U.S. patent application number 17/020210 was filed with the patent office on 2020-12-31 for dynamically adjustable multiphasic defibrillator pulse system and method.
This patent application is currently assigned to CardioThrive, Inc.. The applicant listed for this patent is CardioThrive, Inc.. Invention is credited to Peter D. Gray, Douglas M. Raymond, Shelley J. Savage, Walter T. Savage.
Application Number | 20200406045 17/020210 |
Document ID | / |
Family ID | 1000005086890 |
Filed Date | 2020-12-31 |
United States Patent
Application |
20200406045 |
Kind Code |
A1 |
Raymond; Douglas M. ; et
al. |
December 31, 2020 |
DYNAMICALLY ADJUSTABLE MULTIPHASIC DEFIBRILLATOR PULSE SYSTEM AND
METHOD
Abstract
A dynamically adjustable multiphasic pulse system and method are
provided. The dynamically adjustable multiphasic pulse system may
be used as pulse system for a defibrillator or cardioverter.
Inventors: |
Raymond; Douglas M.;
(Livermore, CA) ; Gray; Peter D.; (Vallejo,
CA) ; Savage; Walter T.; (Concord, CA) ;
Savage; Shelley J.; (Concord, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CardioThrive, Inc. |
Concord |
CA |
US |
|
|
Assignee: |
CardioThrive, Inc.
Concord
CA
|
Family ID: |
1000005086890 |
Appl. No.: |
17/020210 |
Filed: |
September 14, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15853552 |
Dec 22, 2017 |
10773090 |
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17020210 |
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15484055 |
Apr 10, 2017 |
9855440 |
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15853552 |
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14303541 |
Jun 12, 2014 |
9616243 |
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15484055 |
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14303541 |
Jun 12, 2014 |
9616243 |
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15484055 |
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61835443 |
Jun 14, 2013 |
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61835443 |
Jun 14, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 1/3625 20130101;
A61N 1/36125 20130101; A61N 1/3906 20130101; A61N 1/3912 20130101;
A61N 1/36153 20130101; A61N 1/3904 20170801 |
International
Class: |
A61N 1/39 20060101
A61N001/39; A61N 1/362 20060101 A61N001/362; A61N 1/36 20060101
A61N001/36 |
Claims
1. A multiphasic pulse generator, comprising: a plurality of
subsystems wherein each subsystem has a power source and an energy
reservoir; at least one of the plurality of subsystems that
generates a first phase of a pulse that has a shape and is one of a
positive phase of the pulse and a negative phase of the pulse; at
least one of the plurality of subsystems that generates a second
phase of the pulse that has a shape and is an opposite polarity
phase to the first phase of the pulse; and a switch element that
switches between the subsystems to generate a therapeutic pulse
having at least one positive phase and at least one negative
phase.
2. The generator of claim 1, wherein each subsystem further
comprises a circuit that adjusts the shape of the phase of the
pulse.
3. The generator of claim 2, wherein the circuit includes an array
of selectable resistors.
4. The generator of claim 2, wherein the circuit includes an array
of selectable resistors.
5. The generator of claim 1, wherein the switch element further
comprises a high voltage switch element.
6. The generator of claim 5, wherein the high voltage switch
element further comprises one or more semiconductor circuits.
7. The generator of claim 6, wherein the one or more semiconductor
circuits further comprises one or more insulated gate bipolar
transistors.
8. The generator of claim 1, wherein each subsystem further
comprises control logic to control the generation of the phase of
the pulse.
9. The generator of claim 8, wherein each of the control logic
further comprises a lookup table to select the pulse shape
10. A method for generating a therapeutic pulse, comprising:
providing a plurality of subsystems wherein each subsystem has a
power source and an energy reservoir; using one of the plurality of
subsystems to generate one or more positive phases for a pulse;
using a different one of the plurality of subsystems to generate
one or more negative phases for a pulse using a second power source
and a second energy reservoir; and switching between the one or
more positive phases and the one or more negative phases to
generate a therapeutic pulse having at least one positive phase and
at least one negative phase.
