CA2014881A1 - Angioplasty autoperfusion catheter flow measurement method and apparatus - Google Patents
Angioplasty autoperfusion catheter flow measurement method and apparatusInfo
- Publication number
- CA2014881A1 CA2014881A1 CA002014881A CA2014881A CA2014881A1 CA 2014881 A1 CA2014881 A1 CA 2014881A1 CA 002014881 A CA002014881 A CA 002014881A CA 2014881 A CA2014881 A CA 2014881A CA 2014881 A1 CA2014881 A1 CA 2014881A1
- Authority
- CA
- Canada
- Prior art keywords
- autoperfusion
- lumen
- measurement means
- improved
- catheter system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/06—Measuring blood flow
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
- A61M25/104—Balloon catheters used for angioplasty
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4444—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device related to the probe
- A61B8/445—Details of catheter construction
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
- A61M2025/1043—Balloon catheters with special features or adapted for special applications
- A61M2025/1097—Balloon catheters with special features or adapted for special applications with perfusion means for enabling blood circulation only while the balloon is in an inflated state, e.g. temporary by-pass within balloon
Abstract
ANGIOPLASTY AUTOPERFUSION CATHETERE
FLOW MEASUREMENT METHOD AND APPARATUS
ABSTRACT OF THE INVENTION
An angioplasty autoperfusion catheter flow measurement apparatus includes a balloon catheter having an autoperfusion lumen incorporated therein which is acoustically in communication with a flow velocity measuring system. The flow measuring system may include a Doppler transducer, usually a section of piezoelectric material, located adjacent to the autoperfusion lumen and connected to an external activating and measuring device that indicates the velocity of the blood flowing through the autoperfusion lumen at a remote location outside the patient's body.
FLOW MEASUREMENT METHOD AND APPARATUS
ABSTRACT OF THE INVENTION
An angioplasty autoperfusion catheter flow measurement apparatus includes a balloon catheter having an autoperfusion lumen incorporated therein which is acoustically in communication with a flow velocity measuring system. The flow measuring system may include a Doppler transducer, usually a section of piezoelectric material, located adjacent to the autoperfusion lumen and connected to an external activating and measuring device that indicates the velocity of the blood flowing through the autoperfusion lumen at a remote location outside the patient's body.
Description
~ ~ 8 1 ANGIOPLASTY AUTOPERFUS~N~ hT~ETER
FLOW_MEASUREMEMT METHOD AND APPARATVS
BACXGROU~D OF THE INVEN~ION
Field ~of the Inyention This invention relat~ to the ~i~ld o~
intravenous catheters, and more particularly, to balloon angioplasty catheter~ with autoper~usion and flow measurement capabilities.
S Descri~tion of ~he_Related Art The use of balloon dllatation angioplasty as an alternative to heart bypass Eurgery has increased as ~mproved cath~ter system~ and technlgues have been developed ~o advance the probability o~ su2cess o~ such non-surgical solutions to blockage in arteries supplying blood for the heart. Balloon angioplasty involves the in~ertion of a catheter into the area o~
stenosis in the artery and~ n~lation of a balloon incorporated near the distal tip of ths catheter. This procedure provides a mean~ of dilating the plaque on the artery wall, thereby providing a greater area through which blood may flow in the artery. The balloon is usually inflated through a lumen within the catheter by pumping fluid into the lumen from an external sourca located outside o~ the body. A common - fluid used ~or this in~latlon i6 radiopaque dye.
- A variety o~ techniques and apparatus suitable for balloon angioplasty have been developed and one 25 problem with the basic balloon dilation catheters has been caused by blood stoppaqe khrough the artery when the balloon is being inflated. Thus, it ls gQnerally necessary to limit the amount o~ time that the balloon , :
: .:
..
. ~ .
8 ~
can be in~lated in order to limit the possibility o~
angina or further heart damage. In order ko increase the amoun~ of time available ~or balloon inflation without causing the~e undesirable side e~ect~, autoperfusion catheter ~y~tems have been developed which incorporate a conduit for blood ~low pa~t the balloon subsystem in the distal ~nd of the catheter.
Such autoperfusion catheters incorporate an entry upstream of the balloon, a lumen within the portion o~
10 the catheter incorporating the balloon, an exit to ths lumen located near the distal end and down~trea~ of the balloon.
Thus, a passage for the flow of blood provided to bypass the in~lated balloon, thereby - 15 providing an opportunity to keep blood flowing to the heart muscle while the balloon is being inflat~d during the angiopla6ty procedure.
While auch autoperfusion catheters are an improvement over prQVioU8 non perfusion oathe~er~, they 20 nonetheless do not guarantee an adeguate ~low of blood pa6t the balloon since, for example, ~he ~mall orifices and lumen associated with ~he bypas~ of blood may become occluded without an immediate external ind~cation. Flow may al~o~be compromised if the entry 25 or exit holes in th~ lumen àre positioned too C106~ to the artery wall or plaqua. Such probls~ would not ea~ily be detected externally from the body except for the subsequent complaints o~ chest pain by the patient. Such complaints may be delayed in pati~nts 30 with high pain threshholds and/or by the ~onooml~ant use o~ drugs. Therefore, there is a need fox a meanR
of directly and oontinuously measuring th~ blood flow in an autoper~u~ion oakheter ~or use aa a monitor~ng 35 tool to help opti~ize the autoperfusion feature of the catheter during a balloon d~latation angioplasty procedure. To be ef~ective, ~uch a flow measurement means should be simple t small, easily incorporated in 201~8~
: ~3~
an otherwise ~tandard autoperfu~ion balloon dilakation angiopla~ty cathater ~y~kem and ~hould be amenable to a variQty o~ output~ that could be ~onltored by the physician per~orming the angioplasty or an a~ tant.
~he mea6urement should be quantitative or qualitative, the latter providing trend in~ormation.
- 10 ThQ ~urpose o~ a balloon dilatation angioplasty catheter iB to prov~de a mechani~ and apparatus to place and inflate a balloon that is formed integral with the catheter into an area of steno~i~ in - an artery. The placemenk of the balloon is accomplished by means o~ remote manipulation of a catheter incorporating the balloon near ~he di~tal tip o~ thQ catheter, generally by mean~ of slidiny the cathet~r over a guid~ wirQ which ia manipulat~d into ~he appropriate position by a physician aftor being 20. remotely ins~rted lnto an arterial br~nch o~ th~ heart.
