# US 8,543,206 B2 · Early detection of lead failure using an impedance histogram

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- Number: US 8,543,206 B2
- Document ID: US8543206B2
- Status: Granted
- Kind: B2
- Application number: 12/823,870
- Filed: 2010-06-25
- Published: 2011-12-29
- Granted: 2013-09-24
- Earliest claimed: 2010-06-25
- Assignees: Pacesetter, Inc.
- Applicants: Mihir Naware; Cecilia Qin Xi
- Inventors: Mihir Naware; Cecilia Qin Xi
- Web page: https://patentgrep.com/patent/US8543206B2

## CPC

- A61B 5/0538: invasively, e.g. using a catheter
- A61N 1/37: Monitoring; Protecting
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B)

## Abstract

Testing lead conditions in an implantable medical device includes continuously sampling the impedance values of a lead associated with the implantable medical device. The sampling is conducted over a predetermined period of time. An impedance histogram is then generated using the sampled impedance values by separating each measured impedance value into a specific bin assigned to contain a particular range of impedance levels. The lead condition of the tested lead can then be determined based on one or more characteristics of the impedance histogram.

## Claims

### Claim 1

A method for testing a lead condition in an implantable medical device, said method comprising:
continuously sampling, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
generating an impedance histogram using said sampled impedance values;
determining, using a microprocessor, said lead condition of said lead based on one or more characteristics of said impedance histogram, wherein said determining comprises:
examining a spread of impedance values of said impedance histogram;
determining if the spread of impedance values is either within a minimum threshold value or exceeds said minimum threshold value;
determining that said lead condition comprises a stable lead if said spread of impedance values is within a minimum threshold value; and
determining that said lead condition comprises an unstable lead if said spread of impedance values exceeds said minimum threshold value; and
following a determination that the lead condition comprises an unstable lead;
if the implantable medical device is in a lead maturation period, maintaining the implantable medical device in the lead maturation period; and
if the implantable medical device is in a post-lead maturation period, at least one of: restricting functionality of the implantable medical device, disabling functionality of the implantable medical device, notifying a user of an anomaly in the lead, marking the lead as needing attention, notifying a medical professional of the existence of an unstable lead, and storing data regarding the lead condition, uploading the data to an external monitoring device, and displaying data regarding the lead condition to a user.

### Claim 2 (depends on 1)

The method of claim 1 wherein said impedance histogram includes a plurality of bins, each bin of said plurality representing a range of impedances, said plurality of bins covering all impedances measurable by said implantable medical device continually sampling said lead.

### Claim 3 (depends on 2)

The method of claim 2 wherein said generating said impedance histogram comprising:
determining an individual impedance value of each of said sampled impedance values; and
placing each of said sampled impedance values into and associated one of said plurality of bins according to said individual impedance value.

### Claim 4 (depends on 1)

The method of claim 1 wherein said predetermined time period is selectable by a medical professional managing care of said implantable medical device.

### Claim 5 (depends on 1)

The method of claim 1 wherein said predetermined period of time is at least 16 seconds in duration.

### Claim 6 (depends on 1)

The method of claim 1 wherein said determining said lead condition of said lead further comprises:
determining a highest impedance bin;
examining the highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device; and
in response to said highest impedance bin containing at least one of said sampled impedance values, identifying said lead condition as comprising an intermittent open circuit.

### Claim 7 (depends on 1)

The method of claim 1 wherein said determining said lead condition of said lead further comprises:
determining a lowest impedance bin;
examining the lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
in response to said lowest impedance bin containing at least one of said sampled impedance values, identifying said lead condition as comprising an intermittent short circuit.

### Claim 8

A method for testing a lead condition in an implantable medical device, said method comprising:
continuously sampling, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
generating an impedance histogram using said sampled impedance values;
determining, using a microprocessor, said lead condition of said lead based on one or more characteristics of said impedance histogram, wherein said determining comprises:
determining a highest impedance bin,
examining the highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device, and
in response to said highest impedance bin containing at least one of said sampled impedance values, identifying said lead condition as comprising an intermittent open circuit; and
in response to identifying the lead condition as comprising an intermittent open circuit, at least one of: restricting and/or disabling functionality of the implantable medical device, and notifying a user that the lead condition comprises an intermittent open circuit.

### Claim 9

A method for testing a lead condition in an implantable medical device, said method comprising:
continuously sampling, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
generating an impedance histogram using said sampled impedance values; and
determining, using a microprocessor, said lead condition of said lead based on one or more characteristics of said impedance histogram, wherein said determining comprises:
determining a lowest impedance bin;
examining the lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
in response to said lowest impedance bin containing at least one of said sampled impedance values, identifying said lead condition as comprising an intermittent short circuit; and
in response to identifying the lead condition as comprising an intermittent short circuit, at least one of: restricting and/or disabling functionality of the implantable medical device, and notifying a user that the lead condition comprises an intermittent short circuit.

