Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/248—Supports; Mounting means by structural association with other equipment or articles with receiving set provided with an AC/DC converting device, e.g. rectennas
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0002—Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network
  • A61B5/0031—Implanted circuitry
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/372—Arrangements in connection with the implantation of stimulators
  • A61N1/378—Electrical supply
  • A61N1/3787—Electrical supply from an external energy source
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2250/0001—Means for transferring electromagnetic energy to implants
  • A61F2250/0002—Means for transferring electromagnetic energy to implants for data transfer
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N1/00—Electrotherapy; Circuits therefor
  • A61N1/18—Applying electric currents by contact electrodes
  • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
  • A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
  • A61N1/372—Arrangements in connection with the implantation of stimulators
  • A61N1/37211—Means for communicating with stimulators
  • A61N1/37217—Means for communicating with stimulators characterised by the communication link, e.g. acoustic or tactile
  • A61N1/37223—Circuits for electromagnetic coupling

Definitions

• This invention relates to monitoring the treatment of human or non-human animals by means of implantable passive telemetric sensors. It is applicable to a variety of treatments but will be described hereinafter with particular reference to hyperthermia treatment, it being understood that the invention is not restricted to this type of treatment. Also, the invention will be described in relation to human patients, although it is to be understood that the monitoring involved may also be applied to non-human animals.
• a method of monitoring treatment of a human or non-human animal which comprises implanting into the body of the human or non-human animal at or close to the desired locus of treatment a sensor which is adapted (a) to receive and to rectify an electromagnetic (e.g. radio) signal directed from outside the body towards it, and (b) to transmit data relating to treatment parameters by wireless telemetry to a receiver external to the body of the human or non- human animal; and processing the data transmitted by said sensor to provide information on the treatment.
• an electromagnetic e.g. radio
• a device for implantation into the body of a human or non-human animal which device comprises a sensor which is adapted (a) to receive and to rectify an electromagnetic (e.g. radio) signal directed from outside the body towards it, and (b) to transmit data relating to treatment parameters by wireless telemetry to a receiver external to the body of the human or non-human animal .
• a sensor which is adapted (a) to receive and to rectify an electromagnetic (e.g. radio) signal directed from outside the body towards it, and (b) to transmit data relating to treatment parameters by wireless telemetry to a receiver external to the body of the human or non-human animal .
• Such a device is able to operate by power generated from radio signals directed towards the device from outside the body; the implanted device can thus be totally passive unless and until activated by the external radio signal, which can thus serve (i) as the means for delivering power to the device, and (ii) as a polling mechanism to activate the device and elicit a response therefrom.
• the senor is a miniature pressure sensor; this may, for example, be associated with a stent whose function is to maintain the lumen patency of a duct, vessel or organ.
• a stent whose function is to maintain the lumen patency of a duct, vessel or organ.
• Such devices may be employed at many sites within the body and may provide valuable information during the treatment of a wide range of conditions.
• the sensor may, for example, be incorporated in a transjugular intrahepatic portosystemic shunt (TIPS) or in a stent within the renal artery.
• TIPS transjugular intrahepatic portosystemic shunt
• the desired locus of treatment may be, for example, a tumour; a blood vessel (for example, where levels of circulating species, or general flow rates, are to be monitored); or a duct, e.g. the pancreatic duct or bile duct.
• a tumour for example, a tumour
• a blood vessel for example, where levels of circulating species, or general flow rates, are to be monitored
• a duct e.g. the pancreatic duct or bile duct.
