Abstract:
A combined multi-lumen central access catheter with a fixedly coupled filter, and an imaging modality to conduct intravascular imaging and ascertain a state of capture of thrombus in the filter and a method of capturing thrombus in a filter mounted on a catheter and imaging the state of capture of thrombus in the filter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This Application is a continuation of U.S. patent application Ser. No. 13/918,601, filed Jun. 14, 2013, now U.S. Pat. No. 9,039,729; which is a continuation of U.S. patent application Ser. No. 13/735,810, filed Jan. 7, 2013, now U.S. Pat. No. 9,039,728; which is continuation-in-part of U.S. patent application Ser. No. 12/684,839, filed Jan. 8, 2010, now U.S. Pat. No. 8,613,753; which is a continuation-in-part of U.S. patent application Ser. No. 11/849,225 filed Aug. 31, 2007, now U.S. Pat. No. 8,668,712; and claim the benefit of priority from U.S. Provisional Application No. 61/668,308, filed Jul. 5, 2012; each of which are hereby incorporated by reference in their entirety and from which priority is hereby claimed. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]    The present invention pertains generally to the field of vascular filters for capturing embolic material in the blood flow. 
         [0003]    The accepted standard of care for patients with venous thromboembolism (VTE) is anticoagulant therapy. Inferior vena cava (IVC) filters are reserved for those patients who fail anticoagulant therapy, or have a complication or contraindication to anticoagulant therapy. Until the early 1970&#39;s, the only method of IVC interruption was surgical, either by clipping, ligation or plication. The first clinical experience of an endoluminally-placed device to interrupt IVC flow was reported by Mobin-Uddin et al. in 1969. However, it was not until the introduction of a stainless steel umbrella-type filter by Greenfield et al. in 1973 that an effective method of endoluminally trapping emboli while simultaneously preserving IVC flow became possible. Indeed, for many years, the Greenfield filter set a benchmark by which newer filters were measured. Early generations of filters were inserted by surgical cut-down and venotomy. Eventually filters were able to be inserted percutaneously: initially through large 24 Fr sheaths, though newer generations of filters are able to be delivered through 6 Fr systems. 
         [0004]    Despite the safety and efficacy of modern day filters, systemic anticoagulation remains the primary treatment for VTE. Either unfractionated or low molecular weight heparin followed by three months of oral anticoagulation in patients with proximal deep venous thrombosis (DVT) is approximately 94% effective in preventing pulmonary embolism (PE) or recurrent DVT. The routine placement of IVC filters in addition to anticoagulation in patients with documented DVT was investigated by Decousus et al. in a randomized trial. Decousus H, Leizorovicz A, Parent F, et al.  A clinical trial of vena cava filters in the prevention of pulmonary embolism in patients with proximal deep - vein thrombosis. N Engl J Med  1998; 338:409-415. This study revealed that the use of a permanent filter in addition to heparin therapy significantly decreased the occurrence of PE within the first 12 days compared to those without a filter. However, no effect was observed on either immediate or long-term mortality, and by 2 years, the initial benefit seen in the group of patients with filters was offset by a significant increase in the rate of recurrent DVT. 
         [0005]    Despite the efficacy of anticoagulant therapy in the management of VTE, there are certain situations and conditions in which the benefits of anticoagulation are outweighed by the risks of instituting such a therapy. These include contraindications and complications of anticoagulant therapy. In such circumstances, there may be absolute or relative indications for filter insertion 
         [0006]    Currently, there are several different types of permanent cava filters that are FDA approved. These include the Bird&#39;s Nest filter (Cook Incorporated, Bloomington, Ind.), Vena Tech LGM filter (B. Braun, Bethlehem Pa.), Vena Tech LP (B. Braun), Simon Nitinol filter (Bard, Covington, Ga.), Titanium Greenfield filter (Boston Scientific, Natick Mass.), Over-the-Wire Greenfield filter (Boston Scientific), TrapEase filter (Cordis Corp.), SafeFlo filter (Rafael Medical Technologies, Inc.), and the Günther Tulip filter (Cook Medical). 
         [0007]    Well-founded concerns over the long-term complications of permanent IVC filters, particularly in younger patients in need of PE prophylaxis with a temporary contraindication to anticoagulation, has led to the development of temporary and retrievable filters. Temporary filters remain attached to an accessible transcutaneous catheter or wire. These have been used primarily in Europe for PE prophylaxis during thrombolytic therapy for DVT. Currently these devices are not approved for use in the United States. Retrievable filters are very similar in appearance to permanent filters, but with modifications to the caval attachment sites and/or hooks at one end that can facilitate their removal. Retrievable filters are currently available in the United States, examples of these as set forth in  Endovascular Today&#39;s  2012 Buyer&#39;s Guide include the ALN Optional Filter (ALN), Option (Argon Medical Devices) Gunther Tulip (Cook Inc.), Celect and Opt Ease (Cordis Corp.), and Eclipse and Meridian nitinol filters (Bard Peripheral Vascular, Tempe, Ariz.). 2012  Buyer&#39;s Guide, Endovascular Today  2011; Dec.: 98. The time limit of retrievability is in part dependent on the rate of endothelialization of the device, which typically occurs within 2 weeks. However, differences in design may extend the time period in which the filter may be safely retrieved. 
         [0008]    Currently no consensus exists as to which patients have an indication for a retrievable filter. However, it is generally accepted that patients at high risk for pulmonary embolism or with documented PE and with a temporary contraindication to anticoagulation are candidates. 
         [0009]    Certain circumstances preclude the placement of a filter in the infrarenal IVC. This includes thrombus extending into the infrarenal IVC, renal vein thrombosis or pregnancy. The safety of suprarenal placement of IVC filters is well documented, with no reported instances of renal dysfunction and no differences in the rates of filter migration, recurrent PE or caval thrombosis. 
         [0010]    The rate of upper extremity DVT is on the rise. This is predominantly due to an increasing number of patients having short- and long-term upper extremity central venous access catheters. In one study, 88% of patients found to have an upper extremity DVT had a central venous catheter present at the site of thrombosis at the time of diagnosis or within the previous two weeks. Pulmonary embolism may complicate upper extremity DVT in 12-16% of cases. In patients who have such a complication or contraindication to anticoagulation, a filter can be safely placed immediately below the confluence of the brachiocephalic veins. However, misplacement of an SVC filter is theoretically more likely than with an IVC filter because of the relatively short target area for deployment. 
         [0011]    The most common imaging modality used for filter insertion is fluoroscopy, performed either in an interventional suite or an operating room. Bedside placement of filters has inherent advantages, particularly for critically ill patients in intensive care settings where transport can be avoided. Portable fluoroscopy, surface duplex ultrasound and intravascular ultrasound (IVUS) have all been used to assist with bedside filter placement. 
         [0012]    Vena cava filter placement frequently occurs concomitantly with central access line placement or in critically ill patients that already have a central access line in place. Heretofore, however, there have been no devices which combine the function of a central access catheter and a removable vena cava filter. 
       SUMMARY OF THE INVENTION  
       [0013]    The present invention relates to multi-lumen central access catheter having a proximal end and a distal end thereof relative to the longitudinal axis of the catheter, a vena cava filter near the distal end of the central access catheter, at least one of a port proximal the vena cava filter or a port distal the vena cava filter. The proximal and distal ports, which may be positioned entirely or partially distant from an open area bounded by the filter member, and lumens associated therewith, are also open to fluid flow to provide means for introducing fluids, such as an anticoagulant, thrombolytic or other bioactive agents, contrast medium, blood transfusions, intravenous fluids or other medications. Alternatively, the proximal and distal ports may be used for withdrawal or evacuation of fluids or other material through the catheter. 
         [0014]    The present invention may be configured for either a femoral approach or a jugular approach to the inferior vena cava. Vena cava filters are typically deployed infrarenaly, but may also be deployed suprarenaly. It will be understood that within the inferior vena cava blood flow is superior, i.e., toward the patients head. Thus, in all embodiments, the vena cava filter will be positioned so that it opens inferiorly, i.e., away from the patient&#39;s head and toward the direction of the blood flow. It will be appreciated, therefore, that in the present invention, the vena cava filter will have a different axial orientation on the central access catheter depending upon whether the device is intended for use in a femoral approach or a jugular approach. 