: After the ballosn is properly placed in the area of 8teno8i~, the balloon, located near the dietal end o~ the catheter, is inflated by in~ecting or pumpi~g a radiopa~ue dye ~lution into the lumen communicating between the bàlloon and a mani~old ~t the proxi~al end of the catheter looated outsids of the body. A~ the balloon $s in~lated, the ~teno~
expanded by the angloplasty catheter. However, i~ the balloon is le~t inflated too longl th~ blood ~low to the artery feeding the heart will be blocXed ~or a ~u~ficient time to cause angina or perhaps even d amage to the hQart muscle. Xn order to signi~icantly incxea5g the allowable in~lation time wlthout causing uch damage, autoper~usion catheters have b~n developed which incorporate a means o~ moYing blood past the in~lated b~lloon thxough the use o~ a lumen or channel internal to the catheter and having blood rlow 2 ~ 8 ~
orifices communicating with the arterial lumen. Given the complex nature o~ such autoper~usion, the possibility of failure or clogging of the autoperfusion channel and the possibility that, for a variety of reasons, the channel may not be providiny an adequate flow of blood to prevent angina or heart damage is a real concern to the medical profession.
Thus, there is a need for a flow indication device in a catheter which is both inexpensiv~ (since the catheter is conventionally disposable), does not interfere with the operation of the catheter and does not compromise the autoperfusion lumen.
SUMMARY OF THE INVENTION
The present invention provides an improved autoperfusion angioplasty catheter system of the type incorporating a balloon located near the distal tip o~ the catheter, an autoperfusion lumen within the balloon, and autoperfusion orifices located proximally and distally from the balloon, the orifices providing means to allow the flow of blood through the autoperfusion lumen when the balloon is inflated, the improvement comprising: measurement means located adjacent the autoperfusion lumen and in commUniGation therewith; means to activate the measurement means from a remote location; and indication means to provide at the remote location an indication o~ flow movement as measured by the measurement means.
- The present invention also provides, in an autoperfusion catheter of the type that incorporates an inflatable balloon near the distal end of the catheter, an autoperfusion lumen internal to the balloon, autoperfusion vents placed proximally and distally from the balloon, the . .
~ o ~
vents in communication with the autoperfusion lumen and the exterior of the catheter to provide a passage for blood past the balloon when it is inflated, an improvement which comprises: flow measurement means located adjacenk and in communication with the autoperfusion lumen; m e a n s t o communicate between the flow measurement means and a remote location; control means at the remote location whereby the ~low measurement means may be activated and measurement of flow to the autoperfusion lumen may be received; and indicator means at the rem~te location whereby an indication of the Plow measurement may be provided.
The present invention also provides an improved autoperfusion catheter of the type that incorporates an inflatable balloon means near the distal end of the catheter, an autoper~usion lumen, autoperfusion vents placed proximally and distally from the balloon, the vents providing means to allow the flow of blood in the autoperfusion lumen when the balloon is inflated, wherein the improvement compri~es flow measurement means located adjacent to and in communication with the autoperfusion lumen.
Other ~eatures and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectioned plan view of the flow sensor of the present invention as it appears in an angioplasty balloon dilatation catheter system incorporating autoperfusion, with the balloon portion shown in cross-section to illustrate placement of the sensor.
, '. ' ~ , '' ' 8 ~ ~
Figure 2 is an enlarged cross-sectional side view of an angioplasty balloon dilatation catheter incorporating the present invention, illustrating one preferred placement of the sensor adjacent to the autoperfusion lumen.
Figure 3 is a cross-sectional view of the catheter system incorporating the invention taken along line 3-3 of Fig. 2, illustrating the placement of the conductors in the inflation lumen and the guidewire within the autoperfusion lumen.
Figure 4 is a cross-sectional view of the catheter system taken along line 4-4 of Figure 2, illustrating the balloon surrounding the central autoperfusion lumen and guidewire.
Figure 5 is a plan view of a preferred embodiment of the Doppler sensor and the connections between the piezoelectric chip and the conductors.
Figure 6 is a plan view showing an alternative construction of the connections between the piezoelectric chip of the sensor and the conductors in communication with the sensor.
Figure 7 is a cross-sectional side view of an alternative construction of the present invention illustrating the sensor placed distally from the balloon and located within a sealed portion of the inflation lumen.
DETAILED DESCRIPTION OF THE P~U~ Y~ G~
A typical autoperfusion balloon dilatation catheter incorporates an autoperfusion channel within the balloon section that is connected to vents in the catheter wall located proximally and distally from thP balloon. Thus, when the balloon is inflated to displace the plaque from the central portion of the artery, blood flows through the ~: , : ~ . . ; ' ~ . .
2~1~881 autoperfu~ion channel and provides blood flow to the muscle being served by the artery. Un~ortunately, previous applications of autoperfusion catheters did not provide an indication of tha blood flow through the autoper~usion channel and the physician was forced to rely upon complaints of angina by the patient or other extrinsic indications of diminished blood flow.
The present invention provides a means of directly indicating the flow velocity of blood within the autoperfusion channel and, in the case of a channel with predictable cross sectional characteristics during the procedure, the volumetric blood flow being supplied through the artery can be calculated. The invention is embodied in a velocity sensor located adjacent to the autoperfusion channel and coupled to the channel in such a way that the velocity within the channel may be measured by the sensor. The measur~d velocity may then be transmitted to a remote location where the velocity or volume flow information may be displayed or otherwise provided to the physician or one of his assistants.
In one embodiment of the invention the sensor incorporates a piezoelectric crystal capable of transmitting sound waves through a coupling medium and the wall of the autoperfusion channel to thereby transmit sound of a predetermined frequency into the fluid flowing through the channel. By using well-known pulse, or continuous wave, Doppler principles and the appropriate choice of frequencieæ
that are interactive with blood, one can determine the velocity of the blood since the frequency of a reflected wave is shifted in proportion to the velocity of the blood flowing through the channel. A frequency of about 20 megahertz (MHz) has been found to work well in this application. The reflected wave is detected by the cxystal and is measured by suitable remotely located electronics that translates the :,' ' . : -.
