U.S. patent application number 15/240036 was filed with the patent office on 2016-12-08 for controller and power source for implantable blood pump.
This patent application is currently assigned to HEARTWARE, INC.. The applicant listed for this patent is HeartWare, Inc.. Invention is credited to Michael Ashenuga, Jeffrey A. LaRose, John Rudser, Charles Joseph Vadala, JR..
Application Number | 20160354527 15/240036 |
Document ID | / |
Family ID | 51061570 |
Filed Date | 2016-12-08 |
United States Patent
Application |
20160354527 |
Kind Code |
A1 |
Vadala, JR.; Charles Joseph ;
et al. |
December 8, 2016 |
CONTROLLER AND POWER SOURCE FOR IMPLANTABLE BLOOD PUMP
Abstract
Methods and apparatus for controlling the operation of, and
providing power for and to, implantable ventricular assist devices
which include a brushless DC motor-driven blood pump, are
disclosed. In one embodiment, a control system for driving an
implantable pump is provided. The digital processor is responsive
to data associated with the operation of the pump received at the
data transfer port, and from the program data stored in memory, (i)
to determine therefrom, the identity of the pump, (ii) to determine
therefrom, electrical characteristics and features of the
identified pump, and (iii) to adaptively generate and apply to the
data port, control signals for driving the identified pump. Latch
mechanisms, an elongated flexible electrical cable with a strain
relief segment, and a lower housing portion that is heavier than an
upper housing portion, may also be provided with the control
system.
Inventors: |
Vadala, JR.; Charles Joseph;
(Boston, MA) ; LaRose; Jeffrey A.; (Sunrise,
FL) ; Rudser; John; (Miami, FL) ; Ashenuga;
Michael; (Roslindale, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HeartWare, Inc. |
Miami Lakes |
FL |
US |
|
|
Assignee: |
HEARTWARE, INC.
MIAMI LAKES
FL
|
Family ID: |
51061570 |
Appl. No.: |
15/240036 |
Filed: |
August 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14843424 |
Sep 2, 2015 |
9446180 |
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15240036 |
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14133905 |
Dec 19, 2013 |
9364596 |
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14843424 |
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61749038 |
Jan 4, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 2205/8262 20130101;
A61M 2205/502 20130101; A61M 2205/18 20130101; A61M 1/127 20130101;
A61M 2205/52 20130101; A61M 1/122 20140204; A61M 2205/8206
20130101; A61M 2205/44 20130101; A61M 1/1086 20130101; G06F 1/263
20130101; A61M 1/12 20130101; A61M 1/101 20130101; G06F 1/3212
20130101; A61M 2205/50 20130101; A61M 1/1053 20130101 |
International
Class: |
A61M 1/12 20060101
A61M001/12; G06F 1/26 20060101 G06F001/26; G06F 1/32 20060101
G06F001/32; A61M 1/10 20060101 A61M001/10 |
Claims
1-18. (canceled)
19. A control system for driving an implantable blood pump in a
patient comprising: a housing including electronic components
configured to drive the pump; and an elongated flexible electrical
cable having a first end, a second end remote from the first end,
an internal portion, and an external portion, the first end
configured to connect to the housing, the second end configured to
operatively connect to the implantable blood pump, the internal
portion configured to be positioned internal to the patient, and
the external portion configured to be positioned external to the
patient; wherein a dynamic member of the external portion of the
cable has an unstrained condition in which the external portion of
the cable has a first length, and a strained condition in which the
external portion of the cable has a second length, the second
length being between about 3.5 feet and about 4 feet and being
greater than the first length.
20. The control system of claim 19, wherein the dynamic member of
the cable comprises a strain relief segment.
21. The control system of claim 19, wherein the dynamic member of
the cable has a helical shape when in the unstrained condition.
22. The control system of claim 19, wherein the dynamic member of
the cable has a length of about 2 feet when in the strained
condition.
23. The control system of claim 19, wherein the external portion of
the cable includes a static member having a length of between about
1.5 feet and about 2 feet.
24. The control system of claim 23, wherein the static member of
the cable includes at least two discontinuous parts.
25. The control system of claim 24, wherein the dynamic member of
the cable is positioned between the at least two discontinuous
parts of the static member of the cable.
26. The control system of claim 19, wherein the housing includes a
first housing portion that includes the electronic components, and
a second housing portion configured to house a battery.
27. The control system of claim 26, wherein the first end of the
cable is configured to connect to the first housing portion.
28. The control system of claim 26, wherein the first housing
portion includes a first latch configured to couple to a
corresponding first recess in the second housing portion, and the
second housing portion includes a second latch configured to couple
to a corresponding second recess in the first housing portion.
29. A surgical method comprising: implanting a blood pump into a
patient; coupling a first end of an elongated flexible electrical
cable to a housing of a control system, the control system
configured to drive the pump; and operatively coupling a second end
of the cable to the blood pump; wherein after coupling the first
end of the cable to the housing and the second end of the cable to
the blood pump, a portion of the cable external to the patient
includes a dynamic member having an unstrained condition in which
the external portion of the cable has a first length, and a
strained condition in which the external portion of the cable has a
second length, the second length being between about 3.5 feet and
about 4 feet and being greater than the first length.
30. The method of claim 29, wherein the dynamic member of the cable
comprises a strain relief segment.
31. The method of claim 29, wherein the dynamic member of the cable
has a helical shape when in the unstrained condition.
32. The method of claim 29, wherein the dynamic member of the cable
has a length of about 2 feet when in the strained condition.
