Note: Descriptions are shown in the official language in which they were submitted.
2Q 1~070
CONTROL SYSTEM FOR DSA AND PTCA
BACKGROUND OF THE INVENTION
The present invention relates to a control system for
DSA (Digital Subtraction Angiography) and PTCA (Percutaneous
Transluminal Coronary Angioplasty). Diagnosis by DSA and
methods of medical treatment by PTCA have become very
popular in these years.
Throughout these medical operations of DSA and PTCA,
the operated portion is observed by an X-ray monitor
television display. For one example of PTCA, a guide
catheter is first inserted into the lumen of the coronary
artery, and subsequently, a balloon catheter is pushed to a
position where the balloon i5 at the target coronary artery.
Here the balloon of the balloon catheter is inflated to
expand the stenosed coronary artery lumen.
Then a syringe is pushed little by little by manually
adjusting the push amount to inject a contrast medium to the
aperture between the guide catheter and the balloon
catheter.
When the whole volume of the contrast medium contained
in the cylinder of the syringe is emptied, the contrast
medium must be replenished from a contrast medium reservoir.
In this replenishment, a three-way cock must be manually
operated to connect the syringe to the reservoir or to the
guide catheter.
As described in the foregoing paragraphs on PCTA, the
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manipulation on pushing the syringe for positioning the
balloon catheter requires a very fine adjustment, and the
pressure injection of the contrast medium requires a
relatively large force for a hand-exerted force.
Moreover, the manual turnover of the three-way cock in
the replenishment is very troublesome to the operator.
And, thus the contol of the syringe has been a burden
which gives the operator an extreme tension and exhaustion.
Especially in brain DSA, the operator will be exposed
to a fairly large amount of radioactivity, because the
operator must be kept close to his patient.
SUMMAR~ OF THE INVENTION
Therefore, an object of this invention is to provide a
power-drive for a syringe, in which the drive unit is
controlled through a hand-control or a foot-control. An
electric circuit translates a fairly large displacement in
the hand- or foot-control to a very fine displacement of the
syringe piston. And, since the syringe piston is displaced
by a motor of the syringe drive unit, the high pressure
exerted on the syringe piston has no relation on the force
for driving the hand-control or the foot-control.
Another object of this invention is to provide means
for presenting necessary informations to the operator. To
this object, a control unit and a display unit are provided.
The allowable ranges of the syringe control can be preset on
the control un~t, and these preset ranges are displayed on
the display unit together with the real values of the
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control. Comparing these values on the display unit, the
operator can control the stroke of the hand-control or the
foot-control to exert most adequate controls to the syringe.
Still another object of this invention is to achieve an
automatic control of the three-way cock.
'rhese and other objects, features and advantages of the
present invention will become clear from the following
description of the preferred embodiments in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a perspective view of an embodiment of the
present invention,
Fig. 2 shows an example of the electric circuit of the
syringe drive unit in Fig. 1,
Fig. 3 shows a perspective view of another embodiment
of this invention,
Fig. 4 shows a section of the pneumatic switch of Fig.
3 in its injection mode,
Fig. 5 shows the same section of the pneumatic switch
in its replenishment mode,
Fig. 6 is a block diagram illustrating the necessary
devices for PTCA in Trans-femoral method,
Fig. 7A~C show pictures displayed on X-ray monitor
television screen.
DETAILED DESCRIPTION OF THE PREFERRÆD EMBODIMENTS
First referring to Fig. 6, devices necessary for PTCA
will be explained. In Fig. 6, 1 is a pace-maker, 2 is a
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guide catheter, 3 is an injection syringe, 4 is a balloon
catheter, 5 is a guide wire, 6 is a pressurizing unit, 7 is
a three-way cock.
The performance of the devices are described in
connection with Figs. 7A~C. As shown in Fig. 7A, the guide
catheter 2 is inserted in the lumen of the coronary artery.
And then, the balloon catheter 4 is positioned where the
balloon 9 is at the target coronary artery 10. (Refer to
Figs. 7B and 7C). Here, the balloon 9 is inflated to expand
the stenosed coronary artery lumen. After that, the syringe
3 is manually pushed to inject a contrast medium to the
aperture between the guide catheter 2 and the balloon
catheter 4.
Now referring to Fig 1, an embodiment of the present
invention will be described. In Fig. 1, 11 is a syringe, 12
is a syringe drive unit, 13 is a control unit, 14 is a hand-
control, 15 is a foot-control, 16 is a display unit, and 17
is a stand. In Fig.l , devices which are not necessary for
explaining this invention are omitted, but it must be
understood that devices described in connection with Fig. 6
are to be equipped in accordance with the necessity.
Fig. 2 shows an example of the electric circuit of-the
syringe drive unit 12. And, in Fig. 2, 21 is a
potentiometer for generating a variable voltage E, the value
of 'he output voltage E is for an example, proportional to
the position X of the hand- or foot-control, 22 is A/D (an
analog-digital converter), 23 is a differentiator, 24 is an
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absolute circuit, 25 is an adder, 26 is a register of modulo
M, 27 is a control signal generator, and 28 is a pulse
motor.
The absolute circuit 24 delivers the absolute value G
of the time derivative dE/dt of the variable voltage E and
the polarity signal S of dE/dt. The absolute value G is
added to the register 26 at F cycles per second. Since the
modulo of the register 26 is M, the overflow pulse from the
register 26 has a frequency of FG/M pulses per second, that
is, the frequency of the overflow pulse is proportional to
the absolute value of dE/dt.
The control signal generator 27 controls the direction
of the motor rotation by the polarity S and the motor speed
by the overflow pulse, the velocity d~/dt of the pulse-motor
28 is proportional to dE/dt. And, as the motor velocity is
integrated to give the displacement of the syringe piston in
the syringe drive unit 12, the displacement of the syringe
piston is controlled to be proportional to the displacement
of the hand- or foot-control, and the ratio of these two
displacement can be so determined as to be most adequate in
the controls.
~ s described in connection with Fig. 7, the operator of
the control system for DSA and PTCA of Fig. 1, controls the
hand-control 14 or the foot-control 15 carefully watching
the screen of the X-ray monitor television as illustrated in
Fig. 7.
Further to help the operator's control, a control unit
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13 and the display unit 16 are provided in this embodiment.
Control parameters, for example, the allowable range of
the amount of the push of the syringe, including the
allowable ranges of~speed of injection, the vGlume of
injection, and the injection pressure, are preset in the
control unit 13.
These data preset in the control unit 13 are displayed
on the display unit 16. And the real data of the control,
for example, the real injection speed,the injection volume,
and the injection pressure are also displayed on the display
unit 16. The operator can watch the display unit 16 and can
compare the real data to its allowable range to control the
hand-control 14 or the foot-control 15.
Fig. 3 shows another embodiment of this invention, and
the same numerals in Fig. 1 indicate the same or the
corresponding parts. And in Fig. 3, 18 is an air sensor, 30
is a contrast medium reservoir, 31 is a replenishment tube,
33 is an injection tube, 4U is a pneumatic switch, 50 is a
bed-side stay, and 60 is an air compressor.
Fig. 4 shows a section of the pneumatic switch 40 of
Fig. 3, and 42 is a piston, 44 is a spring, and 45 is an air
tube. In its injection mode as shown i Fig. 4, the spring
44 is contracted by its own elastic force and opens the
injection tube 33 and closes the replenlshment tube 31.
When the piston of the syringe 11 is to its end
position leaving no contrast medium in the syringe cylinder,
the control unit 13 detects the condition, and actuates the
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air compressor 60 to inject the pressurized air from the air
tube 45. The injected air pushes the piston 42 against the
force of the spring 44. This results in the opening of the
replenishment tube 31 and closing of the injection tube 33.
In this mode of the switch 40 as shown in Fig~ 5, the
contrast medium is replenished from the reservoir 30. And
therefore, the operator will be exempt from the manual
operation of the three-way cock 7 shown in Fig. 6.
Although only preferred embodiments are described in
this specification, it should be understood that various
changes and modifications may be made without departing from
the spirit of this invention.
