MRI conditionally safe lead with multi-layer conductor

摘要

An implantable medical lead exhibits reduced heating under MRI conditions. The lead includes a multi-layer coil conductor including an inner coil layer, a middle coil layer disposed around the inner coil layer, and an outer coil layer disposed around the middle coil layer. Each of the coil layers is characterized by one or more of a filar thickness, a coil pitch, or a coil diameter configured such that the coil conductor exhibits a high inductance when exposed to MRI radiation. Each of the coil layers is electrically connected to the other coil layers to provide parallel conductive paths resulting in a coil conductor resistance suitable for defibrillation lead applications.

主权项

1. An implantable electrical lead, comprising:
a flexible body having a proximal region including a proximal end, a distal region, and a longitudinal body lumen extending from the proximal end through the distal region; a connector assembly configured to mechanically and electrically connect the implantable electrical lead to an implantable pulse generator; an electrode coupled to the flexible body in the distal region; and a multi-layer coil conductor extending within the longitudinal body lumen from the connector assembly to at least the electrode, the multi-layer coil conductor configured to minimize heat rise when exposed to magnetic resonance imaging (MRI) scans, the multi-layer coil conductor including:
a first coil layer including one or more filars wound so as to have a close pitch; anda second coil layer disposed about the first coil layer including one or more filars wound so as to have a close pitch, the second coil layer having a proximal end at the connector assembly and a distal end at the electrode, the second coil layer defining a lumen within which the first coil layer extends from the proximal end to the distal end, the filars of the second coil layer wound in the same pitch direction as the filars of the first coil layer from the proximal end to the distal end; andwherein the first and second coil layers are electrically coupled to one another and configured to provide parallel conductive paths between the connector assembly and the electrode such that the multi-layer coil conductor has a maximum DC resistance of about 3 to 3.5 ohms and the multi-layer coil conductor further has an impedance when exposed to MRI scans that inhibits induced currents resulting from the MRI scans.