U.S. patent application number 11/432162 was filed with the patent office on 2006-11-30 for system for controlling a flow of fluid through a rotational atherectomy device.
This patent application is currently assigned to Shturman Cardiology Systems. Invention is credited to Vladimir Alekseevich Malgichev, Georgy Vasilevich Morov, Leonid Shturman.
Application Number | 20060271242 11/432162 |
Document ID | / |
Family ID | 26955319 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060271242 |
Kind Code |
A1 |
Shturman; Leonid ; et
al. |
November 30, 2006 |
System for controlling a flow of fluid through a rotational
atherectomy device
Abstract
A method system and controller for controlling fluid flow in a
rotational atherectomy device. A source of fluid is provided
through a pump to the rotational atherectomy device, wherein the
pump maintains the fluid flow at a minimal rate during a time
period when a drive shaft of the device is not rotating. A first
control is activated to increase a rate of the fluid flow and
second control is activate to initiate a rotation of the drive
shaft during another time period when the fluid flow is at the
increased rate.
Inventors: |
Shturman; Leonid;
(Greenwich, CT) ; Morov; Georgy Vasilevich;
(Moscow, RU) ; Malgichev; Vladimir Alekseevich;
(Moscow, RU) |
Correspondence
Address: |
Jeffrey R. Stone;Altera Law Group
Suite 100
6500 City West Parkway
Minneapolis
MN
55344-7704
US
|
Assignee: |
Shturman Cardiology Systems
|
Family ID: |
26955319 |
Appl. No.: |
11/432162 |
Filed: |
May 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10272126 |
Oct 16, 2002 |
|
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11432162 |
May 11, 2006 |
|
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60348188 |
Oct 19, 2001 |
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Current U.S.
Class: |
700/282 |
Current CPC
Class: |
A61B 2017/00119
20130101; A61M 3/0208 20140204; A61B 2017/00553 20130101; A61B
2017/00123 20130101; A61B 2017/00137 20130101; A61B 2017/00973
20130101; A61B 17/320758 20130101; A61M 3/022 20140204; A61M 3/0258
20130101; Y10T 137/7793 20150401 |
Class at
Publication: |
700/282 |
International
Class: |
G05D 7/00 20060101
G05D007/00 |
Claims
1-87. (canceled)
88. A system for controlling a flow of fluid through a rotational
atherectomy device comprising: controller coupled to the
atherectomy device, the controller comprising: a pump control
device adapted to control the flow of fluid to the atherectomy
device; a drive shaft control device adapted to control a rotation
of a drive shaft in the atherectomy device; a fluid supply unit; a
first control device coupled to the controller and adapted to
increase a flow of fluid to the atherectomy device via the pump
control device; and a second control device coupled to the
controller and adapted to initiate a rotation of the drive shaft
via the drive shaft control device after activation of the first
control device.
89. The system of claim 88, wherein an increased flow of fluid to
the atherectomy device is relatively independent of a rotation
speed of the drive shaft.
90. The system of claim 88, wherein the controller further
comprises a fluid flow delay device adapted to maintain the
increased flow of fluid through the rotational atherectomy device
for a predetermined time period after a deactivation of the first
control device.
91. The system of claim 88, wherein the controller further
comprises a drive shaft disable device adapted to prevent the
rotation of the drive shaft if the second control device is
activated after the end of a predetermined time period after a
deactivation of the first control device.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to devices and
methods for removing tissue from body passageways and, more
particularly, to a control system for a rotational and or orbital
angioplasty device.
[0003] 2. Brief Description of Related Developments
[0004] There are a number of different techniques and devices which
have been developed for use in removal and/or repair of arteries
and other similar body passages. One objective of some of the
aforementioned devices and techniques is removal of atherosclerotic
plaques from patient's arteries. Atherosclerosis is characterized
by buildup of fatty deposits (atheromas) in the intimal layer
(under the endothelium) of a patient's blood vessels. Very often
over time, what initially is deposited as relatively soft,
cholesterol-rich atheromatous material hardens into a calcified
atherosclerotic plaque. Such atheromas restrict the flow of blood,
and therefore often are referred to as stenotic lesions or
stenoses. If left untreated, such stenoses can cause angina,
hypertension, myocardial infarction, strokes and the like.
[0005] Rotational angioplasty procedures are a common technique for
removing such stenotic material. Such procedures are used most
frequently to commence the opening of calcified lesions in coronary
arteries. Often the rotational angioplasty procedure is not used
alone, but is followed by a balloon angioplasty procedure. This, in
turn, may frequently be followed by placement of a stent to assist
in keeping the artery open. For noncalcified lesions, balloon
angioplasty most often is used alone to open the artery, with
stents often placed to maintain the opened artery. Studies have
shown, however, that a significant percentage of patients who have
undergone balloon angioplasty and had a stent placed in an artery
experience in-stent restenosis (i.e., blockage of the stent) which
most frequently develops over a period of time as a result of
excessive growth of scar tissue within the stent. Rotational
angioplasty devices were utilized in removing the excessive scar
tissue from the stents and, thereby were useful in providing
assistance in restoring the patency of the arteries.
[0006] It should be understood that rotational angioplasty devices
and rotational angioplasty procedures are often referred to as
rotational atherectomy devices and rotational atherectomy
procedures. These terms may be used interchangeably herein.
[0007] One example of a rotational angioplasty device is shown in
U.S. Pat. No. 4,990,134 (issued to Auth), wherein a front or distal
portion of a burr is covered with an abrasive cutting material such
as diamond particles. The diamond coated burr is mounted at the
distal end of a flexible drive shaft. The burr is rotated at high
speeds (typically, e.g., in the range of about 140,000-180,000 rpm)
while it is advanced across the stenosis. The burr has a solid
cross-section and thus, as the burr is removing stenotic tissue, it
blocks blood flow through the artery. Once the burr has been
advanced across the stenosis, the artery will have been opened to a
diameter equal to or only slightly larger than the maximum outer
diameter of the burr. A series of different size burrs may be
utilized to open the artery to a desired diameter. U.S. Pat. No.
5,897,566 (issued to Shturman) shows another rotational angioplasty
device having a drive shaft made from helically wound wires. A
section of the drive shaft has an enlarged diameter. In one
embodiment at least a front or distal segment of this enlarged
diameter section is covered with an abrasive material to define an
abrasive segment of the drive shaft. The enlarged diameter section
is hollow. This Shturman Device of the '566 patent is capable of
opening an artery only to a diameter about equal to the maximum
diameter of the enlarged diameter section of the drive shaft,
thereby providing results similar to the Auth Device of the '134
patent. The Shturman Device of the '566 patent possesses certain
advantages over the Auth Device of the '134 patent because it is
more flexible. Another example of a rotational angioplasty device
is provided in U.S. Pat. No. 6,132,444 (issued to Shturman et al.)
describes a rotational atherectomy device having a flexible,
elongated, rotatable drive shaft with an eccentric enlarged
diameter section. At least part of the eccentric enlarged diameter
section has a tissue removing surface with an abrasive surface to
define a tissue removing segment of the drive shaft. When placed
within an artery against stenotic tissue and rotated at
sufficiently high speeds (e.g. in the range of about 40,000 rpm to
about 200,000 rpm) the eccentric nature of the enlarged diameter
section of the drive shaft causes such section to rotate in such a
fashion as to open the stenotic lesion to a diameter substantially
larger than the maximum diameter of the enlarged diameter section.
