Patent Application
20080097408
Catheter-based optical systems are applicable to a number of diagnostic and therapeutic medical applications. Optical tomography, usually optical coherence tomography (OCT), is used to provide spatial resolution, enabling the imaging of internal structures. Spectroscopy is used to characterize the composition of structures, enabling the diagnosis of medical conditions by differentiating between cancerous, dysplastic, and normal tissue structures, for example. Reflectance analysis is a simplified form of spectroscopy that analyzes optical properties of structures, typically in specified wavelength bands. Fluorescence and Raman spectral analysis involve exciting the tissue at one wavelength and then analyzing light at fluorescence wavelengths or Raman shifted wavelengths due to a process of inelastic photon scattering. They all share certain catheter requirements including the need to transmit an optical signal to the internal structures of interest and then detect returning light, often transmitting that returning light back along the length of the catheter.
For example, in one specific spectroscopic application, an optical source, such as a tunable laser, is used to access or scan a spectral band of interest, such as a scan band in the near infrared wavelengths or 750 nanometers (nm) to 2.5 micrometers (μm) or one or more subbands. The generated light is used to illuminate tissue in a target area in vivo using the catheter. Diffusely reflected light resulting from the illumination is then collected and transmitted to a detector system, where a spectral response is resolved. The response is used to assess the composition and consequently the state of the tissue.
This system can be used to diagnose atherosclerosis, and specifically to identify atherosclerotic lesions or plaques. This is an arterial disorder involving the intimae of medium- or large-sized arteries, often including the aortic, carotid, coronary, and cerebral arteries.
Diagnostic systems including Raman and fluorescence-based schemes have also been proposed. Other wavelengths, such as visible or the ultraviolet, can also be used.
In OCT applications, a coherent optical source is used to illuminate tissue in a target area. By analysis of the interference between light returning from the target area and light returning from a reference arm, depth information is generated providing information of both the surface topology and subsurface structures.
Other, non-optical, technologies also exist. For example, intravascular ultrasound (IVUS) uses a combination of a heart ultrasound (echocardiogram) and cardiac catheterization. In this application, an ultrasound catheter is inserted into an artery and moved to a target area. It then both generates and receives ultrasound waves that can then be constructed into an image showing the surface topology and internal structures at the target area.
The probes or catheters for these applications typically have small lateral dimensions. This characteristic allows them to be inserted into incisions or lumen, such as blood vessels, with lower impact or trauma to the patient. The probe's primary function is to convey light to and/or receive light from a target area or area of interest in the patient for the optical-based technologies. In the context of the diagnosis of atherosclerosis, for example, the target areas are regions of the patient's arteries that may exhibit or are at risk for developing atherosclerotic lesions.
In each of these applications, the target areas or areas of interest are typically located lateral to the catheter head. That is, in the example of lumens, the probe is advanced through the lumen until it reaches the areas of interest, which are typically the lumen walls that are adjacent to the probe, i.e., extending parallel to the direction of advance of the probe. A “side-firing” catheter head emits and/or receives light or ultrasound signals from along the probe's lateral sides. In the example of catheters for optical-based applications, the light propagates through the probe, until it reaches the probe or catheter head. The light is then redirected to be emitted radially or in a direction that is orthogonal to the direction of advancement or longitudinal axis of the probe. In the case of light collection, light from along the probe's lateral sides is collected and then transmitted through the probe to an analyzer where, in the example of spectroscopic analysis in the diagnosis of atherosclerosis, the spectrum of the returning light is resolved in order to determine the composition of the vessel or lumen walls.
In order to fully characterize target areas, relatively long regions of tissue, such as blood vessels, must be scanned and in the case of blood vessels an entire 360 degree circumference of vessels must be captured. To perform this combination of longitudinal and rotational movement, the catheters are typically driven by a device called a pullback and rotation (PBR) system.
Pullback and rotation systems connect to the proximal end of the catheter. They typically hold an outer sheath or jacket stationary while an inner catheter scanning body, including the catheter head are rotated and withdrawn through a segment of the blood vessel. This scanning combined with driving the catheter head produce a helical scan that is used to create a raster-scanned image of the inner walls of the blood vessel.
In general, according to one aspect, the invention features a pullback carriage interlock system for a catheter pullback system. The pullback system comprises a frame, a catheter system interface, attached to the frame, to which a catheter system, comprising an intraluminal catheter, is coupled, a pullback carriage drive system that moves longitudinally relative to the frame to provide longitudinal drive to the catheter system. The pullback carriage interlock system comprises a latching system for holding the pullback carriage drive system when the catheter system is being attached to the pullback system.