11. The method of claim 10 further comprising adjusting a shape of
each of the one or more negative phases and independently adjusting
a shape of each of the one or more positive phases.
12. The method of claim 10 further comprising individually
selecting an amplitude of one or more of the one or more positive
phases and one or more negative phases of the pulse.
13. The method of claim 10 further comprising recharging the energy
reservoir when the energy reservoir is not being discharged.
14. The method of claim 10 further comprising recharging the second
energy reservoir when the second energy reservoir is not being
discharged.
15. The method of claim 10 further comprising alternating between
the one or more positive phases and the one or more negative phases
when generating the therapeutic pulse.
16. The method of claim 10, wherein generating the therapeutic
pulse further comprises selecting a shape of the therapeutic pulse
using a lookup table.
Description
PRIORITY CLAIMS/RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 120 and is a
continuation of U.S. patent application Ser. No. 15/853,552 filed
Dec. 22, 2017 that claims priority under 35 USC 120 and is a
continuation of U.S. patent application Ser. No. 15/484,055, filed
Apr. 10, 2017 and titled "Dynamically Adjustable Multiphasic
Defibrillator Pulse System And Method" (now U.S. Pat. No. 9,855,440
issued Jan. 2, 2018) that in turn claims priority under 35 USC 120
and is a continuation of U.S. patent application Ser. No.
14/303,541, filed Jun. 12, 2014 and titled "Dynamically Adjustable
Multiphasic Defibrillator Pulse System And Method" (now U.S. Pat.
No. 9,616,243 issued on Apr. 11, 2017) which in turn claims
priority under 35 USC 120 and claims the benefit under 35 USC
119(e) to U.S. Provisional Patent Application Ser. No. 61/835,443
filed Jun. 14, 2013 and titled "Dynamically Adjustable Multiphasic
Defibrillator Pulse System and Method", the entirety of all of
which are incorporated herein by reference.
FIELD
[0002] The disclosure relates to medical devices and in particular
to devices and methods that generate therapeutic treatment pulses
used in medical devices, such as cardioverters and
defibrillators.
BACKGROUND
[0003] A primary task of the heart is to pump oxygenated,
nutrient-rich blood throughout the body. Electrical impulses
generated by a portion of the heart regulate the pumping cycle.
When the electrical impulses follow a regular and consistent
pattern, the heart functions normally and the pumping of blood is
optimized. When the electrical impulses of the heart are disrupted
(i.e., cardiac arrhythmia), this pattern of electrical impulses
becomes chaotic or overly rapid, and a sudden cardiac arrest may
take place, which inhibits the circulation of blood. As a result,
the brain and other critical organs are deprived of nutrients and
oxygen. A person experiencing sudden cardiac arrest may suddenly
lose consciousness and die shortly thereafter if left
untreated.
[0004] The most successful therapy for sudden cardiac arrest is
prompt and appropriate defibrillation. A defibrillator uses
electrical shocks to restore the proper functioning of the heart. A
crucial component of the success or failure of defibrillation,
however, is time. Ideally, a victim should be defibrillated
immediately upon suffering a sudden cardiac arrest, as the victim's
chances of survival dwindle rapidly for every minute without
treatment.
[0005] There are a wide variety of defibrillators. For example,
implantable cardioverter-defibrillators (ICD) involve surgically
implanting wire coils and a generator device within a person. ICDs
are typically for people at high risk for a cardiac arrhythmia.
When a cardiac arrhythmia is detected, a current is automatically
passed through the heart of the user with little or no intervention
by a third party.
[0006] Another, more common type of defibrillator is the automated
external defibrillator (AED). Rather than being implanted, the AED
is an external device used by a third party to resuscitate a person
who has suffered from sudden cardiac arrest. FIG. 10 illustrates a
conventional AED 800, which includes a base unit 802 and two pads
804. Sometimes paddles with handles are used instead of the pads
804. The pads 804 are connected to the base unit 802 using
electrical cables 806.