Preferably the eccentric enlarged diameter section of the drive
shaft has a center of mass spaced radially from the rotational axis
of the drive shaft, facilitating the ability of the device to open
the stenotic lesion to a diameter substantially larger than the
maximum diameter of the enlarged diameter section. A drive shaft
having an eccentric enlarged diameter tissue removal section with a
diameter of not more than 2 mm is capable of opening stenotic
lesions to a diameter equal to the original diameter of the
coronary arteries (i.e., to a diameter of more than 3 mm) so that
in a significant percentage of cases balloon angioplasty may not be
needed to complete the procedure. The device is particularly useful
for cleaning out partially blocked stents.
[0008] U.S. Pat. No. 5,314,407 to Auth, which is incorporated
herein by reference in its entirety, shows the details of a type of
an advancer (handle) that may be used in conjunction with
rotational atherectomy devices of the type described in Auth '134
patent and Shturman '566 and '444 patents. A handle of the type
shown in Auth '407 patent has been commercialized by Heart
Technology, Inc. (Redmond, Wash.), now owned by Boston Scientific
Corporation (Natick, Mass.), in the rotational atherectomy
(angioplasty) device sold under the trademark Rotablator..RTM..
[0009] FIG. 1 is an illustration of a rotational angioplasty system
100 of the prior art. As shown in FIG. 1, the prior art system
comprises a rotational angioplasty device 104, a fluid supply 106,
a gas supply 108, a controller 102 and a foot pedal device 110.
[0010] The rotational angioplasty device 104 comprises an advancer
assembly 134 that is located within a body or handle 136. A gas
driven turbine (not shown) is located within the advancer assembly
134 and rotates a flexible, hollow drive shaft 138. An ablative,
diamond coated burr 140 is attached at the distal end of the
flexible drive shaft 138. The flexible drive shaft 138 together
with the burr 140 may be rotated over a guide wire 141.
[0011] As shown in FIG. 1, a flexible sheath 142 extends distally
from the handle 136 and surrounds the flexible drive shaft 138
substantially along its entire length.
[0012] The advancer assembly 134 also carries a water (saline) pump
(not. shown). This water pump is located distally to the gas
turbine and has a shaft that is connected to the turbine shaft. The
output of the fluid pump is in fluid connection with the lumen
formed between the flexible drive shaft 138 and the flexible sheath
142.
[0013] The rotational angioplasty system 100 shown in FIG. 1
includes an infusion bag 128 to administer a saline solution. The
saline bag 128 is pressurized with a pressure cuff 129 to ensure a
steady supply of saline to the water pump within the advancer
assembly 134 and around the drive shaft 138. The rotation of the
gas turbine rotates the fluid pump and increases the fluid flow
rate in a lumen between the flexible drive shaft 138 and the sheath
142. The fluid flow rate in this system depends on the rotational
speed of the gas turbine. Thus, the fluid acceleration in the lumen
between the drive shaft 138 and the sheath 142 can only take place
simultaneously with the increase in rotational speed of the gas
turbine, and the system can not increase the fluid flow rate in the
lumen between the drive shaft 138 and the sheath 142 without
increasing the rotational speed of the gas turbine.
[0014] A certain amount of static pressure must be applied and
maintained against the saline bag 128 in order to provide an
adequate fluid flow rate in the lumen between the drive shaft 138
and the sheath 142. This requires repeated repressurization of the
pressure cuff 129 disposed around the saline bag 128.
[0015] The controller 102 has a front panel 112 that includes a
power switch 113, a turbine control knob 114 (adjusts turbine
pressure and RPMs), a turbine pressure gauge 115, a turbine
(pneumatic) connector 116, a DynaGlide..TM.. (pneumatic) connector
117, and a pair of fiber optic connectors 120. The front panel 112
also includes an event timer 122, a procedure timer 123, and an
optical tachometer display 124. The optical tachometer provides or
registers information about the rotational speed of the gas turbine
of the rotational angioplasty device 104.
[0016] The foot pedal 110 is used as an on/off control for the gas
turbine of the rotational angioplasty device 104. A DynaGlide..TM..
button 126 is located on the right side of the foot pedal housing
132 and is used as an on/off control for the DynaGlide..TM.. mode
of operation.
SUMMARY OF THE INVENTION
[0017] A method system and controller for controlling fluid flow in
a rotational atherectomy device. A source of fluid is provided
through a pump to the rotational atherectomy device, wherein the
pump maintains the fluid flow at a minimal rate during a time
period when a drive shaft of the device is not rotating. A first
control is activated to increase a rate of the fluid flow and
second control is activate to initiate a rotation of the drive
shaft during another time period when the fluid flow is at the
increased rate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing aspects and other features of the present
invention are explained in the following description, taken in
connection with the accompanying drawings, wherein:
[0019] FIG. 1 is a block diagram of a prior art rotational
angioplasty device;
[0020] FIG. 2 is a perspective view of one embodiment of a
rotational angioplasty system incorporating features of the present
invention;
[0021] FIG. 3 is a cross-sectional view of one embodiment of a
roller pump;
[0022] FIG. 4 is a cross-sectional view of a roller pump in a
closed position;
[0023] FIG. 5 is a cross-sectional view of one embodiment of a
roller pump in a closed position with fluid in the fluid line in a
system incorporating features of the present invention;
[0024] FIG. 6 is a cross-sectional view of one embodiment of a
fluid supply line securing device incorporating features of the
present invention;
[0025] FIG. 7 is a block diagram illustrating one embodiment of the
functional aspects of a controller for a system incorporating
features of the present invention;
[0026] FIG. 8 is a timing diagram for pump and turbine activation
periods in one embodiment of a system incorporating features of the
present invention;
[0027] FIG. 9 is a timing diagram illustrating pump and turbine
activation periods in one embodiment of a system incorporating
features of the present invention;
[0028] FIG. 10 is a timing diagram of pump and turbine activation
periods in one embodiment of a system incorporating features of the
present invention;
[0029] FIG. 11 is a timing diagram of pump and turbine activation
periods in one embodiment of a system incorporating features of the
present invention;
[0030] FIG. 12A is a schematic diagram of one embodiment of a
timing circuit to produce a delayed time period feature of a system
incorporating features of the present invention;
[0031] FIG. 12B is a schematic diagram of one embodiment of a
timing circuit to produce a delayed time period in a system
incorporating feature of the present invention;
[0032] FIGS. 13 and 14 are partial cross-sectional views of a pump
cover sensor in embodiments of systems incorporating features of
the present invention;
[0033] FIGS. 15 and 16 are partial cross-sectional views of
embodiments of fluid level detection systems for a system
incorporating features of the present invention;
[0034] FIGS. 17 and 18 are embodiments of fluid level detection
systems for a system incorporating features of the present
invention;
[0035] FIGS. 19 and 20 are embodiments of fluid level detection
systems for a system incorporating features of the present
invention;
[0036] FIGS. 21 and 22 are embodiments of fluid level detection
systems for a system incorporating features of the present
invention;
[0037] FIG. 23 is one embodiment of a fluid level detection system
for a system incorporating features of a present invention;
[0038] FIG. 24 is a block diagram of one embodiment of a control
system for a system incorporating features of the present
invention;
[0039] FIG. 25 is a block diagram of one embodiment of a control
system for a system incorporating features of the present
invention; and
[0040] FIG. 26 is a perspective view of one embodiment of a system
incorporating features of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] Referring to FIG. 2, there is shown a perspective view of a
rotational angioplasty system 10 incorporating features of the
present invention. Although the present invention will be described
with reference to the embodiment(s) shown in the drawings, it
should be understood that the present invention can be embodied in
many alternate forms of embodiments. In addition, any suitable
size, shape or type of elements or materials could be used.