, 2014L8~1 measured wave into an indication of the velocity of blood flowing through the chann~l. The electronics providing this derived indication of velocity can also operate associatively with electronics that provide control of the emission of frequency of the crystal and other related functions.
Communication between the crystal and the remote electronics is conveniently accomplished by very small wires or other conductors located in a noninterference fashion in one of the lumens of the catheter. Such wires may be conveniently located for instance, within the inflation lumen which is used to inflate and deflate the balloon during the procedure.
The entire flow measuring apparatus can be made small enough so that it does not significantly interfere with the primary functions of the catheter system by either significantly altering its external diameter in any critical area, thereby decreasing the ~lexibility of the catheter, or altering the functioning of the balloon inflation, the guide wire system or autoperfusion channel.
From the above, it should be appreciated that the present invention represents a substantial improvement in autoperfusion catheter systems, in that it consists of a simple, reliable and accurate means of indicating flow velocity within an autoperfusion channel to a physician performing an angioplasty.
- Figure 1 is a sectioned overall view of an autoperfusion catheter system 2 incorporating the present invention. An outer cover or wall 4 houses a plurality of lumens including one which provides a passageway for a guide wire 6, which during the initial stages of the angioplasty procedure protrudes from the distal end of the catheter 2.
A balloon 8 is formed external to and attached to the exterior of outer cover 4 and is inflated through an inflation manifold port 12 located in a manifold 10. A radiopaque collar 14 is 8 8 ~
provided around the outer covers to give an external indication of the location of the balloon 8 to the physician during the procedure. Autoperfusion inlet por~s 16 are provided proximally to the balloon 8 and autoper~usion outlet ports 18 are provided distally from the balloon 8 to provide blood flow past balloon 8 when it is inflated during the procedure. An autoperfusion lumen or channel 26 (shown in detail in Fig. 2) is built into the catheter and acts as a conduit or channel for the blood to flow from the inlet port 16 to the east port 18.
Means for measuring the flow of blood within the autoperfusion channel 26 are shown as a flow sensor 20 located adjacent to and in acoustic communication with the autoperfusion channel 26. The sensor 20 may be conveniently located within the balloon 8 away from the inflation lumen port 22 that is found at the distal end of the inflation lumen 24. Thus, the present invention providss a means for measuring the flow of blood within the autoperfusion lumen without interfering with either the autoperfusion function or any other functions provided by the angioplasty catheter system.
Figure 2 is an enlarged cross-sectional view taken longitudinally through the balloon and catheter system of Figure 1. In this view it may be readily seen that the outer cover 4 of catheter 2 encloses the in~lation lumen 24 and autoperfusion lumen 26. The inflation lumen 24 is in communication with the inside of balloon 8 through inflation lumen port 22 while autoperfusion lumen 26 acts as an autoperfusion channel between ports 16 and outlet ports 18 to thereby bypass the balloon ~ when it is inflated during an angioplasty procedure. As was described above, a radiopaque collar 14 is provided to assist the physician in locating the balloon portion of the catheter system during the angioplasty .
~ . : . ; .
2(~1~881 procedure. During the time that the procedure is being performed, the guidewire 6 is retracted in the autoperfusion lumen 26 until the tip 28 of guidewire 6 is retracted behind the proximal end of autoperfusion inlet ports 16 to thereby provide a clear flow of blood through inlet ports 16 into the autoperfusion channel 26.
As may be seen more clearly in Fig. 2, the flow sensor 20 may consist of a piezoelectric chip or crystal 30 that is connected to an external signal source and measurement electronics (not shown in Fig. 2) through conductors 32 that are spot welded, soldered or attached with conductive adhesive, at connections 34 to the chip. The Doppler chip may be angled to point upstream (as illustrated) or downstream for velocity measuring purposes. The conductors 32 may be placed in inflation lumen 2~ without interfering with the inflation process of balloon 8 and the sensor 20 may be placed a distance away from lumen port 22, thereby eliminating interference between the function of port 22 during the inflation or deflation process. The flow sensor 20 may b~
attached to a wall 36 of autoperfusion lumen 26 by a suitable adhesive 38 to promote ultrasonic transmissions 40 through the wall 36 into the blood flow in the autoperfusion lumen 2S.
The same flow sensor can be used to receive the reflected waves 42 that bounce off the flowing blood cells. Remote electronics may activate the piezoelectric chip 30 through the conductors 32 to thereby emit the ultrasonic transmissions 40 in the form of waves into the blood flowing through autoperfusion lumen 26 causing a Doppler frequency shift in the reflected wave 42 which again is detec,ted by the piezoelectric chip 30 in the form of signals which can be transmitted through the conductors 32 to a remote location where the signals are processed and recorded. These signals can be derived to provide an indication of the velocity of . '' .
.
~01~8~1 flow through the lumen. If the cross-sectional area of the autoperfusion lumen can be kept constant in the vicinity of sensor 20, the volumetric flow through the lumen may be derived Prom this information and displayed to the physician during the procedure.
Figure 3 is an illustration of the cross section of the catheter system along line 3-3 of Figure 2, illustrating the guide wire 6 within autoperfu~ion channel 26 and conductors 32 within inflation lumen 24, all enclosed by the outer cover 4 of the catheter 2. Figure 4 also shows a cross-sectional view of the catheter system at a location further down along the distal end of the catheter 2. This figure shows the balloon as it is expanded after inflation during the angioplasty procedure. The autoperfusion lumen 26 is also shown as it houses the guide wire 6.
Figure 5 is an enlarged detail of the flow sensor 2~ illustrating the relationship of piezoelectric chip 30 and one preferred embodiment of connection between the chip 30 and the conductors 32. In this embodiment, connectors 46, made from conductive metal or similar material, are spot welded or soldered to the piezoelectric chip 30 and are also spot welded or soldered to conductors 32 to provide electrical communication with the remote electronics. The conductors 46 may alternatively be formed of conductive epoxy, paint, or ink that may be npainted" in place. Adhesive 38 i5 provided to adhesively attach the chip 30 to the autoperfusion lumen wall 36 and to maintain the stability between the connectors 46 and the chip 30. As is further illustrated in FIG. 2, the backside of the piezoelectric chip may be coated with a sound insulator 44, such as foam or epoxy with hollow beads of glass or the like, to prevent propagation of ultrasound in a direction other than the desired direction. The entire apparatus may be further surrounded by an electrical insulator . . .
