Abstract:
A method and apparatus for accessing the pericardial space which provides for stable short term or long term placement of a delivery catheter or cannula having its distal most end located in the pericardial space. The catheter or cannula may be introduced into the pericardial space either transvenously through the wall of a heart chamber or transthoracically by penetrating the chest wall and the pericardium. Some embodiments are provided with a mechanism for stabilizing the distal end of the catheter or cannula, which mechanism may employ an extensible elastic, generally tubular member located at the distal end of the catheter or cannula. The device may be provided with a mechanism for extending the tubular member longitudinally, causing its diameter to diminish substantially. The tubular member may be passed through the wall of the heart or the pericardium in its extended configuration and thereafter, the distal-most portion of the tubular member may be moved proximally, causing its diameter enlarge, anchoring the distal end of the catheter or cannula to the pericardium or to the wall of a heart chamber. In these embodiments, the device is preferably provided with a shoulder or flange located proximal to the extendible tubular member, for location on the opposite side of the heart wall or pericardium from the distal end of the catheter or cannula.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to diagnostic and therapeutic devices for insertion into a patient&#39;s body, and more particularly to devices for access to and delivery of treatment in the pericardial space.  
           [0002]    Access to the pericardial space is desirable in order to provide a variety of cardiac therapies, including delivery of drugs or genetic agents, placement of electrical leads for pacing, cardioversion, defibrillation or EGM monitoring, removal of pericardial fluid for diagnostic analysis, or other purposes. A variety of mechanisms have been developed for accessing the pericardial space, ranging from a simple puncture by means of a large bore needle to intricate catheter or cannula based systems provided with sealing and anchoring mechanisms. Access to the pericardial space may be accomplished from either outside the body, by piercing the pericardium or from inside the heart, by piercing the wall of a heart chamber.  
           [0003]    Prior art mechanisms adapted to access the pericardial space by piercing the heart chamber include U.S. Pat. No. 5,797,870 issued to March et al, which discloses use of a transvenous catheter provided with a hollow helical needle to pierce the wall of a heart chamber. Alternatively access to the pericardial space may also be accomplished by means of a transvenous catheter which pierces the wall of a heart chamber and allows passage of a lead therethrough is disclosed in U.S. Pat. No. 4,946,457 issued to Elliot, U.S. Pat. No. 4,991,578 issued to Cohen. and U.S. Pat. No. 5,330,496 issued to Alferness. Particularly in the context of access to the pericardial space via the right atrium, it has been proposed that the transvenous catheter pierce the right atrial wall, as in U.S. Pat. No. 4,946,457 issued to Elliot or that the catheter pierce the right atrial appendage as in U.S. Pat. No. 5,269,326 issued to Verrier. Access to the pericardial space from the exterior of the body, accomplished by passing a cannula or catheter type device through the chest wall and thereafter passing the cannula or catheter through the pericardium into the pericardial space is disclosed in U.S. Pat. No. 5,827,216 issued to Igo, U.S. Pat. No. 5,336,252 issued to Cohen and PCT Patent Application WO/99/13936, by Schmidt.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed toward providing a mechanism for accessing the pericardial space which provides for stable short term or long term placement of a delivery catheter or cannula having its distal most end located in the pericardial space. The catheter or cannula may be introduced into the pericardial space either transvenously through the wall of a heart chamber or transthoracically by penetrating the chest wall and the pericardium.  
           [0005]    In particular, some embodiments of devices according to the present invention are provided with a mechanism for stabilizing the distal end of the catheter or cannula. In a first embodiment of the invention, the mechanism for stabilizing the distal portion of the catheter or cannula comprises an extensible elastic, generally tubular member located at the distal end of the catheter or cannula. The device is provided with a mechanism for extending the tubular member longitudinally, causing its diameter to diminish substantially. The tubular member is passed through the wall of the heart or the pericardium in its extended configuration and thereafter, the distal most portion of the tubular member is moved proximally, causing its diameter enlarge, anchoring the distal end of the catheter or cannula to the pericardium or to the wall of a heart chamber. In these embodiments, the device is preferably provided with a shoulder or flange located proximal to the extendible tubular member, for location on the opposite side of the heart wall or pericardium from the distal end of the catheter or cannula.  