33. The method of claim 29, wherein the external portion of the
cable includes a static member having a length of between about 1.5
feet and about 2 feet.
34. The method of claim 29, wherein the static member of the cable
includes at least two discontinuous parts.
35. The method of claim 34, wherein the dynamic member of the cable
is positioned between the at least two discontinuous parts of the
static member of the cable.
36. The method of claim 29, wherein the housing includes a first
housing portion that includes the electronic components, and a
second housing portion configured to house a battery.
37. The method of claim 36, wherein the step of connecting the
first end of the cable to the housing includes connecting the first
end of the cable to the first housing portion.
38. The method of claim 36, wherein the first housing portion
includes a first latch configured to couple to a corresponding
first recess in the second housing portion, and the second housing
portion includes a second latch configured to couple to a
corresponding second recess in the first housing portion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of the filing
date of U.S. Provisional Patent Application No. 61/749,038 filed
Jan. 4, 2013, the disclosure of which is hereby incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to the field of implantable medical
devices. In particular, this invention is drawn to controllers and
power supplies for motor-driven implantable medical device
applications.
APPLICATIONS INCORPORATED BY REFERENCE
[0003] U.S. Patent Publication No. 2012/0226350, titled "Controller
and Power Source for Implantable Blood Pump" is hereby incorporated
by reference herein. U.S. Patent Publication No. 2012/0086402,
titled "Fault-Tolerant Power Supply" is hereby incorporated by
reference herein.
BACKGROUND OF THE INVENTION
[0004] Implantable medical devices, such as ventricular assist
devices, are being developed for long term treatment of chronic
heart failure. Such devices require a pumping mechanism to move
blood. Due to the nature of the application, the pumping mechanism
must be highly reliable. Patient comfort is also a significant
consideration.
[0005] Electrically powered pumping mechanisms typically rely on a
motor such as a brushless DC motor. Brushless DC motors offer
maintenance advantages in implant applications due to the lack of
wear-prone brushes. Due to the lack of these electro and mechanical
commutation components, commutation is generally provided
electrically by drive electronics.
[0006] A prior art HeartWare Ventricular Assist System,
manufactured by HeartWare Inc, Framingham Mass., is an example of
an implantable ventricular assist device. At the core of the
HeartWare Ventricular Assist System is a small implantable
centrifugal blood pump called a HVAD.RTM. pump employing a
brushless DC motor.
[0007] When implanted in a patient in a typical scenario, the pump
draws blood from the left ventricle and propels that blood through
an outflow graft connected to the patient's ascending aorta. The
device is capable of generating up to 10 liters of blood flow per
minute. With a displaced volume of only 50 cc, the HVAD pump is
suitable for implantation in the pericardial space, directly
adjacent to the heart Implantation above the diaphragm leads to
relatively short surgery time and quick recovery.
[0008] The HVAD pump has only one moving part, an impeller, which
spins at a rate between 1800 and 4000 revolutions per minute. The
impeller is suspended within the pump housing through a combination
of passive magnets and hydrodynamic thrust bearings. This
hydrodynamic suspension is achieved by a gentle incline on the
upper surfaces of the impeller blades. When the impeller spins,
blood flows across these inclined surfaces, creating a "cushion"
between the impeller and the pump housing. There are no mechanical
bearings or any points of contact between the impeller and the pump
housing.
[0009] Device reliability is enhanced through the use of dual motor
stators with independent drive circuitry, allowing a seamless
transition between dual and single stator mode if required. The
pump's inflow cannula is integrated with the device, and surgically
implanted into the heart's ventricle. This proximity is expected to
facilitate ease of implant and to help ensure optimal blood flow
characteristics. The use of a wide-bladed impeller and clear flow
paths through the system minimizes risk of pump-induced hemolysis
(damage to blood cells) or thrombus (blood clotting).
[0010] Typically, while the pump is implanted in the patient, a
controller and the drive electronics for the pump, and other
control subsystems for the pump, including the power supply, are
located outside the patient, for example, in a control/power supply
module tethered by a transcutaneous electrical cable, to the
implanted pump of the overall HeartWare Ventricular Assist
System.
[0011] For the HeartWare Ventricular Assist System, an external (to
the patient) controller includes the drive electronics for the pump
(coupled directly to the windings of the motor) and provides drive
and control signals to the pump. The controller also provides
feedback and alarms to the patient regarding the operation of the
device. Commutation control for the brushless DC motors is effected
by the controller and the drive electronics, in a feedback manner.
The controller provides a commutation control signal for a selected
phase of the motor in accordance with a sampled back-emf voltage of
that phase (sensed via the tether cable). The back-emf is sampled
only while the corresponding selected phase drive voltage is
substantially zero. The frequency of the brushless DC drive voltage
is varied in accordance with the commutation control signal. In one
form, the back-emf is normalized with respect to a commanded rotor
angular velocity. A speed control generates a speed control signal
corresponding to a difference between a commanded angular velocity
and an angular velocity inferred from the frequency of the drive
voltage.
[0012] A redundant power supply is provided by two batteries, or
one battery and an AC adapter or DC adapter. The redundant power
supply provides power for the controller, and particularly the
drive electronics. When the battery is depleted (for example, after
approximately 6 hours), the controller automatically switches to
the standby power source, battery or adapter, and the depleted
battery is replaced.
[0013] A "Patient Pack" assembly includes a carrying case that
holds the controller and power source(s). The case can be adapted
to be carried over the patient's shoulder or worn around the
patient's waist.
[0014] While the prior art HeartWare Ventricular Assist System in
the aggregate, performs the desired ventricular assist functions
required for long term treatment of chronic heart failure, there is
a need for improved subsystems and subassemblies which would
provide enhanced blood flow results and improved
patient-convenience features, easing the maintenance burden on the
patient, thereby providing an improved quality of life.
BRIEF SUMMARY OF THE INVENTION
[0015] In one embodiment, a control system for driving an
implantable blood pump includes a first housing including
electronic components configured to drive the pump and a second
housing including a battery. The first housing includes a first
latch member extending from the first housing on a first side of
the first housing and first and second recesses on a second side of
the first housing. The second housing includes a third recess on a
first side of the second housing and second and third latch members
extending from the second housing on a second side of the second
housing. When the first side of the first housing is aligned with
the first side of the second housing, the first latch member aligns
with the third recess, the second latch member aligns with the
first recess, and the third latch member aligns with the second
recess. The second and third latch members may each include bottom
connected to the second housing and a top curving away from the
first side of the second housing.
[0016] In another embodiment of the invention, a control system for
driving an implantable blood pump includes an internal battery, an
external battery, and a processor configured to perform an
estimation of a remaining run time of the internal and external
batteries. The estimation includes determining a remaining capacity
of the internal battery, determining a remaining capacity of the
external battery, determining a consumption rate of the internal
battery, and determining a consumption rate of the external
battery. Determining the remaining capacity of the external battery
includes determining a value of the remaining capacity of the
internal battery and modifying the value of the remaining capacity
of the internal battery to account for a loss in efficiency when
the external battery charges the internal battery.
[0017] In another embodiment of the invention, a control system for
driving an implantable blood pump includes a first housing
including electronic components configured to drive the pump,
speakers, and a vibrating mechanism. The vibrating mechanism
vibrates during a first interval following the detection of an
alarm condition and the speakers sound an audible alarm during a
second interval following the detection of the alarm condition. The
first interval precedes the second interval, and the speakers are
silent during the first interval.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] A more complete appreciation of the present invention and
many of the attendant advantages thereof will be better understood
by reference to the following detailed description when considered
in connection with the accompanying drawings, wherein:
[0019] FIG. 1 is front-top-side view of a control system and
connecting cable of the disclosure;
[0020] FIG. 2 is partially rear-side view of the control system and
connecting cable of FIG. 1;
[0021] FIGS. 3A-B are side views of the control system and
connecting cable of FIG. 1, showing a battery-containing portion
detached from a processor-containing portion, and the
battery-containing portion attached to the processor-containing
portion, respectively;
[0022] FIGS. 4A-D show top views of the top panel. with a display
device thereon, of the control system of FIG. 1; and
[0023] FIG. 5 is a diagrammatic representation of the control
system and connecting cable of FIG. 1, together with an exemplary
pump.
[0024] FIGS. 6A-E illustrate multiple views of an alternate
embodiment of top and bottom housings of a control system.
DETAILED DESCRIPTION
[0025] A control system 10 for controlling the operation of, and
providing power for and to, implantable ventricular assist devices
which include a pump employing a brushless DC motor-driven blood
pump, is shown in FIGS. 1-4. The control system 10 is shown in
diagrammatic form in FIG. 5, together with an exemplary pump
12.
[0026] As shown in FIGS. 1-5, the control system 10 includes a
housing 16 disposed about an interior region 20. Housing 16 extends
along a housing axis 22 between a top end 16A and a bottom end 16B.
At the top end 16A, a top panel 24 having a substantially planar
outer surface, extends transverse to the housing axis 22. At the
bottom end 16B, a bottom panel 26 having a substantially planar
outer surface, extends transverse to the housing axis 22. Lateral
surfaces LS of housing 16 extend between the circumferential outer
boundary of top panel 24 and the circumferential outer boundary of
bottom panel 26. In the aggregate, the lateral surfaces of housing
16 form a tube-like structure extending along axis 22, with the end
panels 24 and 26 forming closures to the tube, or tube-like,
structure, enclosing the interior region 20.
[0027] The tube-like structure includes a first, or outer, portion
30 (referred to herein as "LS outer portion 30") opposite to a
second, or inner, portion 32 (referred to herein as "LS inner
portion 32"). Opposing uppermost portions of the outermost surfaces
of LS outer portion 30 and LS inner portion 32 are substantially
planar as well as substantially parallel, although as illustrated
particularly in FIGS. 1-4, those portions are not precisely
parallel. Different shapes and relationships may be employed in
other embodiments.
[0028] A first display device 40 is disposed on the outer surface
of top panel 24. A second display device 42 is disposed on the
outer surface of the LS inner portion 32. The second display device
42 is optional and may be omitted from the control system 10. The
housing 16 also includes on a lateral surface, a power port 46 and
a data port 48 disposed within an input/output (I/O) connector
assembly 49. An input device 50 is disposed on the outer surface of
LS outer portion 30.
[0029] An elongated flexible electrical cable 51 extends from a
controller end 52 to a pump end 54. The cable 51 further includes a
flexible, helical-shaped strain relief segment 55 (shown in FIGS.
1-3) between the cable ends 52 and 54. A controller-end connector
assembly 56 is disposed at the controller end 52, and a pump end
connector assembly 60 is disposed at the pump end 54 of cable 51.
The connector assembly 56 includes connector portions 46' and 48'
adapted to mate with the power port 46 and the data port 48,
respectively, of the I/O connector assembly 49.
