Haffajee C, Casavant D, Desai P, Moon R, Voukydis P, Pacetti P
Division of Cardiology, St. Elizabeth's Medical Center, Boston, MA 02135, USA.
Pacing Clin Electrophysiol. 1996 Feb;19(2):136-42. doi: 10.1111/j.1540-8159.1996.tb03304.x.
As implantable cardioverter defibrillators (ICDs) are strictly contraindicated in the presence of unipolar pacemakers, currently available options in patients having such chronic pacing systems include: abandoning the implanted pacemaker and selecting an ICD with ventricular demand (VVI) pacing; or replacing the chronic (dual chamber) unipolar pacing system with a dedicated bipolar version prior to ICD implantation. In three patients with previously implanted unipolar pacemakers, we challenged the premise that all ICD systems are incompatible by combining with a third-generation transvenous ICD system (Medtronic 7217B PCD) incorporating true bipolar sensing, a self-limiting auto-adjusting sensitivity, and a tolerant VF detection algorithm. The potential for pacemaker-ICD interaction was minimized by separating the tip of the ICDs transvenous right ventricular pace/sense-defibrillation coil lead from that of the chronic pacemaker lead by > or = 2-3 cm, and by performing "worst case" intraoperative testing. Although ICD double-counting of the dual chamber pacemaker's atrial and ventricular pacing spikes could be provoked at extreme high output settings, it did not occur at clinically appropriate settings. More importantly, continuous high output asynchronous pacing during ventricular fibrillation (VF) did not interfere with ICD detection. During a mean follow-up period of 18 months, one patient has had VF appropriately terminated by the ICD. In the remaining two patients, proper VF detection and ICD function was reassessed at 3 months and/or at 1 year during noninvasive testing.
These preliminary findings demonstrate that this transvenous ICD system's VF sensing and detection features combined with careful implant technique, rigorous "worst case" testing for possible pacemaker-ICD interaction with regular follow-up, may permit implantation of this ICD system in patients with chronic unipolar pacing systems. Further studies are needed to validate the long-term clinical safety of this promising revised approach to a currently contraindicated device combination.
由于植入式心脏复律除颤器（ICD）在单极起搏器存在时被严格禁忌，对于有这种慢性起搏系统的患者，目前可用的选择包括：放弃植入的起搏器并选择具有心室按需（VVI）起搏功能的ICD；或在植入ICD之前，用专用的双极版本替换慢性（双腔）单极起搏系统。在三名先前植入单极起搏器的患者中，我们对所有ICD系统都不兼容这一前提提出了质疑，我们将第三代经静脉ICD系统（美敦力7217B PCD）与之结合，该系统具有真正的双极感知、自限性自动调整灵敏度和宽容的室颤检测算法。通过将ICD经静脉右心室起搏/感知 - 除颤线圈导线的尖端与慢性起搏器导线的尖端分开≥2 - 3厘米，并进行“最坏情况”的术中测试，使起搏器 - ICD相互作用的可能性降至最低。尽管在极高输出设置下可能会引发ICD对双腔起搏器心房和心室起搏脉冲的双重计数，但在临床适当设置下并未发生。更重要的是，心室颤动（VF）期间的持续高输出异步起搏并未干扰ICD检测。在平均18个月的随访期内，一名患者的室颤被ICD适当终止。在其余两名患者中，在无创测试期间的3个月和/或1年时重新评估了正确的室颤检测和ICD功能。
这些初步发现表明，这种经静脉ICD系统的室颤感知和检测功能，结合仔细的植入技术、针对可能的起搏器 - ICD相互作用进行严格的“最坏情况”测试以及定期随访，可能允许在患有慢性单极起搏系统的患者中植入这种ICD系统。需要进一步研究来验证这种有前景的、针对当前禁忌的设备组合的修订方法的长期临床安全性。