           [0006]    In other embodiments of the present invention, the catheter or cannula takes the form of two nested tubular members, each provided with an extensible flange. The innermost of the two tubular members is provided with one or more radially extending protrusions or recesses, which engage with one or more corresponding protrusions or recesses located on the interior surface of the outer tubular member. Preferably, a series of outwardly directed protrusions on the inner tubular member and a series of inwardly directed protrusions the outer tubular member are provided, together defining multiple detent points for stabilizing the longitudinal position of the inner and outer tubular members relative to one another. More preferably, the protrusions and indentations of the tubular members extend around less than the entire circumference of the tubular members and are arranged so that in a first configuration, the tubular members may be slid longitudinally with respect to one another without interference between the protrusions on the inner and outer tubular members and in a second configuration the protrusions on the tubular members are interlocked to prevent relative longitudinal movement. In use, the catheter or cannula is employed by first passing the distal tip of the inner tubular member through the pericardial wall or the wall of a heart chamber such that the flange located thereon is located inside the pericardial space. The outer tubular member is then moved distally relative to the new tubular member to a point where the inner and outer flanges are located on either side of the pericardium or the heart wall, and the interlocking protrusions on the inner and outer catheter are thereafter employed to stabilize the catheter by preventing further relative longitudinal movements of the inner and outer tubular members.  
           [0007]    In addition to the delivery of drugs, extraction of pericardial fluids, and location of medical electrical leads typically as typically accomplished by means of pericardial access to devices, the devices according to the present invention may also be employed as part of a system for accomplishing cardiac ablation. In this context, after stabilization of the catheter&#39;s or cannula&#39;s distal end in the pericardial space, an ablation catheter is passed through to the catheter or cannula into the pericardial space, is located at a desired location adjacent the epicardium of the heart and is thereafter employed to ablate cardiac tissue. In this context, preferred embodiments of ablation catheters for use according to the invention are provided with one or more suction ports, allowing the distal portion of the catheter to be adhered to the surface of the epicardium by suction, along with one or more electrodes, located to contact the epicardium of the heart when the distal portion of the ablation catheter is secured to the epicardium by suction.  
           [0008]    In additional embodiments of the invention, the catheter or cannula for accessing the pericardial space takes the form of part of an implantable lead system, in which the introducer catheter or cannula is provided with one or more electrodes adapted to be located in a desired chamber or chambers of the heart, and wherein an electrode lead is passed distally through the catheter or cannula into the pericardial space, to locate additional electrodes adjacent desired portions of the epicardium of the heart. For example, electrodes located within the chamber or chambers of the heart may include pacing, cardioversion or defibrillation electrodes, and additional such electrodes may be located on the lead passing through the catheter or cannula into the pericardial space. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a plan view of a first embodiment of a catheter or cannula according to the present invention.  
         [0010]    [0010]FIG. 2 is a cross-sectional view through the distal portion of the catheter or cannula of FIG. 1.  
         [0011]    [0011]FIG. 3 is a cross-section of the distal portion of the catheter or cannula of FIG. 1, illustrating the extension of a resilient tubular member located at its distal tip, as the distal tip of the catheter or cannula is passed through the wall of a heart chamber.  
         [0012]    [0012]FIG. 4 illustrates the configuration of the distal end of the catheter of FIGS.  1 - 3 , after proximal movement of the distal tip of the catheter or cannula results in lateral expansion of the resilient tubular member causing the distal tip of the catheter or cannula to be anchored within the pericardial space.  
         [0013]    [0013]FIG. 5 is a cross-section through an alternative embodiment of a distal end portion of a catheter or cannula otherwise as illustrated in FIGS.  1 - 4 .  
         [0014]    [0014]FIG. 6 is a cross-sectional view through an additional alternative embodiment of a catheter or cannula according to the present invention, also employing an extendible flexible tubular member.  
