Abstract:
The invention is a delivery catheter, e.g., a guide catheter, having expandable elements proximate to the distal end of the catheter. Catheters of the invention are easier to place in proximity to an ostium, thereby increasing the efficiency of contrast delivery while reducing the risk of ischemia due to blocked blood supply. The invention additionally directs the flow of a fluid from the catheter, resulting in better performance with less fluid. For example, a catheter of the invention can be used to produce improved fluoroscopic images with less overall contrast. This improvement also decreases the length of time for a procedure, i.e., because of a need to re-contrast.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority to, and the benefit of, U.S. Provisional Application No. 61/779.422, filed Mar. 13, 2013, which is incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to delivery catheters, e.g., guide catheters, having expandable elements to facilitate placement of the catheter and to direct the flow of a delivered fluid, e.g., a contrast agent. 
       BACKGROUND 
       [0003]    During intravascular procedures, devices used to perform medical procedures are typically visualized within the vasculature using contrast agents and real-time x-ray images. i.e., fluoroscopy. Often the contrast is introduced into the vasculature by placing a guide catheter through the heart and in proximity to an ostium leading to the coronary arteries, e.g., the left anterior descending coronary artery or the left circumflex coronary artery. In this configuration, contrast introduced via the guide catheter will be pushed through the coronary arteries with the natural pumping of the heart, thereby providing images of the arteries on the fluoroscope. 
         [0004]    Placement of the guide catheter near an ostium is a delicate task, however. If the guide catheter is too far away, flushing is less complete and less effective. This can increase the need to add more contrast and increase the length of the flushes. The resultant increase in contrast loading increases the risk of ischemia in the tissues oxygenated by the arteries, while causing stress to the liver and kidneys. Alternatively, if the guide catheter completely blocks the ostium, the contrast will not circulate through the arteries and it will be very difficult to identify the vasculature through which the device is being inserted. 
       SUMMARY 
       [0005]    The invention is a delivery catheter, e.g., a guide catheter, having expandable elements in proximity to the distal end of the catheter. Catheters of the invention are easier to place in proximity to an ostium, thereby increasing the efficiency of contrast delivery while reducing the risk of ischemia due to blocked blood supply. The invention additionally directs the flow of a fluid from the catheter, resulting in better performance with less fluid. For example, a catheter of the invention can be used to produce improved fluoroscopic images with less overall contrast. This improvement reduces the risk of an allergic reaction to the contrast while decreasing the length of time for a procedure, i.e., because of a need to re-contrast. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a generalized depiction of a catheter having distal ports for use in delivering agents, e.g., contrast agents; 
           [0007]      FIG. 2A  depicts an embodiment of the invention having an inflatable member proximal to the distal end of the catheter; 
           [0008]      FIG. 2B  depicts an embodiment of the invention having an inflatable member proximal to the distal end of the catheter; 
           [0009]      FIG. 3  illustrates deployment of a guide catheter of the invention at an ostium; 
           [0010]      FIG. 4A  illustrates an alternative use of a delivery catheter of the invention in a biological lumen; 
           [0011]      FIG. 4B  illustrates an alternative use of a delivery catheter of the invention in a biological lumen. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    The invention is a delivery catheter having expandable members that facilitate placement of the catheter while helping to direct the flow of a fluid delivered with the catheter. The design of the catheter can be used with any number of delivery catheters, however they are especially-suited to be used with guide catheters, such as the type used to deliver contrast agents during endovascular procedures. The expandable members can be balloons, shields, or flaps. In one embodiment, the expandable members are balloon-like elements that are inflated with an increase in pressure at the distal end of the catheter with delivery of a fluid. 
