Abstract:
The present invention generally relates to medical devices, and more particularly to an improved intravascular intervention device. In one embodiment, an intravascular intervention device includes a microcatheter configured for intravascular delivery, an imaging wire received within the microcatheter, and a treatment device received within the microcatheter, wherein the imaging wire and the treatment device may be simultaneously advanced. The treatment device is configured to perform intravascular intervention. For example, the treatment device may be configured to deliver a stent, an embolic coil and/or a thrombolytic agent. In this embodiment, the intravascular intervention device may image the area of interest while performing the intravascular intervention, thus allowing imaging to take place in real time.

Description:
FIELD OF THE INVENTION  
       [0001]     The field of the invention relates to medical devices, and more particularly to an neurovascular intervention device.  
       BACKGROUND OF THE INVENTION  
       [0002]     Intraluminal, intracavity, intravascular, and intracardiac treatments and diagnosis of medical conditions utilizing minimally invasive procedures are effective tools in many areas of medical practice. These procedures are typically performed using diagnostic and interventional catheters that are inserted percutaneously into the arterial network and traversed through the vascular system to the site of interest. The diagnostic catheter may have imaging capability, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery. For example, U.S. Pat. No. 5,368,035, issued to Hamm et al., the disclosure of which is incorporated herein by reference, describes a catheter having an intravascular ultrasound imaging transducer.  
         [0003]     Currently, there exists no indicated intravascular imaging method for the neurovasculature. When evaluating a proposed intravascular imaging device for the neurovasculature, the procedure steps for coronary interventions serve as baseline. Typically, for cardiovascular intervention, the use of the imaging device alternates with the use of the treatment device, i.e., a clinician would insert the imaging device to diagnose the area of interest, and then remove the imaging device to insert the appropriate treatment device. Applied to the neurovascular system this may be particularly undesirable due to time considerations in the treatment of strokes and/or intravascular aneurysms. In such cases, it may be desirable to provide simultaneous and/or real-time intra-lumen imaging of a patient&#39;s vasculature.  
         [0004]     In the case of a stroke caused by embolus, it may be beneficial for the clinician to determine the nature of the embolus in order to plan necessary intervention. The embolus may come in two forms, hard plaque or soft thrombus, and different treatments may be used for each. For soft thrombus, drug treatment may be preferred, since it is a more conservative treatment, but such a treatment may be ineffective for hard plaque, which may require more aggressive treatments such as stent placement. The ability to make a quick assessment benefits the patient by receiving the most applicable intervention as soon as possible.  
         [0005]     In the case of an aneurysm, the ability to characterize the aneurysm accurately is very important, particularly for embolic coiling procedures. The diameter of the neck of the aneurysm, the diameter of the aneurysm itself, the density of the sac thrombus, and the patency of the parent artery are all important items of data when planning intervention. The ability to determine and/or confirm these items of data real time may provide a factor of safety when planning the required intervention. For example, the embolic coils originally chosen for treatment based on angiograms may have to be modified based on findings that the aneurysm neck is larger or smaller than anticipated. Accordingly, an improved intravascular intervention device would be desirable.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention generally relates to medical devices, and more particularly to an improved intravascular intervention device. In one embodiment, an intravascular intervention device includes a microcatheter configured for intravascular delivery, an imaging wire received within the microcatheter, and a treatment device received within the microcatheter, wherein the imaging wire and the treatment device may be simultaneously advanced. The treatment device is configured to perform intravascular intervention. For example, the treatment device may be configured to deliver a stent, an embolic coil and/or a thrombolytic agent. In this embodiment, the intravascular intervention device may image the area of interest while performing the intravascular intervention, thus allowing imaging to take place in real time.  
         [0007]     Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.  
         [0009]      FIG. 1   a  is a cross-sectional side view of a microcatheter in accordance with a preferred embodiment of the present invention.  
         [0010]      FIG. 1   b  is a cross-sectional view of a microcatheter in accordance with a preferred embodiment of the present invention.  
         [0011]      FIG. 1   c  is a cross-sectional view of a microcatheter in accordance with a preferred embodiment of the present invention.  
         [0012]      FIG. 2   a  is a cross-sectional side view of an imaging wire in accordance with a preferred embodiment of the present invention.  
         [0013]      FIG. 2   b  is a cross-sectional view of an imaging wire in accordance with a preferred embodiment of the present invention.  
         [0014]      FIG. 3  is a cross-sectional view of an imaging wire in accordance with a preferred embodiment of the present invention.  
         [0015]      FIG. 4  is a diagram of a medical imaging system in accordance with a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     As described above, an intravascular intervention device that allows the simultaneous delivery of an imaging device and a treatment device may be desirable. Turning to  FIG. 1 a , a microcatheter  100  is shown. The microcatheter  100  is constructed to allow navigation into cerebral arteries. Such a microcatheter  100  has a size range of up to 0.027 inches. An example of such a microcatheter is described in U.S. Pat. No. 4,739,768 to Engelson, which is hereby incorporated by reference in its entirety. The microcatheter  100  includes an outer sheath  110  having a lumen that is capable of receiving an imaging wire  120  and a treatment device  150 . The microcatheter  100  may utilize a guidewire (not shown) to facilitate in advancing the microcatheter  100  to the area of interest. One of ordinary skill in the art will appreciate that both the imaging wire  120  and the treatment device  150  may be capable of being advanced beyond the distal end of the sheath  110  of the microcatheter  100 .  
         [0017]     Turning to  FIG. 1   b , which shows a cross-section of a microcatheter  100 , the microcatheter  100  may receive the imaging wire  120  and the treatment device  150  via a single lumen  103 . Alternatively, turning to  FIG. 1   c,  which shows a cross-section of an alternative microcatheter  100 , the microcatheter  100  may receive the imaging wire  120  and the treatment device  150  through a first lumen  102  and a second lumen  104  respectively.  
         [0018]     Turning to back to  FIG. 1   a,  the imaging wire  120  includes a sheath  121 , preferably braided polymer, that is coupled with a floppy tip  124  at the distal end of the sheath  121 . The sheath  121  includes a lumen that receives an imaging transducer assembly  130  shown in  FIG. 2   a . The imaging wire sheath  121  may be coated with a lubricious coating that enables improved movement within a vessel. The imaging sheath  121  preferably includes a puncture hole  122  towards the distal portion of the imaging wire  120 , which allows blood pressure to fill the cavity around the imaging element  130  to improve imaging. The sheath braid may discontinue for a particular amount of length, thus allowing the imaging transducer to acquire an image with reduced interference. The sheath  121  may be withdrawn completely after reaching the desired position, thus leaving the imaging transducer assembly  130  and the floppy tip  124  exposed to the area of interest. In such a configuration, it may be desirable to coat the assembly  130  with a lubricious and/or thrombolytic agent, such as heparin.  
         [0019]     In an alternative configuration, the sheath  121  may be a thick walled hypotube or partially hollowed rod to allow attachment of the floppy tip  124  and passage of the imaging transducer assembly  130 . In addition, the sheath  121  may include conductive traces that allow the imaging transducer assembly  130  to be electrically coupled with a proximal connector  200  (shown in  FIG. 3 ). A thin coating of insulating material may protect the conductive traces.  
         [0020]     The floppy tip  124  may be composed of a layered coil atop a cylindrical wire that is flattened into a ribbon under the coil. Further, the floppy tip  124  may have a proximally extended axial section over which the imaging transducer  130  may translate (not shown).  
         [0021]     Turning to  FIG. 2   a,  an example of an imaging transducer assembly  130  is shown within the sheath  121  of the imaging wire  120 . The imaging transducer  130  includes a coaxial cable  132 , having a center conductor wire  136  and an outer shield wire  134 , shown in  FIG. 2   b.  A conductive wire, having a diameter of approximately 500 microns, is wrapped around the coaxial cable  132 , forming a coil, which functions as a drive shaft  138 . The wire may be a laser cut Nitinol tube, which allows for torquability and flexibility. Alternatively, the drive shaft  138  may be composed of coaxial cables wound such that the cables are kept separated, via individual shielding or additional wire, while surrounding a neutral core. Further, the drive shaft  138  may be pre-tensioned.  
         [0022]     Connected to the distal end of the drive shaft  138  is a stainless steel housing  140 , which serves to reinforce the structure of the imaging transducer assembly  130 . Surrounding the coaxial cable  132 , within the housing  140  is a silver epoxy  142 , a conductive material. Thus, the housing  140  is electrically coupled to the shield wire  134  of the coaxial cable  132  via the epoxy  142 . On the distal end of the silver epoxy  142  is an insulating substance, e.g., a non-conductive epoxy  144 .  
         [0023]     Alternatively, or in addition to the configuration above, the drive shaft  138  may be printed with one or more conductive traces that allow communication between the imaging transducer  130  and a proximal connector  200  (shown in  FIG. 3 ), which allows the imaging transducer  130  to connect to external circuitry  300  that processes signals, such as imaging and navigational signals, from the imaging transducer  130 , such circuits being well known (shown in  FIG. 4 ). In yet another alternative configuration, the drive shaft  138  may be composed of an extruded polymer reinforced with a polymer/fiber/metal braid with the coaxial cable  132  extruded within the walls (not shown).  
         [0024]     On the distal end of the non-conductive epoxy  144  is a layer of piezoelectric crystal (“PZT”)  147 , “sandwiched” between a conductive acoustic lens  146  and a conductive backing material  148 , formed from an acoustically absorbent material (e.g., an epoxy substrate having tungsten particles). The acoustic lens  146  is electrically coupled with the center conductor wire  136  of the coaxial cable  132  via a connector  145  that is insulated from the silver epoxy  142  and the backing material  148  by the non-conductive epoxy  144 . The acoustic lens  146  may be non-circular and/or have a convex surface. The backing material  148  is connected to the steel housing  140 . It is desirable for the imaging transducer assembly  130  to be surrounded by a sonolucent media. The sonolucent media may be saline. Alternatively, or in addition to, as mentioned above, the sheath  121  of the imaging wire  120  may include a puncture hole  122  to allow blood to surround the imaging transducer assembly  130  as well. As one of ordinary skill in the art may appreciate, the imaging transducer assembly  130  may be translatable relative to the floppy tip  124 . Further, the floppy tip  124  may be detachable, thereby exposing the imaging transducer assembly  130 .  
         [0025]     During operation, the PZT layer  147  is electrically excited by both the backing material  148  and the acoustic lens  146 . The backing material  148  receives its charge from the shield wire  134  of the coaxial cable  132  via the silver epoxy  142  and the steel housing  140 , and the acoustic lens  146 , which may also be silver epoxy, receives its charge from the center conductor wire  136  of the coaxial cable  132  via the connector  145 , which may be silver epoxy as well.  
         [0026]     In an alternative embodiment, transducer  130  is replaced by a phased array as disclosed in Griffith et al., U.S. Pat. No. 4,841,977, which is hereby incorporated by reference in its entirety. Further, other imaging devices may be used, instead of, or in addition to imaging transducers, such as light based apparatuses for obtaining images through optical coherence tomography (OCT). Image acquisition using OCT is described in Huang et al., “Optical Coherence Tomography,” Science, 254, Nov. 22, 1991, pp 1178-1181, which is hereby incorporated by reference in its entirety. A type of OCT imaging device, called an optical coherence domain reflectometer (OCDR) is disclosed in Swanson U.S. Pat. No. 5,321,501, which is incorporated herein by reference. The OCDR is capable of electronically performing two- and three-dimensional image scans over an extended longitudinal or depth range with sharp focus and high resolution and sensitivity over the range.  
         [0027]     Turning to the treatment device  150  shown in  FIG. 1   a,  the treatment device  150  delivers treatment to an intravascular area, such as an area with an aneurysm or an embolism. One of ordinary skill in the art may appreciate that the treatment device  150  may deliver drugs, agents, or medical devices such as embolic coils or stents. U.S. Pat. No. 4,994,069 to Ritchart, entitled “Vaso-Occlusion Coil and Method,” the entirety of which is hereby incorporated by reference, describes a treatment device that delivers one or more vaso-occlusive coils.  
         [0028]     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. For example, the reader is to understand that the specific ordering and combination of process actions described herein is merely illustrative, and the invention can be performed using different or additional process actions, or a different combination or ordering of process actions. As a further example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.