U.S. patent application number 15/832291 was filed with the patent office on 2018-09-06 for artificial heart system.
This patent application is currently assigned to RELIANTHEART INC.. The applicant listed for this patent is Robert Benkowski, Gino Morello. Invention is credited to Robert Benkowski, Gino Morello.
Application Number | 20180250457 15/832291 |
Document ID | / |
Family ID | 37499150 |
Filed Date | 2018-09-06 |
United States Patent
Application |
20180250457 |
Kind Code |
A1 |
Morello; Gino ; et
al. |
September 6, 2018 |
ARTIFICIAL HEART SYSTEM
Abstract
A blood pump system includes two blood pumps, which may be
implanted into a patient. The blood pumps may comprise VAD pumps.
Control devices and methods operate the pumps such that they can
function as a total artificial heart.
Inventors: |
Morello; Gino; (Houston,
TX) ; Benkowski; Robert; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Morello; Gino
Benkowski; Robert |
Houston
Houston |
TX
TX |
US
US |
|
|
Assignee: |
RELIANTHEART INC.
Houston
TX
|
Family ID: |
37499150 |
Appl. No.: |
15/832291 |
Filed: |
December 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11916958 |
Sep 10, 2008 |
9861729 |
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PCT/US2006/022475 |
Jun 8, 2006 |
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15832291 |
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60595131 |
Jun 8, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 1/1031 20140204;
A61M 2205/3334 20130101; A61M 1/101 20130101; A61M 1/122 20140204;
A61M 1/1086 20130101 |
International
Class: |
A61M 1/10 20060101
A61M001/10 |
Claims
1. A heart pump system, comprising: first and second blood pumps;
and a controller operably connected to the first and second
pumps.
2. The system of claim 1, wherein the controller includes first and
second controllers operably connected to the first and second
pumps, respectively.
3. The system of claim 1, wherein the pumps comprise ventricle
assist devices (VADs).
4. The system of claim 1, wherein the controller operates the first
and second pumps in a master/slave configuration.
5. The system of claim 1, wherein the first pump is inserted
between a patient's left atrium and ascending aorta and the second
pump is inserted between the patient's right atrium and pulmonary
artery.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/595,131, filed on Jun. 8, 2005, which is
incorporated by reference.
BACKGROUND
[0002] The invention relates generally to artificial heart
systems.
[0003] Artificial heart system and other implantable blood pump
systems are generally employed either to completely replace a human
heart that is not functioning properly, or to boost blood
circulation in patients whose heart still functions but is not
pumping blood at an adequate rate. Known implantable blood pump
systems are primarily used as a "bridge to transplant." In other
words, existing blood pump system applications are mainly temporary
fixes, intended to keep a patient alive until a donor is available.
However, the shortage of human organ donors, coupled with
improvements in blood pump reliability make long-term, or even
permanent blood pump implementations a reality.
[0004] The present disclosure addresses shortcomings associated
with the prior art.
SUMMARY
[0005] A heart pump system inluces first and second blood pumps
with a controller operably connected to the first and second pumps,
such that the pumps are operable as a total artificial heart. The
controller may first and second controllers operably connected to
the first and second pumps, respectively. In certain exemplary
embodiments, the pumps are ventricle assist devices, wherein the
first pump is inserted between a patient's left atrium and
ascending aorta and the second pump is inserted between the
patient's right atrium and pulmonary artery. The pumps can be
operated, for example, in a master/slave configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Other objects and advantages of the invention will become
apparent upon reading the following detailed description and upon
reference to the drawings in which:
[0007] FIG. 1 is a block diagram of a heart pump system in
accordance with certain teachings of the present disclosure.
[0008] FIG. 2 is a block diagram conceptually illustrating portions
of an artificial heart system in accordance with the teachings of
the present disclosure.
[0009] FIG. 3 illustrates an exemplary heart pump suitable for use
in accordance with the teachings herein.
[0010] FIG. 4 illustrates portions of a pump and pump controller in
accordance with the teachings of the present disclosure.
[0011] FIG. 5 illustrates additional details of the exemplary pump
controller shown in FIG. 4.
[0012] FIG. 6 illustrates an embodiment of an exemplary motor
control circuit in accordance with certain teachings of the present
disclosure.
[0013] FIG. 7 illustrates an overview of the architecture for an
exemplary artificial heart control system in accordance with the
teachings of the present disclosure.
[0014] FIG. 8 illustrates details of an exemplary control system
front panel.
[0015] FIG. 9 illustrates details of an exemplary control system
rear panel.
[0016] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION
[0017] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0018] FIG. 1 shows an exemplary heart pump system 10, which as
shown, functions as a left ventricle assist device (LVAD). The
system 10 includes components designed to be implanted within a
human body and components external to the body. The components of
the system 10 that are implantable include a rotary pump 12 (or
"VAD pump") and a flow sensor 14. The external components include a
portable controller module 16, a clinical data acquisition system
(CDAS) 18, and a patient home support system (PHSS) 20. The
implanted components are connected to the controller module 16 via
a percutaneous cable 22. The controller module 16 may be mounted to
a support device, such as a user's belt 23 or to a vest worn by the
user. Alternatively, the controller module 16 may be placed on the
CDAS 18 or placed on a nightstand when the user is in bed. A spare
controller module 16 may be stored in the PHSS 20. The controller
module 16 includes two connectors 24 and 26 for coupling to one or
more batteries 28, which provide power for the controller module 16
when in a stand-alone mode. The system 10 may further include a
battery charger (not shown in FIG. 1). The same connectors 24, 26
also may couple the controller module to either the CDAS 18 or PHSS
20.
[0019] In accordance with certain teachings of the present
disclosure, two of the pumps 12 are implanted to form a total
artificial heart (TAH) system. Suitable pumps include various
embodiments of pumps disclosed in U.S. Pat. Nos. 5,527,159;
5,947,892 or 5,692,882; all of which are incorporated by reference.
Exemplary implantable pump systems and control methods are
disclosed in U.S. Pat. Nos. 6,652,447; 6,605,032 and 6,183,412;
also incorporated by reference. Other versions employ an
implantable centrifugal pump or a pulsatile pump.
[0020] In the TAH system, two of the pumps 12 are implanted to
function as an artificial heart, providing mechanical assistance in
patients who suffer both right side and left side heart failure.
The pumps 12 can provide biventricular support with one attached to
the right ventricle and one attached to the left ventricle. The
native ventricles are surgically dissected and the remaining atria
utilized as blood filled reservoirs and as points of attachment for
the inlets of the pumps.
[0021] FIG. 2 conceptually illustrates portions of a TAH system 11,
which includes two pumps 12 connected to respective controllers 16
with a system controller 116 connected to the pump controllers 16.
The system controller 116 and pump controllers 16 may be
implemented by a single device, or the functions of the pump
controllers 16 could be combined into a single device connected to
the system controller 116.
[0022] An example of a blood pump 12 suitable for use as part of a
TAH system is illustrated in FIG. 3. The exemplary pump includes a
pump housing 32, a diffuser 34, a flow straightener 36, and a
brushless DC motor 38, which includes a stator 40 and a rotor 42.
The housing 32 includes a flow tube 44 having a blood flow path 46
therethrough, a blood inlet 48, and a blood outlet 50.
[0023] The stator 40 is attached to the pump housing 32, is
preferably located outside the flow tube 44, and has a stator field
winding 52 for producing a stator magnetic field. In one
embodiment, the stator 40 includes three stator windings and may be
three phase "Y" or "Delta" wound. The flow straightener 36 is
located within the flow tube 44, and includes a flow straightener
hub 54 and at least one flow straightener blade 56 attached to the
flow straightener hub 54. The rotor 42 is located within the flow
tube 44 for rotation in response to the stator magnetic field, and
includes an inducer 58 and an impeller 60. Excitation current is
applied to the stator windings 52 to generate a rotating magnetic
field. A plurality of magnets 62 are coupled to the rotor 42. The
magnets 62, and thus the rotor 42, follow the rotary field to
produce rotary motion.
