FDA Gives Medtronic Go Ahead to Test Pacemaker for Use in MRI
January 28, 2008 – Medtronic Inc. has launched a clinical trial to confirm the safety and efficacy of the Medtronic EnRhythm MRI SureScan pacing system, a pacemaker system to be developed and tested specifically for safe use in Magnetic Resonance Imaging (MRI) machines under specified scanning conditions.
The EnRhythm MRI SureScan pacing system consists of the dual-chamber EnRhythm MRI SureScan pacemaker and CapSureFix MRI‘ SureScan pacing leads (Model 5086MRI). The first implant in the U.S. clinical trial was performed by Brian Ramza, M.D., Ph.D., director of Electrophysiology Laboratory Services at the Mid America Heart Institute, Saint Luke’s Hospital, Kansas City, MO.
Currently, individuals with implanted cardiac devices such as pacemakers, implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) devices are prohibited from receiving MRI scans, since MRI machines may interact with traditional systems, potentially compromising therapy and patient safety.
Extensive research and design efforts went into the EnRhythm MRI SureScan pacing system to address and mitigate interactions between the pacing system and the MR environment. The system includes modified hardware to minimize the level of energy transmitted through the lead/device connection point. The pacemaker also includes a new SureScan feature that can be programmed “on” before an MRI scan to eliminate the impact of MRI-generated electrical noise, which can impact pacing therapy. The device and leads also contain radiopaque marks, viewable via X-ray, to indicate that the system is MR-Conditional (a term identifying a device that may be used during an MRI under specified scanning conditions). The CapSureFix MRI SureScan leads are modified versions of the active-fixation Medtronic CapSureFix Novus leads, and are designed to decrease the risk of overheating during an MRI scan without limiting the ability to conduct therapy.
According to J. Rod Gimbel, M.D., FACC, East Tennessee Heart Consultants, who has been widely published on the subject of MRI and implanted cardiac devices, “Despite several small studies that have evaluated the effects of MRI on device patients, the scanning of device patients not approved for MRI remains rather risky. Several troubling events have occurred when scanning device patients, and the explanation for these events remains murky. Today, we go to the MRI suite with the device we have, not the device we wish to have. Physicians and patients would welcome a pacemaker and lead system that has been designed to address the unknowns, potential hazards and risks for a device patient in the MR environment.”
The pacemaker incorporates all diagnostic and therapeutic features of the commercialized Medtronic EnRhythm pacemaker, including an exclusive pacing mode called MVP‘ or Managed Ventricular Pacing, which enables the device to be programmed to deliver pacing pulses to the right ventricle only when necessary. Recent clinical studies have shown that reducing this pacing stimulation may reduce the patient’s risk of developing heart failure and atrial fibrillation.
For more information: www.medtronic.com