U.S. patent application number 14/592595 was filed with the patent office on 2015-07-16 for methods and systems for improved communication between medical devices.
The applicant listed for this patent is Cardiac Pacemakers, Inc.. Invention is credited to William J. Linder, Keith R. Maile, Jeffrey E. Stahmann.
Application Number | 20150196769 14/592595 |
Document ID | / |
Family ID | 52450570 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150196769 |
Kind Code |
A1 |
Stahmann; Jeffrey E. ; et
al. |
July 16, 2015 |
METHODS AND SYSTEMS FOR IMPROVED COMMUNICATION BETWEEN MEDICAL
DEVICES
Abstract
At least one of a first medical device and a second medical
device may be implanted within a patient while the second medical
device may optionally be proximate but external to the patient. At
least one of the medical devices has an antenna having at least two
electrodes and at least one of the medical devices has an antenna
having at least three electrodes. The medical devices can
communicate via conducted communication through the patient's
tissue between a first pair of electrodes and a second pair of
electrodes. At least one of the pairs of electrodes can be selected
in accordance with the signal strength of the communication vector
between the first and second pairs of electrodes.
Inventors: |
Stahmann; Jeffrey E.;
(Ramsey, MN) ; Linder; William J.; (Golden Valley,
MN) ; Maile; Keith R.; (New Brighton, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cardiac Pacemakers, Inc. |
St. Paul |
MN |
US |
|
|
Family ID: |
52450570 |
Appl. No.: |
14/592595 |
Filed: |
January 8, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61926101 |
Jan 10, 2014 |
|
|
|
Current U.S.
Class: |
607/32 ;
607/60 |
Current CPC
Class: |
A61N 1/37223 20130101;
A61N 1/37288 20130101; A61N 1/3756 20130101; A61N 1/37252 20130101;
A61B 5/0028 20130101; A61N 1/3605 20130101; A61B 5/0464 20130101;
H04B 13/005 20130101; A61B 5/4836 20130101; A61N 1/362 20130101;
A61N 1/37217 20130101 |
International
Class: |
A61N 1/372 20060101
A61N001/372; A61N 1/375 20060101 A61N001/375; A61N 1/362 20060101
A61N001/362 |
Claims
1. A method of communicating between a first medical device having
a first antenna and a second medical device having a second
antenna, wherein the first medical device is implanted within a
patient and the second medical device is proximate to the patient,
and wherein the first antenna and/or the second antenna has at
least three electrodes and the other antenna has at least two
electrodes, the method comprising: selecting a first electrode pair
of the antenna that has at least three electrodes; at least one of
sending and receiving a conducted communication signal through
tissue of the patient between the first electrode pair of the
antenna that has at least three electrodes and two of the
electrodes of the other antenna; selecting a second electrode pair
of the antenna that has at least three electrodes, wherein the
second electrode pair is different from the first electrode pair;
and sending a conducted communication signal through tissue of the
patient between the second electrode pair of the antenna that has
at least three electrodes and two electrodes of the other
antenna.
2. The method of claim 1, further comprising: monitoring a measure
related to a signal to noise ratio of the conducted communication
signal using the first electrode pair; if the measure related to a
signal to noise ratio of the conducted communication signal using
the first electrode pair falls below a threshold, then: selecting
the second electrode pair of the antenna that has at least three
electrodes; and sending the conducted communication signal through
tissue of the patient between the second electrode pair of the
antenna that has at least three electrodes and the two electrodes
of the other antenna.
3. The method of claim 1, further comprising: determining a first
measure related to a signal to noise ratio of the conducted
communication signal using the first electrode pair; determining a
second measure related to a signal to noise ratio of the conducted
communication signal using the second electrode pair; and selecting
the first electrode pair or the second electrode pair for
subsequent communication based on the first measure and the second
measure.
4. The method of claim 1, wherein the second medical device is
implanted within the patient but spaced from the first medical
device.
5. The method of claim 1, wherein the second medical device is
disposed outside of the patient and the second antenna is
positioned on a skin surface of the patient.
6. The method of claim 1, wherein the antenna that has at least
three electrodes comprises three electrodes that are arranged in a
triangular configuration.
7. The method of claim 1, wherein the antenna that has at least
three electrodes comprises four electrodes that are arranged in a
rectangular configuration.
8. The method of claim 1, wherein the antenna that has at least
three electrodes comprises four electrodes that are arranged in a
kite configuration.
9. A method of communicating between a first medical device having
a first antenna with at least two electrodes and a second medical
device having a second antenna with at least three electrodes, the
method comprising: testing communication vectors between the at
least two electrodes of the first antenna and each of a plurality
of pairs of electrodes of the at least three electrodes of the
second antenna; selecting a communication vector based on signal
strengths of each of the communication vectors; and at least one of
sending and receiving a conducted communication between the first
medical device and the second medical device using the selected
communication vector.
10. The method of claim 9, wherein the first medical device
comprises an implanted medical device and the second medical device
comprises an external device.
11. The method of claim 9, wherein the first medical device
comprises an external device and the second medical device
comprises an implanted medical device.
12. The method of claim 9, wherein the first medical device
comprises a first implanted medical device and the second medical
device comprises a second implanted medical device.
13. The method of claim 9, wherein selecting a communication vector
comprises selecting the communication vector with the strongest
signal strength.
14. The method of claim 9, wherein selecting a communication vector
comprises not selecting the communication vector with the weakest
signal strength.
15. A communication system, comprising: a first medical device in
communication with a first antenna having at least two electrodes;
and a second medical device in communication with a second antenna
having at least three electrodes; wherein at least one of the first
medical device and the second medical device is configured to: test
communication vectors between the at least two electrodes of the
first antenna and at least two pairs of the at least three
electrodes of the second antenna; select a communication vector
from the tested communication vectors; and at least one of send and
receive a conducted communication along the selected communication
vector.
16. The communication system of claim 15, wherein the at least
three electrodes comprise three electrodes that are arranged in a
triangular configuration.
17. The communication system of claim 15, wherein the at least
three electrodes comprise four electrodes that are arranged in a
rectangular configuration.
18. The communication system of claim 15, wherein the at least
three electrodes comprise four electrodes that are arranged in a
kite configuration.
19. The communication system of claim 15, wherein at least one of
the first medical device and the second medical device are
implanted within a patient.
20. The communication system of claim 15, wherein the first medical
device is a leadless cardiac pacemaker (LCP).
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/926,101 filed Jan. 10, 2014 entitled
"METHODS AND SYSTEMS FOR IMPROVED COMMUNICATION BETWEEN MEDICAL
DEVICES", which application is incorporated herein by reference in
its entirety.
TECHNICAL FIELD
[0002] The present disclosure generally relates to communication
between medical devices, and more particularly, to methods and
systems for improved communication between medical devices.
BACKGROUND
[0003] Pacing instruments can be used to treat patients suffering
from various heart conditions that may result in a reduced ability
of the heart to deliver sufficient amounts of blood to a patient's
body. These heart conditions may lead to rapid, irregular, and/or
inefficient heart contractions. To help alleviate some of these
conditions, various devices (e.g., pacemakers, defibrillators,
etc.) can be implanted in a patient's body. Such devices may
monitor and provide electrical stimulation to the heart to help the
heart operate in a more normal, efficient and/or safe manner. In
some cases, a patient may have multiple devices that operate
together to detect and/or treat various conditions.