-- 2~8~
to provide insulation of the electrical signals from the surrounding inflation liquid medium and other conductors.
Figure 6 illustrates an alternative embodiment of the flow sensor 20 in which the conductors 32 are directly attached to the connections 34 by small pieces of wire 47 that are soldered between the connections 34 and the ends ~8 of conductors 32 with solder or spot welds 50. Alternative means of attaching connectors 34 to the chip 30 include ball bonding and conductive adhesives. The entire assembly may be bonded to autoperfusion lumen wall 36 and surrounded by sound and electrical insulation material 44 and 45 respectively, which also provides a stabilizing overlay to the sensor 20 as was shown in Figs. 2 and 5.
Figure 7 illustrates an alternative construction in which the sensor may be mounted away from the balloon 8 in an extended portion of 51 of the inflation lumen 24. In this embodiment, the inflation lumen port 22 is cut in the wall of the inflation lumen 24 and is sealed from the extended portion 51 by a quantity of adhesive such as epoxy 52. The flow sensor 20 is installed by peeling away a portion 54 of the outer cover 4 that is adjacent to the inflation lumen 24. A
quantity of adhesive such as epoxy 5~ is placed distally from sensor 20 to seal the sensor in the inflation lumen 24 and the flap 54 is later rebonded to the outer cover 4 to seal the assembly. Thus, this configuration provides an equally effective means of coupling the ultrasonic waves emitted by flow sensor 20 into the autoperfusion lumen 26 to thereby measure the velocity of blood flowing therethrough.
The invention has been described in the context of a single Doppler measurement of blood velocity, but those skilled in the art will recognize that various techniques to vary the range gates of the signal may be used to further characterize the flow in the autoperfusion channel. For ~488~
example, but not by way of limitation, variations in the range gate may be used to characterize the profile of velocities in the autoperfusion channel or detect the presence and location of an obstruction such as a blood clot. Multiple range gate data may be used in combination with an algorithm developed for a given-catheter design to allow sore accurate measurement of volumetric flow. Alternatively, the Doppler signal may be processed using spectral analysis techniques known in the art.
Alternative piezoelectric materials (e.g. PZT ceramic or PVDF
polymer) may be used as known in the art.
It is clear that it is also possible to partially recess the sensor within the wall of ths autoperfusion lumen by partially notching the outer surface of the wallO
It should be appreciated that other types of flow or velocity measuring devices can be incorporated into the balloon catheter without departing from the spirit and scope of the invPntion. For example, a hot film anemometer or ultrasound laser measuring device could be used instead of the Doppler crystal. An electromagnetic blood ~low measuring device could also be used. Each device would of course have to be adapted for mounting with the autopsrfusion lumen to provide accurate measurements.
From the above it may be seen that the present invention represents a simple and elegant solution to the measurement of blood flow through an autoperfusion lumen of the type used during an angioplasty procedure. The placement of such a sensor does not interfere in any significant way with the other functions of the autoperfusion balloon dilatation catheter system and provides an important diagnostic aid to the physician during his use of such catheter systems.
While particular forms of the invention have been illustrated and described, it will also be apparent to those .
:
.
8 g :~
skilled in the art that various modifications can be made without departing ~rom the spirit and scope of the invention.
Accordingly, it is not intended that the invention be limited except as by the appended claims.
FLOW_MEASUREMEMT METHOD AND APPARATVS
BACXGROU~D OF THE INVEN~ION
Field ~of the Inyention This invention relat~ to the ~i~ld o~
intravenous catheters, and more particularly, to balloon angioplasty catheter~ with autoper~usion and flow measurement capabilities.
S Descri~tion of ~he_Related Art The use of balloon dllatation angioplasty as an alternative to heart bypass Eurgery has increased as ~mproved cath~ter system~ and technlgues have been developed ~o advance the probability o~ su2cess o~ such non-surgical solutions to blockage in arteries supplying blood for the heart. Balloon angioplasty involves the in~ertion of a catheter into the area o~
stenosis in the artery and~ n~lation of a balloon incorporated near the distal tip of ths catheter. This procedure provides a mean~ of dilating the plaque on the artery wall, thereby providing a greater area through which blood may flow in the artery. The balloon is usually inflated through a lumen within the catheter by pumping fluid into the lumen from an external sourca located outside o~ the body. A common - fluid used ~or this in~latlon i6 radiopaque dye.
- A variety o~ techniques and apparatus suitable for balloon angioplasty have been developed and one 25 problem with the basic balloon dilation catheters has been caused by blood stoppaqe khrough the artery when the balloon is being inflated. Thus, it ls gQnerally necessary to limit the amount o~ time that the balloon , :
: .:
..
. ~ .
8 ~
can be in~lated in order to limit the possibility o~
angina or further heart damage. In order ko increase the amoun~ of time available ~or balloon inflation without causing the~e undesirable side e~ect~, autoperfusion catheter ~y~tems have been developed which incorporate a conduit for blood ~low pa~t the balloon subsystem in the distal ~nd of the catheter.
Such autoperfusion catheters incorporate an entry upstream of the balloon, a lumen within the portion o~
10 the catheter incorporating the balloon, an exit to ths lumen located near the distal end and down~trea~ of the balloon.
Thus, a passage for the flow of blood provided to bypass the in~lated balloon, thereby - 15 providing an opportunity to keep blood flowing to the heart muscle while the balloon is being inflat~d during the angiopla6ty procedure.
