Libbus Imad, Mazar Scott T, Stubbs Scott R, KenKnight Bruce H
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:3681-3684. doi: 10.1109/EMBC.2018.8513067.
Autonomic regulation therapy via vagus nerve stimulation (VNS) was recently approved as a therapy for chronic heart failure, and will likely be utilized in patients who are also indicated for cardiac rhythm management device implantation. This study is designed to assess the degree to which VNS is likely to cause interference in the cardiac sensing of an implantable cardiac rhythm management device.
A VNS stimulation lead and a cardiac sensing lead were placed in a simulated biological medium. A nonconductive carrier frame was used to position the leads at a precise electrode spacing. Stimulation was delivered through the VNS Therapy lead at a maximum output current and a variety of combinations of stimulation frequencies from 5-30 Hz and stimulation pulse widths from 130-1000 μs. The electrode spacing began at 0 cm and was increased in 1 cm increments until the measured signal dropped below the cardiac rhythm management device noise floor for sensing. The test was conducted with both bipolar and unipolar sensing.
In the bipolar sensing configuration, the maximum sensed signal amplitude was 687 μV at an electrode separation of 0 cm, signal frequency of 30 Hz, pulse width of 1000 μs, and output current of 3.5 mA. In the unipolar sensing configuration, the maximum amplitude was 406 μV. In both configurations, the measured signal with maximum stimulation intensity decreased significantly with electrode separation, and dropped below the noise floor at an electrode spacing of 3.0 cm. The sensed signal amplitude was further attenuated at lower stimulation amplitudes and pulse widths.
Even at maximum neural stimulation intensity of 3.5 mA, at an electrode separation of at least 3.0 cm, neural stimulation did not result in a detectable level of interference with either bipolar or unipolar sensing. Because this separation is significantly smaller than the minimum electrode separation of 15 cm in clinical practice, VNS Therapy is not expected to interfere with the function of implantable cardiac devices.
通过迷走神经刺激（VNS）进行的自主神经调节疗法最近被批准用于治疗慢性心力衰竭，并且可能会应用于同时还需要植入心脏节律管理设备的患者。本研究旨在评估VNS对植入式心脏节律管理设备心脏感知功能产生干扰的可能性。
将一根VNS刺激导线和一根心脏感知导线置于模拟生物介质中。使用一个非导电载体框架将导线以精确的电极间距定位。通过VNS治疗导线以最大输出电流以及5 - 30Hz的多种刺激频率组合和130 - 1000μs的刺激脉冲宽度进行刺激。电极间距从0cm开始，以1cm的增量增加，直至测量信号降至心脏节律管理设备的感知噪声阈值以下。该测试采用双极和单极感知方式进行。
在双极感知配置中，在电极间距为0cm、信号频率为30Hz、脉冲宽度为1000μs且输出电流为3.5mA时，最大感知信号幅度为687μV。在单极感知配置中，最大幅度为406μV。在两种配置中，最大刺激强度下的测量信号随电极间距的增加而显著降低，并在电极间距为3.0cm时降至噪声阈值以下。在较低的刺激幅度和脉冲宽度下，感知信号幅度进一步衰减。
即使在3.5mA的最大神经刺激强度下，电极间距至少为3.0cm时，神经刺激也不会对双极或单极感知产生可检测到的干扰水平。由于该间距明显小于临床实践中15cm的最小电极间距，因此预计VNS治疗不会干扰植入式心脏设备的功能。