SUMMARY
[0004] The present disclosure generally relates to communication
between medical devices, and more particularly, to methods and
systems for improved communication between medical devices. For
example, a first medical device and a second medical device may be
implanted within a patient, or the first medical device may be
implanted within the patient and the second medical device may be
proximate but external to the patient. At least one of the medical
devices may have an antenna with at least two electrodes, and at
least one of the medical devices may have an antenna with at least
three electrodes. The medical devices may communicate by
transmitting signals from two of the electrodes of the transmitting
medical device to at least two electrodes of the receiving medical
device. It is contemplated that the medical devices may communicate
via radiofrequency (RF) communication, inductive coupling,
conducted communication, or any other suitable communication
technique.
[0005] It will be appreciated that the relative signal strength
between any two pairs of electrodes, such as a first pair of
electrodes belonging to the transmitting medical device and a
second pair of electrodes belonging to the receiving medical
device, may depend in part on the orientation of the receiving
electrodes relative to the electromagnetic field produced by the
transmitting electrodes. The system may be configured to select a
particular pair of electrodes for the transmitting medical device
and/or the receiving medical device in order help improve the
signal strength of communication between the devices. The different
combination of electrodes that may be used for communication
between medical devices can each be referred to a "communication
vector". In some instances, various communication vectors may be
tested, and the communication vector that produces the highest
relative signal strength and/or signal-to-noise ratio may be
selected for subsequent communication. Various communication
vectors may be re-tested periodically, upon command, when the
relative signal strength and/or signal-to-noise ratio falls below a
threshold, when the relative signal strength and/or signal-to-noise
ratio changes by a threshold, and/or at any other suitable time as
desired.
[0006] An example method of communicating between a first medical
device having a first antenna and a second medical device having a
second antenna is disclosed. The first medical device is implanted
within a patient and the second medical device is proximate to the
patient, and the first antenna and/or the second antenna has at
least three electrodes and the other antenna has at least two
electrodes. The example method comprises:
[0007] selecting a first electrode pair of the antenna that has at
least three electrodes;
[0008] at least one of sending and receiving a conducted
communication signal through tissue of the patient between the
first electrode pair of the antenna that has at least three
electrodes and two of the electrodes of the other antenna;
[0009] selecting a second electrode pair of the antenna that has at
least three electrodes, wherein the second electrode pair is
different from the first electrode pair; and
[0010] sending a conducted communication signal through tissue of
the patient between the second electrode pair of the antenna that
has at least three electrodes and two electrodes of the other
antenna.
[0011] Alternatively or additionally to any of the embodiments
above, the method may further include:
[0012] monitoring a measure related to a signal to noise ratio of
the conducted communication signal using the first electrode
pair;
[0013] if the measure related to a signal to noise ratio of the
conducted communication signal using the first electrode pair falls
below a threshold, then: [0014] selecting the second electrode pair
of the antenna that has at least three electrodes; and [0015]
sending the conducted communication signal through tissue of the
patient between the second electrode pair of the antenna that has
at least three electrodes and the two electrodes of the other
antenna.
[0016] Alternatively or additionally to any of the embodiments
above, the method may further include:
[0017] determining a first measure related to a signal to noise
ratio of the conducted communication signal using the first
electrode pair;
[0018] determining a second measure related to a signal to noise
ratio of the conducted communication signal using the second
electrode pair; and
[0019] selecting the first electrode pair or the second electrode
pair for subsequent communication based on the first measure and
the second measure.
[0020] Alternatively or additionally to any of the embodiments
above, the second medical device may be implanted within the
patient but spaced from the first medical device.
[0021] Alternatively or additionally to any of the embodiments
above, the second medical device may be disposed outside of the
patient and the second antenna is positioned on a skin surface of
the patient.
[0022] Alternatively or additionally to any of the embodiments
above, the antenna that has at least three electrodes may comprise
three electrodes that are arranged in a triangular
configuration.
[0023] Alternatively or additionally to any of the embodiments
above, the antenna that has at least three electrodes may comprise
four electrodes that are arranged in a rectangular
configuration.
[0024] Alternatively or additionally to any of the embodiments
above, the antenna that has at least three electrodes may comprise
four electrodes that are arranged in a kite configuration.
[0025] Another example method of communicating between a first
medical device having a first antenna with at least two electrodes
and a second medical device having a second antenna with at least
three electrodes comprises:
[0026] testing communication vectors between the at least two
electrodes of the first antenna and each of a plurality of pairs of
electrodes of the at least three electrodes of the second
antenna;
[0027] selecting a communication vector based on signal strengths
of each of the communication vectors; and
[0028] at least one of sending and receiving a conducted
communication between the first medical device and the second
medical device using the selected communication vector.
[0029] Alternatively or additionally to any of the embodiments
above, the first medical device may comprise an implanted medical
device and the second medical device may comprise an external
device.
[0030] Alternatively or additionally to any of the embodiments
above, the first medical device may comprise an external device and
the second medical device may comprise an implanted medical
device.
[0031] Alternatively or additionally to any of the embodiments
above, the first medical device may comprise a first implanted
medical device and the second medical device may comprise a second
implanted medical device.
[0032] Alternatively or additionally to any of the embodiments
above, selecting a communication vector may comprise selecting the
communication vector with the strongest signal strength.
[0033] Alternatively or additionally to any of the embodiments
above, selecting a communication vector may comprise not selecting
the communication vector with the weakest signal strength.
[0034] An example communications system is also disclosed. The
example communications system comprises:
[0035] a first medical device in communication with a first antenna
having at least two electrodes; and
[0036] a second medical device in communication with a second
antenna having at least three electrodes;
[0037] wherein at least one of the first medical device and the
second medical device is configured to: [0038] test communication
vectors between the at least two electrodes of the first antenna
and at least two pairs of the at least three electrodes of the
second antenna; [0039] select a communication vector from the
tested communication vectors; and [0040] at least one of send and
receive a conducted communication along the selected communication
vector.
[0041] Alternatively or additionally to any of the embodiments
above, the at least three electrodes may comprise three electrodes
that are arranged in a triangular configuration.
[0042] Alternatively or additionally to any of the embodiments
above, the at least three electrodes may comprise four electrodes
that are arranged in a rectangular configuration.
[0043] Alternatively or additionally to any of the embodiments
above, the at least three electrodes may comprise four electrodes
that are arranged in a kite configuration.
[0044] Alternatively or additionally to any of the embodiments
above, at least one of the first medical device and the second
medical device may be implanted within a patient.
[0045] Alternatively or additionally to any of the embodiments
above, the first medical device is a leadless cardiac pacemaker
(LCP).
[0046] The above summary is not intended to describe each
embodiment or every implementation of the present disclosure.