         [0013]    Catheters having the described expandable members can be any type of catheter. Catheters include any elongated intraluminal device that comprises a tube for delivering the oxygenated particles within the body. In some instances, the catheters will perform additional functions, e.g., angioplasty, imaging, aspiration, pressure or flow measurement, etc. Many catheters for endovascular procedures are around 200 cm in total length and are administered via a cannula (introducer) that has been placed in an artery (e.g., the femoral, brachial, or radial artery). Catheters can be shorter, however, e.g., between 100 and 200 cm, or longer, e.g., between 200 and 400 cm. Often a vascular catheter is delivered along a guidewire. The catheter may have a lumen running the length of the catheter to accept a guidewire (over the rail) or only a portion of catheter, typically the distal tip  410 , will have a guidewire lumen (rapid exchange). 
         [0014]    In some instances, the catheters are placed with a guidewire. Access guidewires (generally “guidewires” herein) are known medical devices used in the vasculature or other anatomical passageway to act as a guide for other devices, e.g., a catheter. Typically, the guidewire is inserted into an artery or vein and guided through the vasculature under fluoroscopy (real time x-ray imaging) to the location of interest. In some procedures one or more devices are delivered over the guide wire to diagnose, image, or treat the condition. Guidewires typically have diameters of 0.010″ to 0.035″, with 0.014″ being the most common. Guidewires (and other intravascular objects) are also sized in units of French, each French being ⅓ of a mm or 0.013″. Guidewire lengths vary up to 400 cm, depending on the anatomy and work flow. The ends of the guidewire are denoted as distal (far from the user, i.e., inside the body) and proximal (near the user, i.e., outside the body). Often a guidewire has a flexible distal tip portion about 3 cm long and a slightly less flexible portion about 30 to 50 cm long leading up to the tip with the remainder of the guidewire being stiffer to assist in maneuvering the guidewire through tortuous vasculature, etc. The tip of a guidewire typically has a stop or a hook to prevent a guided device, e.g., a catheter from passing beyond the distal tip. In some embodiments, the tip can be deformed by a user to produce a desired shape. 
         [0015]    In some instances, the catheter comprises a resilient inner coil, making it possible to shape the catheter and deliver it to targeted anatomy, e.g., the heart. Such catheters are generally known as guide catheters and are often used to deliver fluids, e.g., contrast agents to critical areas, or to deliver the catheter to tortuous locations, such as vasculature or the heart. Because the catheters are rather narrow, e.g., typically 8 French or less, it is also possible to guide a second catheter, for example, an imaging or therapeutic along the guide catheter to a desired location along the guide catheter. 
         [0016]    An embodiment of a catheter system  10  for use with the invention is shown in  FIG. 1 .  FIG. 1  is merely exemplary, as many other configurations of the catheter system  10  are possible to achieve the principles of the invention. The catheter system  10  includes a guide catheter  12  having a catheter body  14  with a proximal end  16  and a distal end  18 . A luminal opening at the distal end  18  allows a fluid to be delivered to a patient. Catheter body  14  is flexible and defines a catheter axis  15 , and may include multiple lumens, such as a guidewire lumen, an inflation lumen, and a fluid delivery lumen. Catheter  12  includes an inflatable balloon  19  (expandable member), proximal to the distal end  18 , and a housing  29  adjacent proximal end  16 . When inflated, balloon  19  assures than no more than a distance d of guide catheter can be inserted into an anatomical structure or it assures that at least a length d of guide catheter stays within a structure. Additional lumens may be provided for other treatments, such as irrigation, aspiration, perfusion, or delivery of a device, e.g., a stent. 
         [0017]    In an embodiment, housing  29  includes a first connector  26  in communication with the guidewire lumen and a second connector  28  in fluid communication with the inflation lumen (not shown). In some embodiments, a separate inflation lumen is not necessary because the balloon  19  is inflated with pressure from the delivery lumen (see  FIG. 2 ). In embodiments using an inflation lumen, the lumen extends between balloons  19  and second connector  28 . Both first and second connectors  26 ,  28  may optionally comprise standard connectors, such as Luer-Loc™ connectors. 