         [0015]    [0015]FIG. 7 illustrates the catheter or cannula of FIG. 6, having the elastic tubular member in an extended condition, as it passes through the wall of a heart chamber.  
         [0016]    [0016]FIG. 8 illustrates the catheter of FIGS. 6 and 7 after proximal movement of the distal end of the catheter causes lateral expansion of the elastic tubular member to anchor the tip of the catheter within the pericardial space.  
         [0017]    [0017]FIG. 9 is a plan view of the third embodiment of a catheter or cannula according to the present invention, employing nested inner and outer tubular members.  
         [0018]    [0018]FIG. 10 is a cross-sectional view of the catheter or cannula of FIG. 9.  
         [0019]    [0019]FIG. 11 is a side, sectional view through the catheter or cannula of FIGS. 9 and 10.  
         [0020]    [0020]FIG. 12 illustrates placement of the catheter or cannula of FIGS.  9 - 11 , such that the distal portion of the inner tubular member extends through the wall of the heart.  
         [0021]    [0021]FIG. 13 illustrates the configuration of the cannula or catheter of FIGS.  9 - 11  after the inner and outer tubular members of the catheter or cannula are moved relative to one another to cause the flanges located thereon to engage the inner and outer surfaces of the heart, stabilizing the distal end of the catheter or cannula within the pericardial space.  
         [0022]    [0022]FIG. 14 illustrates an alternative embodiment of the distal portion of the catheter in FIGS.  1 - 11 .  
         [0023]    [0023]FIG. 15 illustrates a cross-sectional view of an additional embodiment of a catheter or cannula according to the present invention, employing an internal spring within a distally located elastic tubular member, illustrating the tubular member in a longitudinally extended state as it passes through the wall of a heart chamber.  
         [0024]    [0024]FIG. 16 illustrates the catheter or cannula of FIG. 15 after contraction of the spring located within the resilient tubular member causes lateral expansion of the resilient tubular member in the pericardial space, anchoring the distal portion of the catheter or cannula.  
         [0025]    FIGS.  17 - 20  illustrate various types of catheters and leads which may be inserted into the pericardial space via the catheters or cannulas of FIGS.  1 - 16 , discussed above. In particular, FIG. 17 illustrates a drug delivery catheter; FIG.  18  illustrates a pacing/electrogram sensing lead; FIG. 19 illustrates a cardioversion/defibrillation lead; and FIG. 20 illustrates an ablation catheter.  
         [0026]    [0026]FIG. 21 illustrates a cross-section through the distal end of the ablation catheter of FIG. 20. FIG. 22 illustrates the operation of an ablation catheter according to FIG. 20 or  21  to ablate heart tissue.  
         [0027]    [0027]FIG. 23 illustrates an alternative embodiment of the distal portion of an ablation catheter otherwise as illustrated in FIGS.  20 - 22 .  
         [0028]    [0028]FIG. 24 illustrates a cross-section through the distal end of the ablation catheter illustrated in FIG. 23.  
         [0029]    [0029]FIG. 25 illustrates a delivery catheter or cannula according to the present invention, having its distal end passing through the right atrial appendage of a patient&#39;s heart and into the pericardial space, in conjunction with a lead or catheter delivered through the introducer catheter or cannula.  
         [0030]    [0030]FIG. 26 illustrates the distal portion of an alternative embodiment of an introducer catheter or cannula according to the present invention, carrying one or more electrodes located along its length, in conjunction with an electrode lead delivered through the catheter or cannula into the pericardial space.  
         [0031]    [0031]FIG. 27 illustrates the distal portion of an additional alternative embodiment of an introducer catheter or cannula according to the present invention, carrying one or more electrodes located along its length, in conjunction with an electrode lead delivered through the catheter or cannula into the pericardial space.  
         [0032]    [0032]FIG. 28 illustrates the distal portion of an additional alternative embodiment of an introducer catheter or cannula according to the present invention, carrying one or more electrodes located along its length, in conjunction with an electrode lead or other catheter delivered through the catheter or cannula as it passes through a wall of a heart chamber into the pericardial space.  
         [0033]    [0033]FIG. 29 illustrates the distal portion of an additional alternative embodiment of an introducer catheter or cannula according to the present invention, in conjunction with a catheter delivered through the catheter or cannula as it passes through a wall of a heart chamber into the pericardial space.  
         [0034]    [0034]FIG. 30 illustrates the distal portion of the introducer catheter or cannula of FIG. 29, as it passes through a wall of a heart chamber into the pericardial space. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    [0035]FIG. 1 is a plan view of a delivery catheter or cannula according to the present invention. The catheter or cannula is provided with an elongated tubular body  10 , which is provided with a fitting  20  at its proximal end which includes first and second fluid fittings  22  and  24 , which may take the form of luer lock fittings. Shown entering the proximal end of fluid fitting  24  is a stylet  28 , provided with a knob  26  located on its proximal portion. The distal tip of stylet  28  exits the distal tip  32  of the delivery catheter or cannula. The distal tip of the stylet  28  may be rounded or may be beveled or sharpened in order to assist passage of the distal tip  32  of the catheter or cannula through the wall of the patient&#39;s heart or through the pericardium, into the pericardial space. An elastic tubular member  30  is illustrated located at the distal end of the body  10  of the catheter or cannula, and its operation in order to anchor the distal end  32  of the catheter or cannula in the pericardial space is discussed in more detail below. If the catheter or cannula is to be used for fluid delivery, an elastic tubular plastic liner may be added, located interior to coil  34 .  
         [0036]    [0036]FIG. 2 shows a catheter or cannula of FIG. 1 in a sectional view. In this view, it can be seen that the tubular lead body  10  carries a first coil  36 , terminating within a circumferential flange  38  located at the distal end of the catheter or cannula body  10 , and a second coil  34  extending distally thereto through the circumferential flange  38 . A resilient elastic member  30 , for example fabricated of a thin tube of silicone rubber, is shown mounted to and extending from the distal end of the catheter or cannula body  10  to a distal tip member  40 , illustrated in this view as being a metallic member. Tube  30  is generally cylindrical and may be tapered somewhat at its distal end as illustrated. Tube  30  is free of pre-formed corrugations but, as discussed below, will exhibit corrugations in use which will serve to stabilize the distal end of the introducer catheter or cannula in the pericardium or the wall of a chamber of a patient&#39;s heart. Surrounding the distal tip member  40  is a plastic tube  32 , tapered at its distal end to provide a more atraumatic tip configuration for the catheter or cannula. In the embodiment illustrated, the stylet  28  is provided with an enlarged portion  33  which engages a corresponding internal flange in tip member  40 . The stylet  28  may be moved distally with respect to the catheter or cannula to extend the tubular elastic member  30  and the associated coil  34 , causing the elastic tubular member  30  to neck down tightly around coil  34 . Longitudinal extension of tubular member  30  may occur prior to or after passage of the distal tip of the catheter into the pericardial space  
         [0037]    [0037]FIG. 3 illustrates the catheter or cannula of FIG. 2 with the tubular member  30  stretched elastically to a greater length than as illustrated in FIG. 2 by distal movement of stylet  28 . The tubular member  30  and the distal end of the catheter or cannula extend through the wall  100  of the heart chamber into the pericardial space. In this view the effect of stretching the tubular member  30  to cause it to neck down to a reduced circumference and into close contact with coil  34  is apparent. The stretching of the tubular member  30  may be done before or after passage of the tubular member  30  through the wall  100 .  
