Universita` degli Studi di Milano, Milan, MI, Italy.
Intern Emerg Med. 2012 Jun;7(3):281-2. doi: 10.1007/s11739-012-0780-2. Epub 2012 Apr 11.
Nazarian et al. [1] evaluate in a prospective non-randomized trial the safety of a 1.5 T MRI protocol for patients with implanted cardiac devices (ICD and PM). 438 participants (54 % with PM and 46 % with ICD implanted, respectively,after the 1998 and 2000) were enrolled and underwent 555MRI examinations. Patients with a recent implant(\6 weeks), those with abandoned or epicardiac leads, and PM-dependent patients with an ICD were excluded.According to the experimental protocol, an asynchronous pacing mode (VOO/DOO) was programmed in the pacemaker-dependent patients, while an inhibited pacing mode(VVI/DDI) was used for the other patients. The ICD function of non-PM-dependent patients was disabled. During the MRI examination, blood pressure, electrocardiography, pulse oximetry and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had an immediate backup from an electrophysiologist.Device variables including sensing, impedance, capture threshold and battery voltage were evaluated before MRI examination, immediately after MRI and after 3–6 months.Variations exceeding 30, 40 and 50 %for, respectively, lead impedance, sensing and capture threshold were considered as significant changes in lead performance.Baseline and immediate follow-up interrogations were performed in all 438. Long-term follow-up device variables were available for 266 patients (61 %). 3 of 438 patients(0.7 %) experienced acute power-on-reset events. None of them had device dysfunction during long-term follow-up(3–6 months). Right ventricular sensing and atrial, right and left ventricular impedances were reduced immediately after MRI. At long-term follow-up in 61 % of the patients,decreased right ventricular (RV) sensing and lead impedance,increased RV capture threshold and decreased battery voltage were noted. The observed changes did not require device revision or reprogramming. The distributions of changes in device variables were within the 20 % at baseline for most participants. Thoracic MRI sequences had a greater effect on device variables and were more likely to result in artifacts (for instance, image distortion,signal voids or bright areas and poor fat suppression).
纳扎里安等人[1]在一项前瞻性非随机试验中评估了 1.5 T MRI 方案在植入式心脏设备（ICD 和 PM）患者中的安全性。共有 438 名参与者（分别有 54%和 46%的患者植入 PM 和 ICD，时间分别在 1998 年和 2000 年之后）入组并接受了 555 次 MRI 检查。近期植入（\6 周）、废弃或心外膜导联以及依赖 PM 的 ICD 患者被排除在外。根据实验方案，依赖起搏器的患者程控异步起搏模式（VOO/DOO），而其他患者则使用抑制性起搏模式（VVI/DDI）。非 PM 依赖患者的 ICD 功能被禁用。在 MRI 检查期间，由具有心脏生命支持和设备编程经验的护士监测血压、心电图、脉搏血氧饱和度和症状，该护士可随时得到电生理学家的支持。在 MRI 检查前、检查后即刻和 3-6 个月后评估设备变量，包括感知、阻抗、捕获阈值和电池电压。分别超过 30%、40%和 50%的导联阻抗、感知和捕获阈值变化被认为是导联性能的显著变化。所有 438 名患者均进行了基线和即刻随访检查。266 名患者（61%）的长期随访设备变量可用。438 名患者中有 3 名（0.7%）发生急性开机复位事件。在长期随访（3-6 个月）中，他们均无设备功能障碍。MRI 检查后即刻右心室感知和心房、右室和左室阻抗降低。在 61%的患者中，长期随访时注意到右心室（RV）感知和导联阻抗降低、RV 捕获阈值增加和电池电压降低。观察到的变化不需要设备修改或重新编程。大多数患者的基线设备变量变化分布在 20%以内。胸部 MRI 序列对设备变量的影响更大，更有可能导致伪影（例如图像失真、信号缺失或亮点以及脂肪抑制不佳）。