[0030] The pump end connector assembly 60 similarly includes
connector portions 62' and 64' adapted to mate with a pump power
port 62 and pump data port 64 of a pump I/O connector assembly
68.
[0031] The controller-end connector assembly 56 is adapted to mate
with an I/O connector assembly 49 on the housing 16, and the
pump-end connector assembly 60 is adapted to mate with the pump
connector assembly 68 on the pump 12.
[0032] When the controller-end connector assembly 56 is connected
to the I/O connector assembly 49 of the controller 10, and the pump
end connector assembly 60 is connected to the pump I/O connector
assembly 68 of the pump 12, pump drive signals can pass between the
power output port 46 and the pump power port 62. Data can pass
between the data transfer port 48 and the pump data port 64, making
available to data processor 32, the real-time impedances of the
windings of the motor of pump 12.
[0033] In the illustrated embodiment, the housing is split into two
opposed cup-like components: cup-like upper housing portion A
having a circumferential rim R1, and cup-like lower housing portion
B having a circumferential rim R2. Rim R1 of the upper housing
portion A is adapted to interfit with and reversibly couple to the
rim R2 of the lower housing portion B. A latch assembly enables the
quick release of housing portion A from or to lower housing portion
B, in response to depression of a release button RB disposed on the
LS outer portion 30 of upper housing portion A (and an associated
latch assembly. not shown). Rim R1 and rim R2 are shown in FIG. 1
by the reference symbol "R1/R2", and in FIG. 5, rim R1 and rim R2
are depicted as adjacent dashed lines extending across housing
16.
[0034] In the illustrated embodiment, the cup-like housing portion
B provides electrical power for the operation of control system 10.
As shown in FIG. 5, housing portion B includes in its interior, a
power supply support structure 80. The support structure 80 has a
cup-like form adapted to receive a battery 84 in its interior
region. In some forms of the control system 10, the battery 84 is
affixed to housing portion B and the portion B/battery module is
replaceable as a unit. In other forms, the battery 84 is removably
located in housing portion B, and is user-replaceable within
housing portion B. In the illustrated form of FIG. 5, the interior
of the power supply support structure 80 is geometrically keyed to
the shape of the battery 84, to aid a user in replacing the battery
in a fail-safe manner In that structure, both the support structure
80 and the battery 84 are shown with geometric shape keying so that
the battery 84 can only be inserted in support structure 80 in a
single, proper manner A secondary, or back-up, battery 88 is
disposed within the interior of upper housing portion A, and is
coupled to the various elements in control system 10, to provide
back-up power to control system 10 in the event of catastrophic
failure of battery 84 or during routine replacement of battery 84
with a charged or fresh unit.
[0035] As shown in FIG. 5 of the illustrated embodiment, the
support structure 80 also includes power jack 87 so that the
control system 10 can be powered by an external power source.
[0036] In the illustrated embodiment, the cup-like housing portion
A houses the components which provide functional operation of
control system 10, as it relates to the driving of an implanted
pump 12. The housing portion A houses a digital signal processor 92
and an associated memory 94, a pump drive network 98, and, as noted
above the secondary battery 88, as well as cabling which
interconnects the various elements in the control system 10.
[0037] An electrical power conductor assembly P is disposed within
interior region 20. That electrical power conductor assembly P is
associated with the power supply support structure 80, and couples
electrical power from a power supply (whether it be from a battery
84 disposed in support structure 80, from an external source by way
of power jack 87 or from secondary battery 88), and provides
electrical power to all elements in the control system 10. In
addition, the electrical power conductor assembly P provides a
power drive signal line from the digital processor 92, by way of a
power amplifier 98, to the electrical power output port 46, where
that power drive signal can be coupled via cable 51 to the motor
(not shown) of pump 12.
[0038] A data conductor assembly D also is disposed within interior
region 20. The data conductor assembly D provides analog "data"
representative of the current state of the motor of pump 12,
received via cable 51 at data transfer port 48, to the digital
processor 92. In one form, that analog "data" is provided as a
direct line to the windings of the motor of pump 12, from which the
digital processor determines the impedance as a function of time of
the respective windings of the motor. In response to that
"impedance" data, the digital processor determines the appropriate
drive power signal to be applied by way of power port 46 and cable
51, to the motor.
[0039] The input device 50 in some forms, includes a keyboard, and
in other forms includes a connector, and in still other forms,
includes both. Through the input device 50, a user of, or
administrator for, the control system 10 can activate or deactivate
the system 10, or can add, modify or delete any information
associated with the operation of the system 10, for example by
modifying the information stored in memory 94.
[0040] The control system 10 is adapted for use by an ambulatory
patient who has an implanted blood pump. Under control of system
10, the patient's pump performs as programmed. For convenience, the
patient can wear the control system 10 in a holster-like support
extending about his or her waist, with the housing axis 22
substantially vertical and the LS inner portion against the
patient's body. With this configuration, the patient can
conveniently view the display device 40 on top panel 24, without
removing control system 10 from the holster. An administrator, for
example, a physician or nurse, who might hold the system 10 after
removing it from the patient's holster, can view either display
device 40 or display device 42 on LS inner portion 32. In the
illustrated form, display 42 is relatively large compared to
display device 40, so that more complex information can be
displayed to the administrator while relatively simple, albeit
highly useful, information can be displayed to the patient.
