‘Cloaked’ leads may pave way for MRI-compatible ICDs

What works to make stealth aircraft stealthy also can cloak leads to make implantable cardioverter-defibrillators (ICDs) and pacemakers potentially MR compatible, a report in a Nature publication demonstrated.

The April 29 paper in Scientific Reports described technology developed at the Martinos Center for Biological Imaging at Massachusetts General Hospital in Charlestown, Mass., that has been designed to overcome an obstacle for patients implanted with cardiac and other devices: the inability to undergo MR imaging (MRI). The radiofrequency (RF) energy used in MRIs can produce “an antenna effect” and increase temperatures near electrodes, which can burn tissue. MRI conditional devices have become available but with restrictions, Peter Serano and colleagues pointed out.

The research team developed a resistive tapered stripline (RTS) technology using computational modeling and simulations followed by a prototype design that they tested in phantoms scanned with 3T MRI. The RTS approach mimics the structure used in stealth aircraft to avoid detection by abruptly changing conductivity between two sections.

In the case of implantable devices, the RTS wires in the core of leads scattered RF energy to reduce the amount of energy absorbed. The specific absorption rate, which they used to evaluate the power absorbed inside the phantom, was half that seen with a Medtronic 3389 lead tested as a comparator. The cloaking properties still allowed conduction for low-frequency impulses from implanted devices and the RTS design did not affect battery performance.

They proposed that the wires could replace any wires used in commercial leads. They are seeking an Investigational Device Exemption from the FDA to conduct clinical trials of devices that incorporate the RTS wires, according to a news release.