Method and Apparatus for Implantable Cardiac Lead Integrity Analysis

• US 20160271390A1
• Filed: 03/24/2016
• Published: 09/22/2016
• Est. Priority Date: 12/05/2012
• Status: Active Grant

• Current Assignee: Lambda Nu Technology LLC
• Original Assignee: Lambda Nu Technology LLC
• Inventors: Kroll, Mark W., Swerdlow, Charles D.
• Granted Patent: US 9,987,485 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/0563 specially adapted for defibrillation or cardioversion
• 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 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/37 Monitoring; Protecting
• CPC Class Codes: A61N 1/3931 Protecting, e.g. back-up systems
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy
• CPC Class Codes: A61N 2001/083 Monitoring integrity of contacts, e.g. by impedance measurement

Abstract

The present invention relates, generally, to scientific and medical system methods for diagnosis of implantable cardioverter defibrillator (ICD) lead conductor anomalies, in particular conductor migration and externalization within an ICD implantable cardiac lead. The method uses an “imaginary” component of the high frequency transmission line impedance having certain spectral changes that correspond to movements of the conductor or an “imaginary impedance”. This allows the detection of conductor migration and small insulation failures.

Claims

1-10. -10. (canceled)

13. A method of detecting conductor migration, damage, or externalization within an implantable cardiac lead implanted proximate and in electrical communication with a heart of a patient comprising:

applying a frequency signal source to an implantable cardiac lead, the signal source providing frequencies of 100 MHz or higher to the implantable cardiac lead;

measuring an imaginary component of a transmission line impedance of the implantable cardiac lead during a sweeping of 100 MHz to 200 MHz;

determining whether there is a decrease in the peak imaginary impedance to 217Ω

or less; and

providing an indication of potential conductor migration, damage or externalization based there is the decrease in the peak imaginary impedance.

14. An apparatus for detecting conductor migration, damage, or externalization within an implantable cardiac lead implanted proximate and in electrical communication with a heart of a patient comprising:

a microcontroller having a plurality of analog inputs and outputs;

at least one voltage-controlled oscillator connected to one output of the microcontroller;

a high-frequency multiplier connected to an output of the at least one voltage-controlled oscillator through a resistor;

a DC blocking capacitor connected to an output of the high-frequency multiplier;

an input of a Quadrature Demodulator connected to an output of the DC blocking capacitor;

a conductor connected to the output of the at least one voltage-controlled oscillator having a terminus at another input of the Quadrature Demodulator;

a sense resistor connected to the output of the at least one voltage-controlled oscillator wherein a conductor at an output of the sense resistor is connected to a conductor under test, another conductor at the output of the sense resistor is connected to a second another input of the Quadrature Demodulator, wherein prior to the another and second another inputs an impedance matching LC network is provided;

an amplifier having one input connected to the output of the at least one voltage-controlled oscillator and having an another input connected to the output of the sense resistor;

a diode, resistor and capacitor provided to isolate, rectify, and smooth a sensed current signal, the diode connected to an output of the amplifier, the capacitor and resistor connected to an output of the diode and both to ground, and the sensed. current signal fed to an input of the microcontroller;

a diode, resistor and capacitor provided to isolate, rectify, and smooth a VCO voltage, the diode connected to the output of the at least one voltage-controlled oscillator, the capacitor and resistor connected to an output of the diode and both to ground, and the VCO voltage fed to a second input of the microcontroller; and

wherein the Quadrature Demodulator outputs a real component of the current via a first output and an imaginary component of the current via a second output, the real component of the current fed to a third input of the microcontroller and the imaginary component of the current fed to a fourth input of the microcontroller.

15. The apparatus of claim 14, further comprising:

an energy storage capacitor;

an H-bridge having a plurality of switches, the H-bridge operably connected to the energy storage capacitor;

a feed-thru capacitor connected to an output of the H-bridge;

a conductor from the H-bridge connected to an RV coil cable; and

a high-voltage MOSFET having a source connected to an output of the feed-thru capacitor, a drain connected to an implantable cardiac device can, and a gate connected to a lead tester.

16. A system for analyzing an implantable cardiac lead implanted proximate and in electrical communication with a heart of a patient, the system comprising:

an implantable cardiac lead; and

an implantable cardioverter defibrillator (ICD) device including;

a radio adapted to transmit and receive RF transmissions related to the operation of the implantable cardiac device,

a high frequency test circuit adapted to generate a high frequency test signal greater than 10 MHz for application to the implantable cardiac lead;

a frequency oscillator configured to provide a frequency for the RF transmissions and for the high frequency test circuit;

,

a microcontroller configured to control the radio and the high frequency test circuity to generate a high frequency test signal that is applied to the implantable cardiac lead, determine an imaginary component of a transmission line impedance of the implantable cardiac lead in response to the test signal, and communicate via the radio an indication of potential lead failure related to conductor migration, damage, insulation abrasion or externalization within the implantable cardiac lead based on whether the imaginary component of the transmission line impedance is increased relative to a expected value.

17. The system of claim 16, further comprising:

an external high frequency pulse generator; and

an adapter cable operably coupleable to the implantable cardiac lead,

wherein the external high frequency pulse generator is adapted to generate a multitude of high frequency pulses to be applied to the implantable cardiac lead over a frequency sweep range to confirm whether the indication of a potential lead failure is correct.