• the senor is associated with a therapeutic device which is also implanted into the human or non-human animal body in the method of this invention.
• the implanted therapeutic device include:- a device for delivering heat in a localised manner, e.g. to treat a tumour; a pump for assisting blood flow; a stent for ensuring lumen patency of hollow viscera and ducts, e.g. oesophagus, bile duct, pancreatic duct, colon, stomach, rectum and urethra; a pressure sensor for detecting localised pressures, e.g.
• a flow meter for determining passage of a fluid through a duct
• a drug release device for determining passage of a fluid through a duct
• a pacemaker for determining passage of a fluid through a duct
• a detector for particular chemical or biological material or species, e.g. blood or tissue chemical content or cellular content; or combinations of such devices.
• Localised heating can be of benefit in several situations, for example: (a) to stop bleeding, e.g. of a tumour or in a non-malignant condition such as benign ulcers of the stomach or duodenum.
• the therapeutic device may thus be an electrode or an assembly of electrodes which can be activated (preferably remotely) so as to generate localised heating of adjacent tissues.
• An electrode of this sort may, for example, be positioned around a tumour of the prostate, colon, bladder, stomach or lung; it may likewise be positioned adjacent to a duodenal or stomach ulcer.
• the invention also finds application in surgical procedures involving balloon dilatation and/or coronary stenting. These surgical procedures tend to encourage the formation of fibrous tissue which can lead to stenosis, e.g. blockage of a blood vessel after removal of the dilatation equipment. In accordance with this invention, such dangers of stenosis may be removed or mitigated by heating the stent during a coronary stenting procedure or by applying heat adjacent to a region undergoing balloon dilatation. Control of the heating process is assisted by sensing the temperature of the heated component.
• the sensor associated with the therapeutic device will be configured to respond to a parameter (e.g. temperature, flow rate, pressure) which is of significance in the treatment regime being followed.
• a parameter e.g. temperature, flow rate, pressure
• the parameter sensed in the treatment of a tumour by hyperthermia, may be temperature; and in the treatment of an occluded duct, the parameter sensed may be pressure.
• the transmission of data from within the body to an external receiver may be accomplished using low power radiation in the radio frequency or microwave frequency bands. Such transmission is preferably intermittent rather than continuous and will generally be under the control of medical personnel or, in the case of a human patient, of the patient him/herself.
• the senor and the therapeutic device also, if this requires electrical power to operate is/are empowered by wireless means. While in some instances batteries may be implanted as a power source, this is not preferred; the currently preferred mode of delivery is by means of an implanted antenna/rectifier device (a so-called “rectenna”) which receives electromagnetic radiation from an external source and delivers electrical power derived therefrom.
• rectenna implanted antenna/rectifier device
• the power levels involved for sensor applications are less than about lmW; at these levels, the antenna portion of the rectenna can be implemented as a filamentary coil-shaped antenna for low frequencies or as a short dipole antenna for high frequencies.
• a chip-sized (typically less than 1mm 3 ) rectifying circuit comprising a combination of rectifying diodes, a storage capacitor and (optionally) a filter circuit is mounted on the antenna.
• the sensor/rectenna combination occupies a volume of around 60mm° or less.
• Electromagnetic radiation at a frequency of 1 - 2 GHz and with a power density of lmW/cm ⁇ will provide such a rectenna with adequate operating power.
• This may advantageously be provided by an external transmit/receive unit which will direct electromagnetic radiation towards the implanted rectenna in order to power up and interrogate the sensor electronics.
• Such a unit will operate in a duplex fashion, simultaneously transmitting the power signal to the implanted unit(s) and receiving the telemetry signal containing the data required from the unit(s).
• the sensor may be used to monitor pharmacokinetics, e.g. when chronic administration of drugs (e.g. digoxin or tamoxifen) is required.
• drugs e.g. digoxin or tamoxifen
• FIGURE 1 illustrates schematically the basic sensor interrogation system of this invention
