Patent Publication Number: US-2021186726-A1

Title: System and method for controlled delivery of medical devices into patient bodies

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. patent application Ser. No. 16/176,481, filed Oct. 31, 2018. 
    
    
     FIELD OF THE INVENTION 
     The present invention is directed to medical devices, and, in particular, to minimally invasive devices which are used for treatment within the human (or animal) body internal passages, such as, for example, vasculature (such as blood vessels), or bile duct, as well as renal ureteric duct, etc. 
     The subject invention further addresses a delivery system for percutaneous coronary intervention adapted, for example, for intravascular balloon angioplasty. 
     The present invention is also directed to medical devices designed for intravascular deployment of therapeutic elements, such as, for example, stents, using a balloon catheter that is lockable in vivo to a delivery component, such as a guidewire. 
     In overall concept, the present invention is directed to a system and method for deployment of a therapeutic element, such as a stent, in a patient&#39;s body internal passages (for example, intravascular, or other internal tube-like structures in a patient&#39;s body) in a controlled robust manner which permits a reduction of a number of equipment exchanges needed to deploy the therapeutic element at a lesion site within an internal tube-like structure (for example, a blood vessel, in a patient&#39;s body) while securing a delivery component, such as a guidewire, within the blood vessel during advancement of the therapeutic element to the lesion site. 
     Further, the present system is directed to a balloon catheter which is provided with a locking mechanism to lock in vivo to a delivery component, e.g., a guide wire, inserted into the blood vessel under treatment, where the locked balloon catheter facilitates delivery of additional components (such as a therapeutic delivery catheter) along the delivery component (the guidewire) to a target site for treatment while enhancing the stability of the delivery component, when in proximity to the target site. 
     The present invention is also directed to an intravascular delivery system supported by a balloon catheter equipped with a mechanism to anchor and stabilize a guidewire near the target site for superior delivery of additional intravascular components along the guidewire by minimizing movement of the distal end of the guidewire within the blood vessel, thereby enhancing guidewire stability in vivo. 
     The present invention is also directed to an intravascular kink resistant delivery system which is reinforced by an external rail (or a buddy system) to help advancement of the additional intravascular device (such as a stent) to the lesion. 
     In addition, the present invention is directed to a method of using the delivery system where a balloon catheter is delivered to a lesion in a blood vessel over a guidewire and the balloon of the balloon catheter is inflated with a conventional balloon inflation mechanism to dilate the blood vessel and disrupt the lesion. The balloon then is deflated, and moved adjacent to the lesion, and the balloon catheter is locked to the guidewire by inflating the balloon. Subsequently, one or more additional intravascular components may be delivered to the lesion, while the balloon catheter remains locked to the guidewire to anchor and stabilize the guidewire within the blood vessel. 
     BACKGROUND OF THE INVENTION 
     Ischemic cardiovascular syndromes affect blood flow by narrowing, weakening, or blocking a blood vessel, often resulting from the buildup of material (referred to herein as a lesion) within the blood vessel. Ischemic cardiovascular syndromes may include the coronary vascular syndrome, sometimes referred to as coronary artery disease (CAD), generally associated with blood vessels leading to/from the heart, as well as the peripheral vascular syndrome, commonly referred to as the peripheral artery disease (PAD), associated with blood vessels which do not lead to/from the heart or the brain. 
     Endovascular treatment for ischemic cardiovascular syndromes permits access to vascular lesions through percutaneous introduction of catheters through a blood vessel, such as, for example, the femoral artery, and therefore involves less patient trauma than an open surgical approach. 
     Percutaneous transluminal angioplasty of coronary and peripheral arteries (PTCA and PTA, respectively) are widely accepted as the revascularization procedures of choice in patients with ischemic cardiovascular syndromes (e.g., chronic and acute coronary ischemic syndromes) and peripheral ischemic syndromes (such as the chronic limb ischemia, including claudication and critical limb ischemia). 
     However, the use of the conventional percutaneous treatments may be limited due to re-occlusion or restenosis. This could be due to the exuberant proliferation of smooth muscle cells that grow to occlude the treated vessel segment, progression of atherosclerotic plaque or negative remodeling of the treated segment causing reoccurrence of symptoms. Re-occlusion, or restenosis, may necessitate potential re-intervention for additional treatment. 
     Various adjuncts to angioplasty seek to reduce restenosis through numerous techniques. These techniques may include extractional, rotational, orbital, or laser atherectomy, as well as the use of bare metal and bare nitinol stents. More recently, drug eluting stents (DES) started to be used to treat/prevent restenosis. The latter technology has been demonstrated to significantly reduce coronary artery restenosis when compared to angioplasty or bare metal stents. 
     In peripheral arteries, the use of bare nitinol stents has been shown to be superior to balloon angioplasty alone and has emerged as the “default” percutaneous strategy for the treatment of chronic limb ischemic syndromes, particularly in complex disease patterns involving the femoropopliteal artery. 
     Stents have been customarily used for treating occlusive vascular disease. For example, U.S. Pat. No. 5,135,536 to Hillstead and U.S. Pat. No. 5,314,444 to Gianturco describe a stent which comprises an expandable wire tube having a reduced diameter for transluminal placement. Once the stent is positioned within a vessel, a balloon catheter is used to expand the stent to support and reinforce the full circumference of the vessel. Such prior art stents typically have high radial strength to resist collapse due to vessel disease. 