[0007] A typical protocol for using the AED 800 is as follows.
Initially, the person who has suffered from sudden cardiac arrest
is placed on the floor. Clothing is removed to reveal the person's
chest 808. The pads 804 are applied to appropriate locations on the
chest 808, as illustrated in FIG. 10. The electrical system within
the base unit 802 generates a high voltage between the two pads
804, which delivers an electrical shock to the person. Ideally, the
shock restores a normal cardiac rhythm. In some cases, multiple
shocks are required.
[0008] Another type of defibrillator is a Wearable Cardioverter
Defibrillator (WCD). Rather than a device being implanted into a
person at-risk from Sudden Cardiac Arrest, or being used by a
bystander once a person has already collapsed from experiencing a
Sudden Cardiac Arrest, the WCD is an external device worn by an
at-risk person which continuously monitors their heart rhythm to
identify the occurrence of an arrhythmia, to correctly identify the
type of arrhythmia involved and then to automatically apply the
therapeutic action required for the type of arrhythmia identified,
whether the therapeutic action is cardioversion or defibrillation.
These devices are most frequently used for patients who have been
identified as potentially requiring an ICD and to effectively
protect them during the two to six month medical evaluation period
before a final decision is made and they are officially cleared
for, or denied, an ICD.
[0009] The current varieties of defibrillators available on the
market today, whether Implantable Cardioverter Defibrillators
(ICDs) or Automatic External Defibrillators (AEDs) or any other
variety such as Wearable Cardioverter Defibrillators (WCDs),
predominantly utilize either a monophasic waveform or a biphasic
waveform for the therapeutic defibrillation high-energy pulse. Each
manufacturer of defibrillators, for commercial reasons, has their
own unique and slightly different take on waveform design for their
devices' pulses. Multiple clinical studies over the last couple of
decades have indicated that use of a biphasic waveform has greater
therapeutic value than a monophasic waveform does to a patient
requiring defibrillation therapy and that biphasic waveforms are
efficacious at lower levels of energy delivery than monophasic
waveforms.
[0010] All of the current products that use a biphasic waveform
pulse have a single high-energy reservoir, which, while simple and
convenient, results in severe limitation on the range of viable
pulse shapes that can be delivered. Specifically, the second or
Negative phase of the Biphasic waveform is currently characterized
by a lower amplitude starting point than the first or Positive
phase of the Biphasic waveform, as shown in FIG. 3. This is due to
the partial draining of the high-energy reservoir during delivery
of the initial Positive phase and then, after inverting the
polarity of the waveform so that the Negative phase is able to be
delivered, there is only the same partially drained amount of
energy remaining in the energy reservoir. This lower amplitude
starting point constrains and causes the lower initial amplitude of
the Negative phase of the waveform. The typical exponential decay
discharge is shown by the Positive phase of the waveform shown in
FIG. 5 and how the reservoir would have continued to discharge (if
the polarity had not been switched) is shown as a dashed line in
FIG. 5.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIGS. 1A and 1B illustrate a multiphasic waveform system
with a plurality of independent subsystems each with its own energy
reservoir and energy source;
[0012] FIG. 2 illustrates another embodiment of the multiphasic
waveform system with two independent subsystems each with its own
energy reservoir and energy source;
[0013] FIG. 3 illustrates a typical H-bridge circuit;
[0014] FIG. 4 illustrates an H-bridge circuit in the multiphasic
waveform system;
[0015] FIG. 5 illustrates a Biphasic pulse waveform where the
negative phase of the waveform is smaller in amplitude than that of
the positive phase of the waveform;
[0016] FIG. 6 illustrates a shape of a Biphasic pulse waveform that
may be generated by the systems in FIGS. 1 and 2 where the negative
phase of the waveform is identical in amplitude to that of the
positive phase of the waveform;
[0017] FIG. 7 illustrates a shape of Biphasic pulse waveform that
may be generated by the systems in FIGS. 1 and 2 where the negative
phase of the waveform is larger in amplitude to that of the
positive phase of the waveform;
[0018] FIG. 8 illustrates a shape of Multiphasic pulse waveform
that may be generated by the systems in FIGS. 1 and 2 where the
negative phases of the waveform are interlaced or alternated with
those of the positive phases of the waveform, where the amplitudes
of each phase steadily decrease;
[0019] FIG. 9 illustrates a shape of Multiphasic pulse waveform
that may be generated by the systems in FIGS. 1 and 2 where the
negative phases of the waveform are interlaced or alternated with
those of the positive phases of the waveform, where the amplitudes
of each phase remain the same; and
[0020] FIG. 10 diagrammatically illustrates an example of a
conventional defibrillator.