Advantages and attainments, together with a more complete
understanding of the disclosure, will become apparent and
appreciated by referring to the following description and claims
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES
[0047] The disclosure may be more completely understood in
consideration of the following description of various illustrative
embodiments in connection with the accompanying drawings, in
which:
[0048] FIG. 1 illustrates a block diagram of an exemplary medical
device that may be used in accordance with various examples of the
present disclosure;
[0049] FIG. 2 illustrates an exemplary leadless cardiac pacemaker
(LCP) having electrodes, according to one example of the present
disclosure;
[0050] FIG. 3 shows an illustrative system that includes several
medical devices in accordance with the present disclosure;
[0051] FIG. 4 is a diagram of an illustrative electromagnetic field
that may be generated by an electrode pair;
[0052] FIG. 5 is a diagram of a portion of the electromagnetic
field of FIG. 4, illustrating different geometric arrangements of
electrodes relative to the electromagnetic field;
[0053] FIG. 6 is a schematic diagram of a medical device having an
illustrative antenna with three electrodes in accordance with
various examples of the present disclosure;
[0054] FIG. 7 is a schematic diagram of a medical device having an
illustrative antenna with four electrodes in accordance with
various examples of the present disclosure;
[0055] FIG. 8 is a schematic diagram of an illustrative arrangement
of four electrodes in accordance with various examples of the
present disclosure;
[0056] FIG. 9 is a schematic diagram of another illustrative
arrangement of four electrodes in accordance with various examples
of the present disclosure;
[0057] FIG. 10 shows an illustrative system in accordance with an
example of the present disclosure;
[0058] FIG. 11 is a flow diagram of an illustrative method for
communicating between medical devices;
[0059] FIG. 12 is a flow diagram showing another illustrative
method for communicating between medical devices;
[0060] FIG. 13 is a flow diagram showing yet another illustrative
method for communicating between medical devices; and
[0061] FIG. 14 is a flow diagram showing another illustrative
method for communicating between medical devices.
[0062] While the disclosure is amenable to various modifications
and alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit aspects
of the disclosure to the particular illustrative embodiments
described. On the contrary, the intention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the disclosure.
DETAILED DESCRIPTION
[0063] The following description should be read with reference to
the drawings in which similar elements in different drawings are
numbered the same. The description and the drawings, which are not
necessarily to scale, depict illustrative embodiments and are not
intended to limit the scope of the disclosure.
[0064] A normal, healthy heart induces contraction by conducting
intrinsically generated electrical signals throughout the heart.
These intrinsic signals cause the muscle cells or tissue of the
heart to contract. This contraction forces blood out of and into
the heart, providing circulation of the blood throughout the rest
of the body. However, many patients suffer from cardiac conditions
that affect the contractility of their hearts. For example, some
hearts may develop diseased tissues that no longer generate or
conduct intrinsic electrical signals. In some examples, diseased
cardiac tissues conduct electrical signals at differing rates,
thereby causing an unsynchronized and inefficient contraction of
the heart. In other examples, a heart may generate intrinsic
signals at such a low rate that the heart rate becomes dangerously
low. In still other examples, a heart may generate electrical
signals at an unusually high rate. In some cases such an
abnormality can develop into a fibrillation state, where the
contraction of the patient's heart is almost completely
de-synchronized and the heart pumps very little to no blood.
[0065] Many medical device systems have been developed to assist
patients who experience such abnormities. For example, systems have
been developed to sense intrinsic cardiac electrical signals and,
based on the sensed electrical signals, determine whether the
patient is suffering from one or more arrhythmias. Such systems may
also include the ability to deliver electrical stimulation to the
heart of the patient in order to treat the detected arrhythmias. In
one example, some medical device systems include the ability to
identify when the heart is beating at too low of a rate, termed
bradycardia. Such systems may deliver electrical stimulation
therapy, or "pacing" pulses, that cause the heart to contract at a
higher, safer rate. Some medical device systems are able to
determine when a heart is beating at too fast of a rate, termed
tachycardia. Such systems may further include one or more
anti-tachycardia pacing (ATP) therapies. One such ATP therapy
includes delivering electrical stimulation pulses to the heart at a
rate faster than the intrinsically generated signals. Although this
may temporarily cause the heart to beat faster, such a stimulation
protocol may cause the heart to contract in response to the
delivered pacing pulses as opposed to the intrinsically generated
signals. The ATP therapy may then slow down the rate of the
delivered pacing pulses, thereby reducing the heart rate to a
lower, safer level.
[0066] Other medical device systems may be able to detect
fibrillation states and asynchronous contractions. For example,
based on the sensed signals, some systems may be able to determine
when the heart is in a fibrillation state. Such systems may further
be configured to treat such fibrillation states with electrical
stimulation therapy. One such therapy includes deliver of a
relatively large amount of electrical energy to the heart (a
"defibrillation pulse") with the goal of overpowering any
intrinsically generated signals.
[0067] Such a therapy may "reset" the heart, from an electrical
standpoint, which may allow for normal electrical processes to take
over. Other medical systems may be able to sense that intrinsically
generated signals are generated at differing times or that the
heart conducts such signals at differing rates. These abnormalities
may result in an unsynchronized, inefficient cardiac contraction.
The system may further include the ability to administer one or
more cardiac resynchronization therapies (CRTs). One such CRT may
include delivering electrical stimulation to the heart at differing
locations on and/or within the heart. Such methods may help the
disparate parts of the heart to contract near simultaneously, or in
a synchronized manner if the system delivers the electrical
stimulation to the disparate locations at differing times. The
present disclosure relates generally to systems and methods for
coordinating detection and/or treatment of abnormal heart activity
using multiple implanted devices within a patient. In some
instances, a medical device system may include a plurality of
devices for detecting cardiac arrhythmias and delivering electrical
stimulation therapy. For example, illustrative systems may include
devices such as subcutaneous cardioverter-defibrillators (S-ICD),
external cardioverter-defibrillators, implantable cardiac
pacemakers (ICP), leadless cardiac pacemakers (LCPs), and/or
diagnostic only devices (devices that may sense cardiac electrical
signals and/or determine arrhythmias but do not deliver electrical
stimulation therapies).
[0068] FIG. 1 illustrates a block diagram of an exemplary medical
device 100 (referred to hereinafter as, MD 100) that may be used in
accordance with various examples of the present disclosure. In some
cases, the MD 100 may be used for sensing intrinsic cardiac
activity, determining occurrences of arrhythmias, and delivering
electrical stimulation in response to determining an occurrence of
an arrhythmia. In some instances, MD 100 can be implanted within a
patient's body, at a particular location (e.g., in close proximity
to the patient's heart), to sense and/or regulate the cardiac
activity of the heart. In other examples, MD 100 may be located
externally to a patient to sense and/or regulate the cardiac
activity of the heart. In one example, cardiac contractions
generally result from electrical signals that are intrinsically
generated by a heart. These electrical signals conduct through the
heart tissue, causing the muscle cells of the heart to contract. MD
100 may include features that allow MD 100 to sense such electrical
signals and/or other physical parameters (e.g. mechanical
contraction, heart sounds, blood pressure, blood-oxygen levels,
etc.) of the heart. Such electrical signals and/or physical
properties may be considered "cardiac activity." MD 100 may include
the ability to determine occurrences of arrhythmias based on the
sensed cardiac activity. In some examples, MD 100 may be able to
deliver electrical stimulation to the heart in order to treat any
detected arrhythmias. For example, MD 100 may be configured to
deliver electrical stimulation, pacing pulses, defibrillation
pulses, and/or the like in order to implement one or more
therapies, such as bradycardia therapy, ATP therapy, CRT,
defibrillation, or other electrical stimulation therapies.