In the preferred embodiment, a release system is used for unlocking the latching system to enable longitudinal movement of the pullback carriage drive system relative to the frame upon connection of the catheter system to the pullback system. This latching system comprises at least one latch arm that engages a carriage drive frame of the pullback carriage drive system when fully advanced toward the catheter system interface.
Further, the release system preferably unlocks the latching system upon connection of the catheter system to the pullback system, the release system being engaged by the coupling of the catheter system to the catheter system interface.
In general, according to another aspect, the invention features an interlock method for a catheter pullback system. The method comprises preventing longitudinal movement of the pullback carriage drive system, coupling the catheter system to the catheter system interface while preventing the longitudinal movement, and releasing the pullback carriage drive system after coupling of the catheter system.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.
In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings:
Generally, the catheter system 100 comprises an intraluminal catheter 110. This is typically inserted into a lumen within a patient, such as a blood vessel, particularly an artery. It is moved through the arterial network of the patient until a catheter head 130 is proximal or adjacent to a region of interest, such as potential site of a lesion within the coronary or carotid artery, for example.
In other examples, the delivery fiber transmits an excitation optical signal for Raman or fluorescence analysis. A narrowband optical signal is often used in reflectance analysis systems.
In order to enable scanning of the inner luminal walls 2, inner catheter scanning body sb including the head 130 is rotated within a protective jacket or sheath 82, see arrow 84, while typically being simultaneously translated longitudinally within the jacket 82, see arrow 86. The scanning body typically comprises an outer torque cable 85 for transferring rotation to the head 130. In the current embodiment, the torque cable 85 comprises contrahelically wound wire layers to enable low backlash torque transfer along the length of the intraluminal catheter 110. The jacket 82 ensures that the lumen is not damaged by the rotation 84 and longitudinal movement 86 of the inner catheter scanning body sb.
Returning to
The pullback and rotation system 200 controls the movement of the inner catheter scanning body sb and catheter head 130 both in terms of rotation 84 and longitudinal movement 86 to typically helically raster scan the internal walls 2 of the coronary artery, for example, to assess and characterize any tissue, lesions, or other problems in and on those internal walls 2.
In other examples, the catheter and head are configured for OCT analysis. In still other examples, the catheter and head are used for IVUS applications. As such, the optical components are replaced or augmented by ultrasonic transducers in the head 130, for example.
Within the housing 112 is a catheter carriage 118. The optical fiber bundle ofb is secured to the carriage 118 so that rotation 52 of the carriage or longitudinal movement 50 is transferred to the catheter head 130. The optical fiber bundle ofb in one embodiment, comprises the delivery fiber 74, which in one example is single spatial mode fiber that transmits an optical spectroscopy signal, such as a tunable signal generated by a tunable laser, to the catheter head 130, and the collection fiber 72, which is often multimode fiber, that transmits any collected light by the catheter head 130 through the length of the catheter system 100.
The catheter system 100 has a series of components that form a catheter carriage interlock system 180, which prevents the carriage 118 from moving within the housing body 112 both rotationally and longitudinally 50 when the catheter system 100 is not mechanically connected to the pullback and rotation system 200. However, an unlocking or key system on the pullback and rotation system 200 unlocks the carriage interlock system 180 to free the inner carriage 118 to rotate and move longitudinally in the housing 112 when the catheter system 100 is connected to the pullback and rotation system 200.
The interlock system 180 comprises a series of catheter locking levers 116, that prevent the carriage 118 from rotating 52 and being extracted from the housing 112 when the catheter system 100 is not connected to the pullback and rotation system 200 yet allow the carriage 118 to rotate within the housing body 112 and to move axially out of the body 112 when the catheter system 100 is connected to the pullback and rotation system 200. Specifically, in one example, more than two locking levers are used, such as four in one implementation.
Each catheter locking lever comprises a lever pivot 116p, a ring engagement nose 116n, and a lever arm 116a. When the catheter system 100 is not connected to the pullback and rotation system 200, the lever arms 116a of the catheter locking levers 116 are in engagement with an outer periphery 118p of the carriage 118. This prevents the rotation of the carriage 118 within the housing body because of the interference between the lever arm 116a and carriage rotation shoulders 118 of the carriage 118. Specifically, when the carriage 118 is fully inserted into the body, the lever arms 116a are resiliently biased against the catheter carriage 118 at region 118p and fall between adjacent, axially-extending carriage rotation shoulders 118s and thereby prevent the catheter carriage 118 from rotating within the housing body 112.
The resilient biasing of the lever arms 116 is provided by a flexible circular band 116b that extends around the outer periphery of the array of lever arms 116. In a current embodiment, the band 116b is fabricated from a synthetic rubber material such as EPDM (ethylene propylene diene monomer) rubber. This is a low creep, sterilization resistant material. In other implementations, the resilient biasing is performed by spring elements, such as leaf springs, that are integrally formed with the lever arms 116.
