Abstract:
This is a method and an apparatus for the treatment or introduction of contrast fluids into tissue, particularly cardiac tissue. The apparatus includes a catheter having an elongated flexible body and a tissue infusion apparatus including a hollow infusion needle configured to secure the needle into the tissue when the needle is at least partially inserted into the tissue to help prevent inadvertent removal of the needle from the tissue. This permits the selected treatment or contrast fluid to be confined to a specific site. The catheter may also include a visualization assembly including a transducer at the distal end of the body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. Ser. No. 08/403,553, filed Mar. 14, 1995, which in turn is a continuation of U.S. Ser. No. 08/100,086, filed Jul. 30, 1993, the contents of both are hereby incorporated by reference into the present disclosure.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Abnormal heart beats or cardiac arrhythmias can cause significant morbidity and mortality. These arrhythmias arise from a variety of causes, including atherosclerotic heart disease, ischemic heart disease, metabolic or hemodynamic derangements, rheumatic heart disease, cardiac valve disease, certain pulmonary disorders and congenital etiologies. The normal heart rate is about 60 to 100 beats per minute. Arrhythmias refer to tachycardias at rates exceeding 100 beats per minute for a duration of at least 3 beats. Sometimes no treatment is required, such as in the tachycardia following a physiologic response to stress or exercise. However, in some cases, treatment is required to alleviate symptoms or to prolong the patient&#39;s life expectancy.  
           [0003]    A variety of treatment modalities exist, including electric direct current cardioversion, pharmacologic therapy with drugs such as quinidine, digitalis, and lidocaine, treatment of an underlying disorder such as a metabolic derangement, and ablation by either percutaneous (closed chest) or surgical (open chest) procedures. Treatment by ablation involves destruction of a portion of cardiac tissue which is functioning abnormally electrically.  
           [0004]    Normally the heart possesses an intrinsic pacemaker function in the sinoitrial (SA) node which is in the right atrium, adjacent to the entrance of the superior vena cava. The right atrium is one of four anatomic chambers of the heart. The other chambers are the right ventricle, the left atrium, and the left ventricle. The superior vena cava is a major source of venous return to the heart. The SA node is an area of specialized cardiac tissue called Purkinje cells and which usually measures roughly III centimeters by about 2k millimeters. An electrical impulse normally exits from the SA node and travels across the atrium until it reaches the atrioventricular (AV) node. The AV node is located in the right atrium near the ventricle.  
           [0005]    Emerging from the AV node is a specialized bundle of cardiac muscle calls which originate at the AV node in the interatrial septum. This “bundle of His” passes through the atrioventricular junction and later divides into left and right branches which supply the left and right ventricles. The left and right bundles further give rise to branches which become the so-called distal His-Purkinje system which extends throughout both ventricles.  
           [0006]    Thus in a normal situation an impulse originates intrinsically at the SA node, transmits through the atrium and is modified by the AV node. The AV node passes the modified impulse throughout the left and right ventricles via the His-Purkinje system to result in a coordinated heartbeat at a normal rate.  
           [0007]    Many factors affect the heart rate in addition to the intrinsic conduction system. For example, normally the heart rate will respond to physiologic parameters such as stress, exercise, oxygen tension and vagal influences. Additionally, there are multiple causes for an abnormal heartbeat such as an abnormal tachycardia. One group of such causes relates to abnormalities in the hearts conduction system. For example, ectopic or abnormally positioned nodes may take over the normal function of a node such as the SA or AV node. Additionally, one of the normal nodes may be diseased such as from ischemic heart disease, coronary artery disease or congenital reasons. Similarly, a defect can exist in an important part of the conduction system such as the bundle of His or one of the bundle branches supplying the ventricles.  
           [0008]    Treatment of abnormal tachycardias arising from ectopic foci or so-called ectopic pacemakers can include pharmacologic therapy or ablative therapy. The ablative therapy may be accomplished by percutaneous insertion of a catheter or by an open surgical cardiac procedure.  