[0069] FIG. 1 is an illustration of an example medical device 100.
The illustrative MD 100 may include a sensing module 102, a pulse
generator module 104, a processing module 106, a telemetry module
108, and a battery 110, all housed within a housing 120. MD 100 may
further include leads 112, and electrodes 114 attached to housing
120 and in electrical communication with one or more of the modules
102, 104, 106, and 108 housed within housing 120. Leads 112 may be
connected to and extend away from housing 120 of MD 100.
[0070] In some examples, leads 112 are implanted on or within the
heart of the patient. Leads 112 may contain one or more electrodes
114 positioned at various locations on leads 112 and distances from
housing 120. Some leads 112 may only include a single electrode 114
while other leads 112 may include multiple electrodes 114.
Generally, electrodes 114 are positioned on leads 112 such that
when leads 112 are implanted within the patient, one or more
electrodes 114 are in contact with the patient's cardiac tissue.
Accordingly, electrodes 114 may conduct intrinsically generated
electrical signals to leads 112. Leads 112 may, in turn, conduct
the received electrical signals to one or more modules 102, 104,
106, and 108 of MD 100. In a similar manner, MD 100 may generate
electrical stimulation, and leads 112 may conduct the generated
electrical stimulation to electrodes 114. Electrodes 114 may then
conduct the electrical signals to the cardiac tissue of the
patient. When discussing sensing intrinsic signals and delivering
electrical stimulation, this disclosure may consider such
conduction implicit in those processes.
[0071] Sensing module 102 may be configured to sense the cardiac
electrical activity of the heart. For example, sensing module 102
may be connected to leads 112 and electrodes 114 through leads 112
and sensing module 102 may be configured to receive cardiac
electrical signals conducted through electrodes 114 and leads 112.
In some examples, leads 112 may include various sensors, such as
accelerometers, blood pressure sensors, heart sound sensors,
blood-oxygen sensors, and other sensors which measure physiological
parameters of the heart and/or patient. In other examples, such
sensors may be connected directly to sensing module 102 rather than
to leads 112. In any case, sensing module 102 may be configured to
receive such signals produced by any sensors connected to sensing
module 102, either directly or through leads 112. Sensing modules
102 may additionally be connected to processing module 106 and may
be configured to communicate such received signals to processing
module 106.
[0072] Pulse generator module 104 may be connected to electrodes
114. In some examples, pulse generator module 104 may be configured
to generate an electrical stimulation signals to provide electrical
stimulation therapy to the heart. For example, pulse generator
module 104 may generate such a signal by using energy stored in
battery 110 within MD 100. Pulse generator module 104 may be
configured to generate electrical stimulation signals in order to
provide one or multiple of a number of different therapies. For
example, pulse generator module 104 may be configured to generate
electrical stimulation signals to provide bradycardia therapy,
tachycardia therapy, cardiac resynchronization therapy, and
fibrillation therapy. Bradycardia therapy may include generating
and delivering pacing pulses at a rate faster than the
intrinsically generated electrical signals in order to try to
increase the heart rate. Tachycardia therapy may include ATP
therapy as described herein. Cardiac resynchronization therapy may
include CRT therapy also described herein. Fibrillation therapy may
include delivering a fibrillation pulse to try to override the
heart and stop the fibrillation state. In other examples, pulse
generator 104 may be configured to generate electrical stimulation
signals to provide electrical stimulation therapies different than
those described herein to treat one or more detected
arrhythmias.
[0073] Processing module 106 can be configured to control the
operation of MD 100. For example, processing module 106 may be
configured to receive electrical signals from sensing module 102.
Based on the received signals, processing module 106 may be able to
determine occurrences of arrhythmias. Based on any determined
arrhythmias, processing module 106 may be configured to control
pulse generator module 104 to generate electrical stimulation in
accordance with one or more therapies to treat the determined one
or more arrhythmias. Processing module 106 may further receive
information from telemetry module 108. In some examples, processing
module 106 may use such received information in determining whether
an arrhythmia is occurring or to take particular action in response
to the information. Processing module 106 may additionally control
telemetry module 108 to send information to other devices.
[0074] In some examples, processing module 106 may include a
pre-programmed chip, such as a very-large-scale integration (VLSI)
chip or an application specific integrated circuit (ASIC). In such
embodiments, the chip may be pre-programmed with control logic in
order to control the operation of MD 100. By using a pre-programmed
chip, processing module 106 may use less power than other
programmable circuits while able to maintain basic functionality,
thereby increasing the battery life of MD 100. In other examples,
processing module 106 may include a programmable microprocessor.
Such a programmable microprocessor may allow a user to adjust the
control logic of MD 100, thereby allowing for greater flexibility
of MD 100 than when using a pre-programmed chip. In some examples,
processing module 106 may further include a memory circuit and
processing module 106 may store information on and read information
from the memory circuit. In other examples, MD 100 may include a
separate memory circuit (not shown) that is in communication with
processing module 106, such that processing module 106 may read and
write information to and from the separate memory circuit.
[0075] Telemetry module 108 may be configured to communicate with
devices such as sensors, other medical devices, or the like, that
are located externally to MD 100. Such devices may be located
either external or internal to the patient's body. Irrespective of
the location, external devices (i.e. external to the MD 100 but not
necessarily external to the patient's body) can communicate with MD
100 via telemetry module 108 to accomplish one or more desired
functions. For example, MD 100 may communicate sensed electrical
signals to an external medical device through telemetry module 108.
The external medical device may use the communicated electrical
signals in determining occurrences of arrhythmias. MD 100 may
additionally receive sensed electrical signals from the external
medical device through telemetry module 108, and MD 100 may use the
received sensed electrical signals in determining occurrences of
arrhythmias. Telemetry module 108 may be configured to use one or
more methods for communicating with external devices. For example,
telemetry module 108 may communicate via radiofrequency (RF)
signals, inductive coupling, optical signals, acoustic signals,
conducted communication signals, or any other signals suitable for
communication. Communication techniques between MD 100 and external
devices will be discussed in further detail with reference to FIG.
3 below.
[0076] Battery 110 may provide a power source to MD 100 for its
operations. In one example, battery 110 may be a non-rechargeable
lithium-based battery. In other examples, the non-rechargeable
battery may be made from other suitable materials know in the art.
Because, in examples where MD 100 is an implantable device, access
to MD 100 may be limited, it is necessary to have sufficient
capacity of the battery to deliver sufficient therapy over a period
of treatment such as days, weeks, months, or years. In other
examples, battery 110 may a rechargeable lithium-based battery in
order to facilitate increasing the useable lifespan of MD 100.
[0077] In general, MD 100 may be similar to one of a number of
existing medical devices. For example, MD 100 may be similar to
various implantable medical devices. In such examples, housing 120
of MD 100 may be implanted in a transthoracic region of the
patient. Housing 120 may generally include any of a number of known
materials that are safe for implantation in a human body and may,
when implanted, hermetically seal the various components of MD 100
from fluids and tissues of the patient's body.
[0078] In some examples, MD 100 may be an implantable cardiac
pacemaker (ICP). In such an example, MD 100 may have one or more
leads, for example leads 112, which are implanted on or within the
patient's heart. The one or more leads 112 may include one or more
electrodes 114 that are in contact with cardiac tissue and/or blood
of the patient's heart. MD 100 may also be configured to sense
intrinsically generated cardiac electrical signals and determine,
for example, one or more cardiac arrhythmias based on analysis of
the sensed signals. MD 100 may further be configured to deliver
CRT, ATP therapy, bradycardia therapy, defibrillation therapy
and/or other therapy types via leads 112 implanted within the
heart.
[0079] In some instances, MD 100 may be a subcutaneous
cardioverter-defibrillator (S-ICD). In such examples, one of leads
112 may include a subcutaneously implanted lead. In some cases, MD
100 may be configured to sense intrinsically generated cardiac
electrical signals and determine one or more cardiac arrhythmias
based on analysis of the sensed signals. MD 100 may further be
configured to deliver one or more defibrillation pulses in response
to determining an arrhythmia.
[0080] In still other examples, MD 100 may be a leadless cardiac
pacemaker (LCP--described more specifically with respect to FIG.
2). In such examples, MD 100 may not include leads 112 that extend
away from housing 120. Rather, MD 100 may include electrodes 114
coupled relative to the housing 120. In these examples, MD 100 may
be implanted on or within the patient's heart at a desired
location, and may be configured to deliver CRT, ATP therapy,
bradycardia therapy, and/or other therapy types via electrodes
114.
[0081] In some instances, MD 100 may be a diagnostic-only device.
In some cases, MD 100 may be configured to sense, or receive,
cardiac electrical signals and/or physical parameters such as
mechanical contraction, heart sounds, blood pressure, blood-oxygen
levels, etc. MD 100 may further be configured to determine
occurrences of arrhythmias based on the sensed or received cardiac
electrical signals and/or physical parameters. In one example, MD
100 may do away with pulse generation module 104, as MD 100 may not
be configured to deliver electrical stimulation in response to
determining an occurrence of an arrhythmia. Rather, in order to
respond to detected cardiac arrhythmias,
[0082] MD 100 may be part of a system of medical devices. In such a
system, MD 100 may communicate information to other devices within
the system and one or more of the other devices may take action,
for example delivering electrical stimulation therapy, in response
to the receive information from MD 100. The term pulse generator
may be used to describe any such device that is capable of
delivering electrical stimulation therapy to the heart, such as an
ICD, ICP, LCP, or the like. In some instances, the MD 100 may be a
neural stimulation device, or any other medical device, as
desired.
[0083] In some example, MD 100 may not be an implantable medical
device. Rather, MD 100 may be a device external to the patient's
body, and may include skin-electrodes that are placed on a
patient's body. In such examples, MD 100 may be able to sense
surface cardiac electrical signals (e.g. electrical signals that
are generated by the heart or device implanted within a patient's
body and conducted through the body to the skin) In such examples,
MD 100 may still be configured to deliver various types of
electrical stimulation therapy. In other examples, however, MD 100
may be a diagnostic-only device, a neurostimulator, and/or other
implantable medical devices.
[0084] FIG. 2 is an illustration of an exemplary leadless cardiac
pacemaker (LCP) 200. In the example shown, LCP 200 may include all
of the modules and components of MD 100, except that LCP 200 may
not include leads 112. As can be seen in FIG. 2, LCP 200 may be a
compact device with all components housed within LCP 200 or
directly on housing 220. As illustrated in FIG. 2, LCP 200 may
include telemetry module 202, pulse generator module 204,
processing module 210, and battery 212. Such components may have a
similar function to the similarly named modules and components as
discussed in conjunction with MD 100 of FIG. 1.
[0085] In some examples, LCP 200 may include electrical sensing
module 206 and mechanical sensing module 208. Electrical sensing
module 206 may be similar to sensing module 102 of MD 100. For
example, electrical sensing module 206 may be configured to receive
electrical signals generated intrinsically by the heart. Electrical
sensing module 206 may be in electrical connection with electrodes
214, which may conduct the intrinsically generated electrical
signals to electrical sensing module 206. Mechanical sensing module
208 may be configured to receive one or more signals representative
of one or more physiological parameters of the heart. For example,
mechanical sensing module 208 may include, or be in electrical
communication with one or more sensors, such as accelerometers,
blood pressure sensors, heart sound sensors, blood-oxygen sensors,
and other sensors which measure physiological parameters of the
patient. Although described with respect to FIG. 2 as separate
sensing modules, in some examples, electrical sensing module 206
and mechanical sensing module 208 may be combined into a single
module.
[0086] In at least one example, each of modules 202, 204, 206, 208,
and 210 illustrated in FIG. 2 may be implemented on a single
integrated circuit chip. In other examples, the illustrated
components may be implemented in multiple integrated circuit chips
that are in electrical communication with one another. All of
modules 202, 204, 206, 208, and 210 and battery 212 may be
encompassed within housing 220. Housing 220 may generally include
any material that is known as safe for implantation within a human
body and may hermetically seal modules 202, 204, 206, 208, and 210
and battery 212 from fluids and tissues when LCP 200 is implanted
within a patient.
[0087] As depicted in FIG. 2, LCP 200 may include electrodes 214,
which can be secured relative to housing 220 but exposed to the
tissue and/or blood surrounding the LCP 200. As such, electrodes
214 may be generally disposed on either end of LCP 200 and may be
in electrical communication with one or more of modules 202, 204,
206, 208, and 210. In some examples, electrodes 214 may be
connected to housing 220 only through short connecting wires such
that electrodes 214 are not directly secured relative to housing
220. In some examples, LCP 200 may additionally include one or more
electrodes 214'. Electrodes 214' may be positioned on the sides of
LCP 200 and increase the number of electrodes by which LCP 200 may
sense cardiac electrical activity and/or deliver electrical
stimulation. Electrodes 214 and/or 214' can be made up of one or
more biocompatible conductive materials such as various metals or
alloys that are known to be safe for implantation within a human
body. In some instances, electrodes 214 and/or 214' connected to
LCP 200 may have an insulative portion that electrically isolates
the electrodes 214 from, adjacent electrodes, the housing 220,
and/or other materials.
[0088] To implant LCP 200 inside patient's body, an operator (e.g.,
a physician, clinician, etc.), may need to affix LCP 200 to the
cardiac tissue of the patient's heart. To facilitate fixation, LCP
200 may include one or more anchors 216. Anchor 216 may be any one
of a number of fixation or anchoring mechanisms. For example,
anchor 216 may include one or more pins, staples, threads, screws,
helix, tines, and/or the like. In some examples, although not
shown, anchor 216 may include threads on its external surface that
may run along at least a partial length of anchor 216. The threads
may provide friction between the cardiac tissue and the anchor to
help fix anchor 216 within the cardiac tissue. In other examples,
anchor 216 may include other structures such as barbs, spikes, or
the like to facilitate engagement with the surrounding cardiac
tissue.
