Niederer Steven A, Shetty A K, Plank G, Bostock J, Razavi R, Smith N P, Rinaldi C A
Imaging Sciences & Biomedical Engineering Division, King's College London, London, United Kingdom.
Pacing Clin Electrophysiol. 2012 Feb;35(2):204-14. doi: 10.1111/j.1540-8159.2011.03243.x. Epub 2011 Oct 31.
Response to cardiac resynchronization therapy (CRT) is reduced in patients with posterolateral scar. Multipolar pacing leads offer the ability to select desirable pacing sites and/or stimulate from multiple pacing sites concurrently using a single lead position. Despite this potential, the clinical evaluation and identification of metrics for optimization of multisite CRT (MCRT) has not been performed.
The efficacy of MCRT via a quadripolar lead with two left ventricular (LV) pacing sites in conjunction with right ventricular pacing was compared with single-site LV pacing using a coupled electromechanical biophysical model of the human heart with no, mild, or severe scar in the LV posterolateral wall.
The maximum dP/dt(max) improvement from baseline was 21%, 23%, and 21% for standard CRT versus 22%, 24%, and 25% for MCRT for no, mild, and severe scar, respectively. In the presence of severe scar, there was an incremental benefit of multisite versus standard CRT (25% vs 21%, 19% relative improvement in response). Minimizing total activation time (analogous to QRS duration) or minimizing the activation time of short-axis slices of the heart did not correlate with CRT response. The peak electrical activation wave area in the LV corresponded with CRT response with an R(2) value between 0.42 and 0.75.
Biophysical modeling predicts that in the presence of posterolateral scar MCRT offers an improved response over conventional CRT. Maximizing the activation wave area in the LV had the most consistent correlation with CRT response, independent of pacing protocol, scar size, or lead location.
后外侧瘢痕患者对心脏再同步治疗（CRT）的反应降低。多极起搏导线能够选择理想的起搏部位和/或在单个导线位置同时从多个起搏部位进行刺激。尽管有这种潜力，但尚未对多部位CRT（MCRT）优化指标进行临床评估和识别。
使用左心室后外侧壁无瘢痕、轻度瘢痕或重度瘢痕的人体心脏耦合机电生物物理模型，比较通过具有两个左心室（LV）起搏部位的四极导线结合右心室起搏进行MCRT与单部位LV起搏的疗效。
对于无瘢痕、轻度瘢痕和重度瘢痕，标准CRT从基线起最大dP/dt（max）改善分别为21%、23%和21%，而MCRT分别为22%、24%和25%。在存在重度瘢痕的情况下，多部位起搏相对于标准CRT有额外益处（25%对21%，反应相对改善19%）。使总激活时间（类似于QRS波时限）最小化或使心脏短轴切片的激活时间最小化与CRT反应无关。左心室的峰值电激活波面积与CRT反应相关，R²值在0.42至0.75之间。
生物物理模型预测，在存在后外侧瘢痕的情况下，MCRT比传统CRT有更好的反应。使左心室激活波面积最大化与CRT反应的相关性最一致，与起搏方案、瘢痕大小或导线位置无关。