     In the conventional procedure for a stent delivery following percutaneous transluminal angioplasty, initially a guidewire is percutaneously advanced to the lesion within a blood vessel. Subsequently, an angioplasty balloon catheter is advanced over the guidewire to the lesion. The angioplasty balloon catheter may be advanced in an over-the-wire (“OTW”) manner or in a rapid exchange (“RX”) manner. When in place, the balloon is inflated to expand the blood flow channel within the blood vessel at the lesion site. 
     In a subsequent step, the angioplasty balloon catheter is removed from the blood vessel while the guidewire remains in place, and a stent delivery balloon catheter is advanced over the guidewire to the lesion for stent delivery. 
     A drawback of the conventionally performed procedure is the limited safety and the difficulty of advancing the stent delivery balloon catheter across the lesion, even subsequent to the angioplasty due to the fact that the guidewire does not always constitute a sufficiently stable structure for the catheter advancement in the blood vessel. For example, the free distal tip of the guidewire can uncontrollably move around within the blood vessel. The uncontrollable motion of the distal end of the guidewire may cause its retraction into the guidewire lumen in the stent delivery balloon catheter during advancement within the vessel. This may happen when the blood vessel is tortuous, diffusely diseased, severely calcified, or when there is reduced support from the guiding catheter. If a clinician attempts to advance the stent delivery balloon catheter along an unstable distal free tip of the guidewire, there is a risk of vessel damage, including vessel dissection. Accordingly, a clinician often needs to remove the stent delivery balloon catheter and reintroduce an angioplasty balloon catheter over the guidewire to perform additional angioplasty procedures. This exposes an additional risk for the patient health, reduces efficiency of the procedure, abandonment without placement of the therapeutic device and is extremely expensive. 
     Given a growing patient population with conditions associated with a substantial vessel wall calcification, especially in patients suffering diabetes and/or chronic kidney disease, need for intravascular therapies increases dramatically. There is a patient population in which current therapies may be inefficient and/or ineffective. Thus, there is a need for an improved intravascular technology that permits intravascular deployment of a therapeutic element, such as a stent, in a controlled and robust manner. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a system and a method for deployment of a therapeutic element (such as a stent) in a tube-like internal structure in a patient&#39;s body, for example intravascular, or other passages, such as the bile duct or ureteric duct, in a controlled and robust manner that would support a reduced number of equipment exchanges needed to deploy the therapeutic device in proximity to a lesion site within a blood vessel, while efficiently securing (anchoring) a delivery component, such as a guidewire, within the blood vessel during advancement of the therapeutic element to the lesion site. 
     It is another object of the present invention to provide a locking mechanism for releasably securing the balloon catheter in vivo to a delivery component, e.g., a guidewire, so that the balloon catheter, being secured to the guidewire, facilitates the delivery of additional components, e.g., a therapeutic delivery catheter, along the guidewire to a target site while enhancing the stability of the guidewire in the blood vessel, especially near the target site. 
     It is an additional object of the present invention to provide an intravascular delivery system which prevents the guidewire&#39;s distal end from uncontrollable motion throughout the vessel lumen, providing a sufficient rigidity and stability of the guidewire in proximity to the target (lesion) site within a blood vessel, which is beneficial for delivery of a therapeutic element, e.g., a stent to the target site. 
     It is a further object of the present invention to provide an intravascular delivery system using a lockable balloon catheter equipped with a locking mechanism operating to anchor and stabilize the guidewire near the target site within the blood vessel for superior delivery of additional intravascular components along the guidewire, resulting in a reduced displacement of the distal end of the guidewire within the blood vessel, thus attaining enhanced guidewire stability in vivo. 
     It is also an object of the present invention to provide a method of using the subject balloon catheter controllably lockable to a guidewire within the blood vessel of interest for delivering the balloon catheter to a lesion in the blood vessel over a guidewire, inflating the balloon with a conventional balloon inflation system to pre-dilate the vessel and disrupt the lesion (such as, for example, calcified plaque, disposed on the luminal lining), subsequently deflating the balloon for displacement adjacent to the lesion, and locking the balloon to the guidewire by re-inflating the balloon. One or more additional intravascular components may be subsequently delivered to the lesion site while the subject balloon catheter remains locked to the guidewire which, in its turn, is anchored and stabilized within the vessel during the procedure. 
     In addition, it is an object of the present invention to provide a kink resistant intravascular delivery system where the shaft of the catheter is enhanced with an additional support and/or a rail mechanism for advancement of intravascular components along the guidewire while the balloon is in the locked or unlocked configuration. 
     In accordance with one aspect of the subject system, an intravascular system is provided for securely advancing a stent over a guidewire to a lesion within a blood vessel (or the bile duct or the ureteric duct) of a patient. The subject system may include an elongated catheter shaft having a proximal region, a distal region, an inflation lumen extending internal of the elongated catheter shaft between the proximal region and the distal region, and a guidewire lumen which extends between a rapid-exchange (RX) port formed within the elongated catheter shaft and a distal tip of the balloon catheter. 