[0089] The design and dimensions of MD 100 and LCP 200, as shown in
FIGS. 1 and 2, respectively, can be selected based on various
factors. For example, if the medical device is for implant on the
endocardial tissue, such as is sometimes the case of an LCP, the
medical device can be introduced through a femoral vein into the
heart. In such instances, the dimensions of the medical device may
be such as to be navigated smoothly through the tortuous path of
the vein without causing any damage to surrounding tissue of the
vein. According to one example, the average diameter of the femoral
vein may be between about 4 millimeters (mm) to about 8 mm. For
navigation to the heart through the femoral vein, the medical
device can have a diameter of less than 8 mm In some examples, the
medical device can have a cylindrical shape having a circular
cross-section. However, it should be noted that the medical device
can be made of any other suitable shape such as rectangular, oval,
etc. A flat, rectangular-shaped medical device with a low profile
may be desired when the medical device is designed to be implanted
subcutaneously.
[0090] While IMD 100 and LCP 200 are described as suitable example
medical devices, it is contemplated that the present disclosure is
applicable more broadly to communication between any two (or more)
medical devices.
[0091] FIG. 3 is a schematic illustration of a medical device
system 300. As illustrated, medical device system 300 includes a
first MD 310, a second MD 320 and a third MD 330. Each of MD 310,
MD 320 and MD 330 can represent any of a variety of different
medical devices that are configured to deliver electrical
stimulation, pacing pulses, defibrillation pulses, or the like in
order to implement one or more therapies, such as ATP therapy, CRT,
or other electrical stimulation therapies, or are diagnostic only
or other medical devices, as desired. Each of MD 310, MD 320 and MD
330 can include leads or be leadless. It will be appreciated that
while three medical devices are shown in FIG. 3, system 300 may
include just one or two medical devices, or may include four or
more medical devices, depending on the particular application.
[0092] In some embodiments, each of MD 310, MD 320 and MD 330, if
present, may be implanted and/or positioned proximate the patient.
In some embodiments, MD 310 may be implanted, MD 320 may be
external to the patient and MD 330 may be optional. MD 320 may
include a skin patch including two or more electrodes. In some
cases, one or more of MD 310, MD 320 and MD 330 may be a medical
device programmer or communicator that is configured to communicate
with and/or program one or more implanted medical device. For
example, MD 320 may be a medical device programmer or communicator
that is configured to communicate with and/or program one or more
implanted medical device - such as MD 310 and MD 330. In some
embodiments, MD 310 may be implanted within the patient and MD 320
and/or MD 330 may also be implanted within the patient but be
spaced apart from MD 310 and from each other.
[0093] As illustrated, MD 310 includes a first electrode 312 and a
second electrode 314. MD 320 includes a first electrode 322, a
second electrode 324 and a third electrode 326. MD 330 includes a
first electrode 332, a second electrode 334, a third electrode 336
and a fourth electrode 338. In this example, MD 310 has a single
electrode pair 315 that can be used to sense, pace and/or
communicate with another medical device. MD 320 has a first
electrode pair 325 between first electrode 322 and second electrode
324, a second electrode pair 327 between second electrode 324 and
third electrode 326, and a third electrode pair 329 between first
electrode 322 and third electrode 326 that can each be used, either
individually or in combination, to sense, pace and/or communicate
with another medical device. MD 330 has a first electrode pair 333
between first electrode 332 and second electrode 334, a second
electrode pair 335 between second electrode 334 and third electrode
336, a third electrode pair 337 between third electrode 336 and
fourth electrode 338, a fourth electrode pair 339 between first
electrode 332 and fourth electrode 338, a fifth electrode pair 331
between first electrode 332 and third electrode 336 and a sixth
electrode pair 341 between second electrode 334 and fourth
electrode 338 that can each be used, either individually or in
combination, to sense, pace and/or communicate with another medical
device.
[0094] It will be appreciated that the relative signal strength
received at a particular electrode pair can be a function of, at
least in part, the relative orientation of the electrode pair
relative to the electromagnetic field that is being generated by a
transmitting electrode pair. FIG. 4 is a stylized or idealized
electromagnetic field 400 generated by an electrode pair, which
includes a cathode electrode 410 and an anode electrode 420. This
is a stylized electromagnetic field 400 as it would appear in a
homogenous conducting medium. As the patient's tissue near and
around medical devices is not homogenous, the actual
electromagnetic field would vary from that shown. The
electromagnetic field 400 can be considered as including
equipotential lines 430 and electric field lines 440. FIG. 5
provides an enlarged portion 500 illustrating the effects of
electrode orientation relative to the equipotential lines 430 and
the electric field lines 440.
[0095] In the illustration of FIG. 5, it is assumed that a medical
device includes a first electrode 510, a second electrode 520 and a
third electrode 530. A first electrode pair vector A may be
considered as existing between first electrode 510 and second
electrode 520. A second electrode pair vector B may be considered
as existing between first electrode 510 and third electrode 530. A
third electrode pair vector C may be considered as existing between
second electrode 520 and third electrode 530. It will be
appreciated that the relative signal strength between one of
electrode pair vectors A, B and C will be influenced by the angle
between the receiving antenna (one of the electrode pair vectors A,
B and C) and the local electric field produced by the transmitting
antenna (cathode 410 and anode 420 as shown in FIG. 4). As can be
seen, the received signal will be the signal strength times the
cosine of the angle 0 between the corresponding electrode pair
vector A, B or C and the electric field lines 440. The electrode
pair vectors each represent a pair of electrodes of the medical
device. A particular one the electrode pairs A, B, or C selected
for communication, in combination with an electrode pair of the
transmitting antenna (e.g. cathode 410 and anode 420 as shown in
FIG. 4) can be considered a "communication vector".
[0096] As illustrated, electrode pair vector A forms an angle OA
that is 90 degrees. As the cosine of 90 degrees is zero, electrode
pair vector A (between first electrode 510 and second electrode
520) would not receive a signal. Electrode pair vector B forms an
angle AB that is 15 degrees. The cosine of 15 degrees is 0.97, and
thus electrode pair vector B would receive a signal that is 97% of
the strength of the signal at that location. Electrode pair vector
C forms an angle Ac that is 45 degrees. The cosine of 45 degrees is
0.71, and thus electrode pair vector C would receive a signal that
is 71% of the strength of the signal at that location. It will be
appreciated, therefore, that by having several electrode pairs, or
electrode pair vectors, to choose from may facilitate the devices
MD 310, MD 320 and MD 330 of system 300 (FIG. 3) in selecting an
electrode pair or electrode pair vector that helps increase the
relative signal strength and/or signal-to-noise ratio for
communication therebetween. The angles shown in FIG. 5 are
illustrative only, as in practice the medical device that includes
electrodes 510, 520 and 530 may have any particular orientation
with respect to electromagnetic field 400 (FIG. 4), and the
orientation may change over time as the patient breathes, the heart
pumps, or the patient otherwise moves. It is contemplated that a
medical device may have two, three, four or more electrodes that
can be utilized in pairs to help improve communication between
medical devices.