         [0015]    Accordingly, it is an objective of the present invention to provide a multi-lumen catheter coupled to a vena cava filter that is useful both as a central venous access catheter for administration of intravenous fluids, bioactive agents, contrast agents, flushing agents, pressurized fluids for mechanical thrombolysis and/or withdrawal of blood samples and for capture of thrombus or emboli. 
         [0016]    Another aspect of the present invention is to provide a filter geometry in which the proximal portion of the filter, relative to the axis of blood flow, has larger interstitial openings to permit thrombus or embolic material to flow into the filter, while the distal portion of the filter, again relative to the axis of blood flow, has relatively smaller interstitial openings that capture the thrombus or embolic material within the filter. Another way to view this aspect is that the structure of the filter includes a greater open surface area exposed to the flow of embolic material into the filter at its proximal end, while the distal end has smaller open surface area exposed to the flow of embolic material to capture the embolic material in the distal end of the filter member. More specifically, regardless of whether the present invention is delivered by a jugular approach or a femoral approach, the filter geometry is such that the larger interstitial openings of the filter are positioned inferiorly along a longitudinal axis of the filter. 
         [0017]    Each of the foregoing embodiments of the present invention may further be adapted for use with an imaging modality to facilitate intravascular imaging beyond or within the region of the filter member. In this manner, as opposed to the prior art, the condition of the filter member may be visualized from within the filter member, rather than via a traditional external imaging modality such as fluoroscopy, venography, or ultrasound. Additionally, in some embodiments, the imaging modality may pass entirely through the distal tip of the multi-lumen catheter, and enable an operator to use the intravascular imaging modality to visualize the origins of the renal veins. This could allow the operator to place the catheter without use of external imaging (i.e. fluoroscopy, trans-abdominal duplex ultrasound, CT, etc.). 
         [0018]    Generally, intravascular imaging systems utilize a sheath through which a signal is transmitted and received. In the present invention, the multi-lumen catheter with associated filter member may serve as the sheath for introduction of an intravascular imaging system, permitting improved imaging of the condition of the filter member while in use. In particular, the use of an intravascular imaging system with the multi-lumen catheter with associated filter member will permit a medical professional to monitor the condition of the filter member, and utilize appropriate techniques to lyse a collected thrombus. Because of the improved imaging, the lysing techniques may be more specifically and accurately targeted, as compared to lysing techniques applied without the benefit of imaging the condition of the filter member. In other, alternative, embodiments, the intravascular imaging system may also enable a medical professional to visualize the filter catheter for placement within a patient. 
         [0019]    Some non-limiting examples of imaging systems include intravascular ultrasound (IVUS), optical coherence tomography (OCT), side looking OCT, ultrasound, thermography, IR imaging, Florence imaging, luminescent imaging, MRI, videography, photoacoustic, and other similar imaging technologies. These systems may permit 360 degree imaging, or be side looking and rotatable to image through 360 degrees. In one embodiment, the system generally includes an imaging core drive cable and an imaging probe. The imaging probe may be a tip, cone, and/or the like disposed at a distal end of the imaging core drive cable, wherein the imaging probe and/or the drive cable are operably connected to an external system for operating the imaging system. 
         [0020]    In one embodiment, the imaging probe may be disposed within a portion of the central lumen bounded by the filter member. Thus, the imaging probe may be operated to help a user detect the presence of a thrombus captured by the filter member. Further, the imaging probe may also help detect the size and/or position of a captured thrombus. The imaging probe may be rotated and/or translated within the lumen, so as to permit imaging of the entire filter member. Alternatively, the imaging probe may be adapted to permit 360 degree imaging through the wall of the catheter lumen without requiring rotation. In a further embodiment, the imaging probe may be adapted to permit imaging of the length of the filter member without distal or proximal translation. Preferably, the imaging probe is operable to image the filter member in an expanded state. 
         [0021]    In another embodiment, the imaging system may be disposed within a lumen of a multi-lumen sheath associated with a multi-lumen or single lumen filter catheter. 
         [0022]    In one embodiment, the position of the imaging probe relative to the filter member is determined. In one embodiment, the imaging probe may further comprise a radiopaque material to permit external imaging of the probe to determine its location relative to the filter. In an alternative embodiment, the drive cable may have measured markings disposed thereon to permit determination of the position of the imaging probe relative to the filter, based on the relationship between the markings on the drive cable and the conduit into which the imaging probe and drive cable are inserted. 
         [0023]    In order to monitor the condition of the filter member, the imaging probe may transmit and receive an imaging signal through a wall of the lumen. The imaging signal may depend upon the particular imaging system utilized, and generally comprises a transmitted signal, wave, energy, or the like that is emitted from the imaging probe in order to image or visualize the filter member. In one embodiment, the relevant portion of the lumen is a section of the catheter body bounded by the proximal and distal ends of the filter member. The dimensions and/or material of any or all of the catheter body may be selected to maximize imaging signal transmission and/or imaging signal clarity. 
         [0024]    Alternatively, in some embodiments the filter may be attached to an end of a single or a multi-lumen catheter. In these embodiments, the region bounded by the proximal and distal ends of the filter is open and free of imaging obstruction. 
         [0025]    Generally, the imaging system may be used with the filter member to monitor the condition of the filter member and to capture a thrombus within a blood vessel. This may be accomplished by introducing the multi-lumen catheter, having the filter member coupled thereto, into the blood vessel. The catheter may then be deployed within the blood vessel such that the filter has an enlarged diametric opening facing a patient&#39;s blood flow. The imaging system may then be translated through a lumen of the multi-lumen catheter and be operable to image or visualize the condition of the filter member. Alternatively, the imaging system may be used to visualize the filter catheter to assist a medical professional in placement of the filter catheter within a patient. 
         [0026]    In another embodiment, the imaging system may be used with a multi-lumen sheath coupled to a filter catheter, such that the imaging system is disposed within a lumen of the multi-lumen sheath. 
         [0027]    In one embodiment disclosed herein is a method of capturing thrombus within a blood vessel, comprising the steps of: introducing a catheter having a filter member coupled thereto; deploying the catheter within a blood vessel such that the filter has an enlarged diametric opening which opens facing a patient&#39;s blood flow; and imaging the filter member with an imaging system operable to detect a condition of the filter member. 
         [0028]    In one embodiment disclosed herein is a multi-lumen filter catheter, comprising: a multi-lumen catheter body having a plurality of lumens; a filter member coupled to the catheter body; and an imaging system operable to detect a condition of the filter member. 
         [0029]    In one embodiment disclosed herein is a medical device, comprising: a catheter body having a filter member coupled to the catheter body; a multi-lumen sheath, wherein the catheter body is disposed within a lumen of the multi-lumen sheath; and an imaging system operable to detect a condition of the filter member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0030]      FIG. 1  is a perspective view of a central venous access vena cava filter catheter in accordance with a first embodiment of the present invention with the vena cava filter in an unexpanded state. 
           [0031]      FIG. 2  is a side elevational view of a central venous access vena cava filter catheter in accordance with the first embodiment of the present invention. 
           [0032]      FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2 . 
           [0033]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2 . 
           [0034]      FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 2 . 
           [0035]      FIG. 6  is a perspective view of a central venous access vena cava filter catheter in accordance with a second embodiment of the present invention illustrating the vena cava filter in an unexpanded state. 
           [0036]      FIG. 7  is a side elevational view of a central venous access vena cava filter catheter in accordance with the second embodiment of the present invention. 
           [0037]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 . 
           [0038]      FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 7 . 
           [0039]      FIG. 10  is a cross-sectional view taken along line  10 - 10  of  FIG. 7 . 
           [0040]      FIG. 11  is a cross-sectional view taken along line  11 - 11  of  FIG. 7 . 
           [0041]      FIG. 12  is a perspective view of the central venous access vena cava filter catheter of  FIG. 1  illustrating the vena cava filter in a diametrically expanded state. 
           [0042]      FIG. 13A  is a perspective view of a vena cava filter member in accordance with a first embodiment thereof. 
           [0043]      FIG. 13B  is a first side elevational view thereof. 
           [0044]      FIG. 13C  is an end elevational view thereof. 
           [0045]      FIG. 13D  is a second side elevational view thereof. 
           [0046]      FIGS. 14A-14H  are perspective views of alternative embodiments of a vena cava filter member in accordance with the present invention. 
           [0047]      FIGS. 15A-15H  are fragmentary side elevational views of the alternative embodiments of the vena cava filter member illustrated in  FIGS. 14A-14H . 
           [0048]      FIG. 16A  is a side elevational view of the vena cava central line catheter in its undeployed state. 
           [0049]      FIG. 16B  is a side elevational view of the vena cava central line catheter in its deployed state. 
           [0050]      FIG. 17  is a side elevational view of a vena cava filter member in its expanded state in accordance with one embodiment of the present invention. 
           [0051]      FIG. 18  is a perspective view of a vena cava filter member in its expanded state in accordance with an alternative embodiment of the present invention. 
           [0052]      FIG. 19  is a perspective view of a vena cava filter member in its expanded state in accordance with yet another embodiment of the present invention. 
           [0053]      FIG. 20  is a perspective view of a vena cava filter member in its expanded state in accordance with still another embodiment of the present invention. 
           [0054]      FIGS. 21A and 21B  are perspective views of a vena cava filter member mounted at a distal end of a central line catheter having a distal balloon. 
           [0055]      FIGS. 22A and 22B  are perspective views of an alternative embodiment of a vena cava filter member mounted at a distal end of a central line catheter having a distal balloon. 
           [0056]      FIG. 23  is a side cross sectional view of an embodiment of the vena cava filter member mounted at a distal end of a central line catheter in its expanded state, further comprising an imaging modality disposed within a lumen of the catheter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0057]    In the accompanying Figures like structural or functional elements are designated by like reference numerals, e.g.,  16 ,  116 ,  216 ,  316 ,  416  represent similar structural or functional elements across different embodiments of the invention. With particular reference to  FIGS. 1-5 , according to a first embodiment of the invention, there is disclosed a central venous access filter (“CVAF”)  10  that is composed generally of a multi-lumen central venous access catheter body  12  having a proximal port  32  associated with a first lumen  44  and a distal port  34  associated with a second lumen  42 , a filter member  16 , having a first end  18  and a second end  20 , is positioned generally intermediate the distal port  34  and the proximal port  32  and is generally concentric relative to the catheter body  12 . An outer sheath  22  is concentrically disposed over the catheter body  12  such that relative movement of the catheter body  12  and the outer sheath  22  either exposes the filter member  16  or captures the filter member  16  within the outer sheath  22 . The outer sheath  22  terminates in an annular opening at a distal end thereof and at first hub member  225  as depicted in  FIGS. 16A and 16B . The proximal hub  225  will be described more fully hereinafter. The catheter body  12  extends through a central bore in the proximal hub  225  and passes through a central lumen of the outer sheath  22 . A second hub member  227 , as depicted in  FIGS. 16A and 16B , is coupled to a proximal end of the catheter body  12 . The second hub member  227  and the first hub member  225  are removably engageable with each other as will also be described further hereinafter. 
         [0058]    Depending upon the orientation of the filter member  16 , the first end  18  or the second end  20  may either be fixed or moveable relative to the catheter body  12 . Alternatively, as will be discussed further hereinafter, the filter member  16  may have only a first end  18  which is fixed to the catheter body  12   
         [0059]    To facilitate percutaneous introduction of the inventive CVAF  10 , a physician may optionally elect to employ an introducer sheath (not shown) as vascular access conduit for the CVAF  10 . The presence of the filter member  16  at the distal end of the catheter body  12  creates a region of relatively lower flexibility and the practitioner may determine it beneficial to employ an introducer sheath for vascular access. 
         [0060]    As used in this application, unless otherwise specifically stated, the terms “proximal” and “distal” are intended to refer to positions relative to the longitudinal axis of the catheter body  12 . Those skilled in the art will understand that the catheter body  12  has a distal end which is first inserted into the patient and a proximal end which opposite the distal end. Additionally, the terms “inferior” or “inferiorly” are intended to refer to the anatomic orientation of being in a direction away from the patient&#39;s head while the terms “superior” or “superiorly” are intended to refer to the anatomic orientation of being toward the patient&#39;s head. 
         [0061]    The multi-lumen aspect of the inventive central venous access filter catheter  10  is shown more clearly in  FIGS. 2-5 . The catheter body  12  has a proximal section  13  and a distal section  14 . which is longitudinally opposite the proximal section  13 , and which may have a relatively smaller diametric profile than the proximal section  13 . As described above, the first lumen  44  terminates at the proximal port  32 , while the second lumen  42  terminates at the distal port  34 . A central guidewire lumen  30  may be provided that extends the entire longitudinal length of the catheter body  12  and terminates at the distal end of the catheter body  12  at a distal guidewire opening  31  that permits the catheter body to track along a guidewire during a procedure. The central guidewire lumen  30  may also be used to introduce fluids, such as bioactive agents, intravenous fluids or blood transfusions. 
         [0062]    Additionally, at least one of a plurality of infusion lumens  40  are provided, each having at least one infusion port  36  that passes through a wall of the catheter body  12 . Bioactive agents, flushing fluids for flushing or under elevated pressures for mechanical thrombolysis of thrombus in the filter member  16 , contrast agents or other fluids may be infused through the infusion lumens  40  and out of the at least one infusion port  36  to pass into the patient&#39;s venous system for either local or systemic effect. In accordance with one embodiment of the invention, plural infusion ports  36  are provided with multiple ports  36  being provided in communication with a single infusion lumen  40  and spaced along a longitudinal axis of the catheter body  12 . Additionally, plural infusion ports  36  may be provided in a circumferentially spaced manner to provide for fluid infusion at points spaced around the circumference of the catheter body  12 . In this manner, fluid infusion is provided along both the longitudinal axis and the circumferential axis of the catheter body  12  within the spatial area defined by and bounded by the filter member  16 . Because the plural infusion ports  36  communicate with the spatial area defined by and bounded by filter member  16 , fluids introduced through the infusion lumens  40  are directed immediately at thrombus caught within the filter member  16 . This permits thrombolytic agents, high pressure mechanical thrombolysis using a pressurized saline flush to be introduced directly to the situs of thrombus capture within filter member  16 . Alternatively, thermal, ultrasound or other types of thrombolysis may be employed to disrupt thrombus captured by the filter member  16 . For example, the annular space between the outer sheath  22  and the catheter body  12  may be used to introduce a thrombolytic to the filter and shower the filter to disrupt thrombus caught by the filter member  16 . Additionally, the balloon depicted in  FIGS. 21 and 22  may be positioned adjacent the filter member  16  and be provided with plural openings oriented in the direction of the filter member  16  to facilitate thrombolysis. 
         [0063]    It will be understood, by those skilled in the art, that alternative arrangements of the first lumen  44 , the second lumen  42 , the guidewire lumen  30 , or the infusion lumens are possible and contemplated by the present invention. The number and arrangement of lumens in the catheter body  12  is a function of the desired number of operable ports passing through the walls of the catheter body  12 , the relative position of the operable ports, the desired position and geometry of the guidewire lumen  30 , the desired longitudinal flexibility of the catheter body  12 , the desirable degree of kink resistance of the catheter body  12 , and other factors which are known to one of ordinary skill in the catheter arts. 
         [0064]    While the present invention is not limited to specific dimensional sizes of either the catheter body member  12 , the outer sheath  22 , lumen diameter or port dimension, an exemplary outer diameter size of the outer sheath  22  is between 8 Fr (2.7 mm) and 9 Fr (3.0 mm) while an exemplary outer diameter size of the catheter member  12  is between 6 Fr (2.0 mm) and 7 Fr. A diametric transition taper  15  may be provided between the proximal portion  13  and the distal portion  14  of the catheter body  12  corresponding to the thickness of the filter member  16 . In this manner, the outer surface of the filter member  16  is substantially co-planar with the outer diameter of the proximal portion  13  of the catheter body  12  about its entire circumference. Alternatively, the catheter body member  12  may have a constant diameter and the filter member  16  coupled to an outer surface of the catheter body member  12 , with the outer sheath  22  having a luminal diameter sufficient to fit over the filter member  16 . Moreover, the fixed first end  18  of filter  16  is positioned adjacent and in abutting relationship with the diametric transition  15 , while the moveable second end  20  of filter member  16  is concentrically positioned around the distal section  14  of catheter body  12  and is reciprocally moveable thereupon to accommodate diametric expansion of the filter member  16 . Lumen diameter and port dimension are a function of design requirements and are variable depending upon the desired purpose and function of the lumen or port, e.g., pressure sensing, infusion, evacuation, guidewire, flow sensing, or flow conduit. 
         [0065]    In order to aid a physician in visualizing the CVAF  10  in vivo, at least one radio-opaque or other viewable marker may be provided. A first marker  24  is provided at the distal end of the outer sheath  22  and a second marker  26  may be provided at a distal tip  33  of the catheter body  12 . It will be understood that when the outer sheath  22  is in its non-retracted delivery position, that the filter  16  will be covered and the marker  24  and the second marker  26  will be adjacent or in close proximity with one another. Alternatively, the outer sheath  22  may, itself, be made of or include a radio-opaque or other viewable material, such as a metal braid or metal reinforcement within or applied to a polymeric sheath. The first and second markers  24 ,  26  or the material of the outer sheath  22  may enhance visualization of the CVAF  10  under fluoroscopy, ultrasound or other visualization or guidance technique. 
         [0066]      FIGS. 6-11  illustrate a second embodiment of the CVAF  50 . Unlike CVAF  10 , CVAF  50  does not include the central guidewire lumen  30  of CVAF  10 . Rather, while the general construct of CVAF  50  is similar to that of CVAF  10 , a different configuration of the inner lumens is employed. 
         [0067]    CVAF  50 , like CVAF  10 , consists generally of a multi-lumen central venous access catheter body  12  having a proximal port  32  associated with a first lumen  54  and a distal port  34  associated with a second lumen  58 , a filter member  16 , having a fixed first end  18  and a moveable second end  20 , is positioned generally intermediate the distal port  34  and the proximal port  32  and is generally concentric relative to the catheter body  12 . Use of the term “generally intermediate” is intended to mean that at least a substantial portion of the filter member  16  resides intermediate the distal port  34  and the proximal port  32 . Thus, the filter member  16  may partially overlay either or both of the proximal port  32  or the distal port  34 . 
         [0068]    The catheter body  12  has a proximal section  13  and distal section  14 , which is longitudinally opposite the proximal section  13  which may have a relatively smaller diametric profile than the proximal section  13 . As described above, the first lumen  54  terminates at the proximal port  32 , while the second lumen  58  terminates at the distal port  34 . An atraumatic tip  52  terminates the catheter body  12  at its distal end. The atraumatic tip  52  preferably includes a radio-opaque marker to aid in positional visualization of the distal end of the catheter body  12 . 
         [0069]    A plurality of infusion lumens  56  are provided, each having at least one infusion port  36 , preferably plural infusion ports  36 , that passes through a wall of the catheter body  12  and communicates with a space defined within an area bounded by the filter member  16 . Bioactive agents, flushing fluids, pressurized mechanical thrombolytic fluids, or other fluids may be infused through the infusion lumens  56  and out of the at least one infusion port  36  to pass into the space defined by the filter member  16  and ultimately into the patient&#39;s venous system for either local or systemic effect. In accordance with one embodiment of the invention, the each of the plural infusion lumens  56  are in fluid communication with plural ports  36  arrayed along both the longitudinal axis and the circumferential axis of the catheter body. This configuration provides for fluid infusion along both the longitudinal axis and the circumferential axis of the catheter body  12  and in direct communication with the space defined by the filter member  16  that captures thrombus. 
         [0070]    The infusion lumens  56 , the first lumen  54  and the second lumen  58  are bounded by and separated from each other by first catheter septum  51  and second catheter septum  56  which also aid in providing structural support for the catheter body  12 . First catheter septum  51  is a generally diametrically and longitudinally extending member that divides the first lumen  54  from the second lumen  58  along the longitudinal axis of the catheter body  12 . Second catheter septum  56  may comprise a generally U-shaped member that intersects the first catheter septum  51  at a lower aspect of the septum and is connected with an inner wall surface of the catheter body  12  at upper aspects of the septum  51  to define two infusion lumens in lateral regions of the catheter body  12 . 
         [0071]    The filter member  16  has two general configurations. A first configuration consists generally of two opposing generally open conical sections formed by plural interconnected structural elements defining the lateral surfaces of each open conical section, wherein the two opposing generally open conical sections each have open bases facing each other which are interconnected by a generally cylindrical section of the filter member  16 . Each open conical section has an open base and an apex, wherein the apices project in opposing directions, with one apex projecting proximally and another apex projecting distally relative to the axis of the catheter. The plural interconnected structural elements forming the lateral surfaces of each generally open conical section may be strut-like structural members extending generally axially along the longitudinal axis of the filter member  16 . The axially extending strut-like structural members may be linear members or may be curved members. The apices of each of the generally open conical sections are formed either of a generally cylindrical collar that serves to couple the filter member  16  to the catheter body  12 . The generally cylindrical collar is concentrically engaged about the catheter body  12  and may be axially movable thereupon, or is formed by connections between adjacent pairs of longitudinal strut-like structural members which circumscribe a circumference of the catheter body  12 . The generally cylindrical section of the filter member  16  is formed by a generally open lattice of interconnected structural elements which connect the base of a first open conical section to the base of a second open conical section. The generally cylindrical section of the filter member  16  lies in apposition with a vascular wall upon deployment of the filter member  16  with a vascular lumen. 
         [0072]    A second general configuration of the filter member  16  consists generally of a single generally open conical section in which a plurality of longitudinal strut-like structural members form the lateral surfaces of the conical section and are connected to a generally cylindrical collar which couples the filter member  16  to the catheter body  12  at an apex of the generally open conical section. The base of the generally open conical section is formed by opposing ends of the longitudinal strut-like structural members. A generally cylindrical section of the filter member  16 , formed of a generally open lattice of interconnected structural elements, extends from the longitudinal strut-like structural members forming the base of the generally open conical section, to provide a region of the filter member  16  which is in apposition to the vascular wall upon deployment of the filter member. 
         [0073]    One embodiment of the filter member  16  is illustrated in its diametrically expanded configuration in  FIGS. 12-13D . In this embodiment, filter member  16  consists generally of a first end  18  and a second end  20 , each of which consists generally of a tubular structure which is circumferentially positioned about a section of the catheter body  12 . One of the first end  18  and second end  20  are fixedly coupled to the catheter body  12 , while the other is movable relative to the catheter body  12 . At least one of a plurality of first strut members  62 , are coupled at their first end to the first end  18  of filter member  16  and each extends axially relative to the longitudinal axis of the catheter body  12 . Each of the first strut members  62  is an elongate member that, upon diametric expansion of the filter member  16 , flares away from the central longitudinal axis of the catheter body  12 , in a generally tapered conical manner, and terminates in an end section  63  that bends generally parallel to and along the longitudinal axis of the catheter body  12 . A plurality of second strut members  64  are coupled at an end to the second end  20  of filter member  16  and each extends parallel relative to the longitudinal axis of the catheter body  12 . A plurality of third strut members  66  are coupled at ends thereof to an end of the filter member and each extends parallel relative to the longitudinal axis of the catheter body  12 . 
         [0074]    It will be appreciated, by those skilled in the art, that the number of struts employed as the first strut members  62 , the second strut members  64  and the third strut members  66  forming the filter member  16  may be evenly distributed about a 360 degree circumference and define the lateral wall surfaces of the filter member  16 . A circumferential member  70  extends circumferentially to define a circumferential axis of the filter member  16  and has a series of continuous undulations defining peaks a series of peaks  75  and valleys  77  about the circumference of filter member  16 . Each of the plurality of first strut members  62 , the plurality of second strut members  64  and the plurality of third strut members  66  are coupled to the circumferential member  70  at different points about its circumferential axis and intermediate the proximal end  18  and the distal end  20  of the filter member  16 . In its unexpanded state the filter member  16  has a generally tubular shape, while in its expanded state the filter member  16  assumes one of the general configurations discussed above, i.e., either oppositely extending generally open conical sections or a single generally open conical section. 