         [0038]    [0038]FIG. 4 illustrates the catheter or cannula of FIGS.  1 - 3 , after removal of the stylet  28  which in turn allows for the proximal movement of the distal tip of the catheter, in turn causing expansion of the elastic tubular member  30 , to anchor the distal tip of the catheter or cannula within the pericardial space. The distal end of the catheter or cannula body  10  defines a shoulder  10   a  on one side of the wall the heart, while the elastic member  30  forms one or more laterally extending corrugations projection located interior to the wall  100  or the pericardial space. Depending upon the relative dimensions of the heart wall  100  and the tubular member  100  and the relative amount of extensibility of the tubular member, the number and configuration of the formed corrugations may vary. The lateral expansion of the tubular member serves to anchor the distal tip of the catheter in the pericardial space. In the embodiment illustrated, it is assumed that the elasticity of coil  34  and tubular member  30  are sufficient to cause proximal movement of a distal tip of the catheter or cannula, or alternatively, that a mechanism is provided for causing proximal movement of the coil  34 , facilitating proximal movement of the tip of the catheter or cannula and expansion of the tubular member  40 . In such embodiments, distal movement of the coil  34  may be also employed alone or in conjunction with distal movement of the stylet to stretch the resilient tubular member  30 . In additional alternative embodiments, the stylet may also be employed to cause proximal movement of the tip of the catheter or cannula, as illustrated in FIG. 5.  
         [0039]    [0039]FIG. 5 illustrates an alternative configuration for the distal tip portion of the catheter or cannula illustrated in FIGS.  1 - 4 . In this embodiment, all identically labeled components correspond to those illustrated in FIG. 4, however, in this case, the stylet differs in that the expanded portion  33   a  of the stylet takes the form of a ball shaped, rather than a cylindrical shaped member, and that the distal tip member  40   a  is provided with an elastic, generally tubular member  41 , configured to elastically engage the ball shaped protrusion  32   a  of the stylet  28   a . In a fashion analogous to that illustrated for a ball-tip stylet for causing relative proximal and distal movement of a lead as in U.S. Pat. No. 5,344,439 issued to Otten, and incorporated herein by reference in its entirety, the proximal movement of the stylet may be used to affirmatively cause proximal movement of the tip member  40 , up to the limit of allowable proximal motion of the tip, and thereafter, the resiliency of the locking member  41  allows for release of the ball shaped protrusion  32   a , and withdrawal of the stylet  28   a . In this embodiment, as in the embodiment described above in which a coils employed to pull the distal tip of tubular member  34  proximally, the resultant length of the resilient tubular member  30  may actually less than its original length, further facilitating formation of corrugations After the catheter or cannula of FIGS.  1 - 4  or  5  is anchored so that its distal tip is stably located in the pericardial space, the lumen defined by the interior of coil  34  and the aperture through tip member  40  provide a path by which an additional catheter or electrode lead may be passed into the pericardial space. For example, an electrode bearing catheter employed for pacing, electrogram monitoring, cardioversion or defibrillation, may be located. Alternatively, a simple, tubular catheter may be passed into the pericardium which will allow for drug delivery adjacent the localized portion of the heart. As yet, an additional alternative, the device may be employed directly as a drug delivery catheter, by means of fluids injected either through fluid coupling  24  or  22  as illustrated in FIG. 1. As yet an additional alternative, the device may be used to deliver a cardiac ablation lead, for example corresponding to those in FIGS.  20 - 24  and discussed in more detail below.  
         [0040]    [0040]FIG. 6 shows the distal portion of an alternative embodiment of a delivery catheter or cannula according to the present invention. In this embodiment, the body  110  of the device takes the form of a polymeric tube of the sort typically employed in the manufacture of guiding catheters generally, and may be reinforced by means of an embedded braid. Internal to tube  110  is a length of hypodermic tubing  114  which extends back to the proximal end of the device, and is longitudinally moveable within the lumen of tube  110 . An elastic tapered tubular member  112  encircles the distal end of tube  110  and the distal end of hypodermic tube  114  and is adhesively or otherwise bonded to both tubes. In a fashion analogous to that described above in conjunction with the device of FIGS.  1 - 5 , distal movement of hypodermic tubing  114  relative to tube  110  causes elastic member  112  to stretch and to neck down around hypodermic tube  114 .  
         [0041]    [0041]FIG. 7 illustrates the delivery catheter or cannula of FIG. 6 with hypodermic tubing  114  advanced distally out of the distal end of tube  110 , stretching tubular member  112 , causing it to neck down into contact with hypodermic tubing  114 . The device is shown passing through the wall  100  of chamber of a patient&#39;s heart, such that the distal most portion of a hypodermic tubing  114  and tubular member  112  are located within the pericardial space.  
         [0042]    [0042]FIG. 8 shows the device of FIGS. 6 and 7 after the hypodermic tubing  114  is moved proximally relative to tube  110 , causing elastic membrane  112  to bunch up forming one or more corrugations inside the pericardial space or in the wall  100  of a chamber of a patient&#39;s heart, stabilizing the distal end of the device within the pericardial space.  
         [0043]    [0043]FIG. 9 shows an alternative embodiment of a catheter or cannula according to the present invention. In this case, the device body includes two coaxially nested tubes  210  and  212  which are slideable longitudinally with respect to one another. At the proximal end of tube  210  is a fluid fitting  212 , coupled to a lumen within tube  210 , and which as illustrated carries a stylet or guidewire  220 , which extends out of the distal end of tube  210 . The distal portion of tube  210  carries a conical flange  218 , which is preferably manufactured of an elastic material such as silicone rubber and which may optionally be reinforced with radially extending ribs, if desired. The distal end of outer tube  212  has a corresponding conical flange  216 , oppositely directed from flange  218 .  
         [0044]    [0044]FIG. 10 is a cross-section through the body of the device of FIG. 9. From this view it can be seen that the outer surface of tube  210  is provided with outwardly directed projections  222 ,  224  and  226 , which are spaced from one another around the circumference of the tube  210 , and as illustrated are located displaced approximately 120° from one another. The outer surface of tube  210  is preferably provided with a series of such projections, spaced at regular intervals along a portion of tube  210 . Corresponding inwardly directed projections  228 ,  230  and  232  are provided on the inner surface of tube  212 , also spaced approximately 120° from one another. As illustrated, in the configuration shown, the projections of the respective inner and outer tubes  210  and  212  do not engage one another, allowing the tubes to be slid longitudinally. However, if the inner and outer tube are rotated 60° with respect to one another, the projections on each of the inner and outer tubes locate themselves between the projections on the other tube, causing the tubes to be interlocked and preventing further relative longitudinal movement of inner and outer tubes  210  and  212  relative to one another. This locking mechanism is employed in conjunction with stabilization of the device as discussed below.  
         [0045]    [0045]FIG. 11 illustrates the device of FIG. 9 in a sectional view, in which the inwardly directed projections  232  of outer tube  212  and the outwardly projected projections of tube  210  are visible. In this configuration, the tubes are free to slide longitudinally to one another. However, by rotating the tubes 60° relative to one another, the outward projections  222  of tube  210  locate themselves in the recesses  224  between the inwardly projected projections  232  of tube  212 , and the inwardly directed projections  232  of tube  212  corresponding to locate themselves in the recesses  236  defined between the outward projections  222  of tube  210 , preventing further longitudinal movements of tubes  210  and  212 .  
         [0046]    [0046]FIG. 12 illustrates the device of FIGS.  9 - 11  with its distal end inserted in the wall  100  in the chamber of a patient&#39;s heart. The device is positioned so that flange  218  of inner tube  210  is located within the pericardial space, while flange  216  of outer tube  212  is located interior to the patient&#39;s heart.  
         [0047]    [0047]FIG. 13 illustrates the device of FIG. 12 after proximal movement of tube  210  to bring flanges  216  and  218  into contact with the inner and outer surfaces of the wall  100  of the chamber of a patient&#39;s heart, also causing radial expansion of the flanges as illustrated. At this point, the inner and outer tubes are rotated relative to one another so that the inwardly and outwardly directed projections on the outer and inner tubes respectively, interlock with one another, preventing further longitudinal movement and stabilizing the distal end of the catheter in the wall  100  of the patient&#39;s heart. Stylet  220  can now be removed, and the delivery catheter or cannula may be employed to facilitate placement of a lead, catheter or other device in the pericardial space.  
         [0048]    [0048]FIG. 14 illustrates an alternative embodiment of a delivery catheter or cannula generally corresponding to those illustrated in FIGS.  9 - 13 . In this embodiment, however, the flanges  216   a  and  218   a  are provided with slits or recesses as illustrated in order to facilitate radial expansion of the flanges. All other elements correspond to identically labeled elements in FIGS.  9 - 12 .  
         [0049]    [0049]FIG. 15 is an additional embodiment of a delivery catheter or cannula, according to the present invention, shown with its distal portion extending through the wall of a patient&#39;s heart. Like the devices of FIGS.  1 - 5 , discussed above, the device is provided with a body which takes the form of a tube  310 , reinforced by means of an internal coil  318 . The distal end of the tube  310  serves as a radially extending shoulder  310   a , which is located adjacent the inner surface of the wall  100  of a patient&#39;s heart chamber. An elastic tube  312  extends distally from tube  310  to enclose a tip member  314 . Spring  320  extends from a cylindrical flange  322  to the tip member  314 . As illustrated, elastic tube  312  and spring  320  have been elongated due to distal movement of stylet  316 , which is provided with an outwardly directed shoulder engaging the proximal end of tip member  314 .  
         [0050]    [0050]FIG. 16 illustrates the device of FIG. 15 after removal of stylet  316 , allowing spring  320  to retract and cause radial expansion of elastic tube  312  within the pericardial space, stabilizing the distal end of the delivery catheter. All other elements correspond to identically labeled elements in FIG. 15.  
         [0051]    FIGS.  17 - 24  illustrate various types of devices which may be introduced into the pericardial space using the delivery devices illustrated above. In each case, the delivery device is sized so that the lumen through the distal tip member of the delivery device is adequate to permit passage of the lead or cannula to be delivered to the pericardial space.  
         [0052]    [0052]FIG. 17 illustrates a simple catheter for delivery of drugs or for withdrawal of pericardial fluid. The catheter consists of a tube  500  provided with a fluid fitting  502  at its proximal end.  
         [0053]    [0053]FIG. 18 illustrates an electrode lead with may be introduced through any of the delivery devices described above, and which may be employed for detection of electrical signals from the heart or delivery of electrical stimulus pulses such as pacing pulses to the heart. The lead is provided with an elongated insulative body  504  which carries two mutually insulative conductors therein coupled at their distal ends to electrodes  500  and  508 , respectively, and at their proximal end to connector pin and connector ring  514  and  512 , respectively. Connector pin  514  and connector ring  512  are located on a connector assembly  510  which is adapted to be inserted into the connector port of an associated electrical stimulator or monitor.  
         [0054]    [0054]FIG. 19 illustrates a cardioversion or defibrillation lead which may be introduced by means of any of the delivery devices described above. The lead is provided with an elongated insulative lead body  516  which carries an elongated conductor coupled at its distal end to coil electrode  518  and at its proximal end to connector pin  522 . Connector pin  522  is located on a connector assembly  520  adapted to be coupled to a cardioverter or defibrillator.  
         [0055]    [0055]FIG. 20 illustrates an ablation catheter which may be employed in conjunction with any of the delivery devices illustrated above. The ablation catheter is provided with an elongated lead body  524  which is provided with a longitudinally extending internal lumen extending from a fluid coupling  528  at its proximal end to a longitudinally extending recess  536  at its distal end. Fluid coupling  528  is mounted to fitting  526 , which also carries two electrical connectors  530 , which are coupled to the distal ends of conductors  531 , which extend through catheter body  524  to electrodes which are located within the recess  536 , but which are not visible in this view. The distal portion  532  of the device is also provided with two laterally extending flanges  534 , which serve to orient the device such that the recess  536  is located adjacent the surface of the heart tissue, as illustrated in FIGS. 21 and 22, described below.  