[0041] The memory 94 stores program information, for example, for
controlling the operation of one of a number of (same or different
model) implantable blood pumps which might be connected to, and
driven by, the system 10. The digital processor 92 is adapted to
run and control the overall system 10 as well as a pump attached
thereto via cable 51. Display 42 is driven by the processor 92 to
selectively display information which is generally useful to an
administrator of a pump 12, such as a nurse or physician. In
embodiments with or without the second display 42, the control
system 10 may additionally be connected to a monitor, for example
at a hospital or other clinical setting, which may display the type
of information displayed on second display 42 or include
additional, further detailed information that would otherwise be
difficult to display on the second display 42.
[0042] In operation, the control system 10, when deployed, is
coupled by way of cable 51 to a pump 12. Pursuant to its
supervisory program from the memory 94, the system 10 determines
from a coupled pump 12, the identity of the pump, for example the
manufacturer and model number, the serial number, and in some cases
the identity of the patient associated with the pump. From that
determined identity information, system 10 determines certain
electrical characteristics and features of the identified pump, and
in some cases related to the patient associated with the pump.
System 10 then adaptively generates and applies by way of the power
port 46, control signals (e.g. pump drive signals) for driving the
identified pump 12. As noted above, in the illustrated embodiment,
the system 10 effectively monitors in real time, the operation of
the pump 12, based on the impedance of the windings of the pump's
motor, and generates appropriate time-based pump drive signals for
application to those windings, to achieve the performance defined
by the pump's program (which may be customized to the patient)
stored in memory 94.
[0043] In one form, system 10 is adapted to control operation of
one of a number of pumps of the same model, and the program
information stored in memory 94 defines the features and modes of
operation of the identified pump. In some cases this information is
customized on a patient-by-patient basis, for each of a number of
prospective pumps. In another form, system 10 is adapted to control
operation of all of a number of different types of pumps. Similar
control information is provided for each such pump in memory 94. In
some cases, the pumps to be controlled are relatively passive, and
provide information back to the control system 10 in the form of
signal lines coupled to the windings of the pump motor, so that
impedances can be detected and drive signals generated accordingly.
In other cases, the pumps to be controlled are active, and provide
over data port 48, data representative of various conditions in the
pump, for example, identified faults, or data representative of
certain conditions, such as indications of the occurrence of bases
for an imminent failure of the pump. Among the various
determinations made, system 10 generates a signal representative of
the time remaining of operation under battery power, for the
specific battery then installed, taking into consideration of the
current state of charge and expected load/current drawdown. That
time-remaining signal is selectively displayed on one, or both, of
display devices 40 and 42 in human-readable form. The
time-remaining value is based in part on the drive program
associated with the pump, so as to provide a highly accurate
reading all of the time remaining. When the time-remaining value
reaches a threshold or range indicative of danger to the patient,
an alarm is generated, for example, an audible alarm, a vibratory
alarm, and a light alarm, solid or flashing.
[0044] As noted above, the battery-containing lower cup-like
portion B of housing 16 can be separated from the upper cup-like
portion A (by depressing button RB), and a replacement lower
cup-portion B with a fresh, fully charged battery, can replace the
removed portion. A side view of the control system 10 is shown in
FIG. 3A (with lower portion B of housing 16 attached to upper
portion A of housing 16) and FIG. 3B (with lower portion B removed
and displaced from upper portion A.
[0045] Also included within the housing 16, is a wireless
transmitter/receiver TX/RX. A transmitter is coupled to the digital
processor 92 and is adapted to selectively transmit and receive
data. By way of example, the transmitted data may be representative
of indicia of operation of a pump 12 under the control of system
10, to a main processor. The information can be selected to include
data representative of broad aspects of the operation of the
connected pump, such as pump activity, fault conditions,
warning/alarm conditions and other data necessary for comprehensive
logs for the pump. The received data, by way of example, may be
program or control instructions, or modifications, for use in the
control of system 10, and in turn, a pump attached thereto. In
various forms, the control system 10 may include only a
transmitter, or only a receiver, rather than the
transmitter/receiver in the illustrated embodiment. In other
embodiments, the data transfer may be accomplished via a wired
line. This, for example, may be used when attaching the control
system 10 to a hospital monitor to display highly detailed
information stored on the control system 10.
[0046] An exemplary set of information displayed on display device
42, is shown in FIG. 2. The data shown primarily in the form of
icons or indicia. Indicia representative of length of time
remaining for operation at the current state of battery 84 (7
hours, 35 min), battery life, characteristics of the pump attached
to the system 10 (power being dissipated,=3.4 Watts, pump impeller
rotational rate=22000 RPM, and pump output flow rate (6.3 Liters
per minute), are all illustrated in FIG. 2. In addition, there is
an icon overlying a membrane switch that can bring up data
representative of signal strength relevant to the receiver RX, an
icon in the shape of a telephone handset overlying a membrane
switch that can initiate a telephone call, an icon in the shape of
a wrench which overlying a membrane switch that can initiate a tool
or setting screen, and an icon in the shape of loudspeaker
overlying a membrane switch that can bring up an audio volume
control screen. In addition, there is a condition (of control
system 10) indicator, which in FIG. 2 is a heart-shaped icon that
is indicative of "proper operation" of the pump of a patient
connected to the system to. An alternative icon for the condition
indicator is shown in FIG. 4D. The aforementioned data displayed on
display device 42 is primarily of value to an administrator, such
as a physician or nurse.
[0047] An exemplary set of information displayed on display device
40, is shown in FIGS. 4A-D. The data shown in FIGS. 4A-B and 40 is
in the form of indicia representative of length of time remaining
for operation at the current state of battery 84, battery life, and
characteristics of the pump attached to the system 10 (power being
dissipated, pump impeller rotational rate, pump output flow rate).
