. The optimized external cardioversion technique may minimize the need for internal cardioversion, which remains an effective approach when external cardioversion fails.
尽管采用了不同的电极位置，但房颤患者的“传统”体外直流电复律在6%-50%的病例中无效。直流电复律不成功时的一种替代方法是低能量体内复律，但其实施风险较高。我们检验了这样一个假设，即在透视引导下优化电极片位置以尽可能多地覆盖心房肌，可能会提高体外复律的成功率，从而尽量减少体内复律的必要性。
15例（9例男性，6例女性）慢性房颤（>8周）患者（年龄：54±15岁，体重：124±35 kg），其传统体外直流电复律未成功，进入本研究。首先以标准（右前和左后）位置的电极进行重复传统体外直流电复律，然后在透视引导下（使用金属标记物）定位电极进行“优化”体外直流电复律。若复律失败，则进行体内复律。
所有15例患者采用360J电击进行传统体外直流电复律均未成功。8例患者（A组）通过透视引导下的电极片放置，经一或两次360J电击恢复窦性心律（53%）。其余7例患者中的6例（86%）（B组）通过双相电击成功进行了体内复律（12±3J）。A组的体重和体重指数在统计学上低于B组（分别为106±27 vs 145±33 kg，p = 0.03；35±8 vs 45±8 kg/m²，P = 0.48）。年龄、身高、体表面积、房颤持续时间、胺碘酮治疗、射血分数或基础心脏病方面无统计学显著差异。
在某些患者中，体外直流电复律失败部分是由于电极片的传统定位欠佳，在透视引导下通过获得最佳的左右心房向量可对此加以改善。优化的体外复律技术可尽量减少体内复律的必要性，而体内复律在体外复律失败时仍是一种有效的方法。