[0024] The inducer 58 is located downstream of the flow
straightener 36, and includes an inducer hub 64 and at least one
inducer blade 66 attached to the inducer hub 64. The impeller 60 is
located downstream of the inducer 58, and includes an impeller hub
68 and at least one impeller blade 70 attached to the impeller hub
68. The diffuser 34 is located within the flow tube 44 downstream
of the impeller 60, and includes a diffuser hub 72 and at least one
diffuser blade 74 attached to the diffuser hub 72. The exemplary
pump further includes a front bearing assembly 76 attached to the
flow straightener hub 36.
[0025] In the TAH system 11, left side support is provided by a
single pump 12 inserted between the left atrium and ascending aorta
while right side support is provided by another pump 12 inserted
between the right atrium and pulmonary artery. The patient's native
ventricles are removed prior to implantation of the devices. A
biventricular assist device may be realized by leaving the
ventricles intact and modifying the control algorithms
accordingly.
[0026] The pump controller 16 of an embodiment of the present
system is illustrated in greater detail in FIGS. 4 and 5 in block
diagram form. As noted above, a single pump controller 16 may be
configured to control both pumps 12, or two pump controllers 16 may
be used. The pump controller 16 includes a processor, such as a
microcontroller 80, which is coupled to a communications device 81
such as an RS-232 driver/receiver as is known in the art, and a
hardware clock and calendar device 82, which contains clock and
date information, allowing the controller module 16 to provide
real-time clock and calendar information. The microcontroller 80
communicates with the hardware clock 82 via the I.sup.2C protocol.
The microcontroller 80 also is programmed with a selftest routine,
which is executed upon application of power to check components of
the controller module 16.
[0027] The controller module 16 includes first and second
connectors 24, 26 for coupling the controller module 16 to a power
source, such as a battery 28, or the CDAS 18 or PHSS 20. In an
embodiment of the invention, the connectors 24, 26 include a
break-away feature, such that the connectors 24, 26 disengage
themselves if a given force is applied. For example, if a battery
pack connected to the controller module 16 falls on the floor, the
connector will disengage rather than pull the controller module and
in turn, tug on the percutaneous cable.
[0028] A motor controller 84 is coupled to the microcontroller 80,
and the motor controller 84 is coupled to the pump 12. The
operation of the brushless DC motor 38 used in certain embodiments
requires that current be applied in a proper sequence to the stator
windings 52. Two stator windings 52 have current applied to them at
any one time, and by sequencing the current on and off to the
respective stator windings 52, a rotating magnetic field is
produced. In an embodiment of the invention, the motor controller
84 senses back electro motive force (EMF) voltage from the motor
windings 52 to determine the proper commutation phase sequence
using phase lock loop (PLL) techniques. Whenever a conductor, such
as a stator winding 52, is "cut" by moving magnetic lines of force,
such as are generated by the magnets 62 of the brushless DC motor
38, a voltage is induced. The voltage will increase with rotor
speed 42. It is possible to sense this voltage in one of the three
stator windings 52 because only two of the motor's windings 52 are
activated at any one time, to determine the rotor 42 position.
[0029] An alternative method of detecting the rotor 42 position
relative to the stator 40 for providing the proper stator winding
52 excitation current sequence is to use a position sensor, such as
a Hall effect sensor (not shown). However, adding additional
components, such as Hall effect sensors, requires additional space,
which is limited in any implanted device application. Further,
using a position detection device adds sources of system
failures.
[0030] The motor controller 84 switches a series of power switching
devices 86 to regulate the stator winding 52 current. In one
embodiment, the power switching devices 86 comprise metal oxide
semiconductor field effect transistors (MOSFETs).
[0031] The embodiment illustrated in FIG. 3 further includes a pump
motor speed control circuit 88 coupled to the microcontroller 80 to
receive inputs regarding pump operation parameters. The speed
control circuit 88 is coupled to the motor controller 84 through a
switching device 90, which couples either the speed control circuit
88 or a hardware-implemented "safe mode" speed setting 92, which is
independent of the microcontroller 80.
[0032] The switching device 90 is actuated by a microprocessor
failure detector 94, which may comprise an external "watchdog"
timer (not shown) such as a monostable multivibrator, which
continuously monitors the microcontroller 80. Any watchdog timers
internal to the microcontroller 80 are disabled. Alternatively, the
switching device 90 may be actuated by a safety plug 96 which is
adapted to plug into either of the controller module connectors 24,
26. The external watchdog timer is periodically reset by the
microcontroller 80 during normal controller module 16 operation. In
the event that the microcontroller 80 falls, the watchdog timer
will not be reset. Upon the watchdog timer expiration, the watchdog
timer activates the switching device 90, bypassing the
microcontroller 80 and setting the pump 12 to a predetermined speed
setting 92. This insures that the pump 12 continues to operate. In
a further embodiment, the watchdog timer, upon sensing a failure,
triggers an emergency clamp and shuts down the pump 12. The
emergency clamp prevents backward flow through the pump 12.
[0033] FIG. 6 illustrates a schematic diagram of a motor control
circuit 200 in accordance with an exemplary embodiment of the
invention. The motor speed control circuit 200 includes the motor
controller 84, the speed control circuit 88, the fail detector 94,
the switching device 90 and the hard Code speed 92 from FIG. 3.
[0034] The failure detector 94 includes a watchdog timer 210
coupled to the switching device 90. Suitable watchdog timers and
switching devices include, for example, a model MAX705 monostable
multivibrator and a model MAX4514 single pole-single throw CMOS
analog switch, respectively, both available from Maxim Integrated
Products. In operation, the output of the watchdog timer 210 is
logically high during normal system operation (the microcontroller
80 functioning properly), and logically low when a malfunction or
failure of the microcontroller 80 is detected.
[0035] During normal operation, the microcontroller 80 periodically
provides a watchdog timer reset signal to the input of the watchdog
timer 210, which resets the watchdog timer 210, and forces its
output 211 logically high. The output 211 of the watchdog timer is
coupled to the control input 91 of the switching device 90. In the
exemplary embodiment illustrated in FIG. 6, the switching device 90
is configured as a normally open switch. Therefore, the logically
high signal at the control input 91 maintains the switching device
90 in a closed state, allowing the microcontroller 80 to control
the pump 12 in accordance with user input. If the watchdog timer
210 does not receive its periodic watchdog timer reset signal,
after a predetermined time period (for example, one second), it
will time-out and its output 211 will toggle from a logically high
state to a logically low state. The logically low state at the
control input 91 of the switching device 90 will decouple the
microcontroller 80 from the motor controller 84 by opening the
switching device 90. Alternatively, the switching device 90 may be
operated by the safety plug 96 to manually decouple the
microcontroller 80 from the motor controller 84.
[0036] In the embodiment illustrated in FIG. 6, the motor
controller 84 comprises a Micro Linear model ML4425 motor
controller. The motor controller 84 includes a voltage controlled
oscillator, a pulse width modulated speed control circuit, a
commutation logic control circuit, a pulse width modulated current
control circuit, MOSFET drivers, a back EMF sampler circuit, and a
power fail detector. Additional details regarding the features and
operation of the Micro Linear ML4425 motor controller are available
in the appropriate Micro Linear specification sheet.
[0037] The motor controller 84 further includes an onboard voltage
reference V.sub.ref and a speed control voltage input V.sub.spd
that is used as the control reference voltage input for the motor
speed control phase-locked loop (PLL). In a typical implementation
of a motor controller such as the Micro Linear ML4425 motor
controller, predetermined voltage levels of V.sub.spd correspond to
desired motor speeds, and the voltage level corresponding to the
desired motor speed is input to the speed control voltage input
V.sub.spd. With typical motor controller chips, however, motor
speed control is based, at least in part, on the relationship
between the onboard voltage reference V.sub.ref and the speed
control voltage input V.sub.spd. In an embodiment employing the
Micro Linear ML4425 motor controller, in accordance with the
circuit shown in FIG. 6, the onboard voltage reference V.sub.ref
output varies from 6.5 volts to 7.5 volts (6.9 volts nominal).
Thus, if absolute voltage levels corresponding to desired motor
speeds are input to the speed control voltage input V.sub.spd, the
actual pump motor speed may vary as much as .+-.20%.
[0038] To reduce this variation, the speed control circuit 88 shown
in FIG. 6 provides a speed control voltage input V.sub.spd level
that is programmed to some proportion of the onboard voltage
reference V.sub.ref value, rather than an absolute voltage level.
This removes the motor speed control's dependency on the onboard
voltage reference V.sub.ref output. In a particular embodiment of
the invention, this reduces the pump motor speed error from .+-.20%
to approximately .+-.1%.
[0039] In the embodiment illustrated in FIG. 6, the speed control
88 includes a digitally programmable electronic potentiometer 212
that receives inputs from the microcontroller 80. A model X9312T
nonvolatile digital potentiometer available from Xicor, Inc. is a
suitable digital potentiometer. The "high" terminal 214 of the
potentiometer 212 is directly coupled to the onboard voltage
reference V.sub.ref output of the motor controller 84, and the
"low" terminal 216 is coupled to the onboard voltage reference
V.sub.ref through a voltage divider comprising resistors 218, 220.
In a specific embodiment, the resistors 218, 220 comprise 1.02
k.OMEGA. and 1.5 k.OMEGA. resistors, respectively. The
potentiometer 212 thus provides a voltage output V.sub.set at its
"wiper" terminal that varies from about 0.6.times.V.sub.ref to
V.sub.ref. Allowing the speed control voltage input V.sub.spd to
equal the potentiometer 212 output voltage V.sub.set yields a pump
motor speed range of about 7,500 RPM to 12,500 RPM.
[0040] The potentiometer 212 output voltage V.sub.set is coupled to
an input of a first unity gain buffer amplifier 222, the output of
which is coupled, during normal operations, through the switching
device 90 to an input of a second unity gain buffer amplifier 224.
The output of the second unity gain buffer amplifier 224 is
connected to the V.sub.spd input of the motor controller 84 via a
resistive divider comprising resistors 226, 228. The values of
resistors 226, 228 should be selected so as to achieve two desired
ends: 1.) minimize the loading of the V.sub.set signal when the
microcontroller 80 is operating normally, and the switching device
80 is therefore closed; and 2.) provide the proper V.sub.spd
voltage to realize the desired "safe mode" pump motor speed when
the switching device 90 is opened via the watchdog timer 210 or the
safety plug 96. In one particular embodiment, the predetermined
"safe mode" speed setting is 8,500 RPM. Hence, the resistors 226,
228 comprise 31.6 k.OMEGA. and 66.5 k.OMEGA. resistors,
respectively, to achieve a V.sub.set value equal to
0.68.times.V.sub.ref when the switching device 90 is open.
[0041] The microcontroller 80 may further be programmed with a pump
restart feature for restarting the pump 12 in the event of a pump
failure. The pump restart leaves the motor speed preset to its
latest value. When the restart is activated, the microcontroller 80
initiates a start-up sequence of the motor controller 84, and locks
a predetermined time period of pump performance data into the
controller module's memory. The controller module memory is
discussed further below. If the pump 12 successfully restarts in
response to the pump restart feature within a given time limit (10
seconds in one embodiment), a diagnostic alarm is enabled and the
motor controller 84 returns the pump 12 to the latest preset speed.
If the pump 12 fails to restart, an emergency alarm is enabled and
the restart sequence repeats. The microcontroller 80 may be
programmed to limit the number of restart attempts. In a particular
embodiment, the controller module 16 limits the number of restart
attempts to three for a given pump stoppage.
[0042] The microcontroller 80 includes a multiple channel analog to
digital (A/D) converter, which receives indications of motor
parameters from the motor controller 84. Thus, the controller
module 16 may monitor parameters such as instantaneous motor
current, the AC component of the motor current, and motor speed. In
an embodiment of the invention, the controller module 16
incorporates low pass digital filtering algorithms to calculate the
mean values of parameters such as motor current to an accuracy of
.+-.1% of full scale.
[0043] As shown in FIG. 6, a series of memory devices 122 are
additionally coupled to the microcontroller 80 to save system
parameters in the event of an emergency, such as a pump shutdown.
In one embodiment of the invention, the memory devices comprise
three 128K banks of SRAM, which store pump parameters such as pump
voltage, current, RPM and flow. The first of the three SRAM banks,
segment 0, is the "looping bank," which employs a continuous,
circular buffer that continuously stores the current performance
data. Upon a predetermined event, such as a pump shutdown and
restart, the microcontroller 80 is programmed to transfer the data
from the circular buffer to one of the other memory banks.
[0044] The second SRAM bank, segment 1, contains the pump
performance data prior to the first alarm or restart that occurs
after initial power-on or a clearing of segment 0 by the CDAS (CDAS
communications with the controller module will be further discussed
below). The third bank, segment 2, contains pump performance data
prior to the most recent restart event. After each restart event
(or any alarm if segment 0 is clear) the data in the active looping
bank are transferred to segment 0 or segment 1, as appropriate. For
example, following initial start-up, if the pump stops, the
processor transfers the data from the memory segment 0, the
circular buffer, to memory segment 1. Assume that the pump then
restarts. The pump performance data in the circular buffer
associated with any subsequent predetermined events are transferred
from memory segment 0 to segment 2, such that segment 2 always has
the data associated with the most recent pump event.
[0045] In one embodiment of the invention, memory segments 0 and 1
each store 55 seconds of pump performance data segments, including
pump speed (RPM), voltage, flow rate, instantaneous motor current
and time. Further, sample rates for these parameters may be as
follows: instantaneous motor current, 2000 samples per second; flow
rate, 333 samples per second; pump speed, 10 samples per second;
and voltage, 10 samples per second. The sampling resolution for
these parameters is eight bits in one embodiment of the
invention.
[0046] Each memory segment includes predetermined boundaries for
each sampled parameter. For example, pump motor current requires
110,000 bytes to store 55 seconds at 2000 samples per second which
may be stored in a predetermined memory array. Defining parameter
boundaries in this fashion allows a technician to request
parametric data by reading a range of blocks. The last block in
each memory segment contains time stamp information available from
the real-time clock and calendar along with a start and stop memory
pointer for each parameter.
[0047] A single host computer, such as the system controller 116,
may be used to link and control both pumps 12 such that each side
may be controlled individually or in a master/slave configuration.
Additionally, the clinician may enter any linear or non-linear
function describing the desired side-to-side relationship when the
system is configured for master/slave operation. Blood flow rate
and/or pump speed may be used as the independent and dependent
variables respectively.
[0048] The system controller 116 features two analog voltage inputs
and outputs proportional to pump speed and/or flow. The analog
voltage inputs correspond to the desired target pump speed and/or
flow and the analog voltage outputs corresponds to the actual pump
speed and/or flow.
[0049] In certain exemplary embodiments, the control system 116
first establishes serial communication with each pump controller 16
and subsequently requests an Operational Parameters Data Block at a
rate of once per second. Upon receipt of the data block, it then
extracts the actual pump speed and/or flow from this block of data,
and then transmits the necessary number of increment or decrement
pump speed commands such that the actual speed and/or flow of the
pump tracks the target speed and/or flow. A manual bypass switch on
the front panel and a loss-of-power bypass mechanism has been
included for safety,
[0050] The pumps 12 may thus be controlled in a variety of ways.
For example, the common host computer 116 may be programmed to
output target reference voltages proportional to the desired left
side and right side pump speed or to the desired left side and
right side blood flow rate.
[0051] A "break-out box" may be used, which is designed to
synchronize itself to transmitted requests for the pump's
operational parameters and to transparently inject the correct
number of increment and decrement pump speed commands such that the
actual pumps' speeds match the desired speeds, and/or the desired
pump flows match the desired flows. The "break-out box" may operate
in any of three primary modes of operation:
[0052] a) CDAS Mode whereby an attached clinical data acquisition
system (CDAS) is routed directly to its respective VAD Controller
16 and used to provide manual control of the pump 12;
[0053] b) "CLCS Mode" whereby an attached clinical data acquisition
system establishes a serial communication link with its respective
VAD Controller 16 and subsequently provides timing information for
the "break-out box" to synchronize itself to. In this mode, the
"break-out box" AND clinical data acquisition system are able to
directly control pump speed;
[0054] c) CLCS Mode whereby no clinical data acquisition systems
are attached and the "break-out box" autonomously establishes it
own communication link with the VAD Controller 16 and solely
controls the pinup's speed.
[0055] The "break-out box" can be configured to perform various
functions. It can provide visual indication of serial communication
and pump status via front panel LED indicators, and/or it can
provide a serial data port which transmits system operational
information (e.g. current operating mode, number of commands
issued, target reference, actual speed/flow, etc.). It can also
provide a serial data port through which periodic firmware updates
may be programmed negating the need to open the system and replace
the processors or processor memories. The status indicators are
used to indicate which mode the system is in, receipt of valid or
alternate data blocks from attached controllers, pump off
information, and the transmission of pump speed increment and
decrement commands. In still further embodiments, the "break-out
box" also contains a medical-grade power supply to power the
attached pumps. The "break-out box" may be manually switched such
that the attached clinical data acquisition system may directly
control the implanted pumps. The "break-out box" further can be
programmed to automatically switch the attached clinical data
acquisition system to control the implanted pumps in the event that
power to the "break-out box" is removed.
[0056] The host computer 116 allows the clinician (user) to control
each pump 16 independently or in a master/slave mode. Thus, in
various implementations, the left side pump functions as the master
and the right side pump functions as the slave and the control
variable is pump speed, or the left side pump functions as the
slave and the right side pump functions as the slave. The control
variable can be pump speed or pump flow, for example. An equation
which governs the master/slave relationship may be input into the
controller 116. Further, a plurality of governing control
equations, each of which is utilized at various operating points
within the range of operation, may be used. The equations may be
linear or non-linear, single or multivariate, etc.
[0057] Preferably, each side's pump information is monitored,
displayed, and stored onto a non-volatile memory device (e.g. hard
disk drive). Such pump information typically includes pump speed,
pump flow, pump current, pump power, left atrial pressure, aortic
pressure, right atrial pressure, pulmonary artery pressure, and
differential pressure across each pump. Standard clinical pumps and
related controllers may be controlled via the attachment of a
standard clinical data acquisition system, with control provided by
a single host computer executing the desired control algorithm(s).
Standard clinical data acquisition systems may remain connected for
data monitoring and control purposes concurrently with the host
computer. The host computer system may be selectively removed from
the control loop and control relinquished to a standard clinical
data acquisition system for safety. In some implementations, the
single host computer executing the desired control algorithm only
controls a single side while manual control is maintained on the
other side.
[0058] FIG. 7 shows a simplified overview of the architecture for
an exemplary TAH control system 116. The system 116 includes left
and right side closed-loop controllers 316a, 316b. A 12-pin
connector 320 connects the system to an external computer.
Additional 12-pin connectors 322, 324 connect the left and right
side controllers 316a, 316b to the left and right side CDASs and
left and right side pump controllers. The connectors 322,324 allow
the user to attach a CDAS on the left and right side for manual
control. Each of the controllers 316a, 316b includes corresponding
speed and serial inputs 330, 332, and speed and power outputs 334,
336.
[0059] FIGS. 8 and 9 detail positions of each controls and
indicators on the Control System front panel. The particular
control system 116 includes switches that allow the user to
manually enter bypass mode, and LED indicators that are used to
report which mode the system is in, whether the system is receiving
operational parameter blocks or other data, whether the system is
transmitting increment or decrement pump speed commands, and if the
pumps are off. The following is a detailed list of all of the
system's controls and indicators and what their respective
functions are:
[0060] Front Panel Switches: [0061] MODE CDAS/CLCS--These
two-position rocker switches 350 enable the Control System to
actively transmit increment speed and decrement speed commands to
each of the VAD Controllers when in "CLCS MODE" or to force the
system into its safe bypass mode of operation when in "CDAS
MODE".
