Fröhlig G, Helwani Z, Kusch O, Berg M, Schieffer H
Medizinische Universitätsklinik, Innere Medizin III, Homburg, Germany.
Pacing Clin Electrophysiol. 1999 Nov;22(11):1604-13. doi: 10.1111/j.1540-8159.1999.tb00379.x.
In an attempt to evaluate the prevalence and predisposing factors of bipolar ventricular far-field oversensing, 57 patients were studied who had a Medtronic dual chamber pacemaker implanted (models 7940: n = 6; 7960i: n = 41; 401: n = 3; 8968i: n = 7) and bipolar atrial leads with a dipole spacing from 8.6 to 60 mm attached to various parts of the atrial wall (lateral/anterior: n = 30; appendage: n = 10; atrial septum: n = 10; floating: n = 7). Median bipolar sensing threshold for P waves was 4.0 mV (2.8-4.0 mV, lower and upper quartile) with standard leads and 0.35 (0.25-1.4) mV with single pass (VDD) devices. At the highest sensitivity available, 43 of 50 DDD pacemakers but only two of seven VDD systems detected intrinsic R waves in the atrium (P < 0.01). Ventricular far-field oversensing occurred at 0.5 mV in 28 (56%) and at 1.0 mV in 16 of 50 DDD units (32%), respectively, and there was one observation in a septal implant at a sensitivity of even 2.8 mV. With ventricular pacing, VDD systems were as susceptible to far-field signals as DDD pacemakers. Outside the postventricular blanking period (100 ms), evoked R waves were detected by 27 of 57 systems (47%) at maximum atrial sensitivity, by 10 (18%) at 0.5 mV, and by 2 (4%) at a setting of 1.0 up to 1.4 mV, respectively. There was no definite superiority of any lead position, there was a trend in favor of the atrial free wall for better intrinsic R wave rejection, but just the opposite was the case for paced ventricular beats. Bipolar signal discrimination tended to be higher with short tip-to-ring spacing (1 7.8 mm) but the difference to larger dipole lengths (30-60 mm) was not significant in terms of the R to P wave ratio and the overall far-field susceptibility. In summary, bipolar ventricular far-field oversensing in the atrium is common with short postventricular blanking times and high atrial sensitivity settings that may be warranted for tachyarrhythmia detection and mode switching. A potentially more discriminant effect of shorter dipole lengths (< or = 10 mm) remains to be tested.
为了评估双极心室远场过度感知的发生率及诱发因素，我们对57例植入美敦力双腔起搏器的患者进行了研究（型号7940：n = 6；7960i：n = 41；401：n = 3；8968i：n = 7），这些患者使用的双极心房导线偶极间距为8.6至60毫米，附着于心房壁的不同部位（外侧/前侧：n = 30；心耳：n = 10；房间隔：n = 10；游离：n = 7）。标准导线记录P波的双极感知阈值中位数为4.0 mV（四分位间距2.8 - 4.0 mV），单通道（VDD）装置记录的为0.35（0.25 - 1.4）mV。在最高可用灵敏度下，50台DDD起搏器中有43台，但7台VDD系统中只有2台检测到心房内的固有R波（P < 0.01）。50台DDD装置中，分别有28台（56%）在0.5 mV、16台（32%）在1.0 mV时出现心室远场过度感知，在1例房间隔植入患者中，灵敏度为2.8 mV时也有1次观察到该现象。在心室起搏时，VDD系统与DDD起搏器一样容易受到远场信号的影响。在心室后空白期（100毫秒）之外，57个系统中有27个（47%）在最大心房灵敏度时检测到诱发R波，在0.5 mV时10个（18%）检测到，在1.0至1.4 mV设置时2个（4%）检测到。没有哪种导线位置具有明确的优势，虽然有趋势显示心房游离壁更有利于更好地抑制固有R波，但对于起搏的心室搏动情况则相反。尖端到环间距短（≤7.8毫米）时双极信号辨别能力往往更高，但在R波与P波比值及总体远场易感性方面，与较大偶极长度（30 - 60毫米）的差异不显著。总之，心房内双极心室远场过度感知在心室后空白期短和心房高灵敏度设置时很常见，而这些设置可能是检测快速心律失常和模式转换所必需的。偶极长度较短（≤10毫米）的潜在更强辨别作用仍有待测试。