[0097] FIG. 6 illustrates a medical device (MD) 600 that includes a
first electrode 610, a second electrode 620 and a third electrode
630. A total of three electrode pair vectors 640, 650 and 660 may
be formed using the three electrodes of MD 600. MD 600 may
represent an implanted medical device or an external medical
device. MD 600 may, in some cases, represent an external patch that
is secured to the skin of a patient, and may communicate with an
implanted medical device such as a leadless cardiac pacemaker
(LCP). As illustrated, electrodes 610, 620 and 630 are equally
spaced forming an equilateral triangle. In some embodiments,
electrodes 610, 620 and 630 may instead be unequally spaced,
thereby forming a non-equilateral triangle.
[0098] FIG. 7 illustrates a medical device (MD) 700 that includes a
first electrode 710, a second electrode 720, a third electrode 730
and a fourth electrode 740. In FIG. 7, a total of 6 electrode pair
vectors 750, 752, 754, 756, 758 and 760 may be formed using the
electrodes of MD 700. MD 700 may represent an implanted medical
device or an external medical device. MD 700 may, for example,
represent an external patch that is secured to the skin of a
patient. As illustrated, electrodes 710, 720, 730 and 740 are
spaced about MD 700 in a kite pattern. In some embodiments,
electrodes 710, 720, 730 and 740 may instead be spaced about MD 700
in a variety of different patterns. It will be appreciated that the
relative angles between pairs of electrodes 710, 720, 730 and 740
may be varied by altering the relative dimensions, i.e., length
and/or width of the spacings between the electrodes of MD 700.
[0099] FIGS. 8 and 9 provide additional examples of possible
electrode pair vector angles in medical devices having 4 electrodes
arranged in a rectilinear configuration (FIG. 8) or in a kite like
configuration (FIG. 9). It will be appreciated that these are
illustrative only, as the angles in FIG. 8 may be altered by
changing the relative length and width of a square or rectangle
extending through the four electrodes. Similarly, the angles in
FIG. 9 may be altered by changing the relative length and width of
a kite-shape extending through the four electrodes.
[0100] It can be seen that having two electrodes can provide a
situation in which there can be no or substantially no signal
strength at the location of a receiving antennae, depending on
orientation of the receiving antennae relative to the emitted
electric field. Having three electrodes provides three possible
electrode pair vectors that can be selected, whereby selecting the
electrode pair vector with the greatest signal strength, may help
improve the signal strength received by the receiving antennae.
Having four electrodes provides six possible electrode pair vectors
that can be selected. In some cases, and to provide even more
vectors, two or more of the electrodes may be effectively shorted
together so that the shorted electrodes collectively act as an
electrode. For example, and specifically with respect to FIG. 7,
electrodes 730 and 740 may be effectively shorted together and may
act as a single electrode (e.g. anode), and electrode 710 or
electrode 720 may act as the other electrode (e.g. the cathode).
This is just one example.
[0101] In some instances, the medical devices described herein,
including MD 100, LCP 200, MD 310, MD 320, MD 330, MD 600 or MD 700
may be programmed or otherwise configured to test various
communication vectors and to select the appropriate communication
vector for communication. In some embodiments, the strongest
communication vector may be selected. In some embodiments, the
weakest communication vector may be excluded from use. In some
embodiments, depending on the purpose of the communication, several
communication vectors may be used in combination.
[0102] In some instances, one vector may be used during a first
part of a single communication and a second vector may be used
during a second part of the communication. This may occur when, for
example, a device programmer or an S-ICD is communicating with a
LCP. The LCP may be moving during each beat of the heart, and the
angles between the various electrodes may change over time. In some
cases, it may be advantageous to use a first vector to start
communication, and then as the LCP moves, switch to a second vector
to complete the communication.
[0103] Alternatively, or in addition, communication may be
simultaneously performed using two or more vectors. This may
provide one or more redundant communication paths, so that if one
communication path becomes less effective or drops out, then the
redundant communication path(s) can be used. For example, and
specifically with respect to FIG. 7, communication may be
simultaneously performed using a first vector 754 extending between
electrodes 730 and 740 and a second vector 758 extending between
electrodes 720 and 740. Then, if communication using the first
vector 754 becomes less effective or drops out, the system can
still communicate using the second vector 758. In some cases,
communication may be performed simultaneously using both vectors,
and the system may select the communication path with the highest
signal strength, the communication path that provided successful
transmission, and/or may use any other criteria for selecting from
the two or more communication paths. In some cases, a communication
may be performed using multiple vectors, and the results may be
compared. If there is no difference in the results, then either
result may be used. If there is a difference, other criteria may be
used to help identify the correct result. For example, a parity bit
and/or checksum may be used to identify which transmissions were
successful. If no transmissions were successful, a signal may be
sent notifying the sender to repeat the transmission using a
different vector or set of vectors.
[0104] FIG. 10 provides an illustrative medical system in which an
LCP 782 is shown fixed to the interior of the left ventricle of a
heart 788 and an LCP 784 is shown fixed to the interior of the
right ventricle of heart 788. In some embodiments, there may be
additional LCPs implanted in heart 788. In other cases, there may
only be one LCP, such as LCP 784. In some embodiments, one or more
LCPs may be fixed to the exterior of the heart 788. In FIG. 10, an
example SICD 786 is shown. The example SICD 786 includes a lead 790
bearing one or more electrodes 792, 794 and 796. In some
embodiments, the lead 790 may include more than three electrodes.
In some cases, once lead 790 has been implanted, electrodes 792,
794 and 796 may be considered as being aligned vertically proximate
the patient's sternum. Optionally, an additional electrode may be
disposed on a horizontal (once implanted) portion of lead 790. It
will be appreciated that as illustrated, SICD 786 may be considered
as having a total of four electrodes, as the housing of SICD 786
may also function as an electrode. In some instances, lead 790 may
be positioned subcutaneously adjacent heart 788. In some cases, the
illustrative medical system may include an external patch such as
MD 700 previously discussed with respect to FIG. 7 for connecting
to, for example, an external medical device.
[0105] In some cases, there may be a desire for communication
between two or more of LCP 782, LCP 784, SICD 786 and/or an MD 700.
It will be appreciated, for example, that for communication between
the LCP 782 and MD 700, there may be a total of four (or more)
electrodes on MD 700 and two to four (or more) electrodes on LCP
782, and thus many different communication vectors may be tested
and selected as discussed previously. In some cases, particularly
in conducting communication between SICD 786 and any of the other
devices shown, it will be appreciated that electrodes 792, 794 and
796 are arranged in a largely linear fashion near a distal end of
lead 790. Accordingly, in some cases, selecting between these three
electrodes for use in a communication vector with an LCP 872 or 784
may not substantially change the geometry of the vector and thus
may not substantially improve the communication vector. In some
embodiments, communication with SICD 786 may benefit from also
considering one or more can electrodes, such as can electrode 797
of the SICD 786. When so provided, the SICD may have four different
electrodes 792, 794, 796 and 797, and each LCP 782 and 784 may have
two to four (or more) electrodes. This may provide many vectors to
choose from with a variety of different vector geometries.
