Minimally invasive implantable device for monitoring physiologic events

• US 5,987,352 A
• Filed: 03/03/1998
• Issued: 11/16/1999
• Est. Priority Date: 07/11/1996
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Carney, James K., Varrichio, Anthony J., Lee, Brian B., Warkentin, Dwight H., Klein, George J., Turi, Gregg, Riff, Kenneth M.
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US09/033,678
• Time in Patent Office: 623 Days
• Field of Search: 600/509, 607/36
• US Class Current: 600/509
• CPC Class Codes: A61N 1/08 Arrangements or circuits for monitoring, protecting, controlling or indicating for external stimulators A61N1/3603; for implantable neurostimulators A61N1/36128; for heart stimulators A61N1/37; for defibrillators A61N1/3925
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/372 Arrangements in connection with the implantation of stimulators
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators

Abstract

A minimally invasive implant, means for insertion, and description of how to most efficiently use it are described n several embodiments. This implant preferably has a segmented looping memory for storing triggered physiologic events. Preferred events for setting autotriggers to record physiologic signals occurring during events include arrhythmias and syncopal events. Preferably the device can function without a microprocessor. An outside device or other patient activated manual trigger is included. Auto triggers and manually set triggers may be of different sizes. The preferred physiologic events are ECG signals. Electrode spacing can be critical. Additional sensors may be provided to the device. Preferred communications with the device is through telemetry such as is used for pacemakers and other implanted devices.

Claims

1. A minimally invasive implant for implantation beneath a skin and into a living body comprising;

a shell housing means having an inside and an outside,

said outside forming a shape and having electrodes for sensing a physiologic parameter of said body, said electrodes located on said outside such that a substantially fixed spacing is maintained between said electrodes on said outside'"'"'s shape, said electrodes being for electrical connection with the body and wherein said housing shape has a longitudinal dimension exceeding a transverse dimension, said transverse dimension being of a size suitable for insertion into said body with minimal opening requirements to the skin of said body, said minimal opening size being substantially no greater than 1/2 inch in maximum diameter,

said inside having a power source and electronic circuitry powered thereby comprising at least an input means for sensing an electrical signal due to a physiologic parameter of said body connected to at least one of said electrodes, a memory means connected to accept output from said means for sensing, said memory means triggerable to use segments of said memory means by a trigger means and to store said output, as digital data representative of said physiologic parameter, and telemetry means connected to transmit data from said memory means upon activation of said telemetry means by a receiver means outside said body.

2. An implant as set forth in claim 1 wherein said outside shape has exactly two electrode areas located substantially at opposite ends of said longitudinal dimension.

3. An implant as set forth in claim 2 wherein said input means is a differential amplifier connected between said two electrode areas.

4. An implant as set forth in claim 1 wherein said memory is organized into a continuous loop such that each new datum regarding said physiologic parameter is stored in a subsequent memory location until said memory is full wherein the first location is overwritten and wherein a memory control means marks off segments of said memory such that triggered segments are not overwritten but skipped.

5. An implant as set forth in claim 1 wherein said memory is organized into a set of segments controlled by a mode control means for indicating location addresses of each segment and wherein each segment is organized into a continuous loop such that each new chunk of data regarding said physiologic parameter is stored in a subsequent memory location in a first segment loop until a trigger occurs indicating that an event should be stored, whereupon the trigger location is recorded and compared with a program counter which is updated by one memory chunk location after each new chunk is written, such that when said program counter value compares positively to said trigger location value, said segment loop memory is full whereupon the address of the next available segment is loaded into the program counter and the next chunk of data is stored at that new program counter location.

6. An implantable device as set forth in claim 5 wherein a counter means counts the number of segments holding recorded event data due to triggering events.

7. An implant as set forth in claim 1 wherein said electronic circuitry further comprises a memory controller means for storing data and wherein said memory controller means further comprises a data compression algorithm for directing the accumulation of said data into said memory means in accord therewith.

8. An implant as set forth in claim 7 wherein said memory controller means stores data in accord with a turning point data compression algorithm implemented in hardware.

9. An implant as set forth in claim 1 having an automatic trigger means comprising means for determining if a series of signals representing QRS complexes represents a heart rate that exceeds or falls below a predetermined range of rates.

10. An implant as et forth in claim 9 wherein said autotrigger means is enhanced by an additional sensor means in the device that determines position and movement, such that indications of VVS, are triggered based on output from said sensor means.

11. An implant as set forth in claim 9 wherein said device comprises communication circuit means responsive to patient signals that activate a trigger responsive to patient input.

12. An implant as set forth in claim 9 wherein said autotrigger means is enhanced by an additional sensor means in the device that determines position and movement, such that indications of VVS and other conditions leading to a loss of consciousness are triggered based on output from said position and movement sensor means.

13. An implant as set forth in claim 1 having an automatic trigger means comprising means for determining if a series of signals representing QRS complexes represents a heart rate that exceeds or falls below a predetermined range of rates, and additionally having a patient activatable manual trigger means.

14. An implant as set forth in claim 13 wherein when the trigger is manual, a temporal size of the memory available to be reserved for a recorded event is larger than the temporal memory size available to an automatically triggered event.

15. An implant as set forth in claim 1 wherein the exterior of the device has at least 3 electrodes wherein one is located on an appendage off a main body.

16. An implant as set forth in claim 1 provided with a suture securing means.

21. An implant as set forth in any of claims 1-6 or 7-20, wherein a sensor provides temperature data for recording in said memory.

17. A device for recording physiologic events for implant into a body, said device being encapsulated in a hermetically sealed housing, having a longitudinal dimension substantially greater than a transverse dimension and wherein a transverse cross-section of the device is substantially elliptical or otherwise substantially flat wherein a substantially flat surface resulting from said substantially elliptical or otherwise flat cross section provides resistance to turning while implanted and having two electrodes substantially separated from each other along the longitudinal dimension, and having a memory for said recording.

18. A device as set forth in claim 17 provided with a suture securing means.

19. A device as set forth in claim 17 wherein said device has a shape adapted to be injectable with a trocar-like device, so as to be shaped for slidable mechanical urging against an inner surface of such a trocar-like device.

20. A device as set forth in claim 19 wherein said device additionally has inherent surface characteristics adapted to avoid movement once insertion is complete.

22. An implant for recording physiologic events in a body, having a hermetically sealed housing with a longitudinal dimension substantially greater than a transverse dimension and wherein a transverse cross-section of the device is substantially elliptical or otherwise substantially flat wherein a substantially flat surface resulting from said substantially elliptical or otherwise flat cross section provides resistance to turning while implanted, and having sensors within said housing for generating data regarding physiologic conditions within a patient'"'"'s body and circuit means for storing representations of said conditions in a memory means also within said housing.