         [0018]    Housing  29  additionally provides a connection to a pump  38  coupled to a fluid source, e.g., saline or contrast. The pump  38  may be any pump suitable to deliver sufficient pressure to push the fluid through the delivery lumen to be administered via the distal opening. In some embodiments, the pump  38  will be designed to give an initial burst of pressure to inflate the balloon  19 . The pump  38  may be a peristaltic pump, or the pump  38  may be a syringe. The reservoir  40  is any suitable reservoir to hold the fluid prior to delivery to the patient. The reservoir  40  may comprise pressure and temperature controls to maintain the fluid in optimum condition. In simple embodiments, both the pump  38  and the reservoir  40  take the form of a single syringe. In advanced embodiments, as shown in  FIG. 1 , the pump  38  and the particle reservoir  40  may be controlled by a controller  42  that is interfaced with patient monitoring equipment, e.g., a blood oxygen sensor, or a pressure sensor. 
         [0019]    The controller  42  may include a processor, or is coupled to a processor, to control and/or record treatment. The processor will typically comprise computer hardware and/or software, often including one or more programmable processor units running machine readable program instructions or code for implementing some or all of one or more of the methods described herein. The code will often be embodied in a tangible media such as a memory (optionally a read only memory, a random access memory, a non-volatile memory, or the like) and/or a recording media (such as a floppy disk, a hard drive, a CD, a DVD, a non-volatile solid-state memory card, or the like). The code and/or associated data and signals may also be transmitted to or from the processor via a network connection, and some or all of the code may also be transmitted between components of catheter system  10  and within processor  42 . 
         [0020]    While the guide catheter  12  of the catheter system  10  of  FIG. 1  uses a separate inflation lumen to expand the balloon  19 , the balloon can also be expanded using the pressure of the fluid to be delivered with the distal end  18  of the catheter, as shown in  FIGS. 2A and 2B . In a first embodiment  100 , shown in  FIG. 2A , the distal end  18  does not have a restriction, thus fluid must be overpressurized to deliver the fluid and expand the balloon  19 . In a second embodiment, shown in  FIG. 2B , the distal end  18  comprises a restriction  120  causing the pressure of the delivered fluid to build up at the distal end  18 , thereby expanding the balloon  19 . 
         [0021]    As shown in  FIG. 3 , the guide catheter having expandable members can be used to effectively and reliably place the distal tip  18  of the catheter inside an ostium  310  of an artery  330 . This placement assures that the length d of the guide catheter inside the ostium is appropriate for the procedure. In some embodiments, the guide catheter will have markers distal to the balloon  19 , allowing a surgeon to modify the length of the distance d as needed for the procedure. An additional benefit of the balloons is that fluids flushed from the catheter will be directed distally away from the tip. This feature is more readily appreciated on viewing  FIG. 4 , discussed below. 
         [0022]    An alternative use of a catheter of the invention is shown in  FIGS. 4A-4B . In this embodiment, the catheter  200  has been placed in a lumen  280 , which may be an artery or vein on the order of the same size as the catheter  200 . The catheter  200  includes a balloon  210 , a catheter body  230 , a distal tip  235 , and a fluid delivery lumen  250 . The balloon  210  has a proximal side (depicted as left in  FIGS. 4A-4B ) and a distal side (depicted as right in  FIGS. 4A-4B ). The balloon  210  expands radially when inflated with a fluid or a gas, e.g., as discussed above. The balloon  210  is constructed from a compliant material that can withstand high pressures. 
         [0023]    The sequence of insertion, inflation, and fluid delivery is shown in  FIGS. 4A-4B , respectively. As shown in  FIG. 4A , prior to inflation, the balloon  210 , positioned near the distal tip  235 , is placed within a biological lumen  280 . In an embodiment, the balloon  210  has helical folds to facilitate conversion between an expanded (inflated) configuration and a low profile configuration, needed for delivery and removal. 
         [0024]    Once the catheter  200  is in place, the balloon  210  is inflated to obstruct the lumen, as shown in  FIG. 2B . For example, the balloon  210  may be inflated with saline or another biocompatible fluid. Alternatively, the balloon  210  may be expanded with the delivery fluid, e.g., using the pressure of the fluid as described above with respect to  FIGS. 2A and 2B . Once the balloon  210  is inflated, a fluid introduced via the distal end  235  can only travel to the distal side of balloon  210 . When used with a contrast agent, the inflated balloon  210  will result in sharp line on the fluoroscope detailing the exact location of the catheter end. This method will also be useful if the catheter is inserted against the normal flow of fluid in the lumen, e.g., blood flow. Once the angioplasty procedure is complete, the balloon  210  is deflated, returning the catheter  200  to roughly the configuration in  FIG. 4A . In this configuration, it is safe to remove the catheter  200  from the biological lumen  280 . 
         [0025]    The methods of the invention can also be used with various imaging catheters. For example, the imaging could be IVUS, OCT, or visible imaging. IVUS uses a catheter with an ultrasound probe attached at the distal end. Systems for IVUS are also discussed in U.S. Pat. No. 5,771,895, U.S. Pat. Pub. 2009/0284332, U.S. Pat. Pub. 2009/0195514, U.S. Pat. Pub. 2007/0232933, and U.S. Pat. Pub. 2005/0249391, the contents of each of which are incorporated herein by reference. OCT uses interferometric measurements to determine radial distances and tissue compositions. Systems for OCT imaging are discussed in U.S. Pat. No. 7,813,609 and US Patent Publication No. 20090043191, both of which are incorporated herein by reference in their entireties. Visible imaging can be accomplished using known digital imaging technology, for example, using a megapixel CCD arrays. The CCD array may be incorporated into the catheter, or the images can be collected with an optical fiber and directed onto a CCD outside of the catheter. In most instances, visible imaging will additionally require an illumination source, which can be provided using an optical fiber coupled to an illumination source, or an illumination source can be incorporated into the catheter, e.g., an LED. Direct imaging with other wavelengths, e.g., infrared, is also possible using known light sources and detection equipment. For example, a catheter could incorporate an infrared light source and an infrared photodiode array to produce infrared images of the interior of a lumen. The devices of the invention may include static imaging assemblies that do not move with respect to the catheter body, or the invention may include moving imaging assemblies. For example, the imaging assembly may be a phased array of ultrasonic transducers for IVUS imaging, or a collection of CCD arrays. An array of elements will typically cover a circumference of the catheter to provide a 360° view of the lumen. In other embodiments, the imaging assembly may rotate or translate using drive cables within the catheter body. Catheters having imaging assemblies that rotate and translate are known generally as “pull-back” catheters. The principles of pull-back OCT are described in detail in U.S. Pat. No. 7,813,609 and US Patent Publication No. 20090043191, both of which are incorporated herein by reference in their entireties. The mechanical components, including drive shafts, rotating interfaces, windows, and couplings, are similar between the various forms of pull-back imaging. 
         [0026]    While the invention is described as delivering fluids, e.g., contrast, to the vasculature, it is understood that similar methods could be used to deliver fluids to a number of tissues that are accessible via the various lumen of the body, including, but not limited to vasculature of the lymphatic and nervous systems, various structures of the gastrointestinal tract including lumen of the small intestine, large intestine, stomach, esophagus, colon, pancreatic duct, bile duct, hepatic duct, lumen of the reproductive tract including the vas deferens, uterus and fallopian tubes, structures of the urinary tract including urinary collecting ducts, renal tubules, urethra, and bladder, and structures of the head and neck and pulmonary system including sinuses, parotid, trachea, bronchi, and lungs. 
         [0027]    Additional embodiments of the invention including other combinations of oxygenated particle delivery, treatment and assessment will be evident to those of skill in the art in view of this disclosure and the claims below. 
       INCORPORATION BY REFERENCE 
       [0028]    References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, and web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes. 
       EQUIVALENTS 
       [0029]    Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.