The engagement of the lever arms 116a against region 118p of the catheter carriage 118 also prevents the catheter carriage 118 from being extracted from the housing body 112. Specifically, if an extraction force is applied to the catheter carriage 118 relative to the housing body 112, the lever arms 116a slide along portion 118p of the catheter carriage 118 to engage with the extraction shoulder 118e. This mechanical interference thus prevents the catheter carriage 118 from being extracted from the housing body 112 or falling out when the catheter system 100 is not coupled to the pullback and rotation system 200.
The pullback and rotation system 200 also comprises a carriage drive system 300 that couples to the catheter carriage 118. This carriage drive system 300 generally drives the rotation of the inner catheter scanning body sb and the catheter head 130 of the catheter system 100 via the catheter carriage 118 and also drives the movement of the inner catheter scanning body sb and the catheter head 130 longitudinally in the catheter system 100. The longitudinal movement is provided by the movement of the carriage drive system 300 back and forth in the direction of arrow 50 and the rotation is accomplished by the rotation of a drum system 325 of the carriage drive system 300 in the direction of arrow 52.
In more detail, the carriage drive system 300 travels longitudinally on the pullback and rotation frame 212 on frame rails 212r formed on either side of the center member 212b. Specifically, carriage rollers 330 roll on the rails 212r thereby allowing the carriage drive system 300 to move laterally on the frame 212. The carriage rollers 30 are journaled to roller plates 331 which are attached to a front carriage frame plate 333f and a back carriage frame plate 333b, respectively.
The carriage drum system 325 is mounted to rotate on the front carriage frame plate 333f and the back carriage frame plate 333b. Specifically, the carriage drum system 325 comprises a front carriage drum roller 314 and a rear carriage drum base 330. Optical/electronic boards 335 extend between the drum base 330 and drum roller 314 and contain the electronic, optical, and opto-electronic components of the rotating drum system 325. The front carriage drum roller 314 supports a carriage coupler mount 310. The carriage coupler mount 310 holds a male optical duplex coupler 312 that connects to the female duplex optical coupler 120 of the catheter system 100. Specifically, this provides the optical connection between a delivery channel provided by delivery fiber 74 and collection channel provided by the collection fiber 72 of the optical fiber bundle ofb. A catheter alignment bayonet 114 projects proximally from the female duplex optical coupler 120.
The carriage coupler mount 310 also has a bayonet scabbard 310s that is a port for receiving the catheter alignment bayonet 114. Thus, upon insertion of the catheter system 100 into the pullback and rotation system 200, the catheter alignment bayonet 114 extends into the bayonet scabbard 310s to insure that the catheter system 100 and specifically the catheter carriage 118 is rotationally aligned to the drum system 325 of the carriage system 300 thus ensuring alignment between the female duplex optical coupler 120 and the male optical duplex coupler 312.
Further, the carriage coupler mount 310 further comprises a bayonet presence detector 310d that senses the presence of the catheter alignment bayonet 114 to thereby signal to the PBR system 200 when the catheter system 100 is properly connected to the PBR system.
The drum system 325 rotates relative to the carriage frame plates 333f, 333b under power of a carriage motor encoder 320. Specifically, the carriage motor encoder 320 drives a roller 323 that engages teeth on the outer periphery of the front drum 314. Thus, the motor encoder 320 drives the drum system 323 to rotate 52 under angular control of its encoder. Three carriage rollers 327, each having a female V-shape profile, provide support to the drum 325 by engaging a V-shaped outer periphery 314p of the front drum 314 at three distributed points of contact allowing its rotation.
The carriage drive system 200 also comprises a drum angular position detection system. Specifically, an angular position detector 324 is attached to the back carriage frame 333b of the carriage frame. The drum base 330 further comprises a flag 322 that passes in proximity to the angular position detector 324 and in this way the angular position of the drum system 325 in the carriage drive system 300 is detected and specifically its proper orientation to receive the catheter system 100 and in the alternative used to calibrate the encoder of the motor encoder 320 to a known reference.
An electrical slip ring system 363 transmits electrical power and signals to and from the rotating drum. Specifically, a spectral analysis system 22 is provided, in one embodiment, to receive spectral data from the slip ring system 363 to enable analysis of the target tissue. A stabilizing bracket 365 prevents the nominally stationary side of the rotary coupling from rotating due to torque transfer through the coupling from the rotating drum 325.
