Maastricht University Medical Centre, Department of Cardiology, PO Box 5800, 6202 AZ, Maastricht, the Netherlands.
Eur J Heart Fail. 2014 Nov;16(11):1214-22. doi: 10.1002/ejhf.178. Epub 2014 Oct 15.
Current targeted left ventricular (LV) lead placement strategy is directed at the latest activated region during intrinsic activation. However, cardiac resynchronization therapy (CRT) is most commonly applied by simultaneous LV and right ventricular (RV) pacing without contribution from intrinsic conduction. Therefore, targeting the LV lead to the latest activated region during RV pacing might be more appropriate. We investigated the difference in LV electrical activation sequence between left bundle-branch block (LBBB) and RV apex (RVA) pacing using coronary venous electro-anatomic mapping (EAM).
Twenty consecutive CRT candidates with LBBB underwent intra-procedural coronary venous EAM during intrinsic activation and RVA pacing using EnSite NavX. Left ventricular lead placement was aimed at the latest activated region during LBBB according to current recommendations. In all patients, LBBB was associated with a circumferential LV activation pattern, whereas RVA pacing resulted in activation from the apex of the heart to the base. In 10 of 20 patients, RVA pacing shifted the latest activated region relative to LBBB. In 18 of 20 patients, the LV lead was successfully positioned in the latest activated region during LBBB. For the whole study population, LV lead electrical delay, expressed as percentage of QRS duration, was significantly shorter during RVA pacing than during LBBB (72 ± 13 vs. 82 ± 5%, P = 0.035).
Right ventricular apex pacing alters LV electrical activation pattern in CRT patients with LBBB, and shifts the latest activated region in a significant proportion of these patients. These findings warrant reconsideration of the current practice of LV lead targeting for CRT.
目前的左心室（LV）靶向性导联植入策略旨在针对固有激活过程中的最晚激活区。然而，心脏再同步治疗（CRT）最常通过同时LV 和右心室（RV）起搏来实现，而不依赖固有传导。因此，针对 RV 起搏时最晚激活区的 LV 导联可能更为合适。我们通过冠状静脉电解剖图（EAM）研究了左束支传导阻滞（LBBB）和 RV 心尖（RVA）起搏时 LV 电激活顺序的差异。
连续 20 例 LBBB 的 CRT 候选者在固有激活和使用 EnSite NavX 的 RVA 起搏时进行了经皮冠状静脉 EAM。根据目前的建议，LV 导联的植入旨在实现 LBBB 时的最晚激活区。在所有患者中，LBBB 与环形 LV 激活模式相关，而 RVA 起搏则导致从心脏顶部到底部的激活。在 20 例患者中的 10 例中，RVA 起搏改变了相对于 LBBB 的最晚激活区。在 20 例患者中的 18 例中，LV 导联在 LBBB 时成功定位在最晚激活区。对于整个研究人群，RVA 起搏时 LV 导联的电延迟（以 QRS 持续时间的百分比表示）明显短于 LBBB（72±13% vs. 82±5%，P=0.035）。
在 LBBB 的 CRT 患者中，RVA 起搏改变了 LV 电激活模式，并使这些患者中的相当一部分的最晚激活区发生转移。这些发现需要重新考虑目前 CRT 的 LV 导联靶向策略。
