Ahmed Intisar, Netlefold Chloe, Anderson Robert D, Masse Stephane, Burg Melanie R, David Tirone E, Heggie Jane, Ouzounian Maral, Nanthakumar Kumaraswamy
Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada.
CJC Open. 2025 Jun 10;7(9):1162-1169. doi: 10.1016/j.cjco.2025.06.003. eCollection 2025 Sep.
Despite advancements in postoperative temporary epicardial pacing leads, sensing malfunction can still happen. Oversensing presents as inappropriate inhibition of pacing (a major concern for pacemaker-dependent patients), whereas undersensing may lead to an extremely rare complication of ventricular fibrillation from R on T. The single-lead and dual-lead configurations have key structural differences related to the size of the bipole electrodes and the spacing between them. We assessed how this affects the sensing function.
Five porcine studies were conducted using open chest and Langendorff models. We used 2 pacing wire configurations and compared the sensed electrograms. We compared a newer single-lead configuration (small, closely spaced electrodes) with a dual-lead (large, widely spaced) configuration. The primary outcome was the amplitude of the R wave. Secondary outcomes were the relative size of the T wave and the effect of sampling frequency and low-pass filtering.
The sensed QRS was significantly larger in the widely spaced, larger electrodes when compared with closely spaced, smaller electrodes across all sampling frequencies and filter settings (6.9-29.7 mV vs 1.7-8.6 mV, < 0.001). The average amplitude of the T wave was closer to the average QRS amplitude with the newer configuration across all settings. The mean T wave to R wave difference ranged from 3.0 to 3.7 mV for the single lead and 1.0 to 21.5 mV for the dual lead configuration. Large, widely spaced electrodes resulted in much larger sensed QRS signals and a safer programming window for sensitivity.
The smaller, closely spaced electrodes detect a relatively small QRS and a larger T wave, leading to a narrower safety window and an increased risk of sensing malfunction (Central Illustration). To avert catastrophic consequences, the electrophysiologic implications of new temporary pacing wires must be considered during postoperative care.
尽管术后临时心外膜起搏导线有所改进，但仍可能发生感知故障。感知过度表现为不适当的起搏抑制（这是起搏器依赖患者的主要担忧），而感知不足可能导致极其罕见的R波落在T波上引起室颤的并发症。单极和双极配置在双极电极的大小及其间距方面存在关键结构差异。我们评估了这如何影响感知功能。
使用开胸和Langendorff模型进行了五项猪实验研究。我们使用了两种起搏导线配置并比较了感知到的心电图。我们将一种较新的单极配置（小的、间距紧密的电极）与双极配置（大的、间距宽的电极）进行了比较。主要结局是R波的振幅。次要结局是T波的相对大小以及采样频率和低通滤波的影响。
在所有采样频率和滤波设置下，与间距紧密的较小电极相比，间距宽的较大电极感知到的QRS波明显更大（6.9 - 29.7 mV对1.7 - 8.6 mV，<0.001）。在所有设置下，采用新配置时T波的平均振幅更接近QRS波的平均振幅。单极配置的平均T波与R波差值范围为3.0至3.7 mV，双极配置为1.0至21.5 mV。大的、间距宽的电极产生的感知QRS信号大得多，且灵敏度编程窗口更安全。
较小的、间距紧密的电极检测到的QRS波相对较小，T波较大，导致安全窗口变窄，感知故障风险增加（见中心插图）。为避免灾难性后果，术后护理期间必须考虑新型临时起搏导线的电生理影响。
