Note: Descriptions are shown in the official language in which they were submitted.
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EAVESDROPPING DEVICE
Technical field
The present invention relates to an eavesdropping device comprising a receiver
and
a high-impedance interface for acquiring physiological variables measured in a
body.
Background art
Today, there is an increased need for invasive measurements of physiological
variables. For example, when investigating cardiovascular diseases, it is
strongly desired to
obtain local measurements of blood pressure and flow in order to evaluate the
condition of
the subject under measurement. Therefore, methods and devices have been
developed for
disposing a miniature sensor inside the body of an individual at a location
where the
measurements should be performed, and for communicating with the miniature
sensor.
Typically, the miniature sensor is arranged at a distal end of a guide wire,
which is generally
known in the art, and used for example in connection with treatment of
coronary disease.
The distal end of the guide wire is inserted into the body of a patient, for
example
into an opening into the femoral artery, and placed at a desired location.
Once the guide
wire is placed by the physician into the appropriate location, the miniature
sensor can
measure the blood pressure and/or flow. Measurement of blood pressure is a way
to
diagnose e.g. the significance of a stenosis. Further, a catheter of
appropriate type may be
guided onto the guide wire. Balloon dilation may then be performed. When
measuring distal
blood pressure (Pd), the sensor must be inserted into a vessel distal of the
stenosis. For
evident reasons, the dimensions of the sensor and the guide wire are fairly
small; the guide
wire typically has a diameter of 0.35 mm.
When diagnosing the significance of a stenosis in a hospital or a clinic, a
catheter in
connection with a first sensor is inserted into a patient proximal to a
potential stenosis
(typically visualized by means of flouroscopy). The sensor is connected to a
central
monitoring device via electrical leads. The central monitoring device used to
monitor the
patient's vital status, including blood pressure measured via the first
sensor, is referred to
as a cathlab monitor. In case of a stenosis, the vessel is narrower than
normal, which
impedes the flow of blood at the stenosis. When a narrowing of a vessel is
seen on an
angiogram, it is recommended that Fractional Flow Reserve (FFR) should be
measured to
determine the extent of the blood pressure difference proximal and distally of
the stenosis.
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FFR is approximated as Pd/Pa. The FFR is a measure of the pressure distal to a
stenosis relative to the pressure proximal to the stenosis. Thus, FFR
expresses vessel
blood flow in the presence of a stenosis compared to the vessel blood flow in
the
hypothetical absence of the stenosis. Other physiological parameters may
further be
measured and transferred to the cathlab monitor. Should the FFR measurement
show that
there is a large drop in pressure in the vessel, treatment of the patient is
required, for
example by means of opening the vessel up with a balloon or stent, or by
surgery for a
coronary artery bypass.
To measure the distal blood pressure, the aortic blood pressure sensor is in
prior art
disconnected from the patient and the cathlab monitor. Then, a second sensor
is used
(which was discussed in the above) to measure Pd. This second sensor is
inserted into the
patient distal of the potential stenosis. The second sensor and the first
sensor are
connected to a small and easy-to-use monitoring device offering additional
functionality.
Thus, as can be seen in Fig. 3, pressure signals are connected to the smaller
monitoring
device 304 which in turn relays the pressure signals to the cathlab monitor
305.
This approach has drawbacks. For instance, connecting the smaller monitoring
device to an up-and-running system requires disconnection of connectors
carrying pressure
signals to the cathlab monitor and reconnection of these connectors to the
cathlab monitor
via the smaller monitor. Further, in addition to the obviously tedious manual
disconnecting
operation, the disconnection of pressure signal connectors implies
recalibrating the
monitors, which is an undesired procedure.
An object of the present invention is to solve, or at least mitigate, the
above
mentioned problems in the prior art.
Summary of the invention
The present invention provides an eavesdropping device for acquiring measured
physiological variables of an individual, which eavesdropping device comprises
a
receiver and a communication interface.
