TET system for implanted medical device

• US 9,192,704 B2
• Filed: 11/01/2013
• Issued: 11/24/2015
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Heartware,Inc. (Medtronic Plc)
• Original Assignee: Heartware,Inc. (Medtronic Plc)
• Inventors: Yomtov, Barry, Batty, John Robert
• Primary Examiner(s): Stice, Paula J
• Application Number:
  US14/070,165
• Publication Number:
  US 20140073839A1
• Time in Patent Office: 753 Days
• Field of Search: 320/108
• US Class Current: 1/1
• CPC Class Codes: A61M 2205/8243 by induction
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/508 Electronic control means, e.g. for feedback regulation
• CPC Class Codes: A61M 60/538 Regulation using real-time blood pump operational parameter data, e.g. motor current
• CPC Class Codes: A61M 60/873 specially adapted for wireless or transcutaneous energy transfer [TET], e.g. inductive charging
• CPC Class Codes: A61M 60/875 specially adapted for optimising alignment of external and implantable coils
• CPC Class Codes: A61M 60/876 Implantable batteries
• CPC Class Codes: H02J 13/00022 using wireless data transmission
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A TET system is operable to vary an amount of power transmitted from an external power supply to an implantable power unit in accordance with a monitored condition of the implantable power unit. The amount of power supplied to the implantable power unit for operating a pump, for example, can be varied in accordance with a cardiac cycle, so as to maintain the monitored condition in the power circuit within a desired range throughout the cardiac cycle.

Claims

1. A system, comprising:

(a) an implantable electrical device adapted for mounting within a body of a patient;

(b) an implantable power unit adapted for mounting within the body of the patient, the power unit having a receiving coil, and a power circuit connected to the receiving coil so that power applied to the receiving coil can be transmitted to the implantable device;

(c) an external power supply having a transmitting coil adapted for transcutaneous inductive coupling with the receiving coil to define a system having a resonant frequency varying in relation to a distance between the transmitting and receiving coils, a drive circuit operable to apply an alternating current having a variable transmission frequency to the transmitting coil at a variable drive pulse width, and a control circuit operable to (i) monitor a parameter related to mutual inductance between the transmitting and receiving coils; and

(ii) adjust the transmission frequency to a value having a predetermined difference from the resonant frequency, such that the control circuit is operable, using the monitored parameter, to maintain the transmission frequency with the predetermined difference from the resonant frequency.

2. A system as claimed in claim 1, wherein the control circuit is operable to maintain the transmission frequency below the resonant frequency.

3. A system as claimed in claim 2, wherein the predetermined difference is a percentage difference from the resonant frequency.

4. A system as claimed in claim 1, wherein the control circuit is operable to adjust the variable transmission frequency from a current value to a new value different from the current value when the difference between the new value and the current value is greater than a threshold.

5. A system as claimed in claim 4, wherein the control circuit includes a table storing a plurality of frequency values corresponding to different values of the monitored parameter, wherein the control circuit is operable to use the monitored parameter to look up the new value from the table.

6. A system as claimed in claim 1, wherein the monitored parameter includes an estimate of the distance between the transmitting and receiving coils.

7. A system as claimed in claim 6, wherein the control circuit is operable to estimate the distance using at least a measurement of a voltage across the transmitting coil.

8. A system as claimed in claim 7, wherein the control circuit is operable to estimate the distance by also using a measurement of the current supplied to the transmitting coil.

9. A system as claimed in claim 1, wherein the implantable device is a circulatory assist pump having an electric motor with a time-varying power demand.