While auch autoperfusion catheters are an improvement over prQVioU8 non perfusion oathe~er~, they 20 nonetheless do not guarantee an adeguate ~low of blood pa6t the balloon since, for example, ~he ~mall orifices and lumen associated with ~he bypas~ of blood may become occluded without an immediate external ind~cation. Flow may al~o~be compromised if the entry 25 or exit holes in th~ lumen àre positioned too C106~ to the artery wall or plaqua. Such probls~ would not ea~ily be detected externally from the body except for the subsequent complaints o~ chest pain by the patient. Such complaints may be delayed in pati~nts 30 with high pain threshholds and/or by the ~onooml~ant use o~ drugs. Therefore, there is a need fox a meanR
of directly and oontinuously measuring th~ blood flow in an autoper~u~ion oakheter ~or use aa a monitor~ng 35 tool to help opti~ize the autoperfusion feature of the catheter during a balloon d~latation angioplasty procedure. To be ef~ective, ~uch a flow measurement means should be simple t small, easily incorporated in 201~8~
: ~3~
an otherwise ~tandard autoperfu~ion balloon dilakation angiopla~ty cathater ~y~kem and ~hould be amenable to a variQty o~ output~ that could be ~onltored by the physician per~orming the angioplasty or an a~ tant.
~he mea6urement should be quantitative or qualitative, the latter providing trend in~ormation.
- 10 ThQ ~urpose o~ a balloon dilatation angioplasty catheter iB to prov~de a mechani~ and apparatus to place and inflate a balloon that is formed integral with the catheter into an area of steno~i~ in - an artery. The placemenk of the balloon is accomplished by means o~ remote manipulation of a catheter incorporating the balloon near ~he di~tal tip o~ thQ catheter, generally by mean~ of slidiny the cathet~r over a guid~ wirQ which ia manipulat~d into ~he appropriate position by a physician aftor being 20. remotely ins~rted lnto an arterial br~nch o~ th~ heart.
: After the ballosn is properly placed in the area of 8teno8i~, the balloon, located near the dietal end o~ the catheter, is inflated by in~ecting or pumpi~g a radiopa~ue dye ~lution into the lumen communicating between the bàlloon and a mani~old ~t the proxi~al end of the catheter looated outsids of the body. A~ the balloon $s in~lated, the ~teno~
expanded by the angloplasty catheter. However, i~ the balloon is le~t inflated too longl th~ blood ~low to the artery feeding the heart will be blocXed ~or a ~u~ficient time to cause angina or perhaps even d amage to the hQart muscle. Xn order to signi~icantly incxea5g the allowable in~lation time wlthout causing uch damage, autoper~usion catheters have b~n developed which incorporate a means o~ moYing blood past the in~lated b~lloon thxough the use o~ a lumen or channel internal to the catheter and having blood rlow 2 ~ 8 ~
orifices communicating with the arterial lumen. Given the complex nature o~ such autoper~usion, the possibility of failure or clogging of the autoperfusion channel and the possibility that, for a variety of reasons, the channel may not be providiny an adequate flow of blood to prevent angina or heart damage is a real concern to the medical profession.
Thus, there is a need for a flow indication device in a catheter which is both inexpensiv~ (since the catheter is conventionally disposable), does not interfere with the operation of the catheter and does not compromise the autoperfusion lumen.
SUMMARY OF THE INVENTION
The present invention provides an improved autoperfusion angioplasty catheter system of the type incorporating a balloon located near the distal tip o~ the catheter, an autoperfusion lumen within the balloon, and autoperfusion orifices located proximally and distally from the balloon, the orifices providing means to allow the flow of blood through the autoperfusion lumen when the balloon is inflated, the improvement comprising: measurement means located adjacent the autoperfusion lumen and in commUniGation therewith; means to activate the measurement means from a remote location; and indication means to provide at the remote location an indication o~ flow movement as measured by the measurement means.
- The present invention also provides, in an autoperfusion catheter of the type that incorporates an inflatable balloon near the distal end of the catheter, an autoperfusion lumen internal to the balloon, autoperfusion vents placed proximally and distally from the balloon, the . .
~ o ~
vents in communication with the autoperfusion lumen and the exterior of the catheter to provide a passage for blood past the balloon when it is inflated, an improvement which comprises: flow measurement means located adjacenk and in communication with the autoperfusion lumen; m e a n s t o communicate between the flow measurement means and a remote location; control means at the remote location whereby the ~low measurement means may be activated and measurement of flow to the autoperfusion lumen may be received; and indicator means at the rem~te location whereby an indication of the Plow measurement may be provided.
The present invention also provides an improved autoperfusion catheter of the type that incorporates an inflatable balloon means near the distal end of the catheter, an autoper~usion lumen, autoperfusion vents placed proximally and distally from the balloon, the vents providing means to allow the flow of blood in the autoperfusion lumen when the balloon is inflated, wherein the improvement compri~es flow measurement means located adjacent to and in communication with the autoperfusion lumen.
Other ~eatures and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectioned plan view of the flow sensor of the present invention as it appears in an angioplasty balloon dilatation catheter system incorporating autoperfusion, with the balloon portion shown in cross-section to illustrate placement of the sensor.
, '. ' ~ , '' ' 8 ~ ~
Figure 2 is an enlarged cross-sectional side view of an angioplasty balloon dilatation catheter incorporating the present invention, illustrating one preferred placement of the sensor adjacent to the autoperfusion lumen.
Figure 3 is a cross-sectional view of the catheter system incorporating the invention taken along line 3-3 of Fig. 2, illustrating the placement of the conductors in the inflation lumen and the guidewire within the autoperfusion lumen.
Figure 4 is a cross-sectional view of the catheter system taken along line 4-4 of Figure 2, illustrating the balloon surrounding the central autoperfusion lumen and guidewire.
Figure 5 is a plan view of a preferred embodiment of the Doppler sensor and the connections between the piezoelectric chip and the conductors.
Figure 6 is a plan view showing an alternative construction of the connections between the piezoelectric chip of the sensor and the conductors in communication with the sensor.
Figure 7 is a cross-sectional side view of an alternative construction of the present invention illustrating the sensor placed distally from the balloon and located within a sealed portion of the inflation lumen.
DETAILED DESCRIPTION OF THE P~U~ Y~ G~
A typical autoperfusion balloon dilatation catheter incorporates an autoperfusion channel within the balloon section that is connected to vents in the catheter wall located proximally and distally from thP balloon. Thus, when the balloon is inflated to displace the plaque from the central portion of the artery, blood flows through the ~: , : ~ . . ; ' ~ . .
2~1~881 autoperfu~ion channel and provides blood flow to the muscle being served by the artery. Un~ortunately, previous applications of autoperfusion catheters did not provide an indication of tha blood flow through the autoper~usion channel and the physician was forced to rely upon complaints of angina by the patient or other extrinsic indications of diminished blood flow.
The present invention provides a means of directly indicating the flow velocity of blood within the autoperfusion channel and, in the case of a channel with predictable cross sectional characteristics during the procedure, the volumetric blood flow being supplied through the artery can be calculated. The invention is embodied in a velocity sensor located adjacent to the autoperfusion channel and coupled to the channel in such a way that the velocity within the channel may be measured by the sensor. The measur~d velocity may then be transmitted to a remote location where the velocity or volume flow information may be displayed or otherwise provided to the physician or one of his assistants.
In one embodiment of the invention the sensor incorporates a piezoelectric crystal capable of transmitting sound waves through a coupling medium and the wall of the autoperfusion channel to thereby transmit sound of a predetermined frequency into the fluid flowing through the channel. By using well-known pulse, or continuous wave, Doppler principles and the appropriate choice of frequencieæ
that are interactive with blood, one can determine the velocity of the blood since the frequency of a reflected wave is shifted in proportion to the velocity of the blood flowing through the channel. A frequency of about 20 megahertz (MHz) has been found to work well in this application. The reflected wave is detected by the cxystal and is measured by suitable remotely located electronics that translates the :,' ' . : -.
, 2014L8~1 measured wave into an indication of the velocity of blood flowing through the chann~l. The electronics providing this derived indication of velocity can also operate associatively with electronics that provide control of the emission of frequency of the crystal and other related functions.
Communication between the crystal and the remote electronics is conveniently accomplished by very small wires or other conductors located in a noninterference fashion in one of the lumens of the catheter. Such wires may be conveniently located for instance, within the inflation lumen which is used to inflate and deflate the balloon during the procedure.
The entire flow measuring apparatus can be made small enough so that it does not significantly interfere with the primary functions of the catheter system by either significantly altering its external diameter in any critical area, thereby decreasing the ~lexibility of the catheter, or altering the functioning of the balloon inflation, the guide wire system or autoperfusion channel.
From the above, it should be appreciated that the present invention represents a substantial improvement in autoperfusion catheter systems, in that it consists of a simple, reliable and accurate means of indicating flow velocity within an autoperfusion channel to a physician performing an angioplasty.
- Figure 1 is a sectioned overall view of an autoperfusion catheter system 2 incorporating the present invention. An outer cover or wall 4 houses a plurality of lumens including one which provides a passageway for a guide wire 6, which during the initial stages of the angioplasty procedure protrudes from the distal end of the catheter 2.
A balloon 8 is formed external to and attached to the exterior of outer cover 4 and is inflated through an inflation manifold port 12 located in a manifold 10. A radiopaque collar 14 is 8 8 ~
provided around the outer covers to give an external indication of the location of the balloon 8 to the physician during the procedure. Autoperfusion inlet por~s 16 are provided proximally to the balloon 8 and autoper~usion outlet ports 18 are provided distally from the balloon 8 to provide blood flow past balloon 8 when it is inflated during the procedure. An autoperfusion lumen or channel 26 (shown in detail in Fig. 2) is built into the catheter and acts as a conduit or channel for the blood to flow from the inlet port 16 to the east port 18.
Means for measuring the flow of blood within the autoperfusion channel 26 are shown as a flow sensor 20 located adjacent to and in acoustic communication with the autoperfusion channel 26. The sensor 20 may be conveniently located within the balloon 8 away from the inflation lumen port 22 that is found at the distal end of the inflation lumen 24. Thus, the present invention providss a means for measuring the flow of blood within the autoperfusion lumen without interfering with either the autoperfusion function or any other functions provided by the angioplasty catheter system.
Figure 2 is an enlarged cross-sectional view taken longitudinally through the balloon and catheter system of Figure 1. In this view it may be readily seen that the outer cover 4 of catheter 2 encloses the in~lation lumen 24 and autoperfusion lumen 26. The inflation lumen 24 is in communication with the inside of balloon 8 through inflation lumen port 22 while autoperfusion lumen 26 acts as an autoperfusion channel between ports 16 and outlet ports 18 to thereby bypass the balloon ~ when it is inflated during an angioplasty procedure. As was described above, a radiopaque collar 14 is provided to assist the physician in locating the balloon portion of the catheter system during the angioplasty .
~ . : . ; .
2(~1~881 procedure. During the time that the procedure is being performed, the guidewire 6 is retracted in the autoperfusion lumen 26 until the tip 28 of guidewire 6 is retracted behind the proximal end of autoperfusion inlet ports 16 to thereby provide a clear flow of blood through inlet ports 16 into the autoperfusion channel 26.
As may be seen more clearly in Fig. 2, the flow sensor 20 may consist of a piezoelectric chip or crystal 30 that is connected to an external signal source and measurement electronics (not shown in Fig. 2) through conductors 32 that are spot welded, soldered or attached with conductive adhesive, at connections 34 to the chip. The Doppler chip may be angled to point upstream (as illustrated) or downstream for velocity measuring purposes. The conductors 32 may be placed in inflation lumen 2~ without interfering with the inflation process of balloon 8 and the sensor 20 may be placed a distance away from lumen port 22, thereby eliminating interference between the function of port 22 during the inflation or deflation process. The flow sensor 20 may b~
attached to a wall 36 of autoperfusion lumen 26 by a suitable adhesive 38 to promote ultrasonic transmissions 40 through the wall 36 into the blood flow in the autoperfusion lumen 2S.
The same flow sensor can be used to receive the reflected waves 42 that bounce off the flowing blood cells. Remote electronics may activate the piezoelectric chip 30 through the conductors 32 to thereby emit the ultrasonic transmissions 40 in the form of waves into the blood flowing through autoperfusion lumen 26 causing a Doppler frequency shift in the reflected wave 42 which again is detec,ted by the piezoelectric chip 30 in the form of signals which can be transmitted through the conductors 32 to a remote location where the signals are processed and recorded. These signals can be derived to provide an indication of the velocity of . '' .
.
~01~8~1 flow through the lumen. If the cross-sectional area of the autoperfusion lumen can be kept constant in the vicinity of sensor 20, the volumetric flow through the lumen may be derived Prom this information and displayed to the physician during the procedure.