The eavesdropping device of the present invention is typically applied in a
system
comprising a first sensor arranged to be disposed in the body of the
individual for measuring
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aortic blood pressure Pa, and a second sensor arranged for measuring distal
blood pressure
Pd. Further, the system comprises a central monitoring device for monitoring
the measured
physiological variables and a communication link between the sensors and the
central
monitoring device for communicating signals representing the measured
physiological
variables from the sensors to the central monitoring device.
The eavesdropping device is configured such that the communication interface
is
arranged at the communication link to communicate at least the signal
representing the
aortic blood pressure to the receiver of the eavesdropping device. Moreover,
the receiver of
the eavesdropping device is connected to the communication link, in parallel
with the central
monitoring device, and arranged with at least one high-impedance input. The
signal
representing the aortic blood pressure Pa is communicated to the high-
impedance input via
the communication interface, and the receiver of the eavesdropping device is
further being
arranged to receive the signal representing the measured distal blood pressure
Pd from the
communication link. By means of the blood pressure signals of the respective
sensor, FFR
can be calculated.
The present invention is advantageous in that the central monitoring device,
being
for example a so called cathlab monitor, can be connected directly to the
sensors by means
of appropriate connecting means. Thereafter, the sensors and the central
monitoring device
are balanced, i.e. the aortic and distal blood pressure is zeroed respectively
such that a
correct pressure reference level is introduced in the measurement system. Now,
once the
balancing has been effected, the eavesdropping receiver, being for example a
RadiAnalyzerC), can be connected to the communication link connecting the
sensors to the
central monitoring device, in parallel with the central monitoring device, via
a high-
impedance interface formed by the receiver and the communication interface of
the
eavesdropping device. That is, the eavesdropping receiver is able to
"eavesdrop" on the
communication link, thus being capable of accessing and monitoring the
measured aortic
blood pressure without affecting the pressure signal to any noticeable degree.
In the prior
art, as soon as a second monitoring device is to be connected between the
sensors and the
central monitoring device, connectors via which the pressure signals are
supplied to the
central monitor must be disconnected and coupled to the second monitor.
Thereafter, the
pressure signals are relayed from the second monitor to the central monitor.
This prior art
procedure requires a further balancing step to be undertaken; first, the
sensors and the
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second monitor are balanced and second, the central monitor and the second
monitor are
balanced.
In an embodiment of the present invention, the communication link is arranged
to
communicate the signal representing measured aortic pressure via a wired
connection to
the central monitoring device, and via a wireless connection formed by the
communication
interface to the eavesdropping receiver. The signal representing measured
distal blood
pressure is communicated to the central monitoring device using either a wired
or a wireless
channel, and is communicated to the eavesdropping receiver using a wireless
channel
although a wired connection indeed can be used . As can be understood, various
combinations are possible. It can also be envisaged that either, or both, of
the measured
pressure signals are communicated to the eavesdropping receiver using wired
connections.
The distal pressure signals are preferably transported to the eavesdropping
receiver
using a wireless channel, while the aortic pressure signals preferably are
transported to the
eavesdropping receiver on a wireless channel to avoid further cabling,
although it is still
advantageous with respect to the prior art to transport the aortic pressure
signals to the
eavesdropping receiver using a wired connection.
However, in any selected combination the eavesdropping receiver is connected
in
parallel to the central monitoring device via a high-impedance communication
interface of
the eavesdropping device. Thus, the central monitoring device is, by
appropriately using
wired and/or wireless channels, connected and balanced to the two sensors,
while the
eavesdropping receiver is connected in parallel with the central monitoring
device, via the
high-impedance interface, without affecting the communicated aortic pressure
signals.
Hence, with these embodiments, the number of required steps involving
calibration and
reconnecting of cables are reduced. The connection of the eavesdropping
receiver in
parallel with the central monitoring device via a high-impedance communication
interface
clearly solves a number of prior art problems.
In a further embodiment of the present invention, the communication interface
is
supplied with power from the central monitoring device. In a further
embodiment, the
communication interface is arranged with a battery for power supply. In yet
another
embodiment, the battery can be charged from the central monitor.
In these embodiments, the (wireless or wired) communication interface can
easily be
connected by a user to the aortic sensor device and the central monitoring
device by means
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of suitable connectors, without the user having to take into account powering
of the
communication interface. From a user's perspective, the supply of power is
completely
automated. Advantageously, the communication interface is premounted on a
sensor cable
which a user easily and straight-forwardly connects to the central monitor
while initiating a
measuring procedure.
A further advantage to have the eavesdropping receiver wirelessly connected to
the
communication link in parallel with the central monitoring device is that no
cabling is
necessary for the eavesdropping receiver.
The invention also includes various methods having one or more of the steps or
actions or features described in this patent specification.
Further features of, and advantages with, the present invention will become
apparent
when studying the appended claims and the following description. Those skilled
in the art
realize that different features of the present invention can be combined to
create
embodiments other than those described in the following.
Brief description of the drawings
The preferred embodiments of the present invention will be described in more
detail
with reference made to the attached drawings, in which:
Fig. 1 shows a longitudinal section view of an exemplifying sensor guide
construction
that may be employed in the present invention;
Fig. 2 shows a prior art sensor device for measuring a physiological variable
in a
body;
Fig. 3 illustrates how prior art measurements of FFR are undertaken using the
sensor device discussed in connection with Figs. 1 and 2;
Fig. 4 shows an embodiment of the eavesdropping device of the present
invention;
Fig. 5 shows a further embodiment of the eavesdropping device of the present
invention;
Fig. 6 shows another embodiment of the eavesdropping device of the present
invention;
Fig. 7 shows still another embodiment of the eavesdropping device of the
present
invention;
Fig. 8 shows yet a further embodiment of the eavesdropping device of the
present
invention.
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Detailed description
In the prior art, it is known to mount a sensor on a guide wire and to
position the
sensor via the guide wire in a blood vessel in a living body to detect a
physical parameter,
such as pressure or temperature. The sensor includes elements that are
directly or
indirectly sensitive to the parameter. Numerous patents describing different
types of
sensors for measuring physiological parameters are assigned to the present
assignee. For
example, temperature can be measured by observing the resistance of a
conductor having
temperature sensitive resistance as described in U.S. Patent No. 6,615,067.
Another
exemplifying sensor may be found in U.S. Patent Nos. 6,167,763 and 6,615,667,
in which
blood flow exerts pressure on the sensor which delivers a signal
representative of the
exerted pressure.
In order to power the sensor and to communicate signals representing the
measured
physiological variable to a control unit acting as an interface device
disposed outside the
body, one or more cables for transmitting the signals are connected to the
sensor, and are
routed along the guide wire to be passed out from the vessel to an external
control unit via a
connector assembly. The control unit may be adapted for performing the
functions of the
previously mentioned signal conversion device, namely to convert sensors
signals into a
format accepted by the ANSI/AAMI BP22-1994 standard. In addition, the guide
wire is
typically provided with a central metal wire (core wire) serving as a support
for the sensor.
Fig. 1 shows an exemplifying sensor mounted on a guide wire, i.e. a sensor
guide
construction 101. The sensor guide construction has, in the drawing, been
divided into five
sections, 102-106, for illustrative purposes. The section 102 is the most
distal portion, i.e.
that portion which is going to be inserted farthest into the vessel, and
section 106 is the
most proximal portion, i.e. that portion being situated closest to a not shown
control unit.
Section 102 comprises a radiopaque coil 108 made of e.g. platinum, provided
with an arced
tip 107. In the platinum coil and the tip, there is also attached a stainless,
solid metal wire
109, which in section 102 is formed like a thin conical tip and functions as a
security thread
for the platinum coil 108. The successive tapering of the metal wire 109 in
section 102
towards the arced tip 107 results in that the front portion of the sensor
guide construction
becomes successively softer.
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At the transition between the sections 102 and 103, the lower end of the coil
108 is
attached to the wire 109 with glue or alternatively, solder, thereby forming a
joint 110. At the
joint 110 a thin outer tube 111 commences which is made of a biocompatible
material, e.g.
polyimide, and extends downwards all the way to section 106. The tube 111 has
been
treated to give the sensor guide construction a smooth outer surface with low
friction. The
metal wire 109 is heavily expanded in section 103 and is in this expansion
provided with a
slot 112 in which a sensor element 114 is arranged, e.g. a pressure gauge. The
sensor
requires electric energy for its operation. The expansion of the metal wire
109 in which the
sensor element 114 is attached decreases the stress exerted on the sensor
element 114 in
sharp vessel bends.