Alternatively, or in addition, the SICD electrodes 792, 794 and 796
may be arranged in a non-linear manner, such as in a
cross-pattern.
[0106] One or all of the electrodes 792, 794, 796, 797 and the SCID
786 housing may be used only for communication; alternatively one
or all of the electrodes 792, 794, 796, 797 and the SCID 786
housing may also be used for other purposes such as sensing a
physiological parameter (e.g. intrinsic cardiac activity, thoracic
impedance) and/or delivering one or more electrical therapies (e.g.
cardioversion/defibrillation shocks, cardiac paces, neural
stimulation energy).
[0107] In some cases, it will be appreciated that which specific
vector or vectors are most useful for communicating between any
particular pair of devices may change over time. For example, LCP
782 and/or LCP 784, if present, may move and change orientation
somewhat with each heartbeat. As the patient breathes, and their
chest rises and falls, the SICD 786 and an external device such as
MD 700 may also move. Accordingly, in some embodiments, it may be
advantageous to use a first vector for part of a communication, and
then as one or more devices move relative to one another, such as
with the heartbeat and/or patient respiration, switch to a second
vector to continue the communication. In some cases, signal
strength, error rate and/or communication parameter may be
monitored over time, and the vector may be automatically switched
if desired. While a first and second vector are used here an
example, it is contemplated that the system may switch between more
than two different vectors if desired. It is contemplated that the
vectors may be switched in real or near real time, and/or may be
updated from time to time, e.g. every minute, hour, day, month,
each doctor visit, and/or any other suitable time.
[0108] FIG. 11 is a flow diagram showing an illustrative method
1000 that may be carried out via any of the medical devices
described herein, including MD 100, LCP 200,
[0109] MD 310, MD 320, MD 330, MD 600 or MD 700. At block 1010, a
first electrode pair of an antenna having at least three electrodes
is selected. A communication signal, such as a conducted
communication signal, may be sent through tissue of the patient
between the first electrode pair of the antenna having at least
three electrodes and two electrodes of another antenna, as
generally seen at block 1020. At block 1030, a second electrode
pair of the antenna having at least three electrodes is selected.
The second electrode pair selected being different from the first
selected electrode pair. A communication signal is again sent
through tissue of the patient between the first electrode pair of
the antenna having at least three electrodes and two electrodes of
another antenna, as generally seen at block 1040.
[0110] FIG. 12 is a flow diagram showing an illustrative method
1100 that may be carried out via any of the medical devices
described herein, including MD 100, LCP 200, MD 310, MD 320, MD
330, MD 600 or MD 700. At block 1110, a first electrode pair of an
antenna having at least three electrodes is selected. A
communication signal is sent through tissue of the patient between
the first electrode pair of the antenna having at least three
electrodes and two electrodes of another antenna, as generally seen
at block 1120. At block 1130, a second electrode pair of the
antenna that has at least three electrodes is selected. The second
electrode pair is different from the first selected electrode pair.
A communication signal may be sent through tissue of the patient
between the first electrode pair of the antenna having at least
three electrodes and two electrodes of another antenna, as
generally seen at block 1140.
[0111] During operation, and as seen at block 1150, a measure
related to a signal-to-noise ratio of the conducted communication
signal using the first electrode pair may be monitored. If the
measure related to the signal-to-noise ratio falls below a
threshold or changes by more than a threshold, the second electrode
pair of the antenna having at least three electrodes is selected,
as generally shown at block 1160. At block 1170, a communication
signal may then be sent through tissue of the patient between the
second electrode pair of the antenna having at least three
electrodes and the two electrodes of the other antenna.
[0112] FIG. 13 is a flow diagram showing an illustrative method
1200 that may be carried out via any of the medical devices
described herein, including MD 100, LCP 200,
[0113] MD 310, MD 320, MD 330, MD 600 or MD 700. At block 1210, a
first electrode pair of an antenna having at least three electrodes
is selected. A communication signal is sent through tissue of the
patient between the first electrode pair of the antenna having at
least three electrodes and two electrodes of another antenna, as
generally seen at block 1220. At block 1230, a second electrode
pair of the antenna that has at least three electrodes is selected.
The second electrode pair is different from the first selected
electrode pair. A communication signal is sent through tissue of
the patient between the first electrode pair of the antenna having
at least three electrodes and two electrodes of another antenna, as
generally seen at block 1240.
[0114] During operation, and as block 1280, a first measure related
to a signal-to-noise ratio of the communication signal using the
first electrode pair is determined. A second measure related to a
signal-to-noise ratio of the communication signal using the second
electrode pair is determined, as generally indicated at block 1290.
At block 1292, the first electrode pair or the second electrode
pair is selected for subsequent communication based on the first
measure and the second measure.
[0115] FIG. 14 a flow diagram showing an illustrative method 1300
that may be carried out via any of the medical devices described
herein, including MD 100, LCP 200, MD 310, MD 320, MD 330, MD 600
or MD 700. At block 1310, communication vectors are tested between
at least two electrodes of a first antenna and each of a plurality
of pairs of electrodes of a second antenna that has at least three
electrodes. In an embodiment, a communication vector is tested
periodically, for example once per second, minute, day or month. In
another embodiment, a communication vector is tested only when a
communication parameter fails to meet a predetermined criteria. In
some embodiments, a communication vector is tested during an office
visit. In other embodiments, a communication vector is tested
during an interaction between a medical device and an external
system that is configured to provide device or patient data to a
clinician at a remote location. A communication vector is selected
based on a communication parameter of one or more of the
communication vectors, as generally indicated at block 1320. The
communication parameter could, for example, be an absolute signal
strength, a relative signal strength and/or a signal-to-noise
ratio, or any other parameter affecting or potentially affecting
communication. At block 1330, a conducted communication is sent
between a first medical device and a second medical device using
the selected communication vector.
[0116] As detailed above, the medical devices referenced herein may
by any suitable medical device. In some non-limiting example, the
methods 1000, 1100, 1200, 1300 may be used in communication between
an LCP and a medical device programmer or communicator, an LCP and
an Sub-coetaneous Implantable Cardioverter Defibrillator (SICD), an
LCP and a co-implanted diagnostic device, an LCP and a
neurostimulator device, an LCP and another LCP, and/or between any
other suitable medical devices, as desired.
[0117] In some embodiments, any of these methods described herein
could embody receiving a communication instead or, or in addition
to, sending a communication signal. In some embodiments, a
selection or determination of a communication vector used for
sending a communication signal may be the same as a communication
vector used for receiving a communication signal. In some
embodiments, a selection or determination of a communication vector
used for sending a communication signal may be different than a
communication vector used for receiving a communication signal.
[0118] Those skilled in the art will recognize that the present
disclosure may be manifested in a variety of forms other than the
specific embodiments described and contemplated herein. As one
example, as described herein, various examples include one or more
modules described as performing various functions. However, other
examples may include additional modules that split the described
functions up over more modules than that described herein.
Additionally, other examples may consolidate the described
functions into fewer modules. Accordingly, departure in form and
detail may be made without departing from the scope and spirit of
the present disclosure as described in the appended claims.
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