There also is a loudspeaker-shaped icon indicative of auditory
alarms being on or off (where an "X" overlays the
loudspeaker-shaped icon when alarms are "muted temporarily"). As in
the illustrated display device 42 in FIG. 2, there also is an icon
that is indicative of "proper operation" of the pump of a patient
connected to the system 10. In FIGS. 4A-B, that icon is
heart-shaped, indicating "proper operation", or "situation good",
of the pump of a patient connected to the system 10. In FIG. 4D,
the condition indicator icon is in the form of the international
traffic signal for "attention", a triangle with an exclamation
point in its interior. The data in display device in FIG. 4A is
representative of "all is well", and has a white or blue backlight.
The data in display device in FIG. 4B is representative of "alert
condition," and has a yellow backlight. When control system 10 is
in its "alarm condition," the display 40 alternates with that shown
in FIG. 4B and that shown in FIG. 4C, with the latter displaying
"PRESS SCREEN TO MUTE ALARM," with a yellow backlight. The data in
display device in FIG. 4D is representative of "Situation requires
immediate attention," and has a red backlight.
[0048] The backlight values (blue/white, yellow, red) are
qualitative indicators of great importance to the user/patient
having his or her implanted blood pump under the control of the
control system 10.
[0049] As described above, system 10 is capable of generating a
signal representative of the time remaining of operation under
battery power, for the specific battery then installed, taking into
consideration of the current state of charge and expected
load/current drawdown. The system 10 uses a runtime estimation
algorithm to estimate the remaining runtime, or "Predicted
Runtime," of both the external battery 84 and internal battery 88.
The runtime estimation algorithm for both batteries 84, 88 may be
periodically executed to determine the Predicted Runtime of each
battery. Generally, Predicted Runtime is estimated as the ratio of
the remaining battery capacity, or "Battery Capacity," to the rate
of battery consumption, or "Consumption Rate." Stated otherwise,
Predicted Runtime =Battery Capacity/Consumption Rate.
[0050] The internal battery 88 may include a battery management
system (BMS) chip which may directly provide the remaining capacity
of the internal battery 88. When the runtime estimation algorithm
for the internal battery 88 is initiated, the value for Battery
Capacity is equated to the remaining capacity provided by the BMS
chip.
[0051] The external battery 84 may also include a BMS chip which
may directly provide the remaining capacity of the external battery
84. However, for the external battery 84, the runtime estimation
algorithm also takes into account the capacity of the external
battery 84 to transfer charge to the internal battery 88, as well
as efficiency losses and losses in the boost stage, when
determining Battery Capacity. The capacity for the external battery
84 to transfer charge to the internal battery 88 is equated to the
remaining capacity of the internal battery 88, provided by the BMS
chip of the internal battery 88. This value may be modified with a
Loss Coefficient to account for loss of capacity when charge is
transferred from the external battery 84 to the internal battery
88. One such loss in efficiency may result from the boost circuit
used in charging the batteries. For example, the algorithm may
assume a 10% loss of capacity during transfer from the external
battery 84 to the internal battery 88. If assuming a 10% loss of
capacity, the capacity of the external battery 84 to transfer
charge to the internal battery 88 would be calculated as the value
of Battery Capacity for the internal battery 88 multiplied by the
Loss Coefficient, in this case 1.1. Thus, the value for Battery
Capacity of the external battery 84 is calculated as the difference
between the remaining capacity of the external battery 84, as
provided by the BMS chip of the external battery 84, and the
capacity to transfer charge to the internal battery 88, as modified
by a Loss Coefficient. Stated otherwise, External Battery
Capacity=Loss Coefficient*Internal Battery Capacity.
[0052] The value determined for Consumption Rate at any given point
may be determined by one of at least three different methods. The
first method calculates an instantaneous consumption rate,
determined as the product of average current and voltage of the
battery. This first method may be used when certain conditions are
met. For example, the first method may be used when (1) the
internal battery 88 is not charging (i.e. it is either discharging
or idle); (2) no AC power adapters are connected to the system 10;
(3) the pump 12 is running; and (4) power is being provided to the
system from the battery.
[0053] The second method for determining Consumption Rate is used
when one of the conditions described with the first method is not
satisfied. The second method entails using the most recently stored
value calculated according to the first method. This second method,
for example, prevents the Consumption Rate as being defined as 0 or
another artificially small number when the pump has periodically
stopped. If the first method was used when the pump had
periodically stopped and there was an artificially low Consumption
Rate, the value of Run Time would be calculated as an artificially
high value. This artificially low Consumption Rate would not be
expected to continue for the foreseeable future, as the pump would
realistically start pumping again. Similar concerns arise for the
other conditions described above. If the Consumption Rate is
calculated according to the second method with both the internal
battery 88 and external battery 84 connected, the value for
Consumption Rate is used for the stored Consumption Rate of both
batteries. If it is calculated only with the internal battery 88
connected, the value is used for the stored Consumption Rate of the
internal battery 88 only.
[0054] If the system 10 is in an initialization phase, wherein no
Consumption Rate has been stored according to the first method, and
conditions for calculating the Consumption Rate according to the
first method are not satisfied, a third method may be used. In the
third method, a table of values is stored in memory to estimate the
Consumption Rate based on the RPM of the pump 12 and a hematocrit
setting previously entered by a user or administrator.
[0055] The Predicted Runtime calculated based on the determined
values of Battery Capacity and Consumption Rate may then be
digitally filtered. In a preferred embodiment, the filter used is a
low pass infinite impulse response filter.
[0056] After filtering, the Predicted Runtime may then be
discretized at different levels based on the magnitude of the
Predicted Runtime. For example, if the Predicted Runtime is greater
than 6 hours, the Predicted Runtime may be reported in increments
of 30 minutes. As another example, if the Predicted Runtime is
between 3.5 hours and 6 hours, the Predicted Runtime may be
reported in increments of 15 minutes. Similarly, if the Predicted
Runtime is between 1.5 hours and 3.5 hours, the Predicted Runtime
may be reported in increments of 5 minutes. Further, if the
Predicted Runtime is less than 1.5 hours, the Predicted Runtime may
be reported in increments of 1 minute. For example, if the
Predicted Runtime is calculated as 1.88 hours (1 hour and 52 8
minutes), it may be discretized such that the display reads a
battery life of 1 hour and 50 minutes. The rationale is that, if
the Predicted Runtime is comparatively long, it is less critical
that the user know very precisely the amount of battery life
remaining before requiring recharging or replacement of the
battery. Contrariwise, if the Predicted Runtime is comparatively
short, it is more critical that the user know very precisely the
amount of battery life remaining before requiring recharging or
replacing the battery. In one embodiment, the discretization
algorithm always occurs downward, such that the discretized
Predicted Runtime is always less than the calculated Predicted
Runtime. The rationale for this embodiment is that it is better to
provide the user with an underestimate of Predicted Runtime than an
overestimate of Predicted Runtime.
[0057] As described above, an elongated flexible electrical cable
51 extends from a controller end 52 to a pump end 54 and includes a
flexible, helical-shaped strain relief segment 55 (shown in FIGS.
1-3) between the cable ends 52 and 54. As one cable end 54 remains
within the body when the pump 12 is implanted in the body while the
other cable end 52 is outside the body connected to the control
system 10, a portion of cable 51 extends through the patient's
skin. The strain relief segment 55 is positioned outside the body.
If the control system 10 is moved far enough away from the body,
the relief segment 55 begins to unwind. By virtue of the relief
segment 55 unwinding, the cable 51 does not significantly pull on
the body site through which the cable 51 extends. If the cable 51
had no relief segment 55, tension on the cable 51 would directly
translate to tension at the body site through which the cable 51
extends, or ultimately on the point of connection of the cable 51
to the pump 12. Avoiding such tension on the portion of the body
through which the cable 51 extends also reduces irritation on the
skin and promotes healing of the skin site through which the cable
51 extends. Additionally, the strain relief segment 55 may be
calibrated such that if the control system 10 is dropped by the
patient, the strain relief segment 55 will uncoil such that the
control system 10 contacts the ground prior to the strain relief
segment 55 fully uncoiling. This functions to reduce the likelihood
that, if the control system 10 is dropped, the weight of the
control system 10 will result in components of the pump 12 or cable
51 within the body causing internal bodily harm. In one example,
the strain relief segment 55 uncoils or unwinds to a length of
approximately 2 feet (0.610 meters) while the remainder of the
cable 51 positioned outside the body is between approximately 18
inches (0.457 meters) and 2 feet (0.610 meters). In this
embodiment, the total length of the cable 51, when the strain
relief segment 55 is uncoiled or unwound, is between approximately
3.5 feet (1.067 meters) and 4 feet (1.219 meters). As the cable 51
usually exits the body near the lower abdomen area, the total
length of the cable 51 outside of the body is enough for the
control system 10 to reach the ground when the strain relief
segment 55 is uncoiled.
[0058] In addition, as described above, cup-like lower housing
portion B may adapted to receive a battery 84 in its interior
region. Normally, the battery 84 is built into the housing B. The
lower housing portion B, including its components, preferably is
heavier than the upper housing portion A such that the center of
gravity for the control system 10 is situated within the lower
housing portion B. This may be accomplished by virtue of the weight
of the battery 84 alone. Alternately, the lower housing portion B
may be formed of heavier materials or may include additional
material, such as weighted plates, to lower the center of gravity
of the control system 10. Because the assembly of lower housing B
and upper housing A has a low center of gravity, if the control
system 10 is dropped, the lower housing portion B will be more
likely to make initial contact with the ground. This may be
beneficial in that the upper housing portion A, which houses the
electronics to control the pump 12, is less likely to be damaged if
the control system 10 is dropped and impacts the floor.
[0059] Still further, as described above, certain conditions of the
control system 10, such as a low battery condition, may generate an
alarm condition, for example by sounding an audible alarm or
causing vibrations of the control system 10. In one embodiment,
audible alarms are used in combination with vibratory alarms. In a
further embodiment, the audible and vibratory alarms are staged in
sequential phases. For example, as an operating condition is
reached that causes the control system 10 to alert the user, a
first stage vibratory alarm may be generated. Following a certain
period of time, on the order of seconds, a second stage audible
alarm may sound in addition to, or to replace, the vibratory alarm.
The benefit of such a staged alarm configuration is that the
vibratory alarm gives the patient a first notice of the alarm
condition, upon which the user may act to temporarily mute upcoming
audible alarms. This may be particularly beneficial if the user
does not want to call attention to himself. Since it is generally
imperative that a user become aware of an alarm condition in such a
control system 10, it may be imprudent to set an alarm to solely a
vibratory function, as a user may be more likely to fail to notice
if a vibratory alarm is occurring. By allowing a staged alarm
configuration, the user is given a first chance to privately notice
and temporarily disable an alert notice. If the first vibratory
alarm is overlooked, however, the control system 10 will produce a
more noticeable audible alarm to increase the likelihood of the
user becoming aware of the alarm condition.
