Weiss D N, Shorofsky S R, Peters R W, Gold M R
Department of Medicine, University of Maryland Medical System, Baltimore, USA.
J Interv Card Electrophysiol. 1998 Sep;2(3):273-7. doi: 10.1023/a:1009745222443.
The impedance of internal defibrillator shocks is an important determinant of defibrillation efficacy. To assess the effect of delivered energy on impedance, we studied 97 patients with 4 different lead systems. The lead systems evaluated were two epicardial patches, a hybrid system of a patch and right atrial coil, a dual coil transvenous lead and a transvenous lead with a subcutaneous patch. Impedances were measured for 6 shock energies between 0.1 and 30 J. Shock impedance increased at low energies for all lead systems (p < 0.001), although the rate of increase varied markedly between systems. The energy factor (FE), which is the ratio of impedances for the 0.1 and 10 J shocks, was least for the platinum transvenous lead (1.2 +/- 0.02) and greatest for the titanium hybrid lead (4.2 +/- 0.2). Reversing the polarity of the hybrid lead markedly attenuated the impedance rise. These findings indicate that there is at least a modest rise (20%) of shock impedance at very low delivered energies. The largest increases noted with titanium lead systems are primarily due to polarization. Titanium transvenous leads should be avoided when low energy shocks are utilized such as for the cardioversion of ventricular tachycardia or atrial fibrillation.
体内除颤电击的阻抗是除颤效果的一个重要决定因素。为了评估输送能量对阻抗的影响，我们对97例使用4种不同导联系统的患者进行了研究。所评估的导联系统包括两片心外膜贴片、一片贴片与右心房线圈的混合系统、双线圈经静脉导联以及带有皮下贴片的经静脉导联。测量了0.1至30 J之间6种电击能量下的阻抗。所有导联系统在低能量时电击阻抗均增加（p < 0.001），尽管不同系统之间增加速率差异显著。能量因子（FE），即0.1 J和10 J电击时阻抗的比值，对于铂制经静脉导联最小（1.2 +/- 0.02），对于钛制混合导联最大（4.2 +/- 0.2）。反转混合导联的极性可显著减弱阻抗上升。这些发现表明，在极低的输送能量下，电击阻抗至少有适度上升（20%）。钛制导联系统中观察到的最大增加主要归因于极化。当使用低能量电击（如用于室性心动过速或心房颤动的心脏复律）时，应避免使用钛制经静脉导联。
