Patent Document

PRIORITY CLAIM 
       [0001]    The present application claims the benefit of copending U.S. Provisional Patent Application Ser. No. 60/081,292 filed Jul. 16, 2008, which application is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a treatment system for percutaneous coronary angioplasty or peripheral angioplasty in which a dilation catheter is used to cross a lesion in order to dilate the lesion and restore normal blood flow in the artery. It is particularly useful when the lesion is a calcified lesion in the wall of the artery. Calcified lesions require high pressures (sometimes as high as 10-15 or even 30 atmospheres) to break the calcified plaque and push it back into the vessel wall. With such pressures comes trauma to the vessel wall which can contribute to vessel rebound, dissection, thrombus formation, and a high level of restenosis. Non-concentric calcified lesions can result in undue stress to the free wall of the vessel when exposed to high pressures. An angioplasty balloon when inflated to high pressures can have a specific maximum diameter to which it will expand but the opening in the vessel under a concentric lesion will typically be much smaller. As the pressure is increased to open the passage way for blood the balloon will be confined to the size of the open in the calcified lesion (before it is broken open). As the pressure builds a tremendous amount of energy is stored in the balloon until the calcified lesion breaks or cracks. That energy is then released and results in the rapid expansion of the balloon to its maximum dimension and may stress and injure the vessel walls. 
         [0003]    During angioplasty therapy, plaque debris can be produced. If such debris were permitted to freely translate within the blood stream, it could potentially coagulate down stream and result in another vein or artery reduction. Hence, it is desirable to preclude such debris from being freely carried within the blood stream during the angioplasty procedure. The present invention addresses this and other issues. 
       SUMMARY OF THE INVENTION 
       [0004]    In one embodiment, the invention provides a system comprising a guide wire, an embolic protection basket carried on the guide wire, and a catheter carried on the guide wire adjacent the embolic protection basket. The catheter includes an elongated carrier and a balloon about the carrier in sealed relation thereto. The balloon is arranged to receive a fluid therein that inflates the balloon, and agenerator within the balloon forms a mechanical shock wave within the balloon. 
         [0005]    The generator may be an arc generator and include at least one electrode that forms an electrical arc. 
         [0006]    The embolic protection basket may be downstream from the catheter. The system may further include a power source that provides electrical energy to the arc generator. The embolic protection basket may be a collapsible structure. 
         [0007]    The system may further comprise a push tube that pushes the embolic protection basket into position along the guide wire. The embolic protection basket may be a collapsible structure and the system may further comprise an over tube that maintains the embolic protection basket in a collapsed condition. 
         [0008]    The system may further comprise a push tube that pushes the embolic protection basket into position along the guide wire. The embolic protection basket may be a collapsible structure and the system may further comprise an over tube that maintains the embolic protection basket in a collapsed condition as the push tube pushes the embolic protection basket into position along the guide wire. 
         [0009]    The guide wire may include a stop that positions the embolic protection basket on the guide wire. The catheter may include a lumen for being received on the guide wire. 
         [0010]    The invention further provides a method comprising providing a guide wire, inserting the guide wire into a vessel of interest of a patient, providing an embolic protection basket, advancing the embolic protection basket along the guide wire within the vessel, and providing a catheter including an elongated carrier, a balloon about the carrier in sealed relation thereto, the balloon being arranged to receive a fluid therein that inflates the balloon, and agenerator within the balloon that forms a mechanical shock wave within the balloon. The method further includes the steps of guiding the catheter into the vessel of the patient to a position adjacent to and up stream from the embolic protection basket, admitting fluid into the balloon, and causing the generator to form a series of mechanical shocks within the balloon. 
         [0011]    The generator may be an arc generator including at least one electrode that forms electrical arcs to form the shockwave. The causing step may include the step of applying high voltage pulses to the generator. 
         [0012]    The embolic protection basket may be a collapsible structure and the step of advancing the embolic protection basket along the guide wire within the vessel may be performed with the embolic protection basket maintained in a collapsed state. The embolic protection basket may be maintained in a collapsed state by enclosing the embolic protection basket within an over tube. The method may include the further step of releasing the embolic protection basket from the collapsed state by separating the embolic protection basket from the over tube prior to applying high voltage pulses to the arc generator to form a series of mechanical shocks within the balloon. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The various embodiments of the invention, together with representative features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein: 
           [0014]      FIG. 1  is a view of the therapeutic end of a typical prior art over-the-wire angioplasty balloon catheter; 
           [0015]      FIG. 2  is a side view of a dilating angioplasty balloon catheter with two electrodes within the balloon attached to a source of high voltage pulses according to one embodiment of the invention; 
           [0016]      FIG. 3  is a schematic of a high voltage pulse generator; 
           [0017]      FIG. 3A  shows voltage pulses that may be obtained with the generator of  FIG. 3 ; 
           [0018]      FIG. 4  is a side view of the catheter of  FIG. 2  showing an arc between the electrodes and simulations of the shock wave flow; 
           [0019]      FIG. 5  is a side view of a dilating catheter with insulated electrodes within the balloon and displaced along the length of the balloon according to another embodiment of the invention; 
           [0020]      FIG. 6  is a side view of a dilating catheter with insulated electrodes within the balloon displaced with a single pole in the balloon and a second being the ionic fluid inside the balloon according to a further embodiment of the invention; 
           [0021]      FIG. 7  is a side view of a dilating catheter with insulated electrodes within the balloon and studs to reach the calcification according to a still further embodiment of the invention; 
           [0022]      FIG. 8  is a side view of a dilating catheter with insulated electrodes within the balloon with raised ribs on the balloon according to still another embodiment of the invention; 
           [0023]      FIG. 8A  is a front view of the catheter of  FIG. 8 ; 
           [0024]      FIG. 9  is a side view of a dilating catheter with insulated electrodes within the balloon and a sensor to detect reflected signals according to a further embodiment of the invention; 
           [0025]      FIG. 10  is a pressure volume curve of a prior art balloon breaking a calcified lesion; 
           [0026]      FIG. 10A  is a sectional view of a balloon expanding freely within a vessel; 
           [0027]      FIG. 10B  is a sectional view of a balloon constrained to the point of breaking in a vessel; 
           [0028]      FIG. 10C  is a sectional view of a balloon after breaking within the vessel; 
           [0029]      FIG. 11  is a pressure volume curve showing the various stages in the breaking of a calcified lesion with shock waves according to an embodiment of the invention; 
           [0030]      FIG. 11A  is a sectional view showing a compliant balloon within a vessel; 
           [0031]      FIG. 11B  is a sectional view showing pulverized calcification on a vessel wall; 
           [0032]      FIG. 12  illustrates shock waves delivered through the balloon wall and endothelium to a calcified lesion; 
           [0033]      FIG. 13  shows calcified plaque pulverized and smooth a endothelium restored by the expanded balloon after pulverization; 
           [0034]      FIG. 14  is a schematic of a circuit that uses a surface EKG to synchronize the shock wave to the “R” wave for treating vessels near the heart; 
           [0035]      FIG. 15  is a side view, partly cut away, of a dilating catheter with a parabolic reflector acting as one electrode and provides a focused shock wave inside a fluid filled compliant balloon; 
           [0036]      FIG. 16  is a side view, partly in section, of an embolic protection basket being guided into position in accordance with an embodiment of the invention; 
           [0037]      FIG. 17  is a side view, partly in section, of the embolic protection basket after reaching its deployment position in accordance with an embodiment of the invention; 
           [0038]      FIG. 18  is a side view, partly in section, of the embolic protection basket after being deployed in a vein or artery to be treated in accordance with an embodiment of the invention; 
           [0039]      FIG. 19  is a side view, partly in section, of the embolic protection basket combined with a shockwave angioplasty device as angioplasty therapy is applied to the vein or artery in accordance with an embodiment of the invention; and 
           [0040]      FIG. 20  is a side view, partly in section, of the embolic protection basket combined and shockwave angioplasty device being removed from the vein or artery after angioplasty therapy in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0041]      FIG. 1  is a view of the therapeutic end of a typical prior art over-the-wire angioplasty balloon catheter  10 . Such catheters are usually non-complaint with a fixed maximum dimension when expanded with a fluid such as saline. 
         [0042]      FIG. 2  is a view of a dilating angioplasty balloon catheter  20  according to an embodiment of the invention. The catheter  20  includes an elongated carrier, such as a hollow sheath  21 , and a dilating balloon  26  formed about the sheath  21  in sealed relation thereto at a seal  23 . The balloon  26  forms an annular channel  27  about the sheath  21  through which fluid, such as saline, may be admitted into the balloon to inflate the balloon. The channel  27  further permits the balloon  26  to be provided with two electrodes  22  and  24  within the fluid filled balloon  26 . The electrodes  22  and  24  are attached to a source of high voltage pulses  30 . The electrodes  22  and  24  are formed of metal, such as stainless steel, and are placed a controlled distance apart to allow a reproducible arc for a given voltage and current. The electrical arcs between electrodes  22  and  24  in the fluid are used to generate shock waves in the fluid. The variable high voltage pulse generator  30  is used to deliver a stream of pulses to the electrodes  22  and  24  to create a stream of shock waves within the balloon  26  and within the artery being treated (not shown). The magnitude of the shock waves can be controlled by controlling the magnitude of the pulsed voltage, the current, the duration and repetition rate. The insulating nature of the balloon  26  protects the patient from electrical shocks. 
         [0043]    The balloon  26  may be filled with water or saline in order to gently fix the balloon in the walls of the artery in the direct proximity with the calcified lesion. The fluid may also contain an x-ray contrast to permit fluoroscopic viewing of the catheter during use. The carrier  21  includes a lumen  29  through which a guidewire (not shown) may be inserted to guide the catheter into position. Once positioned the physician or operator can start with low energy shock waves and increase the energy as needed to crack the calcified plaque. Such shockwaves will be conducted through the fluid, through the balloon, through the blood and vessel wall to the calcified lesion where the energy will break the hardened plaque without the application of excessive pressure by the balloon on the walls of the artery. 
         [0044]      FIG. 3  is a schematic of the high voltage pulse generator  30 .  FIG. 3A  shows a resulting waveform. The voltage needed will depend on the gap between the electrodes and generally 100 to 3000 volts. The high voltage switch  32  can be set to control the duration of the pulse. The pulse duration will depend on the surface area of the electrodes  22  and  24  and needs to be sufficient to generate a gas bubble at the surface of the electrode causing a plasma arc of electric current to jump the bubble and create a rapidly expanding and collapsing bubble, which creates the mechanical shock wave in the balloon. Such shock waves can be as short as a few microseconds. 
         [0045]      FIG. 4  is a cross sectional view of the shockwave catheter  20  showing an arc  25  between the electrodes  22  and  24  and simulations of the shock wave flow  28 . The shock wave  28  will radiate out from the electrodes  22  and  24  in all directions and will travel through the balloon  26  to the vessel where it will break the calcified lesion into smaller pieces. 
         [0046]      FIG. 5  shows another dilating catheter  40 . It has insulated electrodes  42  and  44  within the balloon  46  displaced along the length of the balloon  46 . 
         [0047]      FIG. 6  shows a dilating catheter  50  with an insulated electrode  52  within the balloon  56 . The electrode is a single electrode pole in the balloon, a second pole being the ionic fluid  54  inside the balloon. This unipolar configuration uses the ionic fluid as the other electrical pole and permits a smaller balloon and catheter design for low profile balloons. The ionic fluid is connected electrically to the HV pulse generator  30 . 
         [0048]      FIG. 7  is another dilating  60  catheter with electrodes  62  and  64  within the balloon  66  and studs  65  to reach the calcification. The studs  65  form mechanical stress risers on the balloon surface  67  and are designed to mechanically conduct the shock wave through the intimal layer of tissue of the vessel and deliver it directly to the calcified lesion. 
         [0049]      FIG. 8  is another dilating catheter  70  with electrodes  72  and  74  within the balloon  76  and with raised ribs  75  on the surface  77  of the balloon  76 . The raised ribs  75  (best seen in  FIG. 8A ) form stress risers that will focus the shockwave energy to linear regions of the calcified plaque. 
         [0050]      FIG. 9  is a further dilating catheter  80  with electrodes  82  and  84  within the balloon  86 . The catheter  80  further includes a sensor  85  to detect reflected signals. Reflected signals from the calcified plaque can be processed by a processor  88  to determine quality of the calcification and quality of pulverization of the lesion. 
         [0051]      FIG. 10  is a pressure volume curve of a prior art balloon breaking a calcified lesion.  FIG. 10B  shows the build up of energy within the balloon (region A to B) and  FIG. 10C  shows the release of the energy (region B to C) when the calcification breaks. At region C the artery is expanded to the maximum dimension of the balloon. Such a dimension can lead to injury to the vessel walls.  FIG. 10A  shows the initial inflation of the balloon. 
         [0052]      FIG. 11  is a pressure volume curve showing the various stages in the breaking of a calcified lesion with shock waves according to the embodiment. The balloon is expanded with a saline fluid and can be expanded to fit snugly to the vessel wall (Region A) ( FIG. 11A ) but this is not a requirement. As the High Voltage pulses generate shock waves (Region B and C) extremely high pressures, extremely short in duration will chip away the calcified lesion slowly and controllably expanding the opening in the vessel to allow blood to flow unobstructed ( FIG. 11B ). 
         [0053]      FIG. 12  shows, in a cutaway view, shock waves  98  delivered in all directions through the wall  92  of a saline filled balloon  90  and intima  94  to a calcified lesion  96 . The shock waves  98  pulverize the lesion  96 . The balloon wall  92  may be formed of non-compliant or compliant material to contact the intima  94 . 
         [0054]      FIG. 13  shows calcified plaque  96  pulverized by the shock waves. The intima  94  is smoothed and restored after the expanded balloon (not shown) has pulverized and reshaped the plaque into the vessel wall. 
         [0055]      FIG. 14  is a schematic of a circuit  100  that uses the generator circuit  30  of  FIG. 3  and a surface EKG  102  to synchronize the shock wave to the “R” wave for treating vessels near the heart. The circuit includes an R-wave detector  102  and a controller  104  to control the high voltage switch  32 . Mechanical shock can stimulate heart muscle and could lead to an arrhythmia. While it is unlikely that shockwaves of such short duration as contemplated herein would stimulate the heart, by synchronizing the pulses (or bursts of pulses) with the R-wave, an additional degree of safety is provided when used on vessels of the heart or near the heart. While the balloon in the current drawings will provide an electrical isolation of the patient from the current, a device could be made in a non-balloon or non isolated manner using blood as the fluid. In such a device, synchronization to the R-wave would significantly improve the safety against unwanted arrhythmias. 
         [0056]      FIG. 15  shows a still further dilation catheter  110  wherein a shock wave is focused with a parabolic reflector  114  acting as one electrode inside a fluid filled compliant balloon  116 . The other electrode  112  is located at the coaxial center of the reflector  114 . By using the reflector as one electrode, the shock wave can be focused and therefore pointed at an angle (45 degrees, for example) off the center line  111  of the catheter artery. In this configuration, the other electrode  112  will be designed to be at the coaxial center of the reflector and designed to arc to the reflector  114  through the fluid. The catheter can be rotated if needed to break hard plaque as it rotates and delivers shockwaves. 
         [0057]      FIG. 16  shows a guide wire  120  upon which an embolic protection basket  140  may be guided into a desired position within a vessel  130 , such as an artery or vein. The guide wire  120  has a stop  122  for holding the embolic protection basket  140  in place at its desired position within the vessel  130 . As an initial step in the angioplasty procedure, the embolic protection basket  140  is pushed along the guide wire  120  by a push tube  150  and advanced into position in a coronary or peripheral vessel in a manner well known in the art. The basket  140  is initially collapsed and held within an overtube  146  as it is advanced down the guide wire  120  in the collapsed state to its final desired position. 
         [0058]    As may be noted in  FIG. 17 , when the embolic protection basket  140  abuts the stop  122  of the guide wire  120 , it has reached its desired position. The overtube  146  may then be withdrawn while, at the same time, the push tube  150  is held in place releasing the embolic basket  140 . 
         [0059]      FIG. 18  shows the embolic protection basket  140  expanded and deployed in the vessel  130 . The overtube has been withdrawn and the pushtube  150  is being retracted. 
         [0060]      FIG. 19  shows the advancement of the shock wave angioplasty balloon catheter  26  over the guidewire  120  to a position of a lesion in the vessel  130  proximal to the embolic basket  140 . The shock wave catheter  26  while pulverizing the calcium may dislodge calcium or embolic material resulting in debris within the vessel  130 . The embolic protection basket  140  positioned downstream from the angioplasty catheter  26  will capture the debris to preclude it from clotting further down the vessel  130 . 
         [0061]      FIG. 20  shows the embolic basket  140  and contents being withdrawn into the overtube  146  after the angioplasty catheter has been removed. As indicated herein, the angioplasty catheter may be of the type previously described in the various embodiments herein. Further, embolic protection baskets of various types may be employed without departing from the present invention. Embolic protection baskets, also referred to as simply filters, which may be used herein include basket type filters with a fabric or nitinol weave, coiled-up nitinol wire, or balloons that block up or down stream of the blockage used in combination with an aspiration tube. 
         [0062]    While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention as defined by those claims.

Technology Category: 1