[0042] As shown in FIG. 2, the system 10 generally comprises a
rotational angioplasty device ("RAD") 20. The rotational
angioplasty device 20 can also comprise, or may be referred to as a
rotational atherectomy device. As shown in FIG. 2, the RAD is
generally coupled to a controller 60 and a fluid supply 50. The
system 10 can also include an activation device 30 and a gas supply
system 40. Both the activation device 30 and gas supply system 40
can be coupled or connected to the controller 60. In an alternate
embodiment, the system 10 can include such other components
suitable for use in a system for removing tissue from a passageway
in the body.
[0043] Descriptions of some examples of such RAD devices can be
found in U.S. Pat. Nos. 5,897,566; 6,024,749; 6,077,282; 6,129,734;
and 6,132,444 issued to Shturman, each of which is incorporated
herein by reference in its entirety; and in U.S. Pat. Nos.
4,990,134 and 5,314,407 issued to Auth.
[0044] As shown in FIG. 2, the RAD 20 can include a prime mover
carriage 18 and a drive shaft cartridge 16. A fluid supply line 22,
a prime mover speed monitoring line 23, and a gas supply line 24
are adapted to be connected or coupled to the RAD 20. In one
embodiment, the lines 22, 23 and 24 can be a physical part of and
extend from the RAD 20. In an alternate embodiment, the RAD 20
could include one or more couplings or connection ports to allow
one or more of the lines 22, 23 or 24 to be connected to the RAD.
Any one of the lines 22, 23 or 24 could be separate from the RAD
20.
[0045] Extending from one end of the RAD 20 is an elongated tube
28. The elongated tube 28 can include a rotatable flexible drive
shaft 25 that has a tissue removal implement 27 located near the
distal end of the flexible drive shaft 25. The elongated tube 28
can also include an inner lumen (not shown) between an interior
surface of the elongated tube and the drive shaft 25 along or
around which fluid can flow at any suitable or desired rate of
flow.
[0046] A control knob 21 operatively secured to the prime mover
carriage 18 is adapted to facilitate advancing and retracting the
prime mover carriage 18 with respect to the housing 12 of the RAD
20.
[0047] The prime mover carriage 18 generally carries a prime mover
(not shown). Preferably, the prime mover is a compressed gas driven
turbine, and for purposes of this description, will be referred to
herein as a gas turbine. It should be understood however, that any
suitable device can be used to rotate the drive shaft 25 at a
desired rotational speed. For example, an electrically powered
motor could be used. The gas turbine may be powered, for example,
by compressed nitrogen or compressed air supplied from system 40.
The system 40 usually includes a tank 41 with compressed gas and a
pressure regulator 42.
[0048] As shown in FIG. 2, the RAD 20 includes a drive shaft
cartridge 16 that includes the elongated tube 28 extending distally
from the drive shaft cartridge 16. The rotatable flexible drive
shaft 25 is generally disposed within the elongated tube 28. The
flexible drive shaft 25 may be rotated over a guide wire 26. A
distal portion of the drive shaft 25 may extend distally from the
elongated tube 28 and may include the tissue removal implement
27.
[0049] Referring to FIG. 2, the RAD 20 can be coupled to the
controller 60 through one or more connections, including for
example a fluid supply connection, a gas supply connection and a
turbine speed monitoring line connection. Fluid is supplied to the
drive shaft cartridge 16 from the fluid supply 50 through a fluid
supply line 22. As shown in FIG. 2, the fluid supply line 22 is
comprised of more than one sequentially connected fluid lines. In
alternate embodiments a single line, or any suitable combination of
fluid lines may be used. For example, referring to FIG. 2, a short
fluid supply line 54 extends from the drive shaft cartridge 16 and
is coupled to a longer fluid supply line 22 with a luer lock device
52. The fluid line 54 is connected or coupled to the inner lumen of
the elongated tube 28. In an alternate embodiment, the drive shaft
cartridge 16 could include a fitting or coupling to which the fluid
supply line 22 can be directly connected. In this manner a fluid,
such as for example saline, is supplied to the inner lumen of the
elongated tube 28 from the fluid supply 50. The fluid supply line
22 could also comprise one or more parallel fluid lines to couple
the fluid supply(s) to the inner lumen(s) of the elongated tube
28.
[0050] One or more prime mover speed monitoring lines 23 may be
used to monitor the rotational speed of the gas turbine. For
example, in one embodiment the line 23 could comprise a fiber optic
line that is adapted to couple pulses of light from an element of
an optical tachometer (not shown) of the RAD 20 to the controller
60. The number of such pulses per unit of time can be used to
determine a rotational speed of the gas turbine. In an alternate
embodiment any suitable device can be used to communicate the
rotational speed of the gas turbine of the RAD 20 to the controller
60.
[0051] The gas supply line 24 is used to provide a compressed gas
to the guide wire brake (not shown) and further via gas supply line
29 to the prime mover carriage 18 to power the prime mover or gas
turbine. As shown in FIG. 2, the gas supply system 40 is a
compressed gas system that can provide a steady flow of gas to the
controller 60. Generally, any conventional or suitable system 40
can be used to supply the flow of compressed gas via a gas line 43
to the controller 60. As shown in FIG. 2, the compressed gas system
40 comprises one or more tanks or bottles 41 coupled to a regulator
device 42. In an alternate embodiment, the gas system could
comprise a hospital gas system where the supply of compressed gas
is generally delivered via a compressed gas line 43 to the
controller unit 60.
[0052] As shown in FIG. 2, the system 10 can also include a fluid
pump 70. The fluid pump 70 is generally adapted to pump the fluid
from the fluid supply 50 through the fluid supply line 22 to an
inner lumen(s) of the elongated tube 28 and to some other moving
parts of the RAD. Although the elongated tube 28 is referred to
herein as generally having a lumen, in alternate embodiments, the
elongated tube 28 could also include a plurality of lumens.
[0053] The speed at which the pump 70 pumps the fluid is generally
variable and controlled through the controller 60. In the preferred
embodiment, the pump 70 comprises a peristaltic (roller) pump. An
example of one embodiment of a peristaltic pump is shown in FIGS.
3-5. As shown in FIG. 3, a portion 82 of the fluid supply line 22
is passed through the pump 70 and around an outer edge of rollers
80. The tubing portion 82, also referred to herein as the tube or
tubing 82, of the fluid supply line 22 is generally different from
the remainder of the fluid supply line 22 and comprises a tube that
has special mechanical properties that allow the tubing to be used
within the roller portion of the fluid pump 70. In one embodiment,
the tubing 82 can be made from Tygon..RTM.. LFL tubing or a tubing
with similar mechanical properties. One type of tubing suitable for
use with peristaltic (roller) pump(s) is commercially available
from the Plastron, a Tekni-Plex Co., City of Industry, Calif. In
one embodiment, the length of the tubing 82 can be approximately
300 millimeters, although any suitable length can be used.
[0054] In FIG. 3, the pump handle 75 is in an upward position and
the pump cover 74 is open. In the open position, the rollers 80 do
not apply pressure to the tube 82. When the handle 75 is moved
downward, or into a closed position as shown in FIGS. 4 and 5, the
pump rollers 80 apply pressure, or squeeze the tube 82. As the pump
motor rotates as shown in FIG. 5, the rollers 80 rotate and force
fluid 84 in the tube 82 to be pumped through the fluid line 22.