From the sensor element 114 there is arranged a signal transmitting cable 116,
which typically comprises one or more electric cables. The signal transmitting
cable 116
extends from the sensor element 114 to an (not shown) interface device being
situated
below the section 106 and outside the body. A supply voltage is fed to the
sensor via the
transmitting cable 116 (or cables). The signals representing the measured
physiological
variable are also transferred along the transmitting cable 116. The metal wire
109 is
substantially thinner in the beginning of section 104 to obtain good
flexibility of the front
portion of the sensor guide construction. At the end of section 104 and in the
whole of
section 105, the metal wire 109 is thicker in order to make it easier to push
the sensor guide
construction 101 forward in the vessel. In section 106 the metal wire 109 is
as coarse as
possible to be easy to handle and is here provided with a slot 120 in which
the cable 116 is
attached with e.g. glue.
The use of a guide wire 201, such as is illustrated in Fig. 1, is
schematically shown in
Fig. 2. Guide wire 201 is inserted into the femoral artery of a patient 225.
The position of
guide wire 201 and the sensor 214 inside the body is illustrated with dotted
lines. Guide wire
201 , and more specifically electrically transmitting cable 211 thereof, is
also coupled to a
control unit 222 via a wire 226 that is connected to cable 21 1 using any
suitable connector
means (not shown), such as a crocodile clip-type connector or any other known
connector.
The wire 226 is preferably made as short as possible for easiness in handling
the guide wire
201. Preferably, the wire 226 is omitted, such that the control unit 222 is
directly attached to
the cable 21 1 via suitable connectors. The control unit 222 provides an
electrical voltage to
the circuit comprising wire 226, cable 211 of the guide wire 201 and the
sensor 214.
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Moreover, the signal representing the measured physiological variable is
transferred from
the sensor 214 via the cable 211 to the control unit 222. The method to
introduce the guide
wire 201 is well known to those skilled in the art. From the control unit 222,
a signal
representing distal pressure measured by the sensor 214 is communicated to one
or more
monitor devices, preferably using the ANSI/AAMI BP22-1994 standard, either by
means of
wireless communication or via a wired connection.
The voltage provided to the sensor by the control unit could be an AC or a DC
voltage. Generally, in the case of applying an AC voltage, the sensor is
typically connected
to a circuit that includes a rectifier that transforms the AC voltage to a DC
voltage for driving
the sensor selected to be sensitive to the physical parameter to be
investigated.
Fig. 3 illustrates how measurements of FFR are undertaken today using the
sensor
discussed in connection with Figs. 1 and 2. A first sensor 308 (not disposed
in the patient)
measures aortic blood pressure Pa in known manner. A second sensor 309 is
inserted into
the patient 301 for measuring distal blood pressure Pd. A communication link
comprising
channel 302 for carrying the distal pressure and channel 303 for carrying the
aortic pressure
is arranged between the sensors and a second monitoring device 304, for
example a
RadiAnalyzere. It should be noted, as is known in the art, that the
RadiAnalyzer is used to
analyze the data received from one or both sensors and thereafter display data
to the user.
The receiving function in the present invention can be coupled to or
integrated into such a
unit. From the second monitoring device 304, the respective channel is coupled
to a central
monitoring device 305 also referred to as a cathlab monitor. On one or both
monitors, the
two pressure types are used to calculate the FFR as Pd/Pa- Now, as previously
has been
discussed, the prior art approach has drawbacks; connecting the second,
smaller
monitoring device to an up-and-running system requires disconnection of
connectors
carrying pressure signals to the cathlab monitor and reconnection of these
connectors to
the cathlab monitor via the smaller monitor. Further, the disconnection of
pressure signal
connectors implies recalibrating of the monitors, which is an undesired step.