     A balloon is affixed at the distal region of the elongated catheter shaft. A proximal end of the balloon is positioned a short distance of about 5 mm-30 mm apart from the rapid-exchange (RX) port. This arrangement attains stability in advancement of the stent along the guidewire to the lesion site within the blood vessel proximal to the rapid-exchange port while the balloon remains inflated within the blood vessel. 
     A locking portion of the elongated catheter shaft is disposed inside the balloon and extends between the proximal and distal ends of the balloon. The locking portion of the elongated catheter shaft may be configured to transition within the balloon from an unlocked mode of operation (when a diameter of the guidewire lumen is sized to permit its slidable displacement relative to the guidewire disposed within the guidewire lumen) to a locked mode of operation. In the locked mode of operation, the locking portion of the elongated catheter shaft is compressed within the balloon to reduce the diameter of the guidewire lumen, so that the walls of the guidewire lumen come into contiguous contact with the guidewire and become circumferentially coupled to and compress the guidewire to “anchor” the guidewire within the guidewire lumen. 
     The locking portion of the elongated catheter shaft may include a flexible material to facilitate the compression of the guidewire with the walls of the guidewire walls. The flexible material may include a braided material. The braided material may be a metal composition and the braided material may be coated with a polymer such that the locking portion of the elongated catheter shaft within the balloon is fluid impermeable. 
     The balloon catheter may have a plurality of radiopaque markers disposed along the elongated catheter shaft. The radiopaque markers may be positioned adjacent to the rapid-exchange port. 
     In accordance with another aspect of the subject system, a method is provided for safe advancement of an intravascular delivery system over a guidewire along the balloon shaft to a lesion within a blood vessel of a patient. The method may include the steps of:
         fabricating a balloon catheter lockable to a guidewire within the blood vessel. The lockable balloon catheter includes an elongated catheter shaft having a proximal region, a distal region, a first lumen extending between the proximal region to the distal region, and a second lumen extending distally from a rapid-exchange (RX) port within the elongated catheter shaft.       

     A balloon is affixed to the elongated catheter shaft at the distal region such that a proximal end of the balloon is displaced from the rapid-exchange port a short distance of about 5 mm-30 mm to attain a stable advancement of the therapeutic element (stent) over the delivery component (guidewire) to the target site within the body lumen proximal to the rapid-exchange port while the balloon remains inflated within the body lumen. 
     The elongated catheter shaft may be configured to transition within the balloon from an unlocked mode of operation (when a diameter of the second lumen is sized to permit the slidable movement of the delivery component (guidewire) therein), to a locked state (when the elongated catheter shaft is compressed within the balloon to reduce the diameter of the second lumen to circumferentially contact the delivery component (guidewire) to lock the delivery component (guidewire) within the second lumen, responsive to pressurization within the balloon). 
     The subject method further includes the steps of:
         delivering the lockable balloon catheter to the lesion in the blood vessel over the guidewire;   inflating a balloon of the lockable balloon catheter to dilate the blood vessel and disrupt the lesion;   deflating the balloon;   displacing the deflated balloon on the balloon catheter past the lesion within the blood vessel; and   locking the balloon catheter to the guidewire by re-inflating the balloon.       

     Inflating the balloon compresses the walls of the second lumen within the balloon around the guidewire to lock the guidewire in place, and thus locks the balloon catheter to the guidewire. 
     The subject method continues by delivering another catheter (for example, a stent catheter) over the guidewire to the lesion site while the lockable balloon catheter remains locked to the guidewire to anchor and stabilize the guidewire within the blood vessel. 
     The subject system and method reduces the number of equipment exchanges needed to deploy the therapeutic devices at a lesion site within the blood vessel, while securing the delivery component within the blood vessel during advancement of the therapeutic catheter to the lesion site. 
     These and other objects and advantages of the subject system and method will become more apparent to a person of ordinary skill in the art upon reading the Detailed Description of the Subject Invention in conjunction with the Patent Drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an exemplary embodiment of the subject lockable balloon catheter; 
         FIG. 2  depicts an exemplary embodiment of the subject system intravascular delivery which includes a therapeutic delivery catheter, sheaths, and a guidewire, for use with the balloon catheter shown in  FIG. 1 ; 
         FIGS. 3A, 3B and 3C  are schematic representations of the distal region of the subject lockable balloon catheter shown in  FIG. 1  depicted, respectively, in the unlocked state ( FIG. 3A ) and the locked state ( FIG. 3B ), while  FIG. 3C  depicts a longitudinal cross-section of the subject lockable balloon catheter in the locked mode of operation; 
         FIGS. 4A and 4B  are schematic representations of the distal region of an alternative embodiment of the subject balloon catheter formed with a flexible material at the locking portion of the subject catheter within the balloon to facilitate the operation of the subject lockable balloon catheter in the unlocked mode of operation ( FIG. 4A ) and the locked mode of operation ( FIG. 4B ), respectively; 
         FIGS. 4C-4D  show schematically a wire-like kink resistant mechanism ( FIG. 4C ) or an alternative kink resistant mechanism attached at the RX port ( FIG. 4D ) embedded at the distal region of the elongated shaft between the RX port and the balloon; and 
         FIGS. 5A-5L  illustrate the exemplary steps of the intravascular delivery procedure using the subject lockable balloon catheter to deliver a therapeutic device to a target site within a blood vessel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1-4D and 5A-5L  depict a system for deployment of a therapeutic device within a tube-like internal structure of a patient&#39;s body (such as a blood vessel (body lumen), or the bile duct, as well as ureteric duct, etc.). Although the principles of the subject system and method are applicable for treatment procedures associated with different internal passages (tube-like structures) within a patient&#39;s body, the following description of the subject system design and operation will be focused on the intravascular applications. 
     The subject system includes a balloon catheter which is capable of locking in position in vivo to a delivery component, such as, for example, a guidewire, disposed within a blood vessel. Subsequent to locking the lockable balloon catheter to the guidewire, another catheter for delivery of a therapeutic device, such as a stent, may be advanced over the guidewire to a target site in the blood vessel while the locking balloon catheter stably anchors the guidewire in place adjacent to the target site in the blood vessel. 
     The subject system is particularly well-suited for treating conditions associated with vessel wall tortuosity, diffuse disease, calcification or poor guiding catheter support during ischemic cardiovascular syndromes including the coronary vascular syndrome, sometimes referred to as coronary artery disease (CAD), as well as the peripheral vascular syndrome, sometimes referred to as the peripheral artery disease (PAD). 
     Referring to  FIG. 1 , the subject intravascular delivery system  1  includes a balloon catheter  10  which includes an elongated shaft  12  extending between a proximal region  14  and a distal region  16  of the balloon catheter  10 . A balloon  18  is mounted to the elongated shaft  12  at the distal region  16 . The elongated shaft  12  has a portion  17  extended inside the balloon  18  (further referred to herein as a locking portion  17 ). 
     The proximal region  14  of the elongated shaft  12  preferably includes a handle  20  for helping a clinician to manipulate the lockable balloon catheter  10 . 
     A balloon inflation port  22  at the proximal end  23  of the proximal region  14  is coupled to the interior  19  of the balloon  18  through an inflation lumen  24  extending within the elongated shaft  12 , as depicted in  FIGS. 3A-3C . 
     The handle  20  and the balloon inflation port  22  may be elements used in conventional balloon catheters, and are not detailed herein with further specifics. Similar to the proximal region  14  of the subject lockable balloon catheter  10 , the handle  20  and the balloon inflation port  22  may be formed from materials conventionally used in the intravascular catheters, e.g., polyethylene and/or polyterephthalate. 
     The lockable balloon catheter  10  preferably has a length and diameter suitable for use in a cardiac or peripheral vessel under treatment. The balloon catheter  10  may have the length ranging from 60 cm to 180 cm and a diameter ranging from 1.0 mm to 60 mm. 
     The balloon  18  may assume a closed (deflated) configuration (shown in  FIGS. 3A and 4A, 4C, 5B, 5D-5E, and 5H-5I ), or an inflated (expanded) configuration (shown in  FIGS. 1-2, 3B-3C, 4B, 4D, 5C, and 5F-5G ). Shown in  FIG. 1 , the balloon  18  is depicted in an expanded configuration suitable for dilating the blood vessel. The balloon  18  may be formed of a noncompliant material (such as polyethylene), a semi-compliant material (such as polyterephthalate), or a compliant material (such as nylon). 
     The balloon  18  may be sized and shaped for insertion in the blood vessel as appropriate for an intended therapy and a bodily lumen (blood vessel) under treatment. For example, the length of the balloon  18  may range from 1 cm to 20 cm. The balloon  18  may have a diameter, in the expanded configuration, of about 1.0 mm-6.0 mm for insertion in smaller lumens (such as coronary vessels). Alternatively, the balloon  18  may have a diameter of about 4 mm-10 mm for insertion in larger lumens (such as peripheral vessels). The balloon  18  may also have a diameter of about 1 cm-6 cm if the catheter  10  is used for the therapy associated with the thoracic or abdominal aorta. 
     The balloon  18  is preferably affixed to the locking portion  17  of the elongated shaft  12  via thermal bonds, glue welds, or other suitable methods. 
     The balloon  18  is configured to expand when it is pressurized responsive to the introduction of a fluid (air) through the balloon inflation port  22  under control of a balloon inflation system  25 . 
     The balloon inflation system  25  is operatively coupled to the balloon inflation port  22  in a fluidly sealed fashion to support passage of the inflation fluid  27  (such as, for example, saline, iodinated contrast media, or air) to and from the balloon  18 . 
     The balloon inflation system  25 , which is schematically depicted in  FIG. 1 , may be a manual or an automatic system. In the preferred automatic embodiment, the balloon inflation system  25  may include an electronic sub-system, a pneumatic sub-system, and a control software with a corresponding user interface. The electronic sub-system, under control of the control software, supplies power to solenoid pressure valves (which are fluidly coupled to the balloon inflation port  22 ) to control the pressurizing/depressurizing cycles of the operation of the subject balloon system with the air flow. 
     The inflation lumen  24  is configured with and terminates, at its distal end, in a balloon inflation port  26 , which is disposed within the interior  19  of the balloon  18 , preferably, in proximity to the balloon&#39;s proximal end  33 . The inflation lumen  24  extends internally of the elongated shaft  12  between the balloon inflation port  22  and the balloon  18  to provide bi-directional passage of the fluid (air) therealong for pressurizing/de-pressurizing of the balloon  18 . 
     In the pressurized state, the balloon  18  assumes the expanded (inflated) configuration (shown in  FIGS. 1, 2, 3B-3C, 4B, 4D, 5C, and 5F-5G ). While in the depressurized state, the balloon  18  assumes a deflated (closed) configuration (shown in  FIGS. 3A, 4A, 4C, 5B, 5D, 5E, 5H, 5I, and 5J ). 
     The subject intravascular delivery system  1  operates in conjunction with a delivery component  31 , such as, for example, a guidewire. The guidewire  31  is advanced inside the blood vessel towards (and preferably beyond) the lesion site prior to the cardiac (or other intravascular) procedure. The intravascular delivery system  1  is subsequently displaced along the guidewire  31  internally of the blood vessel to a position corresponding to a lesion site for pre-dilatation, or other treatment. 
     The lockable balloon catheter  10  is configured with a guidewire lumen  28  extending internally the elongated shaft  12  between the rapid-exchange (RX) port  30  and the tapered tip  32 . The guidewire  31  extends inside the guidewire lumen  28  and extends distally beyond the tapered tip  32 . 
     The guidewire lumen  28  is sized to permit the passage of the guidewire  31  therethrough. For example, the guidewire lumen  28  may be sized to permit the guidewire to be inserted therethrough to facilitate displacement of the distal region  16  to a desired location along the guidewire  31  in a patient&#39;s vasculature or an organ. 
     As shown in  FIG. 3C , the guidewire lumen  28  may be located centrally in the elongated shaft  12 , or alternatively, may be off-center. Preferably, the guidewire lumen  28  is compressible responsive to actuation of the balloon inflation system  25  by a clinician, e.g., inflation of balloon  18 , to lock the guidewire  31  therein, as will be detailed in further paragraphs. 
     The elongated shaft  12  may preferably be formed of a flexible material to facilitate compression of the guidewire lumen  28 . The elongated shaft  12  may be formed of a flexible material along its entire length, or along a select portion(s) of its length, such as the locking portion  17  within the balloon  18 . 
     In the subject system  1 , the lockable balloon catheter  10  is equipped with a locking mechanism which includes and is supported by cooperation of the balloon inflation system  25 , inflation lumen  24 , balloon  18 , and locking portion  17  of the elongated shaft  12  to transform the subject system between the locked mode of operation and the unlocked mode of operation. 
     In the locked mode of operation, the inflation of the balloon  18  is used to lock the balloon catheter  10  to the guidewire  31 . As an example, the inflation of the balloon  18  at a predetermined pressure (e.g., a high pressure), causes the locking portion  17  of the elongated shaft  12  to press against the guidewire  31  (as depicted in  FIGS. 3B-3C, 4B, and 4D ), thereby causing the walls of the guidewire lumen  28  (extending from the RX port  30  into the balloon  18 ) to compress around the delivery guidewire  31 , thus locking the guidewire  31  within the elongated shaft  12 . In the compressed configuration, the contiguous coupling between the walls of the guidewire lumen  28  and the guidewire  31  prevents relative displacement between the guidewire  31  and the elongated shaft  12 . Thus, the contiguous coupling between the walls of the guidewire lumen  28  and the guidewire  31  resulted from the controlled pressurizing of the balloon  18 , as needed by the therapeutic procedure, locks the guidewire  31  to the elongated shaft  12  of the balloon catheter  10 . 
     When the inflation system  25  of the locking mechanism deflates the balloon, the walls of the guidewire lumen  28  return to their original configuration, thus releasing the guidewire from the coupling with the elongated shaft  12 , thereby transitioning into the unlocked mode of operation. In the unlocked mode of operation, the guidewire and the elongated shaft  12  are free to be displaced one relative to the other. 
     The RX (Rapid Exchange) port  30  is formed at the elongated shaft  12  a short distance from the proximal end  33  of the balloon  18 . This arrangement permits the delivery of a therapeutic delivery catheter along the guidewire  31  to a target site in a blood vessel while the balloon catheter  10  remains locked to the body lumen, as shown in  FIGS. 5G-5J , and as will be detailed in further paragraphs. 
     For example, while a typical rapid-exchange port is conventionally displaced at least 15 cm from a balloon, the RX port  30  in the subject system  1  may be disposed much closer, e.g., about 1-5 mm to 30 mm from the subject balloon&#39;s proximal end  33 . 
     The compactness of the subject structure has a beneficial result, since the guidewire  31  exits from the elongated shaft  12  via the RX port  30  within the blood vessel, and the therapeutic delivery catheter can be positioned in proximity to the RX port  30  and the balloon  18  while the balloon  10  remains securely locked to the guidewire  31  in the body lumen, thus providing favorable stable conditions for stent delivery. The therapeutic delivery catheter is thus anchored and stabilized within the body lumen. 
     The subject balloon catheter  10  may include one or more radiopaque markers to facilitate positioning of the balloon catheter  10  under fluoroscopic imaging. As shown in  FIG. 1 , the balloon catheter  10  includes radiopaque markers  34 ,  36 ,  38 ,  40 , and  42  positioned along the elongated shaft  12 . The radiopaque markers may be fabricated from conventional materials, such as platinum or iridium. The radiopaque markers  34  and  36  are positioned adjacent to the distal end  37  and the proximal end  33  of the balloon  18 , respectively, for visualizing the location of the balloon  18  in the blood vessel. The radiopaque marker  38  is positioned adjacent to the RX port  30  to permit visualization of the location of the RX port  30 . The radiopaque markers  40  and  42  are shaft markers and may be displaced about 90 and 100 cm, respectively, from the distal end (tip)  32  of the elongated shaft  12 . 