Figure 3 is an illustration of the cross section of the catheter system along line 3-3 of Figure 2, illustrating the guide wire 6 within autoperfu~ion channel 26 and conductors 32 within inflation lumen 24, all enclosed by the outer cover 4 of the catheter 2. Figure 4 also shows a cross-sectional view of the catheter system at a location further down along the distal end of the catheter 2. This figure shows the balloon as it is expanded after inflation during the angioplasty procedure. The autoperfusion lumen 26 is also shown as it houses the guide wire 6.
Figure 5 is an enlarged detail of the flow sensor 2~ illustrating the relationship of piezoelectric chip 30 and one preferred embodiment of connection between the chip 30 and the conductors 32. In this embodiment, connectors 46, made from conductive metal or similar material, are spot welded or soldered to the piezoelectric chip 30 and are also spot welded or soldered to conductors 32 to provide electrical communication with the remote electronics. The conductors 46 may alternatively be formed of conductive epoxy, paint, or ink that may be npainted" in place. Adhesive 38 i5 provided to adhesively attach the chip 30 to the autoperfusion lumen wall 36 and to maintain the stability between the connectors 46 and the chip 30. As is further illustrated in FIG. 2, the backside of the piezoelectric chip may be coated with a sound insulator 44, such as foam or epoxy with hollow beads of glass or the like, to prevent propagation of ultrasound in a direction other than the desired direction. The entire apparatus may be further surrounded by an electrical insulator . . .
-- 2~8~
to provide insulation of the electrical signals from the surrounding inflation liquid medium and other conductors.
Figure 6 illustrates an alternative embodiment of the flow sensor 20 in which the conductors 32 are directly attached to the connections 34 by small pieces of wire 47 that are soldered between the connections 34 and the ends ~8 of conductors 32 with solder or spot welds 50. Alternative means of attaching connectors 34 to the chip 30 include ball bonding and conductive adhesives. The entire assembly may be bonded to autoperfusion lumen wall 36 and surrounded by sound and electrical insulation material 44 and 45 respectively, which also provides a stabilizing overlay to the sensor 20 as was shown in Figs. 2 and 5.
Figure 7 illustrates an alternative construction in which the sensor may be mounted away from the balloon 8 in an extended portion of 51 of the inflation lumen 24. In this embodiment, the inflation lumen port 22 is cut in the wall of the inflation lumen 24 and is sealed from the extended portion 51 by a quantity of adhesive such as epoxy 52. The flow sensor 20 is installed by peeling away a portion 54 of the outer cover 4 that is adjacent to the inflation lumen 24. A
quantity of adhesive such as epoxy 5~ is placed distally from sensor 20 to seal the sensor in the inflation lumen 24 and the flap 54 is later rebonded to the outer cover 4 to seal the assembly. Thus, this configuration provides an equally effective means of coupling the ultrasonic waves emitted by flow sensor 20 into the autoperfusion lumen 26 to thereby measure the velocity of blood flowing therethrough.
The invention has been described in the context of a single Doppler measurement of blood velocity, but those skilled in the art will recognize that various techniques to vary the range gates of the signal may be used to further characterize the flow in the autoperfusion channel. For ~488~
example, but not by way of limitation, variations in the range gate may be used to characterize the profile of velocities in the autoperfusion channel or detect the presence and location of an obstruction such as a blood clot. Multiple range gate data may be used in combination with an algorithm developed for a given-catheter design to allow sore accurate measurement of volumetric flow. Alternatively, the Doppler signal may be processed using spectral analysis techniques known in the art.
Alternative piezoelectric materials (e.g. PZT ceramic or PVDF
polymer) may be used as known in the art.
It is clear that it is also possible to partially recess the sensor within the wall of ths autoperfusion lumen by partially notching the outer surface of the wallO
It should be appreciated that other types of flow or velocity measuring devices can be incorporated into the balloon catheter without departing from the spirit and scope of the invPntion. For example, a hot film anemometer or ultrasound laser measuring device could be used instead of the Doppler crystal. An electromagnetic blood ~low measuring device could also be used. Each device would of course have to be adapted for mounting with the autopsrfusion lumen to provide accurate measurements.
From the above it may be seen that the present invention represents a simple and elegant solution to the measurement of blood flow through an autoperfusion lumen of the type used during an angioplasty procedure. The placement of such a sensor does not interfere in any significant way with the other functions of the autoperfusion balloon dilatation catheter system and provides an important diagnostic aid to the physician during his use of such catheter systems.
While particular forms of the invention have been illustrated and described, it will also be apparent to those .
:
.
8 g :~
skilled in the art that various modifications can be made without departing ~rom the spirit and scope of the invention.
Accordingly, it is not intended that the invention be limited except as by the appended claims.
Claims (26)
1. An improved autoperfusion angioplasty catheter system of the type incorporating a balloon located near the distal tip of the catheter, an autoperfusion lumen within the balloon, and autoperfusion orifices located proximally and distally from said balloon, said orifices providing means to allow the flow of blood through said autoperfusion lumen when said balloon is inflated, said improvement comprising:
measurement means located adjacent said autoperfusion lumen and in communication therewith;
means to activate said measurement means from a remote location; and indication means to provide at said remote location an indication of flow movement as measured by said measurement means.
measurement means located adjacent said autoperfusion lumen and in communication therewith;
means to activate said measurement means from a remote location; and indication means to provide at said remote location an indication of flow movement as measured by said measurement means.
2. The improved autoperfusion catheter system of claim 1 wherein said measurement means comprises velocity measurement means.
3. The improved autoperfusion catheter system of claim 2 wherein said velocity measurement means further comprises Doppler velocity measurement means.
4. The improved autoperfusion catheter system of claim 3 wherein said Doppler velocity measurement means further comprises:
a transducer located adjacent to and in communication with said autoperfusion lumen thereby acoustic coupling through the wall of said lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves received by said transducer.
a transducer located adjacent to and in communication with said autoperfusion lumen thereby acoustic coupling through the wall of said lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves received by said transducer.
5. The improved autoperfusion catheter system of claim 1, wherein said measurement means is located within said balloon.
6. The improved autoperfusion catheter system of claim 4 wherein said means to electrically activate said Doppler measurement means from a remote location includes an electronic signal generator.