• FIGURE 2 shows more detail of the disposition of implanted components and their operation in hyperthermia treatment of a patient
• FIGURES 3A and 3B illustrate stents implanted, respectively, in the colon and in the pancreatic duct.
• each sensor chip comprises three basic elements, namely a rectenna 3, electronic processing circuitry 4 in the form of an integrated circuit, and a sensing device 5.
• An antenna 7 (see Fig. 2) is part of the rectenna 3.
• a sensor chip incorporating these components may be no more than 10mm long, 2mm wide and lmm thick.
• a reader/interrogator 6 is used to irradiate the sensor chip(s) with a radio signal which is of sufficient power to enable the rectenna 3 to generate a voltage large enough to cause the electronics component 4 of the sensor to function.
• the reader unit 6 will normally be located just outside, and close to, the body of the patient; it may for example be hand-held; attached to a belt around the patient's body; or otherwise located in a substantially fixed position relative to the body.
• a source 11 of radio waves (typically in the frequency range 100MHz - 2000MHz) feeds a directional antenna 12 through a circulator 13.
• the transmit source 11 may be modulated under control of an integrated circuit 14 which provides signal coding and processing capabilities.
• the unit further comprises a receiver 15 which receives signals transmitted telemetrically by the implanted sensor and which supplies the received signals to the integrated circuit 14 which is adapted to decipher coded transmissions from the sensor chip 1.
• a display screen 16 is also provided in the unit 6 for the purpose of displaying the information received from within the patient.
• the system as described may be used in conjunction with secondary techniques, for example the direct injection of paracrine hormones or of cells secreting paracrine hormones. These are believed to promote apoptosis of tumours and/or to encourage infiltration of the heated tumour by cells of the innate immune system.
• the components for implantation in the present invention it is desirable to minimise the size of the components to reduce tissue damage during the implantation step; to maximise their rigidity to increase the accuracy with which they can be positioned within the body of a patient; and to encapsulate the components in non-toxic, non-reactive material.
• the control system employed preferably allows different modes of activation of the antenna elements 10-13 so as to permit variation of the spatio-temporal heat delivery.
• Figs. 3A and 3B show metallic or metal-containing stents S ⁇ and S2, respectively, in the human colon and pancreatic duct. These serve to maintain the lumen patency of the organs or ducts in which they are implanted, and where partial or complete occlusion (e.g. by a tumour) has occurred.
• By implanting coupling elements and a rectenna in operative connection with the stent heat may be delivered to kill the tumour cells.
• control and monitoring means may be incorporated to provide telemetric control and operation of the hyperthermia treatment.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Animal Behavior & Ethology (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• General Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Pathology (AREA)
• Radiology & Medical Imaging (AREA)
• Molecular Biology (AREA)
• Surgery (AREA)
• Heart & Thoracic Surgery (AREA)
• Biophysics (AREA)
• Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Medical Informatics (AREA)
• Measuring And Recording Apparatus For Diagnosis (AREA)
• Electrotherapy Devices (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)
• Thermotherapy And Cooling Therapy Devices (AREA)
• Accommodation For Nursing Or Treatment Tables (AREA)
• Radiation-Therapy Devices (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

Family

ID=10836009

Family Applications (1)

Country Status (7)

Cited By (9)

Families Citing this family (75)

Family Cites Families (37)

• 1998
  • 1998-07-22 GB GBGB9816011.2A patent/GB9816011D0/en not_active Ceased
• 1999
  • 1999-07-22 EP EP04023681A patent/EP1500411A1/en not_active Withdrawn
  • 1999-07-22 US US09/744,220 patent/US6682480B1/en not_active Expired - Lifetime
  • 1999-07-22 EP EP99934939A patent/EP1128871B1/en not_active Expired - Lifetime
  • 1999-07-22 DE DE69920942T patent/DE69920942T2/de not_active Expired - Lifetime
  • 1999-07-22 AT AT99934939T patent/ATE278437T1/de not_active IP Right Cessation
  • 1999-07-22 JP JP2000560936A patent/JP2002521097A/ja active Pending
  • 1999-07-22 WO PCT/GB1999/002389 patent/WO2000004945A2/en not_active Ceased

Non-Patent Citations (1)

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