First, the
second monitoring device 304 must be calibrated with respect to the distal
pressure channel
302. Second, the second monitoring device 304 must be calibrated with respect
to the aortic
pressure channel 303. Finally, the second monitoring device 304 and the first
monitoring
device 305 must be balanced, implying that both pressure channels 302, 303
running
between the monitors is zeroed. This totals a number of four
calibrating/balancing steps.
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Fig. 4 shows an embodiment of the present invention mitigating mentioned
problems
in the prior art. In Fig. 4, distal pressure channel 402 carries the signal
measured in patient
401 by internal sensor 409 via a wired connection through control unit 406.
Control unit 408
can perform signal conditioning (to be described below) and send the distal
pressure signal
to an eavesdropping receiver 404 and central monitor 405. In another
embodiment, signal
conditioning can be performed by eavesdropping receiver 404 (in such an
embodiment,
functions of unit 406 are incorporated into the eavesdropping receiver and
thus channel 402
is connected from the patient to the eavesdropping receiver and then from the
receiver to
monitor 405). A suitable control unit is a connector for a sensor guidewire
assembly, such
as the female connector for PressureWire , however other control units can
also be used.
Thus, the signal representing measured distal pressure is transmitted to the
eavesdropping
receiver 404 and the central monitor 405 using wired distal pressure channel
402, and the
signal representing aortic pressure measured by external sensor 408 in this
particular
embodiment is transferred to both the receiver 404 and the central monitor 405
using a
wired channel 403. At an appropriate location along the aortic channel 403,
for example at
an input of the central monitoring device 405, a wired communication interface
407 of the
inventive eavesdropping device is arranged. The eavesdropping interface 407
transmits the
signal representing measured aortic pressure to the eavesdropping receiver
404. The
interface 407 can electrically tap into a conductor in channel 403 via a high-
impedance
device (such as a resistor). Alternatively, the interface 407 can sense the
electrical signal in
channel 403 by sensing the magnetic and/or electric field in the vicinity of
channel 403 that
is created by the electrical signal passing through the conductor in channel
403. Since the
eavesdropping interface 407 is arranged with a high-impedance input, the
eavesdropping
does not affect the signal carried over the aortic channel 403. Thus, with the
eavesdropping
device of the present embodiment, only three calibrating/balancing steps are
required, since
there is no need to calibrate the eavesdropped signal. Further, if the cath
lab monitor is up-
and-running, there is no need to make any disconnections in order to couple
the
eavesdropping monitor (i.e. typically a RadiAnalyzer ) to the central
(cathlab) monitor. As
can be seen from Fig. 4, the eavesdropping receiver 404 is connected to the
communication link comprising distal channel 402 and aortic channel 403, in
parallel with
the central monitor 405, which greatly facilitates operation for the medical
personnel.
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The wired communication interface 407 is preferably pre-mounted on the
standard
communication cables for connecting an aortic pressure sensor 408 to a central
monitor
405, such cables and connectors being known in the art, but can also be
designed to be
easily connectable to such cables, e.g. by providing an assembly comprising
suitable
connectors and the transmitting unit. In the latter event, the connectors of
the aortic channel
403 to the central monitor 405 are disconnected and reconnected via the
provided
assembly. In such a procedure, reconnection of cables is necessary, however,
no new
calibration is needed.
Fig. 5 shows a further embodiment of the present invention mitigating
mentioned
problems in the prior art. In Fig. 5, distal pressure channel 502 carries the
signal measured
in patient 501 by internal sensor 509 via a wired connection through control
unit 508. Thus,
the signal representing measured distal pressure is transmitted to the
eavesdropping
receiver 504 and the central monitor 505 using wired distal pressure channel
502, and the
signal representing aortic pressure measured by external sensor 508 in this
particular
embodiment is transferred to the central monitor 505 using a wired channel
503. At an
appropriate location along the aortic channel 503, for example at an input of
the central
monitoring device 505, a wireless communication interface 507 of the inventive
eavesdropping device is arranged. The wireless eavesdropping interface 507
transmits the
signal representing measured aortic pressure to the eavesdropping receiver
504, which is
capable of wireless communication. Since the eavesdropping interface 507 is
arranged with
a high-impedance input, the eavesdropping does not affect the signal carried
over the aortic
channel 503. Thus, with the eavesdropping device of the present embodiment,
only three
calibrating/balancing steps are required, since there is no need to calibrate
the
eavesdropped signal. Further, if the cathlab monitor is up-and-running, there
is no need to
make any disconnections in order to couple the eavesdropping receiver (i.e.
typically a
RadiAnalyzere) to the central (cathlab) monitor. As can be seen from Fig. 5,
the
eavesdropping monitor 504 is connected to the communication link comprising
distal
channel 502 and aortic channel 503, in parallel with the central monitor 505,
which greatly
facilitates operation for the medical personnel.