[0060] As described above, an embodiment of the control system 10
includes an internal battery 88 and an external battery 84. An AC
or DC power adapter may also be coupled to the control system to
provide power. In one embodiment the external battery 84 may be
removed from the control system 10 when the external battery 84 is
low on charge and connected to a charging station to recharge the
external battery 84. Alternatively, or in addition, the external
battery 84, while connected to the control system 10, may be
charged by the control system 10, while the control system 10
itself is being powered by a power adapter. This may be possible,
for example, by a regulating circuit within the control system 10
that dictates the supply of power based on a set of hierarchy
rules. In the hierarchy rules, if a power adapter is connected to
the control system 10 while the external battery 84 is also
connected, the control system directs the power to the external
battery 84, the internal battery 88, and the pump 12. If the
external battery 84 is not connected to the control system 10 but
the power adapter is connected to the control system 10, the
control system directs power to the internal battery 88 and the
pump 12. If the power adapter is not connected to the control
system 10, the control system 10 directs the external battery 84,
if connected, to deliver power to the internal battery 88 and the
pump 12. If neither the external battery 84 nor the power adapter
is connected to the control system 10, only the internal battery 88
remains to power the control system 10 and pump 12.
[0061] An alternate embodiment of the control system housing 16' is
illustrated in FIGS. 6A-E. In this embodiment, housing 16' includes
upper housing 16A' and lower housing 16B'. Lower housing 16B' may
accept a battery in a single configuration keyed to the shape of
the lower housing 16B', or alternatively the lower housing 16B' may
be integral with the battery, the battery and lower housing 16B'
being provided as a unit. Many of the features of the housing 16'
are similar or identical to features described in relation to
housing 16 above. The illustrated embodiment of housing 16',
however, includes an integrated latching mechanism to latch the
battery/lower housing 16B' to the upper housing 16A'. As
illustrated, battery/lower housing 16B' includes two latches 110
extending from an upper surface of the battery/lower housing 16B'.
Each latch extends upwards and hooks back, away from the center of
battery/lower housing 16B'. Near the center of the top of
battery/lower housing 16B' is a recessed area 120, which may be
generally rectangular. Within the recessed area 120 extend
connecting pins 130, which allow electrical connection between the
battery/lower housing 16B' and components of the upper housing 16N.
The battery/lower housing 16B may also include a plate 140 with
recess 150 located on the opposite side of the latches 110. The
plate 140 may be positioned lower than the top surface of the
battery/lower housing 16B'.
[0062] The bottom surface of upper housing 16A', the details of
which are best illustrated in FIGS. 6D-E, includes features
complementary to those of the battery/lower housing 16B'. For
example, upper housing 16A' includes two generally rectangular
recesses 115 configured to receive latches 110 of the battery/lower
housing 16B'. Each latch 110 may be inserted into a respective
recess 115, and as the upper housing 16A' is brought into contact
with battery/lower housing 16B', the hooked shape of the latches
115 helps secure the housing 16' together.
[0063] The upper housing 16A' also may include a generally
rectangular protrusion 125 near the center of the bottom of upper
housing 16A', configured to fit within the recess 120 of
battery/lower housing 16B'. Within a recessed area of the
rectangular protrusion 125 of the upper housing 16A' are a set of
connecting pins 135, which are configured to mate with the
connecting pins 130 of the battery/lower housing 16B' to
electrically connect the housing portions. After the latches 110
are inserted into the recesses 115 and the upper housing 16A' is
rotated toward the battery/lower housing 16B', the rectangular
protrusion 125 of the upper housing 16A' enters the rectangular
recess 120 of the battery/lower housing 16B', after which the
connecting pins 130, 135 mate with each other and electrically
connect the housing.
[0064] The upper housing 16A' may further include a plate 145 and a
latch 155 protruding through the plate, the plate 145 and latch 155
being positioned opposite the recesses 115. When connecting the
upper housing 16A' to the battery/lower housing 16B', after the
latches 110 mate with the recesses 115, and after the connecting
pins 130, 135 mate with each other, the upper housing 16N continues
rotation toward the battery/lower housing 16B'. As this motion
continues, the latch 155 of upper housing 16N enters the recess 150
of battery/lower housing 16B' as the plates 140, 145 make contact.
This final latching action fully secures the upper housing 16A' to
the battery/lower housing 1613'. As described above, the upper
housing 16A' may include a release button RB'. If a user desires to
disconnected the upper housing 16A' form the battery/lower housing
16B', he depresses the release button RB'. Once depressed, the
latch 155 is unlocked from the recess 150, and the upper housing
16A' may be disconnected from the battery/lower housing 16B' in
substantially the reverse order described above relating to
connecting the upper housing 16N with battery/lower housing
16B'.
[0065] Additionally, the bottom surface of upper housing 16A' may
include a heat sink 200, for example comprising a material with
good heat transfer properties. Such a heat sink 200 helps the
control system 10 disperse heat generated during operation of the
control system 10. A gasket 300 (illustrated in FIG. 6B), may also
be provided between the upper housing 16A' and lower housing 16B'
to help prevent water from entering the space between the upper
housing 16A' and lower housing 16B' Importantly, the gasket 300
helps exclude water from the connector pins 130, 135, through which
electricity flows.
[0066] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *