News Column

Patent Issued for Introduction of Medical Lead into Patient

August 27, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Gerber, Martin T. (Maple Grove, MN); Baudino, Michael D. (Coon Rapids, MN), filed on January 21, 2011, was published online on August 12, 2014.

The assignee for this patent, patent number 8801728, is Medtronic, Inc. (Minneapolis, MN).

Reporters obtained the following quote from the background information supplied by the inventors: "A variety of implantable medical devices have been proven to be effective for treatment of a variety of diseases. Many of such devices, such as cardiac pacemakers, defibrillators, spinal cord or deep brain stimulators, gastric stimulators, and the like, employ accessory medical leads to deliver electrical signals from a signal generating device to tissue of a patient at a location removed from the signal generating device. Typically the lead is tunneled from a subcutaneous region of the patient in which the signal generating device is implanted to a target tissue location. It is often important that the lead, or portions thereof, does not shift or move once implanted to ensure that a therapeutic signal continues to be delivered to the target tissue. One mechanism for retaining the implanted position of a lead or portion thereof is the use of tines. The tines or other fixation elements are typically attached to various locations of the lead and are deployed once the lead is properly positioned in the patient. Most often, tines or other fixation elements prevent retrograde movement of the lead. Once the fixation elements are deployed, it can be difficult to change the position of the lead.

"Prior to deploying the fixation elements, it is often desirable to apply electrical signals to the patient via electrodes of the lead, as the lead is being implanted, to determine whether the lead is being positioned in an appropriate location or if the tract of implantation is proceeding in a desired direction. This process is sometimes referred to a trolling, where test electrical signals are applied as the lead is advanced to aid in the proper placement of the lead. However, with the use of standard lead introducer devices, it is not possible to perform such trolling when the self-expanding fixation elements are disposed on the lead distal to the electrodes. That is, absent fixation elements being distal electrodes of the lead, the lead may extended distally beyond the introducer (or the introducer may be withdrawn to expose the distal end of the lead) such that a test electrical signal may be delivered to the patient via electrodes of the lead, and the lead may be withdrawn into the introducer (or introducer advanced) and repositioned. This process may be repeated until the lead is determined to be in an appropriate location, and the introducer may be completely withdrawn. However, when the fixation elements are disposed on the lead distal to the electrodes, the fixation elements will be deployed during the initial test stimulation (when extended beyond the distal end of the introducer), and the ability to reposition the lead will be compromised, if not lost."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "This disclosure, among other things, describes systems, devices and methods that allow for trolling to be performed when leads having self-expanding or self-deploying fixation elements, such as tines, distal to electrodes, are implanted. In some embodiments described herein, leads having an electrode, such as a distal tip electrode, more distal than the fixation element is used for purposes of assisting in the determination of whether the distal electrode is in the desired location of a patient. The lead may have a series of markings that aid in allowing the electrode proximal the fixation element to be advanced to the desired location previously occupied by the distal electrode.

"In various embodiments, a system includes an introducer and a lead. The introducer has a body member having a proximal end and a distal end. The body member defines a lumen extending from the proximal end to the distal end. The lead is configured to be inserted in the lumen of the introducer. The lead includes a lead body having a proximal end and a distal end, a distal electrode at or near the distal end of the lead body, a fixation element proximal the distal electrode, an electrode array proximal the fixation element, and first and second positional markings. The first positional marking is proximal the electrode array and is positioned a distance from the distal electrode equal to, or greater than, the length of an introducer sheath for use in implanting the lead. The second positional marking is located a distance from the first marking equal to the distance from the distal electrode to a desired location in the electrode array. The second positional marking may be proximal or distal to the first positional marking.

"If the second marking is distal to the first positional marking, the distal end of the body member of the introducer may be inserted into the patient and advanced until the distal end is positioned in a location of the patient. The lead may be inserted into the lumen of the introducer until the first marking of the lead is aligned with, or adjacent to, the proximal end of the body member of the introducer, resulting in the distal electrode being extended beyond the distal end of the introducer and the fixation being retained in a retracted position by a portion of the body member of the introducer proximal the distal end. A test electrical signal may be applied to the patient via the distal electrode to determine whether the distal electrode is in a desired location of the patient. If the distal electrode is in the desired location, the introducer body member may be advanced over the lead until the proximal end of the introducer body member is aligned with, or adjacent to, the second marking of the lead. The lead may then be distally advanced through the introducer lumen until the first marking is aligned with, or adjacent to, the proximal end of the introducer. The introducer body member may then be withdrawn over the lead, causing the fixation element to deploy and leaving the lead implanted in the patient such that the desired location of the electrode army is positioned in the desired location of the patient.

"If the second marking is proximal to the first positional marking, the distal end of the body member of the introducer may be inserted into the patient and advanced to a location in the patient. The lead may be inserted into the lumen of the introducer until the first marking of the lead is aligned with, or adjacent to, the proximal end of the body member of the introducer, resulting in the distal electrode being extended beyond the distal end of the introducer and the fixation element being retained in a retracted position by a portion of the body member of the introducer proximal the distal end. A test electrical signal may be applied to the patient via the distal electrode to determine whether the distal electrode is in a desired location of the patient. If the distal electrode is in the desired location, the lead may be advanced distally through the introducer until the second marking is aligned with, or adjacent to, the proximal end of the introducer, causing the fixation element to deploy. The introducer body member may then be withdrawn over the lead, leaving the lead implanted in the patient such that the desired location of the electrode array is positioned in the desired location of the patient.

"In other embodiments described herein, a conductive member, such as a stylet, having a non-conductive distal end portion (or 'dummy' portion) that has a length the same as the length from the distal end of the lead to a desired location of the electrode array (where the lead has a fixation element distal the electrode array) is used in combination with an introducer to identify the proper location for lead placement.

"For example, a system as described herein may include an introducer, a lead and a conductive member. The introducer has a body member having a proximal end and a distal end. The body member defines a lumen extending from the proximal end to the distal end. The lead is configured to be inserted in the lumen of the introducer and has a proximal end and a distal end. The lead has a fixation element, an electrode array and a positional marker. The fixation element is distal the electrode array, and the positional marker is located proximal to the distal end of the lead a distance equal to the length of the introducer (measured as the length from the proximal end to distal end of the introducer body member). The conductive member is also configured to be inserted in the lumen of the introducer. The conductive member has a non-conductive distal end portion extending from the distal end a distance equal to the distance from the distal end of the lead to the electrode. The conductive member also has a first positional marking located proximal to the distal end of the conductive member by a distance equal to the length of the introducer body member, and a second positional marking proximal to the first marking by a distance greater than the length of the non-conductive distal end portion.

"A lead of such a system may be implanted, for example, as follows. The distal end of the body member of the introducer may be inserted into the patient and advanced to a location of the patient. The conductive member may be inserted into the lumen of the introducer until the second marking of the conductive member is aligned with, or adjacent to, the proximal end of the body member of the introducer, resulting in the non-conductive distal end portion of the conductive member and a portion of the conductive member proximal the non-conductive distal end portion extending from the distal end of the introducer. A test electrical signal may be applied to the patient via the conductive portion of the conductive member extending beyond the distal end of the introducer to determine whether the conductive portion is in a desired location of the patient. If the conductive portion is in a desired location of the patient, the introducer may be advanced over the conductive member until the proximal end of the introducer is aligned with, or adjacent to, the first positional marking of the conductive member. The conductive member may be withdrawn from the lumen of the introducer. The distal end of the lead may then be advanced into the lumen of the introducer until the positional marker of the lead is aligned with or adjacent the proximal end of the introducer. The introducer body member may be withdrawn over the lead, deploying the fixation element and leaving the lead implanted in the patient such that the electrode array is positioned in the desired location of the patient.

"One or more embodiments described herein provide one or more advantages over prior leads, introducers, other devices, systems and methods for implanting leads having a fixation element distal to an electrode array. Such advantages will be apparent to those of skilled in the art upon reading the following detailed description."

For more information, see this patent: Gerber, Martin T.; Baudino, Michael D.. Introduction of Medical Lead into Patient. U.S. Patent Number 8801728, filed January 21, 2011, and published online on August 12, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8801728.PN.&OS=PN/8801728RS=PN/8801728

Keywords for this news article include: Medtronic Inc.

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Source: Journal of Engineering


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