           [0009]    Cardiac arrhythmias may be abolished by ablating the tissue responsible for the genesis and perpetuation of the arrhythmias. Steerable ablation catheters using radio frequency (RF) energy are known. The RF energy can be directed to the area to be ablated and causes destruction of tissue by heat. In addition, direct infusion of ethanol has been performed during open heart surgery. Ethanol has also been infused into coronary arteries to ablate a focus such as a ventricular arrhythmia focus or the AV node. Unfortunately this tends to result in a fairly large region of cardiac tissue death or myocardial infarction. With transarterial infusion there is difficulty in precisely controlling the location and extent of the ablation.  
           [0010]    Thus, the prior art lacks catheters useful for direct endocardial infusion of sclerosing agents at the precise location of tachycardia. The present invention addresses these and other needs.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention is directed to methods and devices for delivery of desired compounds (e.g., ablation liquids) to cardiac and other tissue using a novel hollow infusion needle. The needle is typically used to inject an ablation liquid endocardially to produce a more circumscribed lesion than that possible using prior art infusion techniques. The needle is designed such that it can be imbedded in and secured to the tissue to be treated.  
           [0012]    Although ablation of cardiac tissue is a preferred use of the catheters of the invention, they can be used to inject desired compositions for a wide variety of uses. Virtually any therapeutic compound can be delivered intracardially using the catheters of the invention. For instance, the catheters can be used to deliver compositions comprising modified genes to cardiac or other tissue for use in gene therapy protocols. Methods for introducing a variety of desired polynucleotides to target cells using, for example, retroviral vectors are well known. Examples of sequences that may be introduced include antisense polynucleotides to control expression of target endogenous genes. In addition, genes encoding toxins can be targeted for delivery to cancer cells in tumors. In other embodiments, homologous targeting constructs can be used to replace an endogenous target gene. Methods and materials for preparing such constructs are known by those of skill in the art and are described in various references. See, e.g., Capecchi, Science 244:1288 (1989).  
           [0013]    Other uses include intramyocardial delivery of isolated cells or cell substitutes. These approaches typically involve placement of the desired cells on or within matrices or membranes which prevent the host immune system from attacking the calls but allow nutrients and waste to pass to and from the calls (see, Langer et al., Science 260:920-925 (1993)). For instance, sinus node cells can be implanted in a desired location to treat disorders in impulse formation and/or transmission that lead to bradycardia.  
           [0014]    For use in ablation of cardiac tissue, the catheters of the invention have an elongated flexible body and a tissue ablation assembly having a tissue ablation tip, at the distal end of the body. The distal end of the catheter is introduced into a cardiac chamber (or other body region) including the tissue to be ablated. The catheter may be equipped for standard arrhythmia mapping, for example multiple electrodes may be present on the outside of the catheter for recording endocardial electrograms. Alternatively, the catheter may include a visualization assembly at the distal end of the body. The visualization assembly is used to position the tip of the catheter adjacent the tissue to be ablated. Catheters comprising visualization and ablation means are described in copending application, Attorney Docket No. 2307F-449, which is incorporated herein by reference.  
           [0015]    The tissue ablation assembly comprises a hollow infusion needle which can be extended or withdrawn from the distal end of the catheter. The hollow infusion needles of the invention have a securing element configured to engage tissue when the needle is at least partially inserted into the tissue to stop recoil and help prevent inadvertent removal of the needle from the tissue. The securing element can be configured into the form of corkscrew or threads surrounding a straight needle. Alternatively, the securing element can be configured as a plurality of pre-curved needles, which curve towards or away from the longitudinal axis of the catheter. The pre-curved needles can also be used to deliver ablation compounds of desired. Other structures, such as barbs, could also be used as the securing element. The hollow infusion needle is preferably a corkscrew-shaped needle, with a tight curl. The distance between turns is preferably about 0.5 mm or less. Such a needle allows the practitioner to inject through layers by slowly extending the needle, injecting, extending farther and injecting again.  
           [0016]    When used to ablate tissue the catheter can be used with a conventional ablation compounds such as alcohol (e.g., ethanol), collagen, phenol, carbon dioxide and the like. The solution may comprise various components for other purposes as well. For instance, an echocontrast agent for echo imaging may be included. Collagen can also be bound to an iodinated molecule to make it radiodense. Alternatively, when used for gene therapy protocols, the catheters of the invention can be used to introduce desired polynucleotides to the target tissue.  
           [0017]    When performing a percutaneous or closed chest cardiac ablation procedure using the catheters of the invention, fluoroscopy can be used to visualize the chambers of the heart. Fluoroscopy uses roentgen rays (X-rays) and includes use of a specialized screen which projects the shadows of the X-rays passing through the heart. Injectable contrast agents to enhance the fluoroscopic picture are well known in the art and are not described in detail here.  
           [0018]    Typically, the catheter is placed in an artery or a vein of the patient depending on whether the left (ventricle and/or atrium) or right (ventricle and/or atrium) side of the heart is to be explored and portions thereof ablated. Frequently an artery or vein in the groin such as one of the femoral vessels is selected for catheterization. The catheter is passed via the blood vessel to the vena cava or aorta, also depending on whether the right or left side of the heart is to be catheterized, and from there into the appropriate atrium and/or ventricle.  
           [0019]    The catheter is generally steerable and it is positioned against an endocardial region of interest. As mentioned above, the catheter typically includes a means for sensing the electrical impulses originating in the heart. Thus, the electrode catheter can provide a number of electrocardiogram readings from different areas of the internal aspects of the heart chambers. These various readings are correlated to provide an electrophysiologic map of the heart including notation of normal or abnormal features of the heart&#39;s conduction system. Once the electrophysiologic map is produced, an area may be selected for ablation.  
           [0020]    Typically, before final ablation, the suspect area is temporarily suppressed or deadened with a substance such as lidocaine or iced saline solution. Subsequently the area is remapped and the heart reevaluated to determine if the temporary measure has provided some electrophysiologic improvement. If improvement has occurred, then the clinician may proceed with permanent ablation typically using ethanol.  
           [0021]    In one aspect, the present invention provides the novel combination of tissue ablation and tissue imaging in a single catheter to permit ablation of tissue to be properly accomplished by the correct selection of the ablation site and monitoring and controlling the ablation of the tissue being destroyed. The invention is preferably used with imaging ultrasonic transceivers in an ablation catheter to provide real time assessment of lesion volume and to monitor the tissue being ablated. Alternatively, one or more A-mode ultrasonic crystals can be used. As used herein, a visualization means of the invention may be either an imaging or an A-mode ultrasonic device. One or more transponder can also be used to assist in localizing the catheter tip.  
           [0022]    Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    [0023]FIG. 1 is an overall view of a catheter made according to the invention;  
         [0024]    [0024]FIG. 2 is an enlarged, simplified cross-sectional view of the distal end of the flexible body of FIG. 1;  
         [0025]    [0025]FIG. 3 is an enlarged, schematic cross-sectional view of the distal end of the flexible body of FIG. 1 illustrating the general locations of the tip electrode, ultrasonic transducer, and ring electrodes;  
         [0026]    [0026]FIG. 4 is an overall view of an alternative catheter made according to the invention;  
         [0027]    [0027]FIG. 5 is an enlarged, simplified cross-sectional view of the tip and the catheter of FIG. 4, shown with a hollow needle retracted;  
         [0028]    [0028]FIG. 6 is an external view of the tip of FIG. 5 with the hollow needle extended;  
         [0029]    [0029]FIG. 7 is an enlarged view of the needle driver and infusion port mounted to the handle of FIG. 4.  
         [0030]    [0030]FIG. 8 is an enlarged, simplified cross-sectional view of the tip of a catheter with a hollow needle retracted.  
         [0031]    [0031]FIG. 9 illustrates the handle assembly of a catheter of the invention.  
         [0032]    [0032]FIG. 10A is an enlarged,-simplified cross-sectional view of the tip of a catheter with the anchoring needles and hollow needle in the retracted position.  
         [0033]    [0033]FIG. 10B is an enlarged, simplified cross-sectional view of the tip of a catheter with the anchoring needles and hollow needle in the extended position.  
         [0034]    [0034]FIG. 11A is an enlarged, simplified cross-sectional view of the tip of a catheter with the anchoring/infusion needles in the extended position.  
         [0035]    [0035]FIG. 11B is an end view of catheter tip in FIG. 11A.  
         [0036]    [0036]FIG. 12 is an and view of a catheter tip with 10 anchoring/infusion needles.  
         [0037]    [0037]FIG. 13A is an enlarged, simplified cross-sectional view of the tip of a catheter showing the triggering mechanism with the anchoring/infusion needles in the retracted position.  
         [0038]    [0038]FIG. 13B is an enlarged, simplified cross-sectional view of the tip of a catheter showing the triggering mechanism with the anchoring/infusion needles in the extended position.  
         [0039]    [0039]FIG. 14 illustrates the handle assembly of a catheter of the invention showing the trigger for releasing and retracting the anchoring needles.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]    [0040]FIG. 1 illustrates a catheter  2  having a handle  4  from which a flexible body  6  extends. Flexible body  6  extends from one end  8  of handle  4  while ultrasonic cable  10  and a combination electrode/thermistor cable  12  extend from the other end  14  of handle  4 . Distal end  16  of flexible body  6  is steerable, as suggested by the dashed lines  18  in FIG. 1, in a conventional manner using a steering lever  20  mounted to handle  4 . Lever  20  which controls one or more steering cables  22 , see FIG. 2, as is conventional. Distal end  16  has an RF transmitting tip  24  secured thereto. Transmitting tip  24  is connected to an appropriate RF energy source, not shown, through lead  26  which extends along flexible body  6 , through handle  4  and through combined cable  12 .  
         [0041]    Tip  24  has a pair of axially extending bores  28 ,  30  formed from its distal end  32 . Bore  28  is used to house an ultrasonic transducer  34  while bore  30  is used to house a thermistor  36 . Transducer  34  is surrounded by a thermal insulating sleeve  38 , typically made of insulating material such as polyimide. The base  40  of transducer  34  has a lead  41  extending from transducer  34 , along flexible body  6 , through handle  4  and through ultrasonic cable  10 . The ultrasonic transducer comprises a piezoelectric crystal capable of operating at a standard frequency, typically from about 5 to about 50 MHz. The crystal is formed from standard materials such as barium titanate, cinnabar, or zirconate-titanate. The transducer  34  generates an ultrasonic pulse in response to electrical impulses delivered through lead  41 . Ultrasonic echoes are then received by the ultrasonic transducer  34  which generates electrical signals which are delivered to the receiving unit (not shown). The transducer is connected to conventional transmitting and receiving units which include the circuitry necessary for interpreting the ultrasonic information and displaying the information on a visual display. Signal processing may take advantage of change in tissue density or texture as correlated with lesion depth. The ultrasonic signal can be visualized on a two dimensional echocardiograph or using non-imaging A-mode.  
         [0042]    Base  40  of transducer  34  is sealed with a UV potting adhesive  42 , such as Tough Medical Bonder made by Loctite, to provide both thermal and electrical insulation. The catheter also comprises an ultrasonic transponder  44 , shown schematically in FIG. 3, spaced about 2.5 mm from RF transmitting tip  24  at the distel end  16  of body  6 . Transponder  44  is used to help in localization of the catheter tip as is known in the art and described in Langberg et al., JACC 12: 218-223 (1988). In alternate embodiments, multiple transponders can be used to help with assessing catheter tip orientation as well.  
         [0043]    In the embodiment of FIGS.  1 - 3 , the ablation apparatus exemplified by the use of RF transmitting tip  24 . In addition to tip electrode  24 , catheter  2  also includes three ring electrodes  46 ,  47 ,  48  positioned in a proximal direction, that is towards handle  4  relative to tip electrode  24  and transducer  44 . Electrodes  46 - 48  (spaced 2.5 ma apart) are used to record electrical signals produced by the heart (electrocardiograms) for endocardial mapping using a multichannel EKG machine as is known n e art. Thermistor  36  is coupled to combination cable  12  through a lead  50  extending from thermistor  36 , to flexible body  6 , through handle  4  and into combination cable  12 . Thermistor  36  is used to provide information about the temperature of the tissue at the distal end  32  of tip  24 .  
         [0044]    Separately, the above-discussed apparatus used to create ultrasonic visualization of the tissue to be ablated is generally conventional. An discussed above, the ultrasonic visualization means may be used for either imaging or A-mode. One such ultrasonic imaging system is sold by Cardiovascular Imaging systems of Sunnyvale, Calif. Similarly, the RF ablation system, used to ablate the tissue, is also generally conventional, such as is sold, for example, by EP Technologies of Sunnyvale, Calif. What is novel is incorporating both the imaging and ablation structure into a single catheter which permits real time visualization and accurate positioning of the RP transmitter tip  24  with the precise location to be ablated. The amount or volume of tissue ablated can thus be constantly monitored during the procedure so that neither too little nor too much tissue is ablated for maximum control and effectiveness. The use of temperature monitoring using thermistor  36  is also generally conventional as well, but not in conjunction with an ultrasonic imaging assembly. Instead of using RF energy to ablate the tissue, microwave radiation, laser energy, cryoblation or endocardial injection/infusion, for example, can be used in conjunction with ultrasonic transducer  34 .  
         [0045]    The use of catheter  2  proceeds generally as follows. Distal end  16  of body  6  is directed to the appropriate site using conventional techniques and steering lever  20 . Visualization of the tissue to be ablated and localization of the tip  24  is provided by ultrasonic transducer  34 , ultrasonic transponder  44 , and associated leads and cables coupled to a conventional ultrasonic imagining console, not shown. When tip  24  is at the site of the tissue to be ablated, RF generator,, not shown, coupled to combination cable  12 , is activated to produce RF radiation at tip  24  to ablate the tissue. The ablation is monitored by ultrasonic transducer  34  as well as thermistor  36  to help ensure that the proper volume of tissue is ablated. When the proper volume of tissue is ablated, body  6  is removed from the patient. Instead of the use of catheter  2  including an RF transmitter tip  24 , the catheter could use an ablation fluid infusion tip similar to that shown in FIGS.  4 - 7 . Also, preparatory to the ablation sequence, the suspect area can be temporarily suppressed or deadened using catheter  60  using lidocaine or iced saline solution, as discussed in the Background section above.  
         [0046]    Referring the reader now to FIGS.  4 - 7 , a catheter  60  is shown catheter  60  includes a handle  62  from which a flexible body  64  extends. Handle  62  includes a steering lever  65  and combination infusion port  66  and needle driver  68  at the distal end  70  of handle  62 . A pair of cables  72  extend from the proximal end  74  of handle  62 . The distal end  76  of flexible body  64  has a tip assembly  78  mounted thereto. Tip assembly  78  includes mapping electrodes So connected to wires  82  which extend down flexible body  64 , through handle  62  and to cables  72 . Mapping electrodes  80  provide the user with a nonvisual indication of where tip assembly is by monitoring the electro-activity of the heart muscle, as is conventional. Electrodes So are electrically isolated from the remainder of tip assembly  78  by an insulating sleeve  84 .  
         [0047]    A hollow needle  86  is slidably mounted within a second insulating sleeve  88  housed within insulating sleeve  84 . The needle may be formed from standard metal alloys such as titanium alloy, stainless steel, and cobalt steel. The needle  86  is a corkscrew-shaped needle used to inject ablating liquid into tissue and secure the needle to the tissue. Other designs of hollow needles, including the use of barbs on a straight or curved needle, can be used as well. While hollow needle  86  is shown sued with a generally conventional mapping electrode type of catheter, it could be used with an ultrasonic visualization assembly as shown in FIGS.  1 - 3 , as well as other types of visualization assemblies.  
         [0048]    A central bore  90  of hollow needle  86  is coupled to infusion port  66  by an infusion fluid tube  92  which extends along flexible body  64 , through needle driver  68  and to infusion port  66 . Threaded needle driver  68  is connected to a tip extension  94  so that rotating needle driver  68  causes tip extension  94  to rotate about the axis  95  of needle  86  and to move axially within flexible body  64 . This causes hollow needle  86  to rotate about axis  95  and to move axially within sleeve  88  from the retracted position of FIG. 5 to the extended position of FIG. 6.  
         [0049]    Rotating needle driver  68  also rotates hollow needle  86  so that it bores into the tissue to be ablated. When properly in position, an appropriate liquid, such as ethanol, can be infused into the tissue to be ablated through infusion port  66 , infusion fluid tube  92 , hollow needle  86 , and into the tissue. Since the tip  100  of hollow needle  86  is buried within the tissue to be ablated, the operator is assured that the ablation liquid is delivered to the proper place while minimizing ablation of surrounding tissue.  
         [0050]    Turning now to FIG. 8, the distal end  102  of a catheter of the present invention is shown. The hollow corkscrew infusion needle  104  is movably positioned within flexible distal tube  106 . The flexible tube  106  allows movement of the distal end  102  in response to the steering mechanism  112 . The steering mechanism  112  is conventional and functions as is known in the art. The distal end  102  also comprises mapping electrodes  108  which monitor electro activity of the heart muscle as described above. The mapping electrodes are connected through signal wires  111  to standard multichannel EKG machine as is known in the art.  
         [0051]    The braided torque tube  114  is connected to the inside diameter of the infusion needle  104  and provides means for rotating the infusion needle  104  about the longitudinal axis  105  of the catheter and moving the needle  104  axially within the distal tube  106 . The braided torque tube  114  consists of standard flexible tubing overlapped with a wire braid which stiffens the tube and allows torquing of the tube to rotate the needle  104 .  
         [0052]    [0052]FIG. 9 shows the handle assembly  115  of a catheter of the present invention. The braided torque tube  114  is connected to an infusion needle advance/retract knob  116  by which the user controls axial movement of the infusion needle  104 . A female luer lock infusion port is positioned on the advance/retract knob  116 . A standard strain relief means  118  prevents kinking of the flexible tube  119 . Also provided is a handle  120  secured to the catheter through front handle support  122  and rear handle support  124 . The handle assembly  115  is attached to a standard steering/mapping catheter handle  130  as is conventional and signal wires  132  are connected to the appropriate receiving units.  
         [0053]    [0053]FIGS. 10A through 10C show the distal end  134  of a catheter comprising an infusion needle  136  connected to a braided torque tube  138  as described above. The distal tube  142  also comprises an elastomeric seal  152  made from standard materials well known to those of skill in the art. The elastomeric seal  152  provides a seal for the distal tube  142  and prevents blood from flowing into the lumen of the catheter. Typically, the infusion needle  136  is coated with a compound such as mold release, to facilitate movement of the needle through the elastomeric seal  152 .  
         [0054]    Also included in this embodiment is a set of spring loaded pre-curved anchoring needles  144  positioned near the outer edge of the distal tube  142 . The anchoring needles are attached to a shuttle  150  and compression spring  146  which are triggered through pull wires  148  through a trigger device on the handle. The function of the trigger device is shown more fully in FIGS. 13A, 13B and  14 .  
         [0055]    [0055]FIG. 10B shows the extended anchoring needles  144  after the triggering device has released the shuttle  150  and compression spring  146 . This mechanism permits the distal end of the catheter to be attached in an almost instantaneous fashion and eliminates the effects of cardiac motion on the attachment procedure. FIG. 10C is an end view of the distal end  134  showing the position of the pre-curved anchoring needles  144  after release. In the embodiment shown here, the anchoring needles  144  are curved towards the longitudinal axis of the catheter. The anchoring needles  114 , however, can be curved towards or away from the longitudinal axis.  
         [0056]    [0056]FIGS. 11A and 11B show a further embodiment of the catheter comprising anchoring needles  162  which are used for infusion as well as anchoring. In this embodiment, the needles  162  are connected to infusion channel  160  through which the ablation liquid or other compound is delivered to the infusion needles  162 . The infusion needles  162  are shown in the extended position after the shuttle  166  and compression spring  164  have moved the needles  162  axially through the distal tube  156 . As with other embodiments, map electrodes  154  can be used to create an electro physiological map of the tissue. Braided tube  158  is used to anchor the compression spring  164 . The infusion needles are curved outward as well as inward in this embodiment (FIG. 11B).  
         [0057]    [0057]FIG. 12 is an end view of the distal end  168  of a catheter of the invention showing the arrangement of infusion needles  170  in which five needles project away from the longitudinal axis and five project toward the axis.  
         [0058]    [0058]FIGS. 13A and 13B illustrate the trigger assembly by which the pre-curved needles  200  are released from the distal end  202  of the catheters of the present invention. FIG. 13A shows the pre-curved needles  200  in the retracted position within the flexible distal tube  204 . The pre-curved needles  200  are attached to the shuttle  206  which is held in place by three trigger tabs  208 , two of which are illustrated in FIG. 13A. The trigger tabs  208  are permanently fixed to the front stop  210  and pre-loaded against the inner diameter  212  of the distal tube  204 .  
         [0059]    As in the other embodiments disclosed above, the pre-curved needles  200  are fluidly connected to infusion channel  214 , which enters the flexible distal tube distal  204 , through braided tube  211 . Map electrodes  216  are used to create an electro physiological map of the heart as described.  
         [0060]    [0060]FIG. 13B shows the pre-curved needles  200  in the extended position after the trigger tabs  208  have been pulled towards the longitude axis of the catheter by the trigger pull wires  220 . Once the trigger tabs  208  have been pulled towards the longitude axis, the shuttle  206  is released and the compression spring  222  drives the shuttle  206  and needles  200  rapidly towards the distal tip of the catheter. The inertia of the catheter body prevents the tip from withdrawing and needles  200  are subsequently driven into the target tissue. FIG. 13B also shows the position of the trigger tabs  208  an the inner diameter of the shuttle  206  after the shuttle  206  has moved forward. After use the shuttle pull wires  218  are activated to pull the pre-curved needles  200  to the retracted position.  
         [0061]    [0061]FIG. 14A shows the handle assembly  230  comprising a handle body  232  from which this position and ablation tip steering lover  234 . The handle body  232  comprises a needle trigger  236  Which is shown in both the cocked and fired (dashed lines) positions. The distal end of the trigger wires  238  are attached between the distal end  240  and the pivot point  242  to insure the wires  238  are pulled when the lever is pulled. The retractor  244  is shown in the cocked and fired (dashed lines) positions, as well. The pull wires  244  are attached between the pivot point  246  and the distal end of the retractor  248  as for the trigger. The handle assembly includes a lead  250  which allows for connection to appropriate ablation compound as described above.  
         [0062]    Modification and variation can be made to the disclosed embodiments without departing from the subject of the invention as defined in the following claims.