Tsuneharu Sakurai

Influence of Mobile Magnetic Resonance Imaging on Implanted Pacemakers

KISHI, R., et al.: Influence of Mobile Magnetic Resonance Imaging on Implanted Pacemakers. Purpose: Mobile magnetic resonance imaging (MRI) systems will be widely used in Japan. When traveling, mobile MRI generate alternating electromagnetic waves which may cause electromagnetic interference (EMI). This study was designed to determine whether this may influence the function of implanted pacemakers (PM). Methods and Results: The influence of the static magnetic fields was tested in the first method using a PM‐human model (Phantom). Magnetic force was simultaneously measured. The PM was switched to the magnet mode within 90 cm from the vehicle, where the magnetic force was = 2 mT. In the second method, six phantoms were placed on the side of the road, facing in three different directions in X‐Y‐Z axis orientations, at 1.3 m and 2.0 m above the ground. The mobile MRI passed by at a distance of 1 m from the phantoms at the speed of 20 or 40 km/h. In these experiments, magnet mode switch of the PM was observed for 2 seconds when the vehicle passed close to the phantoms, though no electrical noise was recorded. Conclusion: Mobile MRI vehicles can switch a PM to magnet mode when the distance between patient and vehicle is <90 cm, regardless of whether the vehicle is moving or at a stop. Patients with implanted PM should not approach within <1 m of a mobile MRI. No other EMI‐induced PM dysfunction was detected. (PACE 2003; 26[Pt. II]:527–529)

Lead Extractions are not Necessarily Required in the Treatment of Cases with Local Complications Unproven Resional/systemic Infection at the Pacemaker/implantable Cardioverter Defibrillator (ICD) Site

Introduction: In a case of pacemaker and/or implantable cardioverter defibrillator (ICD) implantations, there is the possibility of infections related to the device. In such case, the removal of the total system is desirable, however, the lead extraction can sometimes be difficult. Methods: Among 756 subjects who underwent a device implantation procedure, we experienced 19 cases with a device infection or skin problems requiring a surgical procedure such as thinning or inflammation of the skin over the pocket or lead. We divided these 19 cases into three groups as cases with neither systemic nor local infections (N group), cases with regional but systemic infections (R group), and cases with systemic infections (S group). And the prognoses of these cases were investigated. Results: Out of the 19 cases, 12 cases were classified into N group, 5 cases were classified into R group, and the remaining 2 cases were classified into S group. The lead extractions were performed in one case each in the N, R and S groups. None of the cases in the N group developed a systemic infection over an average observation period of 31 months. Four cases in the R group remain been free from systemic infection over an average observation period of 39.5 months. Conclusion: Lead extractions are the ideal treatment in cases with device implantation site complications, but are not necessary if the extraction is difficult.