[0062] Front Panel Connectors: [0063] CDAS--These connectors 322
enable the user to connect a Clinical Data Acquisition System
(CDAS) to the system. Communication between the attached CDAS and
its respective VAD Controller is achieved when the MODE CDAS/CLCS
rocker switch is placed into the CDAS position or when the entire
Control System is de-energized.
[0064] Front Panel LED Indicators: [0065] CLCS MODE LED--These LEDs
352 indicate the position of the MODE CDAS/CLCS switch. When in the
"CLCS MODE" position, the system will is actively transmit
increment speed and decrement speed commands to the VAD Controller
while in this mode. When the MODE CDAS/CLCS switch is placed into
the "CDAS MODE" position, the system is inhibited from transmitting
increment speed and decrement speed commands to the VAD Controller
while in this mode. [0066] DEC SPD LED--These amber LEDs 354 flash
each time the system transmits a decrement speed command to the VAD
Controller. [0067] INC SPD LED--These amber LEDs 356 flash each
time the system transmits an increment speed command to the VAD
Controller. [0068] VALID DATA LED--These green LEDs 358 flash each
time the system receives a valid OPERATIONAL PARAMETERS data block
transmitted from the VAD Controller. The actual speed and/or flow
data is contained in this data block and is subsequently parsed and
compared to the sampled analog target reference such that the
system can prepare to transmit any necessary increment and/or
decrement commands. [0069] ALT DATA LED--These amber LEDs 360 flash
each time the system receives data other than a valid OPERATIONAL
PARAMETERS data block transmitted from the VAD Controller. No
increment speed or decrement speed commands are transmitted until a
valid OPERATIONAL PARAMETERS data block is received. [0070] PUMP
OFF LED--These red LEDs 362 flash each time the system receives a
valid OPERATIONAL PARAMETERS data block containing "pump off"
information transmitted from the VAD Controller. No increment speed
or decrement speed commands are transmitted until a valid
OPERATIONAL PARAMETERS data block is received and the pump is
running. This prevents the VAD Controller's speed value from being
reprogrammed while the pump is off. [0071] POWER ON LED--This solid
green LED 364 is illuminated when the POWER ON/OFF switch is placed
into the "ON" position.
[0072] FIG. 9 details the position of each connector on the Control
System rear panel: [0073] POWER INPUT--A switched and filtered
IEC-320 power entry module 370 is is used to connect the Control
System to the ac mains using a line cord for the intended country
of use. [0074] MONITOR--DB-9 subminiature connectors 372 are used
to download new aware updates to each side of the Control System
116 and to allow the user to observe system operation using a
standard RS-232 serial port monitor configured for 9600 baud
operation. [0075] DAQ--This connector 320 is used to interface the
Control System controller module to an external computer, such a a
Panel PC mounted on its top enclosure lid. All analog inputs and
outputs for monitoring and control of the VADs are routed through
this port. [0076] CONTROLLER--These connectors 324 are used to
interface each side's respective VAD Controller 16 with the Control
System 116 via in interface cable, such as MicroMed Technology's
standard VAD Controller Interface Cable. Power, serial
communication, and analog flow and current signals are routed
through these ports. [0077] FLOW--These two connectors 376 are used
to route analog flow information from each VAD Controller to an
externally attached data acquisition system. [0078] SPEED--These
two connectors 378 are used to route analog speed information
derived from each VAD Controller's transmitted Operational
Parameters Data Block to an externally attached data acquisition
system. [0079] LAP--This connector 380 is used to route analog left
atrial pressure information from an external pressure transducer to
the system's integral Panel PC with analog I/O board installed.
[0080] RAP--This connector 382 is used to route analog right atrial
pressure information from an external pressure transducer the
system's integral Panel PC with analog I/O board installed. [0081]
AoP--This connector 384 is used to route analog aortic pressure
information from an external pressure transducer the system's
integral Panel PC with analog I/O board installed. [0082] PAP--This
connector 386 is used to route analog pulmonary artery pressure
information from an external pressure transducer to the system's
integral Panel PC with analog I/O board installed.
[0083] The above description of exemplary embodiments of the
invention are made by way of example and not for purposes of
limitation. Many variations may be made to the embodiments and
methods disclosed herein without departing from the scope and
spirit of the present invention.
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