       FIG. 2  shows an alternative configuration of the subject intravascular delivery system which uses the lockable balloon catheter  10  shown in  FIG. 1 . The system includes a therapeutic delivery catheter, one or more sheaths, and the delivery component. In the illustrated example, shown in  FIG. 2 , the system  50  includes the lockable balloon catheter  10 , a sheath  52 , a sheath  54 , a delivery component (guidewire)  56 , and a therapeutic delivery catheter  60 . 
     The sheath  52  is sized and shaped for intravascular delivery procedure. The sheath  52  constitutes a lumen to permit the lockable balloon catheter  10  to be disposed therein for a delivery procedure. 
     The sheath  54  is sized and shaped for intravascular delivery and constitutes a lumen to permit the therapeutic delivery catheter  60  to be disposed therein for the intravascular delivery. The sheaths  52  and  54  may be conventional sheaths used in intravascular procedures. 
     The delivery component  56  is sized and shaped for the intravascular delivery procedure, and may be a guidewire, as illustrated. In one example, the delivery component  56  is a conventional guidewire used in intravascular procedures. 
     The therapeutic delivery catheter  60  is designed to intravascularly deliver a therapeutic device (such as a stent) to a target site in a body lumen. The therapeutic delivery catheter  60  includes an elongated shaft  62  having a proximal region  64  and a distal region  66 . A balloon  68  is mounted at the distal region  66  of the elongated shaft  62 . 
     The proximal region  64  of the elongated shaft  62  is manipulated by a clinician. For this purpose, the proximal region  64  is equipped with a handle  67 . A balloon inflation port  72  is coupled to the interior  73  of the balloon  68  through an inflation lumen  75  extending internally along the elongated shaft  62 . 
     A guidewire port  74  is coupled to the distal region  66  of the elongated shaft  62  through a guidewire lumen  77 . The guidewire lumen  77  is sized to receive the guidewire  56  therein. 
     The handle  67  and the ports  72  and  74  are conventional elements, and similar to the proximal region  64  of the therapeutic delivery catheter  60 , may be formed from materials conventionally used for fabrication of intravascular catheters, e.g., polyethylene or polyterephthalate. The therapeutic delivery catheter  60  preferably has a length and diameter suitable for use in the therapeutic procedures associated with cardiac or peripheral vessels. 
     The therapeutic delivery catheter  60  is configured to deliver a therapeutic device  70 , which may be, for example, a stent. In the example, depicted in  FIG. 2 , the therapeutic delivery catheter  60  includes the balloon  68  disposed at a predetermined location at the distal region  66  of the elongated shaft  62  within the therapeutic device  70 . When the balloon  68  is expanded (as the result of introducing the fluid (or air) into the balloon inflation port  72 ), it causes the therapeutic device  70  to expand from a delivery (deflated) configuration to a deployed (expanded) configuration. 
     While the therapeutic delivery catheter  60  is depicted in the exemplary embodiment as a balloon catheter for stent delivery (e.g., bare metal stent or drug-eluting stent), the therapeutic delivery catheter  60  may also deliver other types of therapeutics and may be, for example, a drug-delivery catheter, a balloon catheter, a drug-eluting balloon catheter, or an energy delivery catheter. Examples of drugs that may be delivered include anti-mitotic drugs, regenerative agents, anti-inflammatory agents, anti-allergenic agents, anti-bacterial agents, anti-viral agents, anticholinergic agents, antihistamines, antithrombotic agents, anti-scarring agents, antiproliferative agents, antihypertensive agents, anti-restenosis agents, healing promoting agents, vitamins, proteins, genes, growth factors, cells, stem cells, vectors, RNA, and/or DNA. The energy delivery catheter may include numerous types of energy, including the ultraviolet light, ultrasound, resistive heat, radio frequency (RF), and cryogenic. 
       FIGS. 3A, 3B, and 3C  depict the distal region  16  of one embodiment of the subject lockable balloon catheter  10 .  FIGS. 3A and 3B  show, respectively, the balloon catheter  10  in the unlocked state ( FIG. 3A ) and the locked state ( FIG. 3B ), while  FIG. 3C  shows the longitudinal cross-section of the subject balloon catheter  10  in its locked state. 
     In  FIG. 3A , the elongated catheter shaft  12  is in the unlocked state (mode of operation). In the unlocked state, the diameter of the guidewire lumen  28  is sized to support the slidable movement (displacement) of guidewire  31  therein. 
     The elongated shaft  12  is designed to transition to the locked state, shown in  FIGS. 3B-3C , by compressing the locking portion  17  of the elongated shaft  12  inside the balloon  18  to reduce the diameter of the guidewire lumen  28  when the balloon  18  is inflated, so that the walls of the elongated shaft  12 , at its locking portion  17 , circumferentially embrace and press on the guidewire  31  to lock the guidewire  31  within the guidewire lumen  28 . For example, introduction of the fluid (air) into the balloon  18  via the inflation lumen  24  and the balloon inflation port  26  inflates the balloon  18  and pressurizes the internal space  19  of balloon  18  to a level that compresses the walls of the locking portion  17  of the elongated catheter shaft  12 , as shown in  FIGS. 3B and 3C . 
     Advantageously, the inflation of the balloon  18 , in addition to coupling the guidewire lumen  28  to the guidewire  31 , may also increase the coupling of the walls of the balloon  18  with the inner lining of the body lumen  100 , thereby anchoring the balloon  18  within the body lumen to stabilize the locked guidewire  31  within the body lumen  100 , as shown in  FIGS. 3A-3B . 
       FIGS. 4A and 4B  depict the distal region of a catheter  10 ′ similar to that shown in  FIGS. 3A, 3B, and 3C . The catheter  10 ′ includes a flexible material  44  at the locking portion  17 ′ of the elongated shaft  12 ′ within the balloon  18 ′ to facilitate the locking mechanism. The lockable balloon catheter  10 ′ is fabricated in the configuration similar to the lockable balloon catheter  10  shown in  FIGS. 1-2 and 3A-3C , so that similar components are indicated with similar number with prime. The flexible material  44  may extend along the elongated shaft  12 ′ only within balloon  18 ′ (only at the locking portion  17 ′) or may extend further along the entire length of the elongated shaft  12 ′. The flexible material  44  may be formed from a braided material, e.g., braided metal, such as stainless steel. The braided material may be coated with another fluid impermeable material, such as a polymer. As is shown, the flexible material  44  at the locking portion  17 ′ is configured to compress upon actuation, e.g., inflating and pressurizing of the balloon  18 , thereby locking the guidewire lumen to the delivery component  56 ′. 
     Referring to  FIGS. 4C-4D , in an alternative implementation, the subject balloon catheter  10 ″ may be enhanced by a kink resistant mechanism  120 . A portion of the subject system between the RX port  30  and the balloon  18 , is vulnerable to possible sharp twists, buckling, and/or curving of the elongated catheter shaft  12  when the inflated balloon  18  is pulled along the guidewire as another delivery device (stent) is advanced over the guidewire. 
     In order to prevent the unwanted deviation of the elongated catheter shaft  12  from the straight configuration during the cardiac procedure, the subject system  10 ″, in its alternative implementation, is configured with the kink resistant mechanism  120 . The kink resistant mechanism  120  may be formed with a Nitinol/Steel wire-like member (or stamped elongated member)  122  affixed internally along the elongated catheter shaft  12  between the RX port  30  and the balloon  18  (as shown in  FIG. 4C ). Alternatively, the kink resistant mechanism  120  may be formed from Nitinol/Steel as an elongated member  124  configured with elongated parts  126  connected (preferably integrally therewith) through a central circular (or oval) shaped part  128 . The elongated member  124  may be embedded in the wall of the elongated catheter shaft  12 , as well as may be attached internally or externally along the elongated catheter shaft  12  (as shown in  FIG. 4D ) with the central part  128  secured to the RX port  30  in alignment with the periphery of the RX port  30 . 
     Alternatively, the kink resistant mechanism  120  may be represented by both members  122  and  124  (combined embodiment) embedded in the wall of the elongated catheter shaft  12  or secured (internally or externally) to the wall of the elongated catheter shaft  12  between the RX port  30  and the balloon  18 . 
     In either configurations, either embedded, or secured internally or externally, or in the combined embodiment, the kink resistant mechanism  120  prevents sharp twisting, buckling, and curling of the elongated catheter shaft  12 , and thus provided a robust system capable of withstanding various scenarios of cardiac procedures. 
     Although shown in  FIGS. 4C-4D  in application to the embodiment depicted in  FIGS. 4A-4B , the kink resistant mechanism  120  is applicable to all alternative embodiments of the subject system shown in  FIGS. 1-5I . 
     The subject method may use the lockable balloon catheter  10  and  10 ′ to perform an interventional procedure. However, only as an example, the subject method is described infra for use with the lockable balloon catheter  10  depicted in  FIGS. 1, 2, and 3A-3C . The alternative catheters  10 ′ shown in  FIGS. 4A-4B  may also be used in a manner similar to that described below. 
     In  FIG. 5A , delivery component (guidewire) is advanced inside the blood vessel and is delivered to a target location. In this example, the delivery component  56  (illustratively, a guidewire) is placed in the vessel V at the location of a lesion L as determined by the fluoroscopic imaging technique, contrast agents and/or conventional interventional techniques. 
     As shown in  FIG. 5B , the balloon catheter  10  is backloaded onto the delivery component  56  by inserting the proximal end  80  of the guidewire  56  into the distal opening  82  of the guidewire lumen  28  located in the distal tip  32  of the balloon catheter  10 . The catheter  10  is advanced through the patient&#39;s vasculature V until the distal region  16  is disposed at the target location (e.g., the lesion L), as determined using the radiopaque markers on the catheter shaft  12  and the fluoroscopic imaging. When so disposed in a patient&#39;s vessel V, the distal region  16  of the balloon catheter  10  will appear as depicted in  FIG. 5B . During the delivery procedure, the balloon  18  of the catheter  10  may be wrapped or folded in the closed configuration. 
     Alternatively, a delivery sheath (such as sheath  52  shown in  FIG. 2 ) may be disposed over the distal region  16  of the balloon catheter  10  to attain a smooth outer surface for the lockable balloon catheter  10 . The sheath  52  then may be retracted proximally to expose the distal region  16  once it has reached the desired location L in vessel V. As shown, the guidewire  56  is disposed in the guidewire lumen  28  within the balloon  18  and exits the catheter  10  at the guidewire RX port  30 . 
     Referring now to  FIGS. 5C and 1 , a conventional inflator system  25  is coupled to the inflation port  22 , and the inflation medium  27 , such as, for example, saline or a saline diluted iodinated contrast agent, is delivered via the inflation lumen  24  to the balloon  18  to cause the balloon&#39;s expansion. In the inflated configuration, the walls  84  of the balloon  18  contact the lesion L and the intima of the vessel V to dilate the vessel V and disrupt the lesion L. Subsequently, as shown in  FIG. 5D , the balloon  18  is deflated. 
     Referring now to  FIG. 5E , the balloon  18 , in its deflated configuration, is advanced along the distal end  86  of the guidewire  56  to a location adjacent to, but beyond, the target site L within the body lumen V. For example, the lockable balloon catheter  10  and the delivery component  56  may be moved distally within the vessel V such that the RX port  30  is disposed distal to the target site L, and the proximal end  80  of the delivery component (guidewire)  56  is located outside of the catheter  10  and extends through the target site within the body lumen V. 
     Subsequently, as shown in  FIG. 5F , the balloon catheter  10  is locked to the delivery component  56  by introduction of the fluid  27  into the balloon  18  via the inflation lumen  24  and the balloon inflation port  26 . Introduction of the fluid  27  under high pressure inflates the balloon  18  and pressurizes the internal space  19  of the balloon  18  to a level that compresses the elongated catheter shaft  12  and forces the guide lumen  28  into tight contact with the delivery component  56  contained therein, thus compressing around the delivery component  56  and locking the delivery component  56  to the elongated shaft  12 . In addition, the inflation of the balloon  18  causes the walls  84  of the balloon  18  with or without a contiguous contact with the internal lining of the vessel V, thereby anchoring the balloon  18  within the vessel V to stabilize the locked delivery component  56  within the vessel V. 
     As presented in  FIG. 5G , when the balloon catheter  10  is locked to the delivery component  56 , and the balloon catheter  10  and the delivery component  56  are anchored in place within the body lumen (with or without contact of the walls  84  of the balloon  18  with the internal lining of the blood vessel V), the therapeutic delivery catheter  60  may be delivered along the delivery component  56  to align the therapeutic device  70  with the target site L. During delivery, the balloon  68  of therapeutic delivery catheter  60  may be folded. Alternatively, a delivery sheath (such as the sheath  54  shown in  FIG. 2 ) may be disposed over the distal region  66  of the catheter  60  to form a smooth outer surface for the therapeutic delivery catheter  60 . The sheath  54  subsequently may be retracted proximally to expose the distal region  66  once it reaches the desired location in the vessel V. In the body lumen, the lockable balloon catheter  10  remains separate from the therapeutic delivery catheter  60 , although both use the same delivery component  56  in the lumen V. 
     Subsequently, as shown in  FIG. 5H , the lockable balloon catheter  10  is unlocked from the delivery component  56 . For example, deflation of the balloon  18  may result in decompression of the elongated shaft  12  so that the diameter of the guidewire lumen  28 , at its locking part  17 , expands to permit slidable displacement of the guidewire  56  therewithin. 
     As shown in  FIG. 5I , the delivery component (guidewire)  56  is then removed from the lockable balloon catheter  10 . For example, the delivery component  56  may be pulled proximally while the lockable balloon catheter  10  is held in place until the distal end  86  of the delivery component  56  exits the RX port  30 . Alternatively, the lockable balloon catheter  10  can be moved distally while the delivery component  56  is held in place until the distal end  86  of the delivery component  56  exits the RX port  30 . 
     As shown in  FIG. 5J , the lockable balloon catheter  10  is then displaced proximally past the target site L while the therapeutic delivery catheter  60  remains positioned at the target site L within the blood vessel V. The lockable balloon catheter  10  may be removed entirely from the patient&#39;s blood vessel V, or may be displaced a suitable proximal distance to permit the therapeutic deployment. Alternatively, the balloon catheter may be moved to a different vessel or a branch of the vessel V. 
     As shown in  FIG. 5K , the therapeutic device (stent)  70  is then deployed at the target site L. For example, the balloon  68  may be inflated to expand, thereby causing the therapeutic device  70  to expand and contact the inner wall of the vessel V. 
     Subsequently, as shown in  FIG. 5L , in the case when the therapeutic device (stent)  70  is designed for implantation, the therapeutic delivery catheter  60  is removed, leaving the therapeutic device  70  implanted at the target location L. 
     Although this invention has been described in connection with specific forms and embodiments thereof, it will be appreciated that various modifications other than those discussed above may be resorted to without departing from the spirit or scope of the invention as defined in the appended claims. For example, functionally equivalent elements may be substituted for those specifically shown and described, certain features may be used independently of other features, and in certain cases, particular locations of elements, steps, or processes may be reversed or interposed, all without departing from the spirit or scope of the invention as defined in the appended claims.