         [0075]    The plurality of first strut members  62  are preferably offset from each other by approximately 120 degrees about the circumference of the catheter body  12 . The plurality of second strut members  64  are also preferably offset from each other by approximately 120 degrees. Finally, the plurality of third strut members  66  are also preferably offset from each other by approximately 120 degrees. Each of the plurality of first strut members  62  couple at a junction  76  to the circumferential member  70  at a peak thereof. Similarly, each of the plurality of third strut members  66  couple at junction  76  to the circumferential member  70  at a peak thereof. In this manner, a first strut member  62  and a third strut member  66  are each coupled to circumferential member  70  at junction  76  and, in this relationship, form a generally linear member that extends along the longitudinal axis of the catheter body and connects between the proximal end  18  of the filter member  16  and the distal end  20  of the filter member  16 . Each of the second strut members  64  couple, at their proximal ends to a valley  77  of the circumferential member  70  and connects at a junction  79 . Unlike the connections at junction  76  between the plurality of first strut members  62  and the plurality of second strut members, in this embodiment of the filter member  16 , there is no member that connects to junction  79  and extends from the first end  18  of the filter member  16 . In this configuration, the circumferential member  70  assumes a generally circumferential tri-leaflet ring having three peaks  75  and three valleys  77  which circumferentially circumscribe a central opening  72  which faces inferiorly relative to the patient&#39;s blood flow such that the blood flow first passes into the central opening  72  and past the third strut members  66  and the second strut members  64  then past the first strut members  62 . 
         [0076]    To facilitate bending and folding of the circumferential member  70  between the expanded and unexpanded states, generally U-shaped hinge members  74  may be provided at each of the valleys  77  of the circumferential member  70 . It will be understood that each of the plurality of first strut members  62 , plurality of second strut members  64 , plurality of third strut members  66  and the circumferential member  70  are preferably fabricated of biocompatible materials, such as shape memory alloys, superelastic materials or elastic materials, including, without limitation, titanium, vanadium, aluminum, nickel, tantalum, zirconium, chromium, silver, gold, silicon, magnesium, niobium, scandium, platinum, cobalt, palladium, manganese, molybdenum and alloys thereof, such as zirconium-titanium-tantalum alloys, cobalt-chromium-molybdenum alloys, nitinol, and stainless steel. 
         [0077]      FIGS. 14A-14H  and corresponding  FIGS. 15A-15H  depict alternative embodiments of the filter member  16 , labeled  80 ,  90 ,  100 ,  110 ,  120 ,  130 ,  140  and  150 , respectively. Like filter member  16 , each of filter members  80 ,  90 ,  100 ,  110 ,  120 ,  130 ,  140  and  150  having a first end  18  and a second end  20  that each consist of a generally ring-like structure intended to circumferentially couple to a catheter body  12  (not shown), with the first end  18  being fixed and the second end  20  being reciprocally moveable axially along the distal portion  14  of catheter body  12 . Like filter member  16 , each of the alternative filter member embodiments depicted in  FIGS. 14A-14H  and  15 A- 15 H, consist of a plurality of first strut members  81 ,  91 ,  101 ,  111 ,  121 ,  131 ,  141  and  151 , respectively, extending distally from the first end  18  of the filter member and a plurality of second strut members  83 ,  93 ,  103 ,  113 ,  123 ,  133 ,  143  and  153 , respectively, extending proximally from the distal end  20  of the filter member, with a diametrically expansible circumferential member  87 ,  97 ,  107 ,  117 ,  127 ,  137 ,  147 ,  157 , respectively, interconnecting the distally extending strut members  81 ,  91 ,  101 ,  111 ,  121 ,  131 ,  141  and  151 , respectively, with the proximally extending strut members  83 ,  93 ,  103 ,  113 ,  123 ,  133 ,  143  and  153 . In the alternative embodiments of filter members  100 ,  110  and  120 , at least some distally extending strut members and at least some of the proximally extending strut members form linear elements that extend along the entire longitudinal axis of the respective filter member, with the circumferential member being comprised of at least one undulating or serpentine ring structure. 
         [0078]    In the alternative embodiments of filter members  80 ,  90 ,  130 ,  140  and  150 , a plurality of distally extending strut members are provided spaced approximately 120 degrees apart from one and other about the circumference of the filter members, and the distally extending strut members bifurcating once or twice distally in a generally Y-shaped manner as in filter members  80 ,  130 ,  140  or  150 , or the proximally extending strut members bifurcating proximally in a generally Y-shaped manner and interconnecting with the distally extending generally Y-shaped strut members to form a diamond-like pattern as in filter member  90 . In filter members  90  and  140 , the circumferential member is formed by the diamond-like pattern formed by the intersection of the plurality of struts. In contrast, in filter members  80 ,  130  and  150 , the circumferential member is formed by at least one undulating or serpentine ring structure which is diametrically expansible. As illustrated in filter members  110 ,  120  and  130 , apical portions of each undulating or serpentine ring structure is interconnected by an interconnecting member  114 ,  124 ,  134 , respectively, either with an adjacent ring structure, as in filter member  110  or to a distal end  20  of the filter member itself. A longitudinally serpentine section  132  in filter  32  may be provided in conjunction with the interconnecting member  134 , to afford greater expansive properties to the circumferential member  137 . 
         [0079]    According to some embodiments particularly well-suited for placement by femoral or other infrarenal approach, the filter member  16  is characterized by a generally conical filter member  16  having a greater open surface area exposed to the flow of embolic material into the filter at its proximal end, while the distal end has smaller open surface area exposed to the flow of embolic material to capture the embolic material in the distal end of the filter member. 
         [0080]    In other embodiments particularly well-suited for placement by a jugular or suprarenal approach, the filter member  16  is characterized by a generally conical filter member  16  having a greater open surface area exposed to the flow of embolic material into the filter at its distal end, which the proximal end of the filter member  16  has a smaller open surface area exposed to the flow to capture smaller embolic material in the distal end of the filter member  16 . 
         [0081]    Additionally, in all of the embodiments the filter member  16  is self-centering to provide proper apposition against the vascular walls and centering within the lumen of a blood vessel. This maximizes the flow dynamics of the filter member  16  within the blood vessel for purposes of capturing embolic material within the struts of the filter and centers the catheter body member  12  within the vascular lumen. 
         [0082]    As noted above, the proximal  32  and distal  34  ports serve as means for measuring flow rates or pressure differentials across the filter  16 . This may be accomplished by including flow sensors and/or pressure transducers  19  in operable association with each port  32 ,  34 , with the associated electrical connections to the flow sensors and/or pressure transducers  19  passing through the respective lumens associated with each port  32 ,  34  and terminating at the proximal end of the catheter body  12 . Where flow sensors  19  are employed, a single flow sensor associated with proximal port  32 , the distal port  34  or the distal end of outer sheath  22  may be sufficient to detect fluid flow rate at the position of the catheter body  12 . By providing a flow sensor at the distal end of sheath  22 , the clinician will be able to determine flow velocity at the distal end of the outer sheath  22  prior to introducing the catheter body  12  and make fine adjustments to the placement of the distal end of the outer sheath  22  to ensure proper placement for the filter member  16 . Plural flow sensors  19  may be employed and operably associated with each of proximal port  32  and distal port  34  to sense changes in flow velocity across the filter member  16 . Alternatively, the flow sensors and/or pressure transducers  19  may reside in communication with the lumens respectively associated with each port  32 ,  34  at the proximal end of the catheter body  12 , thereby eliminating the need for electrical connectors resident with the associated lumens. Furthermore, wireless flow sensors and/or pressure transducers may be provided in communication with each port  32 ,  34 , and be operably coupled to a power source and a transmitter to wirelessly transmit telemetry data from the transducers to a wireless receiver in communication with the transmitter, as is known in the art. 
         [0083]    Alternatively, the proximal  32  and distal ports  34  may be used for monitoring or sensing other conditions in the body that are detectable in the blood. For example, analyte sensors may be introduced to either the lumens communicating with the proximal  32  or distal ports  34  or to the ports themselves to monitor and/or sense chemical or biochemical conditions in the body. An example of this application is monitoring or sampling blood glucose levels for diabetes control. Further, the proximal  32  and distal ports  34  may be used for fluid infusion or for withdrawal or evacuation of fluids or other material through the catheter body  12 . In this later instance, where the proximal port  32  is positioned to underlay the filter member  16 , thrombus collected in the filter member  16  may capable of being lysed, either by thrombolysis through the infusion ports  36  or under the influence of thermal or mechanical lysis, such as by introducing a laser, ultrasound or other system capable of lysing thrombus, which may be introduced through the lumen communicating with the proximal port  32 , or the distal port  34  or the guidewire lumen  30 , or introduced separately from the CVAF  10 , positioned within the space bounded by the filter member  16 , lysing thrombus collected in the filter member  16  and evacuating the lysed thrombus through the proximal port  32   
         [0084]    It is known that flow rate increases proximally within the venous system. For example a flow rate of 1 L/min is typical in one femoral vein, increases to 2 L/min in the inferior vena cava and increasing another 0.7 to 1 L/min proximate the renal veins. Knowing the typical flow velocities in vessels of different transverse cross-sectional areas, coupled with a flow sensor  19  associated with the multi-lumen catheter body  12  may serve to supplement or replace the requirements for fluoroscopy or sonography in placement of the CVAF  10 ,  50 . 
         [0085]    Other sensors, such as, for example, chemosensors, color sensors, electrical sensors or biosensors, may be employed in lieu of or in addition to pressure transducer and/or a flow sensor  19  in order to detect other changes or conditions within the patient&#39;s vasculature. For example, color sensors exist that sense color changes in thrombus, such color changes may be displayed and interpreted by the medical practitioner as an indication of thrombus staging. Analyte sensors, such a as a glucose sensor or an oxygen saturation sensor may also be employed. 
         [0086]    The filter member  16 , or its alternative embodiments described above, may be fixed to the catheter body  12  or may be removably coupled to the catheter body  12  for deployment as either a permanent filter or as a temporary and retrievable vena cava filter. Removable coupling of the filter member to the catheter body  12  may be accomplished with a variety of release and retrieval mechanisms operably associated the catheter body  12  and proximate the diametric transition  15 . Non-limiting examples of such release and retrieval mechanisms include a wire release that engages with a the first end  18  of the filter, a cooperating indexed detent and projection interaction between the catheter body  12  and the first end  18  of the filter, such as a detent in the proximal end of the filter and a cooperating projection in the multi-lumen catheter that is positionally indexed to the detent and releasable from the detent, or, alternatively, a helical slot or threads may be formed in the proximal end  18  of the filter and indexed and cooperating projection in the multi-lumen catheter than permits engagement and disengagement with the helical slot or threads. 
         [0087]    In use, an introducer sheath is first placed into the body in a normal manner for introducing a central venous line, such as by the Seldinger technique. Specifically, after accessing a vein using a large bore needle, under local anesthesia, a guidewire is inserted through the needle bore and passed into the vein. Once the guidewire is positioned, the needle is withdrawn, and a dilator together with the introducer sheath introduced over the guidewire. Once the introducer sheath is positioned at a desired location within the venous system under radiography, the dilator may be removed from the patient. Radiopaque markers associated with the introducer sheath may be employed to assist in positional visualization of the distal end of the introducer sheath. The outer sheath  22  covering the filter  16  is removed while introducing the filter member  16  and catheter body  12  into the introducer sheath. The outer sheath  22  constrains the filter member  16  during its passage through the introducer sheath and positioning the distal end of the catheter within the patient&#39;s vasculature. Once the distal end of the catheter body  12  reaches the distal end of the introducer sheath, the filter is deployed. If the filter therapy alone is desired, the filter member  16  is detached from the catheter body  12  and the catheter body  12 , introducer sheath and guidewire is withdrawn from the patient. Where both central venous access and filter therapy is desired, the introducer sheath and catheter body  12  with the filter member  16  is left in the patient until withdrawal is required. 
         [0088]    Retrieval and removal of a detached filter member  16  is accomplished using a second procedure under local anesthesia which substantially replicates the placement of the CVAF, with a capture sheath (not shown), similar to introducer sheath, being introduced, a retrieval catheter being introduced through the sheath, and engaging the filter member  16 , then withdrawn into the capture sheath to collapse the filter member  16 , with the entire assembly of the filter member  16 , catheter body  12 , outer sheath  22  and guidewire, if used, is withdrawn from the patient. 
         [0089]    As depicted in  FIGS. 16A and 16B , which depict the undeployed state ( FIG. 16A ) and the deployed state ( FIG. 16B ) of the filter member  216 , respectively, common to each of the embodiments of the present invention  200  is an inner catheter  214  that carries the vena cava filter  216  at a distal end thereof. The inner catheter  214  is concentrically and reciprocally engaged within an outer sheath  222  such that relative axial movement of the inner catheter  214  and the outer sheath  222  either exposes the vena cava filter  216  for deployment or captures the vena cava filter  216  for retrieval. A first hub member  225  is coupled to a proximal end of the outer sheath  222  and a second hub member  227  is coupled to a proximal end of the inner catheter  214 . First hub member  225  and second hub member  227  are engageable, such as by a threaded, bayonet, snap fit, friction fit or interference fit fitting, to secure the inner catheter  214  within the outer sheath  222  and restrict relative axial movement of the two elements after deployment of the vena cava filter  216 . A flush line  229  communicates with the first hub member  225  and is in fluid communication with a luminal space within the outer sheath  222 . A plurality of fluid lines  231 ,  233 ,  235 ,  237  communicate with the second hub member  227  and are each in fluid communication with one of the plural lumens within the inner catheter member  214 , e.g., lumens communicating with the proximal, distal or infusion ports (not shown). A distal tip  26  is provided at a distal end of the inner catheter. 
         [0090]    A jugular approach necessitates that the catheter be introduced retrograde relative to the vector of blood flow within the vena cava, i.e., the catheter is introduced through the jugular vein and directed inferiorly toward an infrarenal position. Additionally, since the blood flow opposes the distal end of the catheter and passes toward the proximal end, the vena cava filter must open inferiorly such that its largest diametric section in apposition to the vessel walls opens toward the distal end of the catheter rather than toward the proximal end of the catheter as with the femoral approach. 
         [0091]      FIGS. 17-20  depict alternative embodiments of vena cava filter members in accordance with the present invention.  FIG. 17  illustrates a filter orientation for a femoral approach, while  FIGS. 18-20  illustrate a filter orientation for a jugular approach. As illustrated in  FIG. 17 , filter member  216  defines a relatively larger volume open space  201  and a relatively smaller volume open space  203 . Open spaces  201  and  203  are bounded by structural members of the filter member  216  and are both open toward the direction of blood flow indicated by arrow  5 , with larger open space  201  being relatively upstream the blood flow relative to smaller open space  203  in both the femoral or the jugular orientation of filter member  216 . 
         [0092]    As with all previous embodiments described of the filter member, filter member  216  is formed of plural interconnected structural elements. In accordance with the preferred embodiments of the filter members of the present invention, and as particularly exemplified by filter member  216 , the filter member has a first end  218  and a second end  220 , at least one of which is attached to the distal section  214  of the catheter body  212 . First structural members  217  extend generally axially, either proximally as shown in  FIG. 17  or distally as shown in  FIG. 18 , along the longitudinal axis of the filter member  216 . Again, it is understood that use of the terms “proximal” or “proximally” and “distal” or “distally” are intended to refer to positions relative to the longitudinal axis of the catheter body  212 . The first structural members  217  are connected to either the first end  218  or the second end  220  of the filter member  216 . Second structural members  219  are connected to the first structural members  217  at an end of the first structural members  217  which is opposite that connected to either the first end  218  or the second end  220  of the filter member  216 . In accordance with a preferred embodiment of the invention, the second structural members  219  form at least two successive zigzag shaped structures which are connected to an end of the first structural members and at opposing apices  223  to form conjoined ring-like structures about the circumference of the filter member  216 . In this manner the second structural members  219  generally define lattice-like pattern upon diametric expansion of the filter member  216 . The lattice-like pattern formed by the second structural members  219  projects axially along the longitudinal axis of the catheter  214  tapering to form at least one petal-like projection  225  that terminates in a terminal apex member  227 . As will be appreciated by those skilled in the art,  FIG. 17  depicts three petal like projections  225 , with one being behind the plane of the figure and, therefore, not shown. Each of the petal-like projections  225  act to engage and oppose vascular wall surfaces to seat the filter member  216  against the vessel wall, and center the filter member and catheter  214  within the vascular lumen. As illustrated in  FIG. 17 , third structural members  221  are provided and are connected to each of the terminal apex members  227  and extend axially relative to the catheter  214  and connect with a second end  218  of the filter member  216 . 
         [0093]    In the embodiment illustrated in  FIG. 17 , which is an orientation of the filter member  216  for a femoral approach, and in the embodiment illustrated in  FIG. 19 , which is an orientation of the filter member  216  for a jugular approach, the first end  218  of the filter member  216  is fixedly connected to the catheter  212 , while the second end  220  of the filter member  216  is movably coupled to the catheter  212  and moves axially along the catheter  216  upon expansion or contraction of the filter member  216 . 
         [0094]      FIG. 18  depicts an embodiment of the filter member  216  identical to that illustrated in  FIG. 19 , with the sole exception that the third structural members  219  and the second end  220  of the filter member  216  are omitted. In this embodiment, the terminal apex member  227  of each petal-like member  225  are not connected to a second end  220  of the filter member  216  by the third structural members  219 . 
         [0095]      FIG. 20  depicts an alternative embodiment of the filter member  216  which is similar to that depicted in  FIG. 18 , except that at least one circumferential ring member  252  is connected to the terminal apex member  227  of each of the petal-like members  225  at a juncture  253  with the terminal apex member  227 . The addition of the additional circumferential ring member  252  results in a relative elongation over the length L 1  of the filter member  216  depicted in  FIG. 18  by a length L 2  which facilitates additional apposition between the filter member  216  and the vascular wall and stabilization of the petal-like members  225 . 
         [0096]      FIGS. 21A and 21B  depict an alternative embodiment of the filter member  216  in  FIG. 18 , having first end  318 , first structural elements  317  and second structural elements  319  all analogously arranged as in the embodiment of  FIG. 18 . Filter member  300 , however, employs a modified distal end  314  of the catheter  312  to include an expansive balloon  360 . The guidewire lumen of the multi-lumen catheter  312  may be used in place of a distal port for condition sensing, flushing, infusion or the like. The expansive balloon  360  may be used to break up thrombus captured within the filter member  316 , either by mechanical force through serial dilatation or by infusion of a thrombolytic agent through openings in the balloon  360 .  FIG. 21A  depicts the balloon  360  in its collapsed state, whereas  FIG. 21B  depicts the balloon in its expanded state. 
         [0097]    Alternatively, an expansive balloon  360  may be placed proximal the filter member  300  and serve to temporarily occlude the vessel to facilitate aspiration or evacuation of thrombus from the filter member  30 . 
         [0098]      FIGS. 22A and 22B  depict an alternative embodiment of the filter member  216  in  FIG. 20  having first end  418 , first structural elements  417  and second structural elements  419 , at least one circumferential ring member  452  connected to the terminal apex member  427  of each of the petal-like members  425  at a juncture  453  with the terminal apex member  427 ; all analogously arranged as in the embodiment of  FIG. 20 . Filter member  400 , however, employs a modified distal end  414  of the catheter  412  to include an expansive balloon  460 . The guidewire lumen of the multi-lumen catheter  412  may be used in place of a distal port for condition sensing, flushing, infusion or the like. The expansive balloon  460  may be used to break up thrombus captured within the filter member  416 , either by mechanical force through serial dilatation or by infusion of a thrombolytic agent through openings in the balloon  460 .  FIG. 22A  depicts the balloon  460  in its collapsed state, whereas  FIG. 22B  depicts the balloon in its expanded state. 
         [0099]    Again, an expansive balloon  460  may be positioned proximal the filter member  416  to permit temporary occlusion of the blood vessel and permit aspiration or evacuation of thrombus from the filter member  416 . 
         [0100]    Each of the foregoing embodiments of the present invention may further be adapted for use with an imaging modality to facilitate intravascular imaging of the filter member from beyond or within a lumen of the multi-lumen catheter. Additionally, in some embodiments, the imaging modality may pass entirely through the distal tip of the multi-lumen catheter, and enable an operator to use the intravascular imaging modality to visualize the origins of the renal veins. This could allow the operator to place the catheter without use of external imaging (i.e. fluoroscopy, trans-abdominal duplex ultrasound, CT, etc.). 
         [0101]    Generally, intravascular imaging systems utilize a sheath through which a signal is transmitted and received. In the present invention, the multi-lumen catheter with associated filter member may serve as the sheath for introduction of an intravascular imaging system, permitting improved imaging of the condition of the filter member while in use. In particular, the use of an intravascular imaging system with the multi-lumen catheter with associated filter member will permit a medical professional to monitor the condition of the filter member, and utilize appropriate techniques to lyse a collected thrombus. Because of the improved imaging, the lysing techniques may be more specifically and accurately targeted, as compared to lysing techniques applied without the benefit of imaging the condition of the filter member. In other, alternative, embodiments, the intravascular imaging system may also enable a medical professional to visualize the filter catheter for placement within a patient. 
         [0102]      FIG. 23  depicts a cross-sectional side view of one embodiment of the expanded filter member and catheter assembly of  FIG. 12 , further comprising an imaging modality. In this embodiment, filter member  516  consists generally of a first end  518  and a second end  520 , each of which consists generally of a tubular structure which is circumferentially positioned about a section of the catheter body  512 . One of the first end  518  and second end  520  are fixedly coupled to the catheter body  512 , while the other is movable relative to the catheter body  512 . The filter member is structurally analogous to that discussed above, such as in relation to  FIG. 12  above. In its unexpanded state the filter member  516  has a generally tubular shape, while in its expanded state the filter member  516  assumes one of the general configurations discussed above, i.e., either oppositely extending generally open conical sections or a single generally open conical section. The assembly may further comprise an outer sheath  522  disposed over the catheter body  512 . 
         [0103]    The catheter body  512  includes a distal portion  514  about which the filter member  516  is disposed. Catheter body  512  further includes at least one lumen  530 , such as a central guidewire lumen, which may extend the entire longitudinal length of the catheter body  512  and may terminate at the distal end of the catheter body  512  at a distal opening  531 . The central lumen  530  may be used to house and/or introduce elements of an imaging system. In another embodiment, the lumen into which the imaging system is disposed is not the central lumen, but another lumen of the multi-lumen catheter body  512 , so long as the imaging system is able to image the filter member  516 . Some non-limiting examples of imaging systems include intravascular ultrasound (IVUS), optical coherence tomography (OCT), side looking OCT, ultrasound, thermography, IR imaging, Florence imaging, luminescent imaging, MRI, videography, photoacoustic, and other similar imaging technologies. These systems may permit 360 degree imaging, or be side looking and rotatable to image through 360 degrees. In one embodiment, the system generally includes an imaging core drive cable  630  and an imaging probe  650 . The imaging probe  650  may be a tip, cone, and/or the like disposed at a distal end of the imaging core drive cable  630 , wherein the imaging probe  650  and/or the drive cable  630  are operably connected to an external system (not shown) for operating the imaging system. 
         [0104]    In one embodiment, the imaging probe  650  may be disposed within a portion  600  of the central lumen  530  bounded by a proximal end  518  and a distal end  520  of the filter member  516 . Thus, the imaging probe  650  may be operated to help a user detect the presence of a thrombus captured by the filter member  516 . Further, the imaging probe  650  may also help detect the size and/or position of a captured thrombus. The imaging probe  650  may be rotated and/or translated within the lumen  530 , so as to permit imaging of the entire filter member  516 . Alternatively, the imaging probe  650  may be adapted to permit 360 degree imaging of the filter member  516  without requiring rotation. In a further embodiment, the imaging probe  650  may be adapted to permit imaging of the length of the filter member  516  without distal or proximal translation. Preferably, the imaging probe  650  is operable to image the filter member  516  in an expanded state. 
         [0105]    In one embodiment, the position of the imaging probe  650  relative to the filter member  516  may be determined. In one embodiment, the imaging probe  650  may further comprise a radiopaque material to permit external imaging of the probe  650  to determine its location relative to the filter  516 , which as described above may have its own radiopaque markers. In another embodiment, the drive cable  630  may have measured markings disposed thereon to permit determination of the position of the imaging probe  650  relative to the filter  516 , based on the relationship between the markings on the drive cable  630  and the conduit into which the imaging probe  650  and drive cable  630  are inserted. 
         [0106]    In order to monitor the condition of the filter member  516 , the imaging probe  650  may transmit and receive an imaging signal through a wall of the lumen  530 . The imaging signal may depend upon the particular imaging system utilized, and generally comprises a transmitted signal, wave, energy, or the like that is emitted from the imaging probe  650  in order to image or visualize the filter member  516 . In a preferred embodiment, the relevant portion of the lumen  530  is a section  600  of the distal portion  514  of the catheter body  512  bounded by the proximal end  518  and distal end  520  of the filter member  516 . The dimensions and/or material of any or all of either the bounded portion  600  or the distal portion  514  may be selected to maximize imaging signal transmission and/or imaging signal clarity. Examples of appropriate materials include, but are not limited to, polyethylene, PTFE, and other polymers. 
         [0107]    Alternatively, in some embodiments the filter  516  may be attached to a distal end of a single or a multi-lumen catheter  512 . In these embodiments, the region bounded by the proximal and distal ends of the filter  516  is open and free of imaging obstruction. The imaging modality may be disposed through the lumen of the catheter  512  and translated such that it extends beyond the distal end of the lumen and into the open region between the proximal and distal ends of the filter  516 . 
         [0108]    Where the imaging system is an IVUS system, preferably the portion of the catheter body  512  from which the imaging probe  650  images is acoustically transparent to allow for the transmission of the imaging signal, ultrasound waves for IVUS, through the body  512 . The imaging probe  650  may comprise an ultrasound transducer connected to the distal end of a drive cable  630 , which extends through the lumen  530  of the catheter body  512 . The drive cable  630  is used to rotate and translate the transducer of the imaging probe  650  within the catheter lumen  530 . The drive cable  630  may possess a high torsional stiffness so that the drive cable  630  can transmit torque from a drive motor (not shown) to the transducer to rotate the transducer. In another embodiment, rotation of the transducer is not necessary, such as when the imaging probe  650  is capable of 360 degree imaging. The drive cable  630  may also possess a low bending stiffness allowing the drive to bend along a tortuous path of a blood vessel. The imaging probe  650  is operably connected to ultrasound electronics (not shown) external a patient. In one embodiment, the operable connection may be via a wire that runs along the drive cable  630 . 
         [0109]    As an optical analog of ultrasound, intravascular OCT uses a high-bandwidth light source instead of an ultrasound-emitting crystal to create high-resolution images. OCT is an interferometric technique, typically employing near-infrared light, where an optical beam is directed at tissue, and a small portion of this light that reflects from sub-surface features is collected. Where the imaging system is an OCT system, preferably the portion of the catheter body  512  from within which the imaging probe  650  images is optically transparent to allow for the transmission of the imaging signal, light waves for OCT, through the portion of the catheter body  512 . The imaging probe  650  may comprise an optical emitter connected to the distal end of a drive cable  630 , which extends through the lumen  530  of the catheter body  512 . The drive cable  630  is used to rotate and/or translate the optical emitter of the imaging probe  650  within the catheter lumen  530 . The imaging probe  650  is operably connected to OCT electronics (not shown) external a patient. In one embodiment, the operable connection may be via a wire that runs along the drive cable  630 . In another embodiment, the operable connection may be via an optical waveguide that runs along the drive cable  630 . 
         [0110]    Further, the imaging modality may generally be incorporated into any of the above disclosed embodiments of the multi-lumen catheter and filter member assembly. 
         [0111]    In another embodiment, an imaging probe may be disposed within a lumen of the IVC filter catheter, without an imaging catheter coupled thereto. 
         [0112]    In still another embodiment, an imaging catheter, housing an imaging probe therein, may be disposed within a lumen of the IVC filter catheter. In this embodiment, the imaging catheter is not coupled to the IVC filter catheter, and may be disposed within an appropriately sized lumen of the IVC filter catheter. The imaging modality may thus be positioned within or beyond a lumen of the IVC filter catheter, as a self-contained system. 
         [0113]    In another embodiment, an imaging catheter, housing an imaging core therein, is integral with a lumen of the IVC filter catheter. The imaging core may be translated proximally and/or distally relative to the imaging catheter and/or the IVC filter catheter. 
         [0114]    In another embodiment, a medial filter port may be used as a conduit to deliver an imaging catheter to the caval space within the filter. The imaging catheter may be coupled to the proximal hub of the catheter, by any one of the proximal hubs as disclosed U.S. provisional patent application Ser. No. 61/584,716, filed Jan. 9, 2011, U.S. patent application Ser. No. 13/083,053, filed Apr. 8, 2011, which are hereby incorporated by reference in their entirety. 
         [0115]    In another embodiment, the imaging probe  650  may be disposed within a lumen of a multi-lumen catheter sheath, such as that disclosed in commonly owned and co-pending U.S. provisional patent application Ser. No. 61/668,308, filed Jul. 5, 2012, which is hereby incorporated by reference in its entirety. In this embodiment, the imaging probe  650  may be disposed in the lumen of the multi-lumen sheath rather than the filter catheter. The imaging probe  650  may be translated so as to be disposed within a region bounded by the proximal end  518  and distal end  520  of the filter member  516 . The structure and operation of this embodiment is analogous to those disclosed above. 
         [0116]    Generally, the imaging system may be used with the filter member to monitor the condition of the filter member and to capture a thrombus within a blood vessel. This may be accomplished by introducing the multi-lumen catheter, having the filter member coupled thereto, into the blood vessel. The catheter may then be deployed within the blood vessel such that the filter has an enlarged diametric opening facing a patient&#39;s blood flow. The imaging system may then be translated through a lumen of the multi-lumen catheter and be operable to image or visualize the condition of the filter member. If a thrombus is detected, then a fluid may be infused through at least one lumen in the multi-lumen catheter in communication with at least one infusion port passing through the multi-lumen catheter and open to an inner spatial area bounded by the filter member. Alternatively, other means of lysing a detected thrombus may be utilized, such as thermal or mechanical lysis, such as by introducing a laser, ultrasound, or other system capable of lysing thrombus. 
         [0117]    In another embodiment, the imaging system may be used with a multi-lumen sheath coupled to a filter catheter, such that the imaging system is disposed within a lumen of the multi-lumen sheath and images the filter member. 
         [0118]    It will be appreciated by those skilled in the art that in all embodiments of the described central venous access filter, the filter member has a relatively larger opening that is open inferiorly in a direction that opposes the blood flow vector and employs structural elements that taper superiorly along the direction of the blood flow vector to reduce the open surface area of the filter member and capture thrombus. 
         [0119]    Thus there has been described a central venous access filter in accordance with the foregoing embodiments of the invention which include, generally, a multi-lumen catheter body, a filter member and an introducer sheath. The multi-lumen catheter body has a plurality of ports each of which are in fluid flow communication with at least one lumen in the multi-lumen catheter body. Lumens may include a central guidewire lumen useful for tracking over a guidewire and/or larger volume infusion of bioactive agents, intravenous fluids, blood transfusions, or other fluids; infusion lumens in communication with infusion ports positioned to direct fluids to the space bounded by the filter member for introducing bioactive agents, including thrombolytic agents or flushing agents, including pressurized fluids for mechanical thrombolysis directly to the capture site of the thrombus in the filter member; and lumens communicating with proximal and distal ports which may also be used for fluid introduction and/or may house or communicate with sensors, such as pressure transducers, flow sensors, analyte sensors, color sensors, optical sensors or the like. The filter member may be detachable from the multi-lumen catheter body to permit temporary filter placement and later retrieval by a detachment mechanism that cooperates between the filter and the multi-lumen catheter body. These and other aspects of the present invention are provided by way of non-limiting examples, with the claims appended hereto serving to define the scope of the subject matter regarded as the invention.