Fig. 6 shows another embodiment of the present invention mitigating mentioned
problems in the prior art. In Fig. 6, distal pressure channel 602 carrying the
signal measured
in patient 601 by internal sensor 609 is wireless, which is enabled by means
of control unit
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606 transmitting in compliance with ANSI/AAMI BP22-1994. A suitable control
unit is the
control unit for PressureWire Aeris however other units may be used. Thus,
the signal
representing measured distal pressure is transmitted to the eavesdropping
receiver 604 and
the central monitor 805 using wireless distal pressure channel 602, while the
signal
representing aortic pressure measured by external sensor 608 in this
particular embodiment
is transferred to the central monitor 605 using a wired channel 603. As can be
seen in Fig.
6, the central monitor is capable of wireless communication, possibly using a
dongle
attached to a monitor input and being adapted for communication with the
control unit 606.
At an appropriate location along the aortic channel 603, for example at an
input of the
central monitoring device 605, a wireless communication interface 607 of the
inventive
eavesdropping device is arranged. The wireless eavesdropping interface 607
transmits the
signal representing measured aortic pressure to the eavesdropping receiver
604, which is
capable of wireless communication. Since the eavesdropping interface 607 is
arranged with
a high-impedance input, the eavesdropping does not affect the signal carried
over the aortic
channel 603. Thus, with the eavesdropping device of the present embodiment,
only three
calibrating/balancing steps are required, since there is no need to calibrate
the
eavesdropped signal. Further, if the cathlab monitor is up-and-running, there
is no need to
make any disconnections in order to couple the eavesdropping receiver (i.e.
typically a
RadiAnalyzere) to the central (cathlab) monitor. As can be seen from Fig. 6,
the
eavesdropping receiver 604 is connected to the communication link comprising
distal
channel 602 and aortic channel 603, in parallel with the central monitor 605,
which greatly
facilitates operation for the medical personnel.
Fig. 7 shows a further embodiment of the present invention mitigating
mentioned
problems in the prior art. In Fig. 7, distal pressure channel 702 carrying the
signal measured
in patient 701 by internal sensor 709 is wireless, which is enabled by means
of control unit
706 transmitting in compliance with ANSI/AAMI BP22-1994. Thus, the signal
representing
measured distal pressure is transmitted to the eavesdropping receiver 704 and
the central
monitor 705 using a wireless portion of distal pressure channel 702, while the
signal
representing aortic pressure measured by external sensor 708 in this
particular embodiment
is transferred to the central monitor 705 as well as the eavesdropping
receiver 704 using a
wired channel 703. At an appropriate location along the aortic channel 703,
for example at
an input of the central monitoring device 705, a wired communication interface
707 of the
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inventive eavesdropping device is arranged. The eavesdropping interface 707
transmits the
signal representing measured aortic pressure to the eavesdropping receiver
704. Since the
eavesdropping interface 707 is arranged with a high-impedance input, the
eavesdropping
does not affect the signal carried over the aortic channel 703. Thus, with the
eavesdropping
device of the present embodiment, only three calibrating/balancing steps are
required, since
there is no need to calibrate the eavesdropped signal. Further, if the cath
lab monitor is up-
and-running, there is no need to make any disconnections in order to couple
the
eavesdropping receiver to the central monitor. As can be seen from Fig. 7, the
eavesdropping receiver 704 is connected to the communication link comprising
distal
channel 702 and aortic channel 703, in parallel with the central monitor 705,
which greatly
facilitates operation for the medical personnel.