The delivery tunable optical signal, such as generated by a tunable laser 20, is transmitted on fiber 361, through the input optical fiber rotary coupling 360, to the rotating drum 325. The input optical fiber 361d in the drum 325 connects to a tap 368. This tap 368 directs a portion of the optical signal transmitted by the input optical fiber 361d, the delivery channel, to a delivery signal detector 364 on the drum 325. The remaining signal is transmitted on fiber 361e of the delivery optical fiber 74 of the catheter system 100 via the duplex couplers 312/120. Any collected optical signal collected from the catheter head 110 is transmitted through the collection fiber 72 of the catheter system 100 and received on the collection optical fiber 370 of the collection channel. This optical fiber terminates on a collection optical detector 366.
In general, a delivery channel transmits the optical signals to the intraluminal catheter 100 via the rotating drum 325 through rotary joint 360 and the delivery channel detector 364 on the rotation carriage monitors the optical signals being transmitted on the delivery channel. The collection channel detector 366 detects optical signals from the patient. A noise suppression system uses the delivery channel detector 364 to reduce noise in the optical signals from the patient introduced by the rotary joint 360 and/or laser noise.
Typically, the optical rotary coupler 360 will inject noise. Another source of noise is the laser itself due to temporal fluctuations in optical power output. The tap 368 provides a portion of this delivery optical signal, including any noise to the delivery optical signal detector 364. Then, when the returning optical signal from the catheter head 100 is received and detected by the collection detector 366, the noise added by the rotary coupling 360 and any laser noise is removed by the processing performed by the divider 368. Specifically, the system provides for common mode rejection which will remove noise introduced by the rotary joint 360 and laser noise. Thus, the output optical signal without the noise is then further provided to the spectral analysis engine 22 that resolves the spectral response of the patient tissue that allows for its analysis, for example, determining the state of the tissue. In other examples, OCT analysis is performed to determine the topology of the tissue.
In other embodiments, the delivery optical signal detector is located not on the rotating drum 325 but is between the drum 325 and the laser 20. This is used in situations in which any noise from the rotary coupler 360 is minimal or outside the signal band.
The incorporation of the optical detectors 364, 366 on the rotating drum 325 provides a number of advantages. First, since the collection optical detector 366 is on the drum 325, a second optical rotating coupler is not required. The information in the optical signals is transmitted electrically from the rotating drum 325 via electrical slip ring system 363. One problem that arises when using optical rotating rotary coupling is the potential for the creation of optical noise due to the rotating movement of the coupler 360. This is addressed in the present system by the incorporation of the delivery detector 364 on the rotating drum 325.
In general, the carriage drive interlock is a latching system 252 for holding the carriage drive system 300 of the pullback and rotation system 200 from moving when the catheter system 100 is being attached to the pullback and rotation system 200. It further has a release system for unlocking the latching system 252 to enable longitudinal movement of the carriage drive system 300 relative to the frame 212 upon connection of the catheter system 100 to the pullback and rotation system 200. The interlock latching system 252 ensures that the carriage drive system 300 does not move freely, specifically in response to any attachment force supplied by the operator in order to attach the catheter system 100 to the interface 205 on the pullback and rotation system 200.
Specifically, two carriage latches 250 lock and engage with two opposed carriage latch plates 370 that extend from the front face of the front carriage frame piece 333f. Specifically, each carriage latch 250 engages with a corresponding carriage latch plate 371 (see
The carriage drive system 300 becomes unlatched only upon full insertion of the catheter system 100 onto the pullback and rotation system 200 through the action of the release system. Specifically, the full insertion and attachment of the carriage system 100 causes the catheter sensing pin 256 to move in the direction of arrow 25. This movement pivots the carriage latches 250 in the direction of arrow 26 to disengage from the carriage latch plates 371, thereby freeing the carriage drive system 300 to move longitudinally on the frame rails 212r.
Specifically, the catheter housing interlock system 270 comprises a catheter locking rack frame 158. When this catheter locking rack frame 158 is depressed by the operator in the direction of arrow 32, by applying a downward force on tab 266, it causes the locking cam gear 260 to rotate in the direction of arrow 34. In more detail, guide pin bolts 410 attached to the front member 212f guide the rack frame to slide vertically against the force of bias rack springs 159. A rack gear 158r (see
While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
This application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application No. 60/862,309, filed on Oct. 20, 2006 and is related to U.S. application Ser. No. ______, entitled “Optical Catheter Carriage Interlock System and Method,” by Peter Strickler and John Murphy, Attorney Docket No. 0010.0013US1, filed on even date herewith, U.S. application Ser. No. ______, entitled “Manual and Motor Driven Optical Pullback and Rotation System and Method,” by John Murphy and Peter Strickler, Attorney Docket No. 0010.0013US2, filed on even date herewith and U.S. application Ser. No. ______, entitled “Noise Suppression System and Method in Catheter Pullback and Rotation System,” by Charles Abele and Jay Caplan, Attorney Docket No. 0010.0013US4, filed on even date herewith, all four of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60862309 | Oct 2006 | US |
