Abstract:
A catheter for injecting medicants into the endocardium, myocardium or other portions of the cardiovascular system is presented where the catheter has apertures therein for ejection and retraction of a needle. The catheter is designed for the apertures in the catheter to press against the tissue to be injected in the heart while the heart is beating. A needle for inserting a prescribed dose of a medicant is ejected through the aperture and a plunger, pump, or diaphragm is moved to deliver a dose of the medicant to tissue adjacent the aperture. By use of the catheter gene therapy, wherein a small does of a gene are injected into the endocardium of the right or left ventricle, can be used to grow new blood vessels in the injected area of a damaged heart. The apertures in the catheter can be spaced at a prescribed distance for the dosage of medicant to form a precise pattern of injections in the area to be treated. The catheters may be used for any treatments of a human or animal patient where injections are required in the heart, veins or arteries of the cardiovascular system.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to catheters and more particularly to a catheter for injecting an agent at specified positions of the heart muscle (myocardium).  
           [0003]    2. Description of Related Art  
           [0004]    In the past devices have been used for minimally invasive techniques to access the heart, veins and arteries immediately adjacent by inserting catheters into the larger veins and arteries of the neck, arm and leg. These devices are used for balloon angioplasty, laser surgery, to make endoscopic observations of valves, plaque buildup and other cardiac conditions, or to take pressure and temperature readings in various chambers of the heart and in the nearby veins and arteries. Even microsurgery can be performed by these minimally invasive techniques. Dyes, radioactive materials, radiopaque contrast materials or other substances can be added to the heart by such devices to aid in x-rays, CAT scans or other observations and measurements of the heart. However there is no currently available means for accurate patterned delivery of gene injection therapies or other injections into the myocardium of the various chambers of the heart or into the veins and arteries nearby.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention is for minimally invasive delivery of agents for the treatment of medical conditions in the heart or adjacent veins and arteries where precision injection of genes or other agents is required in the treatment of the patient.  
           [0006]    A catheter is inserted into the patient&#39;s veins or arteries of the arm, leg, or neck and threaded to the heart or other area to be injected with a medicant.  
           [0007]    The catheter firmly presses against the tissue to be injected. The pressure of the catheter against the tissue to be treated may be by a fluid pressure in the catheter, by wires in the catheter or by a catheter with a material shaping to a memory position. The catheter has at least one aperture for a needle to be inserted therethrough or withdrawn therefrom to inject a medicant into tissue adjacent the apertures of the catheter. The needle can be on the end of a stylet which is mechanically sprung to eject from an aperture when the needle point is aligned with an aperture of the catheter. A plunger may be depressed to push a medicant of a known dose into the tissue adjacent the aperture or a pump may be used to inject the medicant. Alternatively a needle can be forced through an aperture by fluid pressure within the catheter acting on a mechanism to insert the needle into the tissue to be injected. The same fluid pressure may be used to pump a known amount of a medicant through the needle, or as above a plunger or a pump may be used.  
         OBJECTS OF THE INVENTION  
         [0008]    It is an object of the invention to minimally invasively inject agents into or through the endocardium or myocardium.  
           [0009]    It is an object of the invention to provide a precision pattern of injections in the endocardium or myocardium.  
           [0010]    It is an object of the invention to provide gene therapy or introduce other therapeutic agents to the heart.  
           [0011]    It is an object of the invention to provide a catheter for injecting a medicant into or through the interior walls of the cardiovascular system such as veins, arteries and chambers of the heart.  
           [0012]    Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective of a heart with the catheter inserted into the left ventricle.  
         [0014]    [0014]FIG. 2 is a sectional view of the left ventricle with a pigtail catheter inserted.  
         [0015]    [0015]FIG. 3 is a sectional view of the catheter and the stylet therein with the needle pointing away from the apertures.  
         [0016]    [0016]FIG. 4 is a sectional view of the catheter and the stylet therein with the needle pointing toward the apertures.  
         [0017]    [0017]FIG. 5 is a sectional view of the left ventricle with a cage catheter therein.  
         [0018]    [0018]FIG. 6 is a sectional view of the left ventricle with a spiral catheter therein.  
         [0019]    [0019]FIG. 7 is a sectional view of the left ventricle with a multiple needle catheter therein.  
         [0020]    [0020]FIG. 8 is a sectional view of a multiple needle catheter with the needle extended.  
         [0021]    [0021]FIG. 9 is a sectional view a multiple needle catheter with the needle withdrawn. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]    The invention presented herein shows the treatment of the left ventricle in the figures and described in the various embodiments of the specification, but it should be understood that any chamber of the heart or nearby veins and arteries may be treated with the device herein presented and variations thereof.  
         [0023]    [0023]FIG. 1 shows a perspective sectional view of a human heart  10  with a catheter  20  inserted therein. It should be understood that although the body of the specification refers to and shows a human heart  10 , any animal having a similar cardiovascular system may be treated by the devices shown herein or modifications thereof, to fit the animal treated. The catheter  20  in the embodiment of FIG. 1 is routed retrograde though the aorta  30  and semilunar valve to the left ventricle  12 .  
         [0024]    The catheter  20  in the first embodiment shown in FIGS. 1 and 2 is a pigtail catheter wherein the catheter  20  has a pigtail  29  at the distal end which is useful for routing the catheter through the aorta  30  and into the left ventricle  12 . The pigtail  29  presents a curved end which will not exit an artery wall or damage heart tissue as it is inserted into the patient.  
         [0025]    As best seen in FIG. 2 catheter  20  is lodged firmly against the endocardium  15  of the left ventricle  12  by the shape of the catheter  20  having a wall portion  28  which in conjunction with the curved base portion  26  acts like a spring for urging the catheter portion with the apertures  25  toward a section of the left ventricle endocardium  15  to be injected with a substance such as a drug, gene or other agents used in a prescribed treatment of a patient. Since the heart will be beating while the catheter  20  is in place the catheter  20  must be made of a flexible and compliant material capable of bending with the beating of the heart such that the apertures  25  will remain adjacent the endocardium  15  when the heart beats. To accomplish this, the apertures  25  are preferably on a curved section of catheter  20  which will nominally match the contours of the wall of the left ventricle to be treated. The catheter  20  may be a balloon type, as in FIG. 4, which is inflated once inside of the left ventricle, with the pressure in the balloon portion  80  holding the catheter to the desired shape. The balloon portion inflation lumen  80  can be filled with a fluid to give the catheter  20  a shape. Balloon wall  85  is attached to one side of the catheter  20  or alternatively made integral with the catheter. In other embodiments the stiffening of the catheter for holding its shape may be by stiffening wires or springs in the catheter. For example in FIG. 4 the inflation lumen  80  could be used to insert a wire for providing a stiff backing for catheter  20 . Alternatively a memory material can be used which is held straight by a stiffening stylet which when removed allows the catheter to take a desired shape.  
         [0026]    The catheter  20  has apertures  25  for allowing a needle or stylet  40  to exit the catheter and access a portion of the endocardium or myocardium  15  for injection of a substance for treating the patient. In the embodiment shown in FIGS. 3 and 4 the stylet  40  has an arched section  43  which is in arched contact with one wall of the catheter  20  such that its distal tip  44  is urged against the opposing wall of the catheter  20 . When the distal tip  44  is on the catheter wall opposite the apertures  25  it may be inserted into or withdrawn from the catheter without emerging from the apertures  25 . When the distal tip  44  is rotated to a position as in FIG. 4 the distal tip  44  will be aligned with the apertures  25 . The compression of the arched portion  43  will force the distal tip  44  to emerge from the apertures  25  of the catheter  20  enough to puncture the endocaridial tissue  15  to a predetermined depth for injection of a substance, when the stylet  40  is drawn up the catheter  20 . Since the distal tip  44  is angled downward away from the arched portion  43 , then as the stylet  40  is drawn further up the catheter  20  the distal tip  44  will be pulled out of the tissue and through the aperture  25  into the catheter  20  and the force of the distal tip  44  on the wall of the catheter  20  will force the arched portion  43  against the opposite wall of the catheter  20  thus spring loading the distal tip  44  for ejection at the next aperture  25 . The process is repeated at all the injection points for the treatment.  
         [0027]    A grove  95  in the wall of catheter  20  will help align the stylet  40  inside of the catheter  20  when either the arch section  43  or the distal tip  44  of the stylet  40  rides in the groove  95 .  
         [0028]    The apertures  25  may be spaced apart at different intervals for different treatments. As an example, for a therapeutic substance, the apertures may be on the order of 10 mm from center to center. The stylet  40  would be on the order of a gauge  25 - 27 . The catheter  20  has markers  27  at the top and bottom of the range of apertures  25  such that the catheter  20  is viewable as to its position in the patient. For example the markers may be magnetic and a magnetic sensor would be used to find the position of the marker. Alternatively if the marker  27  is used in a CAT scan, x-ray or flouroscopy it may be a more or less opaque material than the rest of the catheter  20 , for example a band of gold may be used as the opaque material.  
         [0029]    The groove  95  may extend the length of the catheter  20  or just the length of the  11  section of the catheter  20  having apertures  25  since that is the portion where the distal tip  44  needs to be properly aligned.  
         [0030]    In FIG. 5 a second embodiment is shown as a cage catheter  45 . In the embodiment shown the cage has three struts  50  for forming the cage but any number of struts  50  may be used. For example if two struts  50  are used the cage catheter  45  would form a loop in the left ventricle  12 . In the embodiment shown in FIG. 5 with three struts  50 , the cage catheter  45  performs the function of forming an outer wall pressed against the endocardium  15  in the left ventricle  12  such that the apertures  25  are firmly held in place while the heart  10  is beating. The cage catheter  45  may be a balloon type with a structure as shown in FIG. 4. The struts  50  of the cage catheter  45  are forced outward against the endocardium such as by fluid pressure injected into the cage catheter  45  after it is inserted into the left ventricle  12 . In this manner the heart may continue pumping since the volume of the left ventricle  12  is largely unobstructed. The cage catheter  45  has the advantage of being able to more securely place the apertures  25  next to the endocardium  15  since all the struts  50  are mutually forcing the apertures  25  to the endocardium  15 .  
         [0031]    In the cage catheter  45  embodiment the stylet  40  operates as before, but now has three paths to follow such that the patient can receive more injection points for the treatment or optionally only one strut  50  would have apertures  25  for treating only a small portion of the endocardium  15 . The markers  27  will be used as before to align apertures  25  for the treatment points.  
         [0032]    If the two strut cage catheter  45  is used the stylet  40  can travel around the entire loop with apertures  25  being used serially rather than withdraw the stylet  40  and select a second strut  50 .  
         [0033]    In a third embodiment a spiral catheter  55  is used. The spiral catheter  55  may also be of the balloon type, as in FIG. 4, for inflation once it is inserted in the left ventricle  12 . The spiral shape has the advantage of a single serial draw on the stylet  40  without having to select different struts  50  of the catheter as in the cage catheter  45  embodiment and the circular nature of the spiral catheter  55  can be used to apply pressure to the circumference of the spiral catheter to press the apertures  25  against the endocardium  15 . Depending on the pitch of the spiral, a large number of injection points around the left ventricle  12  may be selected for treatment. As before the markers  27  can be used to align the apertures  25  with the area to be treated.  
         [0034]    The stylet  40  in each of these embodiments may be preloaded in the catheter  20 , the cage catheter  45 , or the spiral catheter  55  or inserted in the catheters after they are in place in the left ventricle  12 . The advantage of preloading is that the stylet  40  would not have to be turned to be aligned or unaligned with the apertures  25  on insertion and withdrawal. In an alternative embodiment a trough or groove  95  as shown in FIGS. 3, 4 may be used on the inside wall of the catheter  20 , the cage catheter  45 , or the spiral catheter  55  to align the stylet  40  by having either the arch  43  or distal tip  44  ride in the trough or groove  95  for only the portion of the catheter opposite the apertures  25 .  
         [0035]    The stylet  40  may have a lumen for transporting a medicant and a plunger, pump or other means of forcing the medicant out of the distal tip  44  when the distal tip  44  is injected into the tissue to be treated with the medicant.  
         [0036]    In a fourth embodiment a multi-needle balloon catheter  90  is inserted into the left ventricle as shown in FIG. 7 and inflated. In the embodiment shown the multi-needle balloon catheter  90  has a two strut cage design but any number of struts may be used. The area treated is selected to be a small area with three needles used but any number of needles spaced close together of further apart can be used.  
         [0037]    [0037]FIG. 8 shows a cross section of the multi-needle balloon catheter  90  which has a needle guard  63  for guiding the needle  65  out of the multi-needle balloon catheter  90  and limiting the stroke of needle  65 . In the embodiment shown, when lumen  80  is filled with a fluid the needle  65  is moved outward from the catheter  90  by fluid pressure on wall  62 . The medicant may be in a sack formed by walls  62 ,  64  of the multi-needle balloon catheter  90 . The medicant under pressure by wall  62  forces the medicant through apertures  67  in needle  65  for administering the medicant to the patient. Elastemetric wall  64  will be compressed during this stage and retract the needle  65  when pressure in lumen  80  is reduced. With the pressure in the catheter removed the needles  65  will be retracted, as in FIG. 9, and the multi-needle balloon catheter  90  can be safely withdrawn from the patient. In an alternate embodiment medicant  70  can be fed to needles  65  by means of tubes  70  connecting the needles  65  along the length of catheter  90 . The medicant will then be injected after the needles  65  are pushed forward by fluid pressure in lumen  80 .  
         [0038]    The catheters  20 ,  45  and  55  and the stylet  40  may be moved into location and precisely placed adjacent areas of the cardiovascular system needing treatment by use of stepper motors for making a series of small movements on the catheters  20 ,  45 ,  55  to place the apertures  25  adjacent the areas to be injected. Stepper motors may also be used to precisely move the stylet  40  within the catheters to position the distal tip  44  at desired locations. Similarly stepper motors may be used in conjunction with a plunger in the stylet  40  to deliver precise amounts of medicant to the areas to be treated. Although stepper motors are mentioned above any type of motor or actuator which can be precisely controlled for the purposes described may be used with the invention.  
         [0039]    The catheter  20 , the cage catheter  45 , and the spiral catheter  55  may all have stiffening stylets inside for holding the catheters straight while they are inserted into the patient. As the stylet is removed the catheter material assumes its material memory shape such as seen in the embodiments for a “J” shape catheter  20 , cage catheter  45  or spiral catheter  55 .  
         [0040]    Obviously , many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. States is: