Division of Cardiology, University of Maryland, Baltimore, 21201, USA.
Circ Arrhythm Electrophysiol. 2011 Apr;4(2):172-84. doi: 10.1161/CIRCEP.110.958744. Epub 2011 Jan 26.
Substrate-guided ablation of ventricular tachycardia (VT) in patients with implanted cardioverter-defibrillators (ICDs) relies on voltage mapping to define the scar and border zone. An integrated 3D scar reconstruction from late gadolinium enhancement (LGE) MRI could facilitate VT ablations.
Twenty-two patients with ICD underwent contrast-enhanced cardiac MRI with a specific absorption rate of <2.0 W/kg before VT ablation. Device interrogation demonstrated unchanged ICD parameters immediately before, after, or at 68±21 days follow-up (P>0.05). ICD imaging artifacts were most prominent in the anterior wall and allowed full and partial assessment of LGE in 9±4 and 12±3 of 17 segments, respectively. In 14 patients with LGE, a 3D scar model was reconstructed and successfully registered with the clinical mapping system (accuracy, 3.9±1.8 mm). Using receiver operating characteristic curves, bipolar and unipolar voltages of 1.49 and 4.46 mV correlated best with endocardial MRI scar. Scar visualization allowed the elimination of falsely low voltage recordings (suboptimal catheter contact) in 4.1±1.9% of <1.5-mV mapping points. Display of scar border zone allowed identification of excellent pace mapping sites, with only limited voltage mapping in 64% of patients. Viable endocardium of >2 mm resulted in >1.5-mV voltage recordings despite up to 63% transmural midmyocardial scar successfully ablated with MRI guidance. All successful ablation sites demonstrated LGE (transmurality, 68±26%) and were located within 10 mm of transition zones to 0% to 25% scar in 71%.
Contrast-enhanced cardiac MRI can be safely performed in selected patients with ICDs and allows the integration of detailed 3D scar maps into clinical mapping systems, providing supplementary anatomic guidance to facilitate substrate-guided VT ablations.
在植入式心脏复律除颤器（ICD）患者中，基于室性心动过速（VT）的基质消融依赖于电压标测来定义瘢痕和边界区。晚期钆增强（LGE）MRI 的整合 3D 瘢痕重建可以促进 VT 消融。
22 例接受 ICD 的患者在 VT 消融前进行了对比增强心脏 MRI，其比吸收率<2.0 W/kg。设备检测显示，ICD 参数在消融前、消融后或 68±21 天随访时没有变化（P>0.05）。ICD 成像伪影在前壁最为明显，分别有 9±4 和 12±3 个 17 个节段可以完全和部分评估 LGE。在 14 例有 LGE 的患者中，重建了 3D 瘢痕模型，并成功与临床标测系统匹配（准确性为 3.9±1.8mm）。使用受试者工作特征曲线，双极和单极电压 1.49 和 4.46 mV 与心内膜 MRI 瘢痕相关性最好。瘢痕可视化消除了 4.1±1.9%<1.5 mV 标测点的假性低电压记录（导管接触不良）。显示瘢痕边界区可识别优秀的起搏标测部位，在 64%的患者中仅需有限的电压标测。尽管有高达 63%的中层心肌透壁瘢痕可通过 MRI 引导成功消融，但 >2mm 的有活力的心内膜仍可记录到>1.5 mV 的电压。所有成功消融部位均有 LGE（透壁性，68±26%），并且位于与 0%至 25%瘢痕交界区 10mm 范围内的占 71%。
在选择的 ICD 患者中可以安全地进行对比增强心脏 MRI，并将详细的 3D 瘢痕图集成到临床标测系统中，为基质指导 VT 消融提供补充解剖指导。
