Sommer Torsten, Naehle Claas P, Yang Alexander, Zeijlemaker Volkert, Hackenbroch Matthias, Schmiedel Alexandra, Meyer Carsten, Strach Katharina, Skowasch Dirk, Vahlhaus Christian, Litt Harold, Schild Hans
University of Bonn, Department of Radiology, Bonn, Germany.
Circulation. 2006 Sep 19;114(12):1285-92. doi: 10.1161/CIRCULATIONAHA.105.597013. Epub 2006 Sep 11.
The purpose of the present study was to evaluate a strategy for safe performance of extrathoracic magnetic resonance imaging (MRI) in non-pacemaker-dependent patients with cardiac pacemakers.
Inclusion criteria were presence of a cardiac pacemaker and urgent clinical need for an MRI examination. Pacemaker-dependent patients and those requiring examinations of the thoracic region were excluded. The study group consisted of 82 pacemaker patients who underwent a total of 115 MRI examinations at 1.5T. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 1.5 W/kg. All pacemakers were reprogrammed before MRI: If heart rate was <60 bpm, the asynchronous mode was programmed to avoid magnetic resonance (MR)-induced inhibition; if heart rate was >60 bpm, sense-only mode was used to avoid MR-induced competitive pacing and potential proarrhythmia. Patients were monitored with ECG and pulse oximetry. All pacemakers were interrogated immediately before and after the MRI examination and after 3 months, including measurement of pacing capture threshold (PCT) and serum troponin I levels. All MR examinations were completed safely. Inhibition of pacemaker output or induction of arrhythmias was not observed. PCT increased significantly from pre- to post-MRI (P=0.017). In 2 of 195 leads, an increase in PCT was only detected at follow-up. In 4 of 114 examinations, troponin increased from a normal baseline value to above normal after MRI, and in 1 case (troponin pre-MRI 0.02 ng/mL, post-MRI 0.16 ng/mL), this increase was associated with a significant increase in PCT.
Extrathoracic MRI of non-pacemaker-dependent patients can be performed with an acceptable risk-benefit ratio under controlled conditions and by taking both MR- and pacemaker-related precautions.
本研究的目的是评估一种在非起搏器依赖型心脏起搏器患者中安全进行胸外磁共振成像（MRI）的策略。
纳入标准为存在心脏起搏器且临床上急需进行MRI检查。排除起搏器依赖型患者和需要检查胸部区域的患者。研究组由82例起搏器患者组成，他们在1.5T下共接受了115次MRI检查。为了将射频相关的导线发热降至最低，将比吸收率限制在1.5W/kg。所有起搏器在MRI检查前均重新编程：如果心率<60次/分钟，则将其编程为异步模式以避免磁共振（MR）诱导的抑制；如果心率>60次/分钟，则使用仅感知模式以避免MR诱导的竞争性起搏和潜在的心律失常。通过心电图和脉搏血氧饱和度监测患者。在MRI检查前、检查后以及3个月后对所有起搏器进行询问，包括测量起搏捕获阈值（PCT）和血清肌钙蛋白I水平。所有MR检查均安全完成。未观察到起搏器输出抑制或心律失常的诱发。MRI前后PCT显著升高（P = 0.017）。在195根导线中的2根中，仅在随访时检测到PCT升高。在114次检查中的4次中，肌钙蛋白在MRI后从正常基线值升高至高于正常水平，在1例中（MRI前肌钙蛋白0.02ng/mL，MRI后0.16ng/mL），这种升高与PCT的显著升高相关。
在可控条件下，通过采取与MR和起搏器相关的预防措施，非起搏器依赖型患者的胸外MRI可以在可接受的风险效益比下进行。