DETAILED DESCRIPTION OF ONE OR MORE EMBODIMENTS
[0021] The disclosure is particularly applicable to a multiphasic
pulse system for an external defibrillator and it is in this
context that the disclosure will be described. It will be
appreciated, however, that the multiphasic pulse system has greater
utility since it may be used to generate one or more pulses for
other systems. For example, the pulse system may be used to
generate therapeutic treatment pulses for other types of
defibrillators, cardioverters or other systems. For example, the
pulse system may be used to generate therapeutic treatment pulses
and then provide the pulses to a patient using paddles or pads.
When used for defibrillation, the pulse system may generates the
pulses and deliver them to a patient through two defibrillation
pads or paddles.
[0022] The multiphasic pulse system overcomes the limitation on the
amplitude of follow on phases of the pulse waveform by using two or
more high-energy reservoirs and/or sources, such as the four shown
in FIGS. 1A and 1B. The pulse system 10 is not limited to any
particular number of energy reservoirs (such as capacitors) or
energy sources (such as batteries). The pulse system 10 may have a
plurality or "n" number (as many as wanted) subsystems 12, 14 that
together can be utilized to provide the various multiphasic
waveforms, examples of which are shown in FIGS. 5-9 and described
below. In the example implementation shown in FIG. 1A, there may be
two sides, such as side A and side B as shown, and each side may
have one or more of the subsystems 12, 14 and each subsystem may
generate a pulse (that may be a positive pulse or a negative
pulse.) The two or more subsystems 12, 14 permit the system to
shape the various characteristics of a positive phase of the
waveform separately from the shaping of the characteristics of the
negative phase of the waveform and vice versa. The above described
functions may be accomplished through the use of a fast switching
high-energy/voltage switch system as described below.
[0023] Each subsystem 12, 14 of each side, as shown in FIG. 1B, may
have a control logic and heart rhythm sense component 20 (that is
connected to a similar component on the other side by a digital
control link 30 as shown in FIG. 1A) that may be also coupled to a
high voltage switching system component 22. The high voltage
switching system component 22 may be implemented using either
analog circuits or digital circuits or even some hybrid of the two
approaches. Furthermore, the high voltage switching system
component 22 may be implemented through the use of mechanical or
solid-state switches or a combination of the two. As shown in FIG.
4, the high voltage switching system component 22 may be
implemented using one or more semiconductor circuits, such as the
insulated gate bipolar transistors. The high voltage switching
system component 22 may be coupled to an energy reservoir 24 and
the energy reservoir 24 may be coupled to a power source 26, such
as a battery. The energy reservoir 24 may further comprise a
reservoir 24A, such as for example one or more capacitors or a
capacitor array, and a high voltage generator 24B. The energy
reservoir 24 may also be coupled, by a high voltage return line 32
to the other side of the system as shown in FIG. 1A. The high
voltage return 32 electrically completes the circuit and is present
in existing defibrillators, but in a slightly different form since
in the existing style of devices it is split into two parts: in the
form of the two leads which go from the main defibrillator device
to the internal or external surface of the patient.