### Claim 10

A method for testing a lead condition in an implantable medical device, said method comprising using a microprocessor to:
continuously sample, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
generate an impedance histogram using said sampled impedance values; and
determine said lead condition of said lead based on one or more characteristics of said impedance histogram, wherein said determining comprises:
determining a spread of said impedance values in said impedance histogram;
examining the spread of said impedance values in said impedance histogram;
determining whether said spread exceeds a predetermined maximum spread or whether said spread falls within a predetermined minimum spread;
when said spread exceeds the predetermined maximum spread, determining said lead condition comprises an immature lead; and
when said spread falls within the predetermined minimum spread, determining said lead condition comprises a mature lead and activating functionality the implantable medical device.

### Claim 11 (depends on 10)

The method of claim 10 wherein the implantable medical device is in a lead maturation period, the method further comprising, when said spread exceeds a predetermined maximum spread, maintaining said implantable medical device in said lead maturation period.

### Claim 12 (depends on 10)

The method of claim 10 wherein the implantable medical device is in a lead maturation period, and further comprising, when said spread exceeds a predetermined minimum spread, deactivating said lead maturation period.

### Claim 13 (depends on 10)

The method of claim 10 further comprising deactivating at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.

### Claim 14 (depends on 10)

The method of claim 10 further comprising activating at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.

### Claim 15

A system for testing lead condition in an implantable medical device, said system comprising:
means for sampling using a continuous stream of voltage or current pulses throughout a predetermined period of time, impedance values of a lead associated with said implantable medical device, wherein the period of time includes at least a cardiac cycle;
means for generating an impedance histogram using said sampled impedance values;
means for determining said lead condition of said lead based on one or more characteristics of said impedance histogram;
means for examining a spread of impedance values of said impedance histogram;
means for determining if the spread of impedance values is either within a minimum threshold value or exceeds said minimum threshold value;
means, executable in response to said spread of impedance values being within said minimum threshold value, for identifying said lead condition as comprising a stable lead; and
means, executable in response to said spread of impedance values exceeding said minimum threshold value, for identifying said lead condition as comprising an unstable lead.

### Claim 16 (depends on 15)

The system of claim 15 further comprising:
means for examining a highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device;
means, executable in response to said highest impedance bin containing at least one of said sampled impedance values, for identifying said lead condition as comprising an intermittent open circuit.

### Claim 17 (depends on 15)

The system of claim 15 further comprising:
means for examining a lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
means, executable in response to said lowest impedance bin containing at least one of said sampled impedance values, for identifying said lead condition as comprising an intermittent short circuit.

### Claim 18

A system for testing lead condition in an implantable medical device, said system comprising:
means for sampling using a continuous stream of voltage or current pulses throughput a predetermined period of time, impedance values of a lead associated with said implantable medical device, wherein the period of time includes at least a cardiac cycle;
means for generating an impedance histogram using said sampled impedance values;
means for determining said lead condition of said lead based on one or more characteristics of said impedance histogram;
means for examining a spread of said impedance values in said impedance histogram;
means for determining whether said spread exceeds a predetermined maximum spread or whether said spread falls within a predetermined minimum spread;
means, executable in response to said spread exceeding the predetermined maximum spread, for identifying said lead condition as comprising an immature lead; and
means, executable in response to said spread falling within the predetermined minimum spread, for identifying said lead condition as comprising a mature lead.

### Claim 19 (depends on 18)

The system of claim 18 wherein said predetermined time period is selectable by a medical professional managing care of said implantable medical device.

### Claim 20 (depends on 18)

The system of claim 18 wherein said implantable medical device is programmed to be in a lead maturation period, the system further comprising a means, executable in response to said spread exceeding a predetermined maximum spread, for maintaining said implantable medical device in said lead maturation period.

### Claim 21 (depends on 18)

The system of claim 18 wherein said implantable medical device is programmed to be in a lead maturation period, the system further comprising a means, executable in response to said spread falling within a predetermined minimum spread, for deactivating said lead maturation period.

### Claim 22 (depends on 18)

The system of claim 18 further comprising:
means for examining a highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device;
means, executable in response to said highest impedance bin containing at least one of said sampled impedance values, for identifying said lead condition as comprising an intermittent open circuit.

### Claim 23 (depends on 18)

The system of claim 18 further comprising:
means for examining a lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
means, executable in response to said lowest impedance bin containing at least one of said sampled impedance values, for identifying said lead condition as comprising an intermittent short circuit.

### Claim 24

A system for testing lead condition in an implantable medical device, said system comprising:
means for sampling using a continuous stream of voltage or current pulses throughout a predetermined period of time, impedance values of a lead associated with said implantable medical device, wherein the period of time includes at least a cardiac cycle;
means for generating an impedance histogram using said sampled impedance values;
means for determining said lead condition of said lead based on one or more characteristics of said impedance histogram;
means for examining a spread of said impedance values in said impedance histogram; and
means for deactivating at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.

### Claim 25 (depends on 24)

The system of claim 24 further comprising:
means for activating at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.

### Claim 26

An implantable medical device (IMD) comprising:
at least one electrical lead;
a programmable microcontroller coupled to said at least one electrical lead, said programmable microcontroller controlling operation of said IMD;
a memory coupled to said programmable microcontroller; and
an early lead failure detection module stored in the memory, wherein, when executed by the programmable microcontroller, said early lead failure detection module configures said IMD:
to continuously sample, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
to generate an impedance histogram using said sampled impedance values;
to determine a lead condition of said lead based on one or more characteristics of said impedance histogram;
to examine a spread of impedance values of said impedance histogram, wherein:
in response to said spread of impedance values being within a minimum threshold value, said lead condition comprises a stable lead; and
in response to said spread of impedance values exceeding said minimum threshold value, said lead condition comprises an unstable lead.

### Claim 27 (depends on 26)

The IMD of claim 26 wherein said early lead failure detection module further configures said IMD:
to examine a lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
to identify said lead condition as comprising an intermittent short circuit in response to said lowest impedance bin containing at least one of said sampled impedance values.

### Claim 28 (depends on 26)

The IMD of claim 26 wherein said early lead failure detection module further configures said IMD:
to examine a highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device; and
to identify said lead condition as comprising an intermittent open circuit in response to said highest impedance bin containing at least one of said sampled impedance values.

### Claim 29

An implantable medical device (IMD) comprising:
at least one electrical lead;
a programmable microcontroller coupled to said at least one electrical lead, said programmable microcontroller controlling operation of said IMD;
a memory coupled to said programmable microcontroller; and
an early lead failure detection module stored in the memory, wherein, when executed by the programmable microcontroller, said early lead failure detection module configures said IMD:
to continuously sample, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
to generate an impedance histogram using said sampled impedance values;
to determine a lead condition of said lead based on one or more characteristics of said impedance histogram;
to examine a highest impedance bin of said impedance histogram, said highest impedance bin defined to hold a high range of highest impedance values measureable by said implantable medical device;
to identify said lead condition as comprising an intermittent open circuit in response to said highest impedance bin containing at least one of said sampled impedance values.

### Claim 30

An implantable medical device (IMD) comprising:
at least one electrical lead;
a programmable microcontroller coupled to said at least one electrical lead, said programmable microcontroller controlling operation of said IMD;
a memory coupled to said programmable microcontroller; and
an early lead failure detection module stored in the memory, wherein, when executed by the programmable microcontroller, said early lead failure detection module configures said IMD:
to continuously sample, over a predetermined period of time, impedance values of a lead associated with said implantable medical device;
to generate an impedance histogram using said sampled impedance values;
to determine a lead condition of said lead based on one or more characteristics of said impedance histogram;
to examine a lowest impedance bin of said impedance histogram, said lowest impedance bin defined to hold a low range of lowest impedance values measureable by said implantable medical device; and
to identify said lead condition as comprising an intermittent short circuit in response to said lowest impedance bin containing at least one of said sampled impedance values.

### Claim 31 (depends on 30)

The IMD of claim 30 wherein said predetermined time period is selectable by a medical professional managing care of said implantable medical device.

### Claim 32 (depends on 30)

The IMD of claim 30 wherein said predetermined period of time comprises a length of at least 16 seconds.

### Claim 33

An implantable medical device (IMD) comprising:
at least one electrical lead;
a programmable microcontroller coupled to said at least one electrical lead, said programmable microcontroller controlling operation of said IMD;
a memory coupled to said programmable microcontroller; and
an early lead failure detection module stored in the memory, wherein, when executed by the programmable microcontroller, said early lead failure detection module configures said IMD:
to continuously sample, using a continuous stream of pulses throughout a predetermined period of time, impedance values of a lead associated with said implantable medical device, wherein the predetermined period of time includes at least a cardiac cycle,
to generate an impedance histogram using said sampled impedance values,
to determine a lead condition of said lead based on one or more characteristics of said impedance histogram, and
to examine a spread of said impedance values in said impedance histogram.

### Claim 34 (depends on 33)

The IMD of claim 33 wherein, in response to said spread exceeding a predetermined maximum spread, said early lead failure detection module further configures said IMD to identify said lead condition as comprising an immature lead.

### Claim 35 (depends on 33)

The IMD of claim 33 further comprising said implantable medical device being in a lead maturation period, wherein in response to said spread exceeding a predetermined maximum spread, said early lead failure detection module further configures said IMD to maintain said IMD in said lead maturation period.

### Claim 36 (depends on 33)

The IMD of claim 33 wherein, in response to said spread falling within a predetermined minimum spread, said early lead failure detection module further configures said IMD to identify said lead condition as comprising a mature lead.

### Claim 37 (depends on 33)

The IMD of claim 33 further comprising said implantable medical device being in a lead maturation period, wherein, in response to said spread falling within a predetermined minimum spread, said early lead failure detection module further configures said IMD to deactivate said lead maturation period.

### Claim 38 (depends on 33)

The IMD of claim 33 wherein said early lead failure detection module further configures said IMD to deactivating at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.

### Claim 39 (depends on 33)

The IMD of claim 33 wherein said early lead failure detection module further configures said IMD to activate at least one functionality of said implantable medical device based, at least in part, on said spread of impedance values.