7. The improved autoperfusion catheter system of claim 5 wherein said means to electrically activate said Doppler measurement means from a remote location further comprises electrical conductors connected to said Doppler velocity measurement means and placed within a lumen of said catheter system.
8. The improved autoperfusion catheter system of claim I wherein said means to provide at a remote location an indication of flow movement further comprises means to visibly display said flow movement.
9. The improved autoperfusion catheter system of claim 1, wherein said means to provide at a remote location an indication of flow movement further comprises means to audibly indicate said flow movement.
10. In an autoperfusion catheter of the type that incorporates an inflatable balloon near the distal end of the catheter, an autoperfusion lumen internal to said balloon, autoperfusion vents placed proximally and distally from said balloon, said vents in communication with said autoperfusion lumen and the exterior of said catheter to provide a passage for blood past said balloon when it is inflated, an improvement which comprises:
flow measurement means located adjacent and in communication with said autoperfusion lumen;
means to communicate between said flow measurement means and a remote location;
control means at said remote location whereby said flow measurement means may be activated and measurement of flow to said autoperfusion lumen may be received; and indicator means at said remote location whereby an indication of said flow measurement may be provided.
flow measurement means located adjacent and in communication with said autoperfusion lumen;
means to communicate between said flow measurement means and a remote location;
control means at said remote location whereby said flow measurement means may be activated and measurement of flow to said autoperfusion lumen may be received; and indicator means at said remote location whereby an indication of said flow measurement may be provided.
11. The improved autoperfusion catheter system of claim 10 wherein said flow measurement means further comprises velocity measurement means.
12. The improved autoperfusion catheter system of claim 11 wherein said velocity measurement means comprises Doppler velocity measurement means.
13. The improved autoperfusion catheter system of claim 12 wherein said Doppler velocity measurement means further comprises:
a transducer of piezoelectric material located adjacent to and in communication with said autoperfusion lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves reflected by blood moving in said autoperfusion lumen and received by said transducer.
a transducer of piezoelectric material located adjacent to and in communication with said autoperfusion lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves reflected by blood moving in said autoperfusion lumen and received by said transducer.
14. The improved autoperfusion catheter system of claim 11 wherein said velocity measurement means is located within said balloon.
15. The improved autoperfusion catheter system of claim 13 wherein said means to electrically activate said Doppler measurement means from a remote location comprises an electronic signal generator.
16. The improved autoperfusion catheter system of claim 13 wherein said means to electrically activate said Doppler measurement means from a remote location further comprises electrical conductors connected to said Doppler velocity measurement means and placed within a lumen of said catheter system.
17. The improved autoperfusion catheter system of claim 15 which further comprises means at said remote location to provide an indication of flow velocity as measured by said Doppler measurement means.
18. An improved autoperfusion catheter of the type that incorporates an inflatable balloon means near the distal end of said catheter, an autoperfusion lumen, autoperfusion vents placed proximally and distally from said balloon, said vents providing means to allow the flow of blood in said autoperfusion lumen when said balloon is inflated, wherein said improvement comprises:
flow measurement means located adjacent to and in communication with said autoperfusion lumen.
flow measurement means located adjacent to and in communication with said autoperfusion lumen.
19. The improved autoperfusion catheter system of claim 18 which further comprises means to activate said flow measurement means.
20. The autoperfusion catheter of claim 18 which further comprises means to provide an indication of velocity in said autoperfusion lumen measured by said flow measurement means.
21. The improved autoperfusion catheter system of claim 18 wherein said flow measurement means further comprises means to detect velocity by sensing changes in electrical resistance of means in contact with said flow of blood.
22. The improved autoperfusion catheter system of claim 18 in which said flow measurement means further comprises means to measure said blood flow by optical velocity detection means.
23. The improved autoperfusion catheter system of claim 18 in which said flow measurement means further comprises Doppler velocity measurement means.
24. The improved autoperfusion catheter system of claim 23 wherein said Doppler velocity measurement means further comprises:
a transducer of piezoelectric material located adjacent to and in communication with said autoperfusion lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves reflected by blood moving in said autoperfusion lumen and received by said transducer.
a transducer of piezoelectric material located adjacent to and in communication with said autoperfusion lumen;
means to excite said transducer to thereby cause said transducer to emit ultrasonic waves of a predetermined frequency; and means to detect a shift in frequency between said emitted ultrasonic waves and reflected ultrasonic waves reflected by blood moving in said autoperfusion lumen and received by said transducer.
25. The improved autoperfusion catheter system of claim 23 wherein said velocity measurement means is located within said balloon.
26. The improved autoperfusion catheter system of claim 23 wherein said means to excite said Doppler measurement means comprises an electronic signal generator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US343,426 | 1989-04-26 | ||
| US07/343,426 US5046503A (en) | 1989-04-26 | 1989-04-26 | Angioplasty autoperfusion catheter flow measurement method and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2014881A1 true CA2014881A1 (en) | 1990-10-26 |
Family
ID=23346070
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002014881A Abandoned CA2014881A1 (en) | 1989-04-26 | 1990-04-19 | Angioplasty autoperfusion catheter flow measurement method and apparatus |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5046503A (en) |
| EP (1) | EP0394969A1 (en) |
| JP (1) | JPH0363059A (en) |
| CA (1) | CA2014881A1 (en) |
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-
1989
- 1989-04-26 US US07/343,426 patent/US5046503A/en not_active Expired - Fee Related
-
1990
- 1990-04-19 CA CA002014881A patent/CA2014881A1/en not_active Abandoned
- 1990-04-24 EP EP90107781A patent/EP0394969A1/en not_active Withdrawn
- 1990-04-26 JP JP2111588A patent/JPH0363059A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5556382A (en) * | 1995-08-29 | 1996-09-17 | Scimed Life Systems, Inc. | Balloon perfusion catheter |
| US5720723A (en) * | 1995-08-29 | 1998-02-24 | Scimed Life Systems, Inc. | Balloon perfusion catheter |
| US5961490A (en) * | 1995-08-29 | 1999-10-05 | Scimed Life Systems, Inc. | Balloon perfusion catheter |
Also Published As
| Publication number | Publication date |
|---|---|
| US5046503A (en) | 1991-09-10 |
| JPH0363059A (en) | 1991-03-19 |
| EP0394969A1 (en) | 1990-10-31 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |