News Column

Patent Issued for Implantable Medical Device Having a Multi-Axis Magnetic Sensor

June 23, 2014



By a News Reporter-Staff News Editor at Cardiovascular Week -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventors Ries, Andrew J. (Lino Lakes, MN); Henschel, Mark E. (Phoenix, AZ); McClure, Lawrence C. (Forest Lake, MN); Ricotta, Mark S. (Tempe, AZ); Wang, Lejun (San Diego, CA), filed on March 7, 2013, was published online on June 10, 2014 (see also Medtronic, Inc.).

The patent's assignee for patent number 8750961 is Medtronic, Inc. (Minneapolis, MN).

News editors obtained the following quote from the background information supplied by the inventors: "A wide variety of implantable medical systems that deliver a therapy or monitor a physiologic condition of a patient have been clinically implanted or proposed for clinical implantation in patients. An example implantable medical system may include an implantable medical lead connected to an implantable medical device (IMD). For example, implantable leads are commonly connected to implantable pacemakers, defibrillators, cardioverters, or the like, to form an implantable cardiac system that provides electrical stimulation to the heart or sensing of electrical activity of the heart. The electrical stimulation pulses can be delivered to the heart and the sensed electrical signals can be sensed by electrodes disposed on the leads, e.g., typically near distal ends of the leads. Implantable leads are also used in neurological devices, muscular stimulation therapy, gastric system stimulators and other implantable medical devices (IMDs).

"Patients that have implantable medical systems may benefit, or even require, various medical imaging procedures to obtain images of internal structures of the patient. One common medical imaging procedure is magnetic resonance imaging (MRI). MRI procedures may generate higher resolution and/or better contrast images (particularly of soft tissues) than other medical imaging techniques. MRI procedures also generate these images without delivering ionizing radiation to the body of the patient, and, as a result, MRI procedures may be repeated without exposing the patient to such radiation.

"During an MRI procedure, the patient or a particular part of the patient's body is positioned within an MRI device. The MRI device generates a variety of magnetic and electromagnetic fields to obtain the images of the patient, including a static magnetic field, gradient magnetic fields, and radio frequency (RF) fields. The static magnetic field may be generated by a primary magnet within the MRI device and may be present prior to initiation of the MRI procedure. The gradient magnetic fields may be generated by electromagnets of the MRI device and may be present during the MRI procedure. The magnetic and RF fields may be generated by transmitting/receiving coils of the MRI device and may also be present during the MRI procedure.

"If the patient undergoing the MRI procedure has an implantable medical system, the various fields produced by the MRI device may have an effect on the operation of the medical leads and/or the IMD to which the leads are coupled. For example, the gradient magnetic fields or the RF fields generated during the MRI procedure may induce energy on the implantable leads (e.g., in the form of a current). The current induced on the implantable leads may cause the IMD to sense a cardiac signal when one is not present, a phenomenon referred to as oversensing, or to not sense a cardiac signal when one is present, a phenomena referred to as undersensing. Oversensing and undersensing may result in the IMD delivering therapy when it is not desired or withholding therapy when it is desired. A need exists for improvements to IMDs that reduce or eliminate the impact of magnetic fields to the IMD operation."

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors' summary information for this patent: "In accordance with an aspect of the invention, an apparatus is provided for detecting exposure of an implantable medical device to magnetic fields. The apparatus includes a three-axis magnetic sensor having a plurality of sensor integrated circuits (ICs) that are aligned in at least three axes, i.e., the X, Y, and Z axis.

"In an embodiment, the three sensor ICs may be coupled to a processor adapted to receive detection signals generated by one or more of the three sensor ICs in response to exposure to a magnetic field force. The processor may evaluate the strength of the magnetic field force and perform a predetermined action in response to the strength of the detected magnetic field.

"In an aspect of the invention, a method is provided for construction of a magnetic sensor. In the method, a substrate is provided with an array of panels with each of the panels having a plurality of subpanels. An IC is electrically coupled to each of the subpanels and stabilized to the substrate with an underfill material. The subpanels corresponding to each panel are excised from the substrate and folded to orient the ICs in three independent axis. For example, the three subpanels may be folded to orient the ICs in mutually orthogonal axis.

"In another aspect of the invention, a method is provided for forming a magnetic sensor. In one embodiment, a method includes mounting three single-axis magnetic sensor integrated circuits (ICs) to a substrate. The ICs are encapsulated to the substrate with a polymer mold compound. The substrate is excised around each of the sensor ICs to form panels that are folded to align the three single-axis sensors in the X, Y, and Z axis.

"In another embodiment, a method includes mounting three single-axis magnetic sensor integrated circuits (ICs) to a substrate. The substrate is excised around each of the sensor ICs and folded to orient the ICs in three independent axis. For example, the folding of the substrate may orient the sensor ICs in a mutually orthogonal three-dimensional orientation. The folded substrate is encapsulated with a polymer mold compound."

For additional information on this patent, see: Ries, Andrew J.; Henschel, Mark E.; McClure, Lawrence C.; Ricotta, Mark S.; Wang, Lejun. Implantable Medical Device Having a Multi-Axis Magnetic Sensor. U.S. Patent Number 8750961, filed March 7, 2013, and published online on June 10, 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=8750961.PN.&OS=PN/8750961RS=PN/8750961

Keywords for this news article include: Therapy, Cardiology, Cardio Device, Medtronic Inc., Medical Devices.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Cardiovascular Week


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