Although the fluid pump 70 shown in FIGS. 3-5 has four rollers, any
suitable number of rollers 80 can be used to provide a desired,
relatively steady fluid flow. In the preferred embodiment, the pump
70 has 6 rollers in order to reduce the amplitude of fluid
pulsations in the fluid line 22. One example of a roller pump that
can be used in one embodiment of the present invention is roller
pump model number 900-1021 manufactured by the Barnant Company,
Barrington, Ill. In the preferred embodiment of the invention, the
roller pump can be powered by an electric motor model number 118752
and planetary gearhead model number 110396, commercially available
from Maxon Precision Motors, Burlingame, Calif.
[0055] Referring to FIGS. 2-6, in one embodiment, a fluid supply
line securing device 90 can be used to keep the tubing portion 82
of the fluid supply line from being pulled through the roller pump
when the pump 70 is operating.
[0056] As shown in FIG. 6, the fluid supply line securing device 90
generally comprises a receiving member 92 that at least partially
surrounds tube 82 and prevents tube 82 from being pulled through
the roller pump. The outer surface of the tube 82 can be bonded in
any suitable manner, such as for example gluing, to an inner
surface of a generally tubular channel of the receiving member
92.
[0057] Referring to FIG. 6, in one embodiment, a generally hollow
sleeve 94 can be adapted to be inserted into a proximal portion of
the tube 82. An outer diameter of the sleeve 94 is generally larger
than an inner diameter of the tube 82 so that a portion of the tube
82 around the sleeve 94 is distended when the sleeve 94 is inserted
into the tube 82. The portion of the tube 82 around the sleeve 94
becomes wedged against the shoulder 98 formed in the tubular
channel of the receiving member 92 and prevents the proximal
portion of the tube 82 from being pulled through the receiving
member 92.
[0058] As shown in FIG. 6, appropriate placement of the tube 82
within the fluid pump 70 requires that a distal end section 96 of
the receiving member 92 becomes abutted against a corresponding
surface 93 of a fluid pump housing 97. This prevents the receiving
member 92 and the tube 82 from being pulled through the fluid pump
when the rollers 80 are rotating.
[0059] Although as shown in FIG. 2, the pump 70 is shown as
integrated into the controller 60, it should be understood that the
pump 70 could also be located externally to the controller 60, and
comprise for example, a stand alone fluid pumping system. In an
alternate embodiment, any suitable device for pumping fluid can be
used, such as for example, a centrifugal pump or syringe type
device. It is a feature of the present invention to be able to
provide a variable and/or regulated flow of fluid through the inner
lumen of elongated tube 28 during the operation of the system
10.
[0060] As shown in FIG. 2, in one embodiment, the fluid supply
system 50 can comprise a fluid bag connected to a drip chamber 52
that is connected to the fluid line 22. The fluid supply line 22
can generally comprise one or more sections of fluid supply tubing
that can be coupled together in any suitable manner. As discussed
above, in the preferred embodiment, the fluid supply line 22
includes a tubing portion 82 that has special mechanical properties
suitable for use with a peristaltic (roller) pump. Preferably, the
tubing portion 82 is not only made from a material that has special
mechanical properties different from the rest of the fluid supply
line 22, but also has inner and/or outer diameters that are
different from the inner and/or outer diameters of the rest of the
fluid supply line 22.
[0061] The system 10 also includes the activation device 30 that is
coupled to the controller 60 via control line or lines 36. Although
as shown in FIG. 2, line 36 is a single line, it should be
understood that in the preferred embodiment, the line 36 comprises
a cable that includes one or more electrical or fiberoptic lines
36. In an alternate embodiment, the line 36 could include pneumatic
or other suitable types of communication lines. The activation
device 30 is generally adapted to control or activate an increased
flow rate of fluid from or through the pump 70. The activation
device 30 can also be used to control the activation of the gas
turbine of the RAD. Generally, the activation device 30 is a
switching device having "ON" and "OFF" positions. In one embodiment
as shown in FIG. 2, the activation device 30 comprises a pair of
pedal switches, a pump pedal 32 and a turbine pedal 34. In a
preferred embodiment, pedal switches 32 and 34 are electrical
switches and control line 36 comprises an electrical cable with
more than one wire therein, each wire adapted to carry electrical
or communication signals. It is a feature of the present invention
to allow an operator of the RAD 20 to increase the speed of the
pump 70 or activate the gas turbine using the foot pedals 32 and 34
shown in FIG. 2, or a single foot switch 1101 as shown in FIG.
26.
[0062] In an alternate embodiment any suitable switching or control
device can be used other than a pedal activated switch to provide
an "ON" or "OFF" activation signal. For example, as shown in FIGS.
25 and 26, a single pedal switch 1010 or 1101 and control systems
1000 or 1100, may be utilized in such a fashion so that a first
activation of the switch (the first pulse or the first control
signal) causes the fluid pump 70 to increase its speed of rotation,
then the second activation of the switch (the second pulse or the
second control signal) causes the fluid pump 70 to continue to
rotate at the increased speed and activates the gas turbine, and
finally, the third activation of the switch (the third pulse or the
third control signal) turns off both the gas turbine and (after a
delay if needed) the fluid pump 70, bringing the entire system to
its "steady-state" or "static" mode. For example, in such static
mode the fluid pump 70 returns to it minimum or "min" fluid flow
rate and the gas turbine is turned "OFF.".
[0063] The controller 60 shown in FIG. 2 is generally adapted to
control and monitor the operations of the system 10, including the
fluid flow rate and gas turbine function and speed. The controller
60 can include displays 61, 63, 64, 65 and 66 to monitor compressed
gas pressure applied to the gas turbine of the RAD, turbine
rotational speed, various procedure time intervals, and other
functions of the system 10, controls and switches 62, 67 and 68 to
operate the various functions of the system 10 as well as
connections to each of the components of the system 10. The
controller 60 will also include the electronics and circuitry
needed to operate the system 10.
[0064] For example, as shown in FIG. 2, display 65 can comprise an
"individual" event timer adapted to display and/or record the
length of time during which the turbine was rotating after each
individual activation ("individual event time"). Display 66 can
comprise a "procedure timer" that displays the sum of the
individual event times, i.e. the total time during which the gas
turbine was operational throughout the angioplasty procedure. Each
of the displays can include a reset button to reset the time. For
example, the "procedure timer" may be used to record a total time
used to completely open the stenotic lesion and then reset back to
"zero." Display 63 can be used to display a rotational speed of the
turbine 19. In an alternate embodiment, any suitable number or
types of displays can be used for indicating the functions and
events of the system 10.
[0065] Referring to FIG. 7, a block diagram illustrating the
functional aspects of one embodiment of the controller 60 is shown.
With reference to FIGS. 2 and 7, the controller 60 can be used to
control the activation and speed of the pump 70, the activation and
speed of the gas turbine of the RAD and, for these purposes, can
include a fluid pump control unit 610 and a pneumatic valve control
unit 650.
[0066] The pump control unit 610 is generally adapted to control
the speed of a fluid pump motor 612 in order to regulate the flow
rate of fluid through the inner lumen of the, catheter 28. The
fluid pump motor 612 is also shown in FIGS. 13 and 14 as a fluid
pump motor 1612. The controller 60 can include a minimum pump speed
setting control or device 621, which can be adjusted to set the
minimum fluid flow rate or speed of the pump motor 612 when the gas
turbine and the drive shaft 25 of the RAD are not rotating, for
example. The maximum pump speed setting control or device 622 can
be adjusted to set a maximum fluid flow rate, or the maximum speed
of the pump motor 612.
[0067] When electric power is applied to the controller 60, the
pump control unit 610 can set the pump motor 612 to operate in a
"steady-state" or "static" mode. In this static mode the gas
turbine and the drive shaft 25 are generally not rotating and
minimal flow rate of fluid is maintained. When, for example, the
fluid pump control switch 632 (which is similar to pedal switch 32
in FIG. 2) is activated, the pump control unit 610 can send a
signal to the pump motor 612 to increase its speed. The increase of
the speed of the pump motor 612 will increase the fluid flow
rate.
[0068] The pneumatic valve control unit 650 generally controls the
operation of the gas turbine 605 of the RAD. When the turbine
control switch 634 (similar to pedal switch 34 in FIG. 2) is
activated the pneumatic valve control unit 650 sends a signal to
activate the turbine pneumatic valve 657, which allows compressed
gas from the turbine pressure regulator 658 to be applied to the
gas turbine 605 of the RAD. The fluid pump control unit 610 also
communicates with the pneumatic valve control unit 650 to
coordinate operation of the fluid pump 70 with the gas turbine of
the RAD. It is a feature of the present invention that the turbine
control switch 634 needs to be activated within a predetermined
time period after the fluid pump control switch 632 is deactivated
in order to activate the gas turbine of the RAD. If the turbine
control switch 634 is not activated within the predetermined time
period after deactivation of the fluid control switch 632,
operation of the gas turbine of the RAD can be either prevented or
delayed. In one embodiment, when the turbine control switch 634 is
activated before activation of the pump control switch 632, of
after the expiration of the predetermined time period, operation of
the gas turbine of the RAD will be delayed for another
predetermined time period after activation of turbine control
switch 634 during which time the fluid pump 70 is pumping fluid at
an increased or maximum speed.
[0069] The turbine pressure regulator 658 could comprise a
Precision Low Pressure Regulator, Type LPR-1/4-4, commercially
available from FESTO Corporation, Hauppauge, N.Y. The turbine
pneumatic valve 657 could comprise a single solenoid valve type
MFM-5-1/8-S-B, also available from the FESTO Corporation.
[0070] Compressed gas pressure at the output of the turbine
pressure regulator 658 is measured and displayed by the turbine
pressure sensor and display device 671, (which is similar to the
turbine pressure display device 61 in FIG. 2). Both turbine
pressure sensor 671 and turbine tachometer 668 may be in
communication with the pneumatic valve control unit 650, which may
be programmed to turn off or deactivate the turbine pneumatic valve
657 if a discrepancy of predetermined magnitude develops between
pressure applied to the gas turbine 605 and the rotational speed of
the turbine.
[0071] When the gas turbine of the RAD is activated, the controller
60 can include an "individual" event time indicator 655 (display 65
in FIG. 2) that indicates the length of time during which the
turbine was rotating after each individual activation. A
"procedure" time indicator 666 (display 66 in FIG. 2) can be used
to display a total time during which the gas turbine was
operational throughout the angioplasty procedure or part
thereof.
[0072] The pneumatic valve control unit 650 could also provide data
storage and/or output signal(s) 654 that could be used to plot the
operation of the gas turbine and other components of the system 10.
For example, the data storage and/or output signal(s) 654 could be
fed to a logger or chart recorder in order to plot the time and
functions of the gas turbine 605, fluid pump 70 and other elements
of the controller 60, such as for example, gas pressure applied to
the gas turbine and its rotational speed, under such pressure, may
be logged.
[0073] During a rotational angioplasty procedure a fluid such as
saline is pumped from the fluid supply 50 through the elongated
tube 28. When the gas turbine of the RAD is activated the drive
shaft 25 is rotated at a high speed. The turbine block 18 can be
moved forward and/or backward with respect to the housing 12 of the
RAD 20 thereby allowing the operator to move the drive shaft 25 and
its abrasive element 27 forward and/or backward across the stenotic
lesion. Generally, in the present invention, when the drive shaft
25 is rotating, saline is being pumped from or through the pump 70
at a higher rate of flow than when the drive shaft 25 is not
rotating. The increased flow of saline can provide, among other
things, enhanced cooling of the treated area and substantially
uninterrupted flushing away of the small particles generated as the
stenotic material is removed by the abrasive element 27. Saline is
pumped through the elongated tube 28 at a minimal flow rate when
the system 10 is in a static state and the drive shaft 25 is not
rotating.
[0074] In the present invention, the controller 60 and the
activation device 30 are adapted to "delay" activation of the gas
turbine of the RAD to provide a "preflush" of saline prior to
initiating "active" rotation of the gas turbine. The term
"preflush" as used herein describes pumping of saline through the
elongated tube 28 at an increased flow rate. For example, referring
to FIG. 8, at time t.sub.o, the gas turbine, represented by its
rotational speed omega., is off, and the saline flow rate Q is at
flow rate Q.sub.1. In one embodiment flow rate Q.sub.1 could be at
a minimum or "min" level when the system 10 is in a static mode.
Upon activation of switch 32, the saline flow rate Q increases from
flow rate Q.sub.1 to Q.sub.2. Saline flow rate Q.sub.2 is a higher
flow rate than Q.sub.1, being for example, a maximum or "max" flow
rate. The gas turbine remains off. It should be understood that
although the saline flow rate Q.sub.2 is shown as increasing to the
"max" upon activation of pedal switch 32, any suitable flow rate
Q.sub.2 can be used. At time t.sub.2, the pedal switch 32 is
deactivated, or is "OFF." The saline flow rate remains at increased
flow rate Q.sub.2 for a period of time shown as t.sub.delay. In
FIG. 8 this t.sub.delay time period corresponds to the time period
between t.sub.2 and t.sub.5. A period of time between t.sub.1 and
t.sub.2, together with that period of time within t.sub.delay
during which saline flow is maintained at an increased flow rate
prior to activation of the gas turbine, is referred to herein as
the "preflush time period." The drive shaft 25 and its abrasive
element 27 are not rotating during the preflush time period.
[0075] The preflush time period prior to activation of the drive
shaft 25 provides several advantages. Some of these advantages can
include for example, flushing both the abrasive element 27 and the
stenotic area to be treated with saline that can include a suitable
concentration of heparin and other pharmaceuticals that can prevent
platelet aggregation and thrombus formation. The dilution of the
blood that flows through the area of treatment and around the
abrasive element may be sufficient to significantly reduce the
potential for platelet activation, platelet aggregation and
thrombus formation. Dilution or even hydrolic occlusion of blood
flow through the area of treatment may also reduce the number of
red blood cells in the treatment area and or around the abrasive
element 27 of the drive shaft 25, and, therefore, prevent hemolysis
of the red blood cells at the time when the drive shaft 25 and its
abrasive element 27 begin and continue to rotate. In general, the
"preflush" flow of fluid to the site of the tissue removal prior to
the turbine activation provides a more favorable environment for
the rotational angioplasty procedure.
[0076] It is a feature of the present invention to provide a
preflush time period so that activation of the gas turbine of the
RAD is prevented or precluded without a continuous preflush time
period. In the present invention, the acceleration of the saline
flow rate is substantially independent from rotation of the gas
turbine and drive shaft 25 of the RAD 20. For example, referring to
FIG. 9, at time t.sub.4, the turbine pedal switch 34 is activated
or is "ON." This activation of switch 34 instructs the controller
60 to activate the gas turbine of the RAD 20 and initiate rotation
of the gas turbine and drive shaft 25. Since the activation of
switch 34 occurs at time t.sub.4 and within the time period
t.sub.delay, the gas turbine of the RAD is activated. As shown in
FIG. 9, the saline flow rate Q remains at increased flow rate
Q.sub.2 during at least the time period t.sub.4 to t.sub.7 when the
gas turbine is "ON" or rotating.
[0077] Referring to FIG. 10, the t.sub.delay time period can be
extended or repeated by reactivating the fluid pump pedal switch
32. For example, at time t.sub.o, the gas turbine is "OFF" and the
fluid flow rate is at Q.sub.1. At time t.sub.1, fluid pump pedal
switch 32 is activated, which, as shown in FIG. 10, is represented
as a depression of pump pedal switch 32.
[0078] Activation of the fluid pump switch 32 causes the saline
flow rate Q to increase from Q.sub.1 to Q.sub.2. At time t.sub.2,
pump pedal switch 32 is released or deactivated and the fluid flow
remains at increased flow rate Q.sub.2. The saline flow rate shall
remain at increased saline flow rate Q.sub.2 for the t.sub.delay
period, shown as from time t.sub.2 to time t.sub.5. As shown in
FIG. 10, at the time t.sub.3 (before the end of the time period
t.sub.delay) fluid pump pedal switch 32 has been activated for a
time period t.sub.3 to t.sub.4. At the time t.sub.4, when the fluid
pump pedal switch 32 is deactivated, the time period t.sub.delay
starts again, running from time t.sub.4 to t.sub.8. It is a feature
of the present invention that this "preflush" or preflush time
period can be executed or extended as many times as desired by the
operator of the system 10.
[0079] Referring to FIG. 9, if the turbine pedal switch 34 is
activated during the t.sub.delay time period, the gas turbine
switches "ON." For example, as shown in FIG. 9, at time t.sub.2,
the fluid pump pedal switch 32 is deactivated and the t.sub.delay
time period starts, with the fluid flow rate remaining at the
increased flow rate Q.sub.2. At time t.sub.4, or before the time
period t.sub.delay has expired, the turbine pedal switch 34 is
activated. The gas turbine goes from "OFF" to "ON" and the saline
flow rate remains at the increased flow rate Q.sub.2. At time
t.sub.7 the gas turbine is switched "OFF" by the release of turbine
pedal switch 34. In one embodiment, as shown in FIG. 9, the saline
flow rate Q can remain at the increased level Q.sub.2 for another
delay time period from time t.sub.7 to time t.sub.9 as represented
by t.sub.delay'. In an alternate embodiment, the fluid flow rate
could go from Q.sub.2 to Q.sub.1 at time t.sub.7. It is a feature
of the present invention to provide a "postflush" or "postflush
time period" of accelerated or increased fluid flow rate after the
gas turbine and drive shaft 25 stop rotating. The time period for
t.sub.delay or t.sub.delay, can be any suitable or desired time
period. The t.sub.delay and t.sub.delay', time periods may comprise
time periods of different length.
[0080] Referring to FIG. 11, if the turbine pedal switch 34 is
activated at any time t.sub.6 after the time period t.sub.delay has
expired at the time t.sub.5, then the controller 60 could prevent
the turbine from activating. If the gas turbine of the RAD 20 has
not been activated during an uninterrupted preflush time period as
shown in FIG. 11, then the controller 60 may also be designed or
programmed to switch the fluid pump 70 into the "preflush" mode
upon activation of the turbine pedal switch 34 and activate the gas
turbine of the RAD 20 only after a predetermined preflush time
period has expired. It is a feature of the present invention to
provide an increased level of fluid flow through an elongated tube
28, and around the drive shaft and through the stenotic treatment
area prior to rotation of the drive shaft 25.
[0081] The fluid pump 70 is not powered by or brought into motion
by the gas turbine or any other prime mover of the RAD and
therefore an acceleration of the fluid flow around the driveshaft
25 is only modestly affected by the rapid rotation of the drive
shaft, which when rapidly rotated can act as a screw pump. In the
preferred embodiment the rapid rotation of the drive shaft 25
causes about a 30% decrease in accelerated fluid flow rate when
compared to accelerated fluid flow rate around a non-rotating drive
shaft.
[0082] Referring to FIG. 12A, a timing circuit 200 could be used to
provide the t.sub.delay time period after deactivation of the pump
pedal switch 32 in the embodiment(s) of the invention shown in FIG.
2 and FIGS. 7-11.
[0083] Switch 232 of the timing circuit 200 remains "open" for as
long as the pump pedal switch 32 is not activated. During that time
period voltage across the capacitor C.sub.1 is equal to the voltage
across capacitor C.sub.2 (voltages at inputs 5 and 7 of the Digital
Circuit NE 555 are equal) and a control signal U.sub.out out is 0
(zero). Activation of pedal switch 32 at the time t.sub.1 in FIG.
8, for example, will "close" switch 232 thereby causing immediate
discharge of the capacitor C.sub.1 through the transistor Q.sub.2.
The control signal U.sub.out of the Digital Circuit NE 555 will
immediately change from 0 to 1.
[0084] At the time t.sub.2 in FIG. 8, for example, when the fluid
pump pedal 32 is released and switch 232 opens, the capacitor
C.sub.1 charges and the Digital Circuit NE 555 provides control
signal U.sub.out equal to 1 until the capacitor C.sub.1 is fully
charged. Therefore the fluid pump 70 continues to pump fluid at an
accelerated or increased fluid flow rate only for as long as the
control signal U.sub.out remains at 1.
[0085] At the time t.sub.5 in FIG. 8, when the capacitor C.sub.1 of
the timing circuit 200 becomes fully charged (voltages at the
inputs 7 and 5 become equal), the control signal U.sub.out will
change from 1 to 0, thereby causing the fluid pump 70 to return to
pumping fluid at the minimum or "min" fluid flow rate.
[0086] The t.sub.delay time period shown in FIGS. 8-11 is defined
by a charge time of the capacitor C.sub.1, in the timing circuit
200. The charge time of the capacitor C.sub.1, and the t.sub.delay
time period shown in FIGS. 8-11 may be adjusted within certain
limits by the potentiometer R.sub.2 in the timing circuit 200.
[0087] A separate timing circuit similar to the timing circuit 200
can be used with the turbine pedal switch 34 in order to provide
the t.sub.delay' time period and "postflush" of accelerated flow of
fluid after the turbine pedal switch 34 is released.
[0088] As shown in FIG. 12B a single timing circuit 210 may provide
equal t.sub.delay and t.sub.delay' time periods. This is
accomplished by connecting in parallel switches 232 and 234, which
correspond to pedal switches 32 and 34 in FIG. 2 and FIGS.
8-11.
[0089] The controller 60 could also include one or more safety
devices to monitor proper operation of the system 10. For example,
in one embodiment as shown in FIG. 7, the controller 60 could
include a pump cover sensor 624. The pump cover sensor 624 could
indicate whether the pump cover 74 shown in FIG. 2 is in an open or
closed position. For example, as shown in FIG. 4, when the pump
handle 75 is in a "DOWN" position, the pump cover sensor 624 can
provide the pump control unit 610 with a suitable signal which
allows the pump control unit 610 to activate the pump motor 612. If
the pump cover 74 is "OPEN", as indicated by the pump cover handle
75 being in an "UP" position as shown in FIG. 3, pump cover sensor
624 will either not provide the signal that is needed to activate
the pump motor 612 or can generate a signal that prevents the pump
motor from being activated. Therefore, when the pump cover 74 is
"OPEN", operation of the pump motor 612 can be prevented or
interrupted.
[0090] In one embodiment as shown in FIGS. 13 and 14 the pump cover
sensor 624 could comprise a switch device 310 adapted to detect a
closed or open position of the pump cover 74. For example, as shown
in FIG. 13 when the pump handle 75 is an "UP" position, the pump
cover 74 is in an "OPEN" position. In FIG. 14 when the pump handle
75 is "DOWN", the pump cover 74 is "CLOSED." In the preferred
embodiment, the switch 310 could comprise a magnetically operated
sealed switch that uses a magnet 312 to preferably determine a
"CLOSED" position of the pump cover 74. Such a switch, also called
a reed switch, is commercially available from Premier Farnell plc
of Chicago, Ill. In an alternate embodiment, any suitable device or
switch can be used to determine an "OPEN" or "CLOSED" position of
the pump cover 74, such as for example, a Hall effect switch, an
optical switch, a mechanical switch or a limit switch.
[0091] As shown in FIG. 7, a fluid alarm unit 630 could be used to
provide an audible and/or visual warning of the pump cover
condition. For example, when the pump cover 74 is open, an audible
alarm device 682 and/or a visual alarm device 684 can be activated
to warn the user of the condition. An indicator 64 of the
controller 60 shown in FIG. 2 could be used to display the visual
warning. An audible alarm or verbal warning may be provided via
siren or speaker 69 shown in FIG. 2.
[0092] As shown in FIG. 7 the controller 60 could also include a
fluid level sensor 626. The fluid level sensor 626 could be used to
detect a low level of fluid in the fluid supply system 50. The
fluid level sensor 626 is in communication with both the fluid pump
control unit 610 and the fluid alarm unit 630. If during an
angioplasty procedure the fluid level in the saline bag 50 reaches
a predetermined low level, then a fluid alarm unit 630 can activate
visual and audible alarm devices 684 and 682 in order to warn or
advice the operator of the system 10 of the condition. The
controller 60 could also include an alarm mute device 636 that can
allow the user to silence or mute the audible alarm device 682 for
a predetermined period of time or a predetermined number of
revolutions of the pump motor 612. Furthermore, in one embodiment
of the invention, operation of the pump motor 612 and/or the gas
turbine could be prevented or stopped if the fluid level sensor 626
detects a predetermined low level of fluid in the saline bag of the
fluid supply 50. If the pump motor 612 is operating and the fluid
sensor 626 detects a low fluid level, in one embodiment the fluid
alarm unit 630 could activate the visual alarm device 684 and/or
provide a verbal warning or activate audible alarm device 682 to
indicate the situation to the user. The alarm mute device 636 can
allow the user to silence the alarm 682 and continue the procedure.
The visual alarm 684 could remain active. The controller 60 could
also be adapted to reactivate the audible alarm 682 after it was
silenced if a predetermined time period elapses or if the fluid
pump 70 or pump motor makes a predetermined number of revolutions
or if the fluid level reaches a next predetermined low level. This
process could continue for as long as the operator desires or until
a predetermined minimum level of fluid is reached. The controller
60 could also include a fluid pump blocking control switch 625,
that when activated, could prevent operation of the fluid pump
motor 612. Referring to FIG. 2, in one embodiment of the present
invention, a push button 82 can be used to silence the audible
alarm device 69 and push button 68 to operate the pump blocking
control or device 625 shown in FIG. 7. In the preferred embodiment
of the invention push button 68 comprises a pushbutton switch with
a red screen. If an operator of the controller 60 activates push
button 68 (prevents or stops operation of the fluid pump 70), then
red screen of the pushbutton switch becomes illuminated by a
filament or LED lamp.
[0093] The pushbutton switches of the type used in the preferred
embodiment of this invention are commercially available from Apem
Components, Inc. of Wakefield, Mass.
[0094] Referring to FIGS. 15 and 16, one embodiment of a fluid
level detection system 300 is shown. In FIG. 2, the fluid container
50 is suspended from a mounting pole or member 302. One end of the
pole 302 is inserted into a receptacle 304. As shown in FIG. 15,
the lower end of the pole member 302 comes to rest against a
horizontal beam member 310. The beam member 310 is adapted to pivot
around a point (not shown). In one embodiment, one end 312 of the
beam member 310 is adapted to move in a downward direction as the
combined weight of the fluid bag 50 and the pole member 302 bears
down on the end 312 of the beam member 310. The combined weight or
force exerted by the fluid bag 50 and the pole member 302
determines the movement or displacement of the end 312. The other
end 314 of the beam member 310 is adapted to move in a direction
opposite to the movement of the end 312. A bias element 316, such
as for example a spring, can be used to apply to the end 314 a
biasing force directed in the direction opposite to the direction
of movement of the end 314 of the beam member 310. Compressing the
bias element 316 using a bolt or screw type device 320 can increase
the tension of the bias element 316 and the force that the bias
element 316 exerts on the end 314. For example, as shown in FIG.
15, a bolt 320 is inserted into a block 318 and as the bolt 320 is
turned, the block 318 moves in a downward direction compressing the
spring 316 and increasing its tension. The increased tension of the
spring 316 increases the biasing force applied to the end 314. In
operation, when a full saline bag is placed on the pole 302, the
end 312 is forced by the combined weight of the bag 50 and pole 302
to deflect downward a certain distance. As the fluid in the bag 50
is depleted, the weight of the fluid bag 50 decreases and the end
312 moves in an upward direction while the end 314 moves downward.
As shown in FIG. 16, when the fluid level in the saline bag 50
reaches a predetermined level, the end 314 of beam member 310 comes
in contact with a switch device 322. The contact of the member 314
with the switch device 322 can cause the fluid alarm unit 630,
shown in FIG. 7, to activate visual and audible alarm devices 684
and 682. In an alternate embodiment, any suitable device or
mechanism can be used to monitor the fluid level in the saline bag.
It is a feature of the present invention to provide a warning to
the operator of the system 10 that the fluid level in the fluid
supply 50 has reached a predetermined low level.
[0095] FIGS. 17 and 18 show another embodiment of a fluid level
detection system 800. In this embodiment, the pole member 302 rests
on a rod 824 that activates switch device 822 when the fluid level
in the fluid supply 50 is above a predetermined low level. As the
fluid level decreases and reaches a predetermined level, a spring
830 or other biasing element starts to move rod 824 in an upward
direction. As shown in FIG. 18, when the fluid level in the fluid
bag 50 reaches a predetermined low level, rod 824 gets out of
contact with and deactivates switch 822, thereby causing fluid
alarm unit 630, shown in FIG. 7, to activate visual alarm device
634 and audible alarm 932.
[0096] In the preferred embodiment, audible alarm device 682 is
activated with a certain predetermined delay with respect to the
visual alarm device 684. Such a sequence of alarms is advantageous
in order to limit any disturbance to the patient.
[0097] FIGS. 19 and 20 show yet another embodiment of a fluid level
detection system 850. In this embodiment a biasing element or
spring 852 is disposed around the lower portion of the pole 854. In
operation, when a full saline bag 50 is placed on the pole 854, the
biasing element 852 becomes compressed between a shoulder 850 of
the pole 854 and an adjustment element or screw 857. The combined
weight of the full bag 50 and the pole itself will force the lower
end of the pole against a switch device 858, thereby providing for
direct activation of the switch device 858 by the lower end of the
pole.
[0098] As shown in FIG. 20, when the fluid level in the bag 50
reaches a predetermined low level, the biasing spring 852 moves the
pole 854 in an upward direction, thereby deactivating switch device
858 and causing fluid alarm unit to activate visual and audible
alarms.
[0099] FIGS. 21 and 22 show yet another embodiment of a fluid
detection system 860 in which a tensiometer device 862 is utilized
instead of a switch device. The tensiometer device measures the
pressure applied to the device and generates a corresponding
electrical signal. A spring type device incorporating e.g. spring
864 can be used to dampen the impact of the pole 866 against the
tensiometer device 862 in order to prevent damage to the
tensiometer device. However, as shown in FIG. 23, the pole 867 of a
modified fluid level detection system 860' can directly contact the
tensiometer device 862. In one embodiment, the tensiometer device
862 can include internal mechanisms to dampen the impact on of the
pole on the tensiometer device, when, for example, a fluid bag 50
is placed on the pole 867.
[0100] As shown in FIG. 7, the controller 60 could also include an
input compressed gas pressure sensor(s) combined with a compressed
gas shutoff valve(s) 670. In the preferred embodiment, the shutoff
valve 670 is generally adapted to shut off the compressed gas
supply to the turbine pressure regulator or the controller 60 when
the input compressed gas pressure from the system pressure
regulator 42 of the compressed gas source 40 exceeds a
predetermined level. An additional pressure sensor combined with
its own low pressure shutoff valve may be adapted to shut off the
compressed gas supply to the turbine pressure regulator 658 or the
controller 60 when the input gas pressure is at or below a
predetermined level. In addition, input pressure sensors may
generate a signal to the pneumatic valve control unit 650 that
preclude activation of the turbine pneumatic valve 657 and
therefore, the gas turbine 605 of the RAD. The signal from the
input pressure sensor(s) may also activate a visual and/or audible
alarm device, either directly or indirectly via the pneumatic valve
control unit 650. The gas pressure alarm device or gas pressure
alarm(s) 673 may be programmed to warn about the input gas pressure
being or becoming either too high or too low. Input compressed gas
pressure that does not exceed a predetermined upper level, or is
within a predetermined range between upper and lower levels is
supplied to the turbine pressure regulator 658. A control knob 62
of the turbine pressure regulator 658 is shown in FIG. 2 and can be
used to adjust the gas pressure applied to the gas turbine of the
RAD.
[0101] A turbine pressure sensor and turbine pressure display
device 671 can be used to display the gas pressure applied to the
gas turbine. The turbine pressure sensor and the turbine pressure
display device 671 can be combined into one device, such as for
example an analog pressure gauge 61 as shown in FIG. 2. Although
the gauge 61 shown in FIG. 2 is illustrated as an analog device,
any suitable indicator can be used, such as for example a digital
display. In an alternate embodiment, the pressure could be
displayed on a system other than the controller 60, such as for
example an external display or monitor.
[0102] The rotational speed of the gas turbine of the RAD shown in
FIG. 2 can be monitored by a turbine tachometer 668 shown in FIG.
7. In the preferred embodiment an improved optical tachometer for
the RAD, such as that described in U.S. Pat. No. 6,039,747 to
Shturman can be used. Referring to FIG. 2, in the preferred
embodiment, the optical tachometer 63 utilizes only one optical
fiber 23 to conduct both uninterrupted light from the controller 60
to the RAD 20 and pulsed light back to the controller 60. In the
rotational angioplasty system of the prior art, shown in FIG. 1 and
described in U.S. Pat. No. 5,314,407 to Auth the turbine optical
tachometer utilizes two optical fibers. The controller 60 of the
present invention can be adapted to interface with this turbine
tachometer of the prior art. In an alternative embodiment, any
suitable device can be used to monitor the rotational speed of the
turbine, including for example optical, electro-optical,
electromagnetic and acoustic tachometers can be used.
[0103] As shown in FIG. 2, the rotational speed of the turbine of
the RAD can be displayed on a turbine tachometer display 63. In the
preferred embodiment of the invention, shown in FIG. 2, a digital
tachometer display 63 is utilized. In an alternate embodiment, any
suitable device, including for example an analog display device,
can be used to display the rotational speed of the gas turbine of
the RAD.
[0104] As shown in FIG. 7, in the preferred embodiment, the
controller 60 may also include a tachometer test device 674 to test
for adequate function of that portion of the turbine tachometer
that is located in the controller 60. A pushbutton switch could be
included on the controller 60 for this purpose.
[0105] In one embodiment, as shown in FIG. 7, the turbine
tachometer 668 can be coupled or connected to the pump control unit
610. The turbine tachometer 668 could provide an input signal to
the pump control unit 610, thereby causing adjustment of the
rotational speed of the fluid pump motor 612 depending on the
rotational speed of the gas turbine.
[0106] It should be understood that although the switches 32 and 34
in FIG. 2, and similar switches in FIGS. 7 and 24, are shown as two
separate pedal activated switches, any suitable switching device(s)
can be used, including a switching device comprising a single
switch.
[0107] Referring to FIG. 24, one embodiment of a control system 900
for controlling fluid pump 904 and gas turbine 305 of rotational
angioplasty device is illustrated. As shown in FIG. 24, a
microcontroller 901, receives a combination of inputs comprising
U.sub.P1 from pump pedal switch 932 (which is similar to the fluid
pump pedal switch 32 in FIG. 2), U.sub.P2 from turbine pedal switch
934 (which is similar to the turbine pedal switch 34 in FIG. 2),
and a turbine speed signal U.omega. from a turbine tachometer 902.
It should be understood that the microcontroller based control
system shown in FIG. 24 can be programmed to perform substantially
all of the functions of the control system shown in FIGS. 2 and 7.
In particular, in one embodiment, the microcontroller 901 can be
programmed to activate a turbine pneumatic valve 903 only if the
fluid pump 904 was activated to pump saline at an accelerated rate
for at least a minimum predetermined period of time using the pump
pedal switch 932 and if the turbine pedal switch 934 was activated
within a predetermined time period t.sub.delay after the pump pedal
switch 932 has been deactivated.
[0108] As shown in FIG. 25, a single pedal activated switch 1010
could be used to control microcontroller 1001 where a first switch
activation establishes a first mode of operation for the system
1000 (e.g. the fluid pump 1004 is "ON"). A second switch activation
establishes a second mode of operation for the system 1000 (e.g.
both the fluid pump 1004 and the gas turbine 1005 are "ON" or
active). A third switch activation returns the system to its
"static" state where the fluid pump is at minimum or "min" flow
rate and the gas turbine is "OFF."
[0109] An example of a single pedal switch 1101 is shown in FIG.
26. All other elements of the system 1100 shown in FIG. 26 are
similar and have the same numbers as the elements of the system 10
shown in FIG. 2.
[0110] It should be understood that the foregoing description is
only illustrative of the invention. Various alternatives and
modifications can be devised by those skilled in the art without
departing from the invention. Accordingly, the present invention is
intended to embrace all such alternatives, modifications and
variances which fall within the scope of the appended claims.
* * * * *