Implantable MRI compatible medical lead with a rotatable control member

Abstract

A medical implantable lead is adapted to be implanted into a human or animal body for monitoring and / or controlling of an organ inside the body. The lead has in a distal end, a combined fixation means and electrode member in form of a helix, which is connected to a rotatable tubular member being connected to a rotatable member at a proximal end of the lead, and which is rotatable in relation to the lead and extendable out from the distal end, by rotation of the control member and the tubular torque transferring member, to be able to fixate the distal end of the lead to the organ by being screwed into the tissue. The helix is electrically connected to a connector at the proximal end by means of at least one electrically conducting wire formed as an electrically conducting coil, which is separate from the tubular torque transferring member and unrotatable in relation to the lead and that has one or more individual wires, each including an electrically conducting wire core and a surrounding electrically insulating layer, wherein the rotatable control member is rotatable within the connector.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a medical implantable lead of the kind being adapted to be implanted into a human or animal body for monitoring and / or controlling of an organ inside the body, comprising at a distal end a combined fixation means and electrode member in form of a helix, which is connected to a rotatable tubular torque transferring member being in its turn connected to a rotatable control member at a proximal end of the lead, and which is rotatable in relation to the lead and extendable out from the distal end, by rotation of the control member and the tubular torque transferring member, to be able to fixate the distal end of the lead to the organ by being screwed into the tissue, wherein the helix is electrically connected to a connector at the proximal end by means of at least one electrically conducting wire.[0003]2. Description of the Prior Art[0004]It is well known in the art to use a medical implantable lea...

AI Technical Summary

Benefits of technology

[0008]It is an object of the invention to provide a medical implantable lead, which in a simple and cost-effective way reduces the induction of current from an electromagnetic field into the electrically conducting coil.

[0011]By forming the medical implantable lead in this way, it is possible to form the tubular torque transferring member with a sufficient mechanical strength and stiffness to be able to transfer the torque required, from the proximal end to the distal end, to rotate the helix for extending it out from the distal end of the lead and screw it into the tissue. The electrically conducting coil, on the other hand, can be optimized to present an as high inductance as possible. For example, since the electrically conducting coil does not have to transfer any torque to the helix, it can be formed of one or only a few wires, which each can be made very thin. In this way, the pitch of the individual wires of the coil will be very low, which will increase the inductance of the coil. Also, since the electrically conducting coil will be positioned around the torque transferring member, the diameter of the coil can be made larger than what is possible with the prior art combined electrically conducting and torque transferring coils. This will also increase the inductance.

[0013]The medical implantable lead can be provided with more than one electrode, e.g. two electrodes for a bipolar lead, three electrodes for a tripolar lead, etc. The electrically conducting wires for each electrode can optionally be provided in separate coils, which are co-axially arranged in relation to each other, or two or more separate electrically conducting wires, dedicated for different electrodes, can be provided side by side in one and the same coil. One advantage with an embodiment according to the latter case is that the overall diameter of the lead can be made smaller than in the former case. However, the inductance will be somewhat lower in the latter case in relation to the former, since the pitch of each individual wire will be somewhat larger. This can be alleviated by forming the coil from wires having a sufficient thin cross section.

Problems solved by technology

This induced current may cause heating at an electrode being in contact with the tissue of the organ, especially if the electrode is in form of a helix which is penetrated into and embedded within the tissue.

If the heating is too high, there is a risk that this will cause damages to the tissue.

However, such shielded medical implantable leads are associated with several disadvantages.

On the one hand, the braided shielding will give the medical implantable lead an increased thickness as well as increased rigidity, which normally is not desirable.

On the other hand, it has appeared that such a braided shielding cannot prevent the induction of electrical current to the coiled conductor in a degree that is sufficient to, without risk, expose an individual, having an implanted lead, to a MRI-scanning.

Such a prior art medical implantable lead comprises passive electronic components, which contribute to making the lead more complex and thus more costly to manufacture.

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