[0024] The control logic and heart rhythm sense component 20 is
well known in the art and the component analyzes the ECG signals
from the patient for treatable arrhythmias and then chooses to
shock the patient when a treatable arrhythmia is detected, along
with guiding the operator through both visual and audible means
through this process when the device is of the external automated
variety. The control logic and heart rhythm sense component 20 also
may control and shape the therapeutic pulse as it is delivered from
the energy reservoir and ensures that it is as optimal as possible
for the individual patient. In the implementations shown in FIGS.
1A and 2, the control logic and heart rhythm sense component 20 may
generate the therapeutic pulse using the one or more groups of
subsystems since each subsystem may have its own control logic 20
(so that each of them can control just the portion/phase of the
pulse/waveform that they deliver. This provides a much higher level
of control over what range of waveform shapes can be
used/delivered, including many that are not possible with the
existing devices. This also provides better weight and size
distribution, as well as size and weight reductions, and the
ability to have the devices look radically different and be handled
in very different ways--ones that are much more operator intuitive.
The disclosed system also provides a much higher level of
redundancy and fault mitigation for the device embodiments that use
it.
[0025] In one implementation, each control logic in each subsystem
may have a circuit that can be used to adjust the shape of each
portion of the therapeutic pulse. The circuit, may be for example,
an array of resistors of various strengths and switches so that one
or more of the resistor may be selected (as an array of selectable
resistors) that can optimize and alter an RC constant of a
subsystem's pulse phase generating circuitry in order to
dynamically shape one or more pulse phases.
[0026] In some embodiments of the system, the system may provide
for the recharging of individual energy reservoirs by the energy
sources during times (including inter-pulse times) that an
individual energy reservoir is not selected for discharge as shown
in FIGS. 1A and 2. This provides the opportunity to interlace
equivalent amplitude initial multiphasic pulses utilizing several
different high energy reservoirs as shown in FIG. 9.
[0027] In one implementation, the system 10 may consist of two or
more high-energy therapeutic pulse delivery sub-systems 12, 14 as
shown in FIG. 2, such as Side A and Side B. In the implementation
shown in FIG. 2, the side A may deliver one or more of a Positive
phase waveform of the Multiphasic therapeutic pulse and Side B may
deliver one or more of a Negative phase waveform of the Multiphasic
therapeutic pulse. The subsystem in each side of the system in FIG.
2 may have the same elements as shown in FIG. 1B and described
above. As shown in FIGS. 1A and 2, the subsystems may be coupled to
the patient 16 by one or more high voltage leads and one or more
sense leads wherein the high voltage leads deliver the therapeutic
pulse and the sense leads are used to detect the heartbeat by the
control unit.
[0028] The system 10 may either be pre-programmed to use a specific
single multiphasic pulse shape, according to which one is shown to
be most efficacious in clinical lab testing/trials, or else it may
select the best one for a given purpose from a lookup table where
they are listed according to their suitability for optimally
resolving different types of arrhythmia that are being screened for
and identified or for the different treatments as described above.
Regardless, the system and method allows the use and application of
a much wider range of pulse shapes than has been previously
possible and this will allow the devices which use this invention
to keep up with clinical developments as waveforms continue to be
improved.
[0029] FIG. 3 illustrates a typical H-bridge circuit 300 and FIG. 4
illustrates an H-bridge circuit concept used in the multiphasic
waveform system. As shown in FIG. 3, an H-bridge circuit is a known
electronic circuit that enables a voltage, such as Vin, to be
applied across a load, M, in either direction using one or more
switches (S1-S4) (see
http://cp.literature.agilent.com/litweb/pdf/5989-6288EN.pdf that is
incorporated by reference herein for additional details about the
H-bridge circuit.) As shown in FIG. 3, the H-bridge circuit may
have a first portion 302 and a second portion 304 that form the
complete H-bridge circuit.