In the embodiments of the present invention shown in Figs. 4-7, the
communication
interface may be supplied with power from the central monitoring device. Thus,
the medical
personnel can connect a cable on which the communication interface is arranged
to the
central monitoring device without having to think about coupling an external
power supply to
the communication interface. Alternatively, the communication interface is
arranged with a
battery for supply of power. Further, the communication interface can be
arranged with a
= rechargable battery, which may be charged by the central monitoring
device.
Fig. 8 shows yet a further embodiment of the present invention mitigating
mentioned
problems in the prior art. In Fig. 8, distal pressure channel 802 carrying the
signal measured
in patient 801 by internal sensor 809 is wireless, which is enabled by means
of control unit
808 transmitting in compliance with ANSI/AAMI BP22-1994. Thus, the signal
representing
measured distal pressure is transmitted to the eavesdropping receiver 804 and
the central
monitor 805 using a wireless portion of distal pressure channel 802. In this
particular
embodiment, the signal representing aortic pressure measured by external
sensor 808 is
transferred to the eavesdropping receiver 804 and the central monitor 805
using a wireless
portion of channel 803. At an appropriate location along the aortic channel
803, a wireless
communication interface 807 of the inventive eavesdropping device is arranged.
The
wireless eavesdropping interface 807 transmits the signal representing
measured aortic
pressure to the eavesdropping receiver 804 and the central monitoring device
805, which
both are capable of wireless communication. The receiver and the central
monitors can
each use a dongle attached to a respective input and being adapted for
wireless
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communication with the communication interface 807. Since the eavesdropping
interface
807 is arranged with a high-impedance input, the eavesdropping does not affect
the signal
carried over the aortic channel 803. Thus, with the eavesdropping device of
the present
embodiment, again only three calibrating/balancing steps are required, since
there is no
need to calibrate the eavesdropped signal Further, as previously mentioned, if
the cathlab
monitor is up-and-running, there is no need to make any disconnections in
order to couple
the eavesdropping receiver to the central monitor. As can be seen from Fig. 8,
the
eavesdropping receiver 804 is connected to the communication link comprising
distal
channel 802 and aortic channel 803, in parallel with the central monitor 805,
which greatly
facilitates operation for the medical personnel.
If the sensor inserted into the body of the individual is not compatible with
the
communication standard used by the cathlab monitor and other equipment used in
connection with the FFR measurements made, which currently is the case in
practice, the
distal pressure signal is converted by a signal conversion unit arranged on
the distal
pressure channel of the communication link such that the converted signal,
i.e. the output of
the signal conversion unit, complies with the communication standard used.
This has been
described in the above, and the standard used for this type of equipment is
normally
ANSI/AAMI BP22-1994. The signal conversion unit is typically arranged at a
guide wire
connector.
Thus, the eavesdropping receiver is typically connected to the signal
conversion unit,
either by wire or wireless, for receiving the measured signal representing
distal pressure.
This requires calibration. For the aortic pressure, the eavesdropping receiver
is connected
to the aortic pressure channel of the communication link via a high-impedance
input into the
eavesdropping interface, thus making it possible for the receiver to eavesdrop
on the aortic
pressure channel. The eavesdropping does not require calibration.
Now, if in the future the sensor inserted into the body of the individual
would become
compatible with the communication standard used by the cathlab monitor and
other
equipment used in connection with the FFR measurements made, the distal
pressure signal
need not be converted by a signal conversion unit. In such a case, the
eavesdropping
receiver can be connected to both the aortic and distal pressure channel via a
respective
high-impedance input, either by means of wired or wireless connections.
Consequently, it is
possible for the receiver of the eavesdropping device to eavesdrop on the
aortic and the
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CA 2964533 2017-04-18
distal pressure channel. Again, the eavesdropping does not require
calibration. With such a
configuration, the eavesdropping device of the present invention would require
only two
calibration steps; the calibration of the distal and aortic pressure channels
against the
central monitoring device.
Even though the invention has been described with reference to specific
exemplifying embodiments thereof, many different alterations, modifications
and the like will
become apparent for those skilled in the art. The described embodiments are
therefore not
intended to limit the scope of the invention, as defined by the appended
claims.
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