[0030] As shown in FIG. 4, the H-bridge circuit may be part of the
control circuits or switching systems shown in FIGS. 1-2. The load
of the H-bridge circuit in the multiphasic system is the patient 16
to which the therapeutic pulse is going to be applied to provide
treatment to the patient. The treatment to the patient, depending
on the power and/or energy level of the therapeutic pulse may be
for cardiac pacing, cardioversion, defibrillation, neurological
therapy, nerve therapy or musculoskeletal therapy. Each side of the
multiphasic system may generate its energy as described above and
an H-bridge circuit 400 may be used to apply two (or more) unique
energy sources to the single load. In the example shown in FIG. 4,
each side of the system (such as side A and side B shown in FIGS.
1A and 2) may have a portion 402, 404 of the H-bridge so that the
multiphasic system has a complete H-bridge circuit that is
combination of portions 402, 404. The multiphasic system may then
be used to deliver the therapeutic pulse through defibrillation
paddles, such as Paddle A and Paddle B as shown in FIG. 4) to the
patient.
[0031] Each portion 402, 404 of the H-bridge has its own energy
source, 1600 VDC in the example in FIG. 4. In each portion of the
H-bridge, the energy source may be switched using switches 406, 408
to make contact with the patient at a separate but specific time.
The switches for each portion may be part of the switching system
shown in FIGS. 1-2. In the example in FIG. 4, each portion may have
two switches and each switch may be a commercially available
insulated-gate bipolar transistor (IGBT.) Each switch may be
controlled by a separate trigger signal as shown to discharge the
energy to the patient. This provides for the two or more energy
sources to discharge their energy to the load (patient) at a
precise time, generating a resulting Biphasic discharge pulse or
other therapeutic pulse shapes (examples of which are shown in
FIGS. 5-9) as defined for an application, or therapeutic
condition.
[0032] In the system, a therapeutic pulse may comprise one or more
positive pulses and one or more negative pulses. As shown in FIGS.
1A and 2, each side (A & B) has one or more independent
high-energy subsystems 12, 14 so that the magnitude and the timing
for each of the Positive & Negative phases of the Multiphasic
therapeutic pulse are independent and can therefore be
independently controlled so as to provide a variety of different
pulses as shown in FIGS. 5-9. FIG. 5 is typical of the current
Biphasic therapeutic pulses available in many defibrillators
currently on the market today (with a positive pulse and negative
pulse as shown) that may also be generated by the systems in FIGS.
1A and 2. FIG. 6 illustrates a therapeutic pulse generated by the
pulse system in which the magnitude of the Positive and Negative
phases of the waveform are equal in starting amplitude.
Furthermore, because each side or portion of the waveform
generating circuit (subsystems A & B) are independent, the
amplitude of the Positive phase of the waveform can be smaller in
magnitude than the Negative phase of the waveform, as illustrated
in FIG. 7. Additionally, due to the independent nature of the two
(or more) subsystems in the circuit, it is possible to alternate
the Positive and Negative phases at intervals throughout the
delivery of the Multiphasic therapeutic pulse as shown in FIGS. 8
and 9, or that the second (or later) phase of the pulse can be of a
measurably lower amplitude than would normally be deliverable from
a single partially depleted energy reservoir. Further, each of the
subsystems may have a dynamically variable and selectable voltage
output such that the amplitude of each pulse phase can be
individually controlled. In one implementation of the system, the
therapeutic pulses in FIGS. 4-9 may be therapeutic defibrillation
or cardioversion pulses. In another implementation of the system,
the therapeutic pulses in FIGS. 5-9 may be lower energy therapeutic
pulses used in the treatment of neurological, nerve or
musculoskeletal conditions. Thus, the pulse generation system may
generate pulse phases at any of a variety of power and energy
levels allowing for the use of the pulses for a variety of purposes
such as in cardiac pacing, cardioversion and defibrillation in
addition to neurological, nerve or musculoskeletal therapies.
[0033] While the foregoing has been with reference to a particular
embodiment of the invention, it will be appreciated by those
skilled in the art that changes in this embodiment may be made
without departing from the principles and spirit of the disclosure,
the scope of which is defined by the appended claims.
* * * * *
References