         [0056]    [0056]FIG. 21 is a cross-sectional view of the distal portion  532  of the device illustrated in FIG. 20. In this view it can be seen that the distal portion of the catheter has a portion which is generally U-shaped in cross section, defining recess  536 , and carries two elongated strip electrodes  542  and  544  located on opposite sides within recess  536 . Laterally extending flanges  534  are located adjacent recess  536  and serve to assure that the recess is oriented with its open portion adjacent heart tissue. Also visible is a lumen  538  which serves to couple the recess  536  to the fluid coupling  528  (FIG. 20) located at the proximal end of the lead. An optional tension wire  540  is shown which may, in some embodiments, be employed to cause deflection of the catheter, in order to facilitate its placement at a desired location on the epicardial surface of the patient&#39;s heart, using a mechanism as generally disclosed in U.S. Pat. No. 5,489,270, issued to Van Erp, incorporated herein by reference in its entirety.  
         [0057]    [0057]FIG. 22 illustrates the ablation catheter of FIGS. 20 and 21 applied to the epicardial surface of a wall  600  of a chamber of the patient&#39;s heart. Application of vacuum to the fluid fitting  528  (FIG. 20) located at the proximal portion of the catheter causes the wall  600  of the chamber of the patient&#39;s heart to be drawn into the recess  536 , between electrodes  542  and  544 . RF energy can then be applied to electrodes  542  and  544  via conductors  531  to create a linear lesion, extending along the length of electrodes  542  and  544 .  
         [0058]    [0058]FIG. 23 illustrates an alternate embodiment of the distal portion of an ablation catheter otherwise corresponding to the catheter illustrated in FIGS.  21 - 22 . In this case, it should be understood that the proximal portion of the catheter corresponds to that illustrated in FIG. 20, with catheter body  610  corresponding to catheter body  524  in FIG. 20. The distal portion of the catheter is provided with laterally extending flanges  612 , corresponding generally to flanges  534 . However, rather than being provided with an elongated recess, the device is provided with a longitudinal series of recesses  614 . The device is also provided with two longitudinally extending electrodes  618  and  620  which may take the form of metal strips or coils, located on either side of recesses  614 . Electrode  618  and  612  are coupled to electrical connectors at the proximal end of the lead, corresponding to electrical connectors  530  in FIG. 20.  
         [0059]    [0059]FIG. 24 illustrates a cross-section through the distal portion of the ablation catheter illustrated in FIG. 23. In this view it can be seen that the recesses  614  are generally conical, and are in fluid communication with an internal lumen  624  which extends back to a fluid coupling at the proximal end of the catheter, corresponding to fluid coupling  528  in FIG. 20. Electrodes  618  and  620  are illustrated in cross-section, located on either side of recesses  614 . An optional tension wire  626  is shown, which may be employed to deflect the ablation catheter assisting its location at a desired location on the epicardium of a patient&#39;s heart. In use, like the ablation catheter of FIGS.  20 - 22 , vacuum is applied to the fluid coupling at the proximal end of the catheter, causing the suction ports  614  to adhere to the epicardial surface of a chamber of the patient&#39;s heart. RF energy is applied between electrodes  618  and  620  to create a generally linear lesion.  
         [0060]    [0060]FIG. 24 illustrates the use of a delivery device according to the present invention to deliver a lead or catheter  420  into the pericardial space. As illustrated, it should be assumed that the delivery device corresponds to that illustrated in FIGS.  1 - 4 , with lead body  10  extending from the superior vena cava, the distal end of the delivery device extending through the wall  400  of the right atrial appendage. As illustrated, elastic tube  20  serves to stabilize the distal end of the delivery device in the right atrial appendage and lead or catheter  420  is delivered through the distal tip of the delivery device, for location between the epicardial surface of the heart and the pericardium, illustrated schematically at  410 .  
         [0061]    Any of the delivery devices illustrated above may be employed in a corresponding fashion to deliver a lead or catheter to the pericardial space, or may be used in the absence of an associated lead or catheter to deliver materials such as drugs or genetic agents to the pericardial space or to withdraw fluid from the pericardial space. Correspondingly, devices according to any of the embodiments illustrated above may also be employed to access pericardial space by passing through the pericardium itself, with the distal end of the catheter stabilized in the pericardium, rather than in the wall of the chamber of a patient&#39;s heart.  
         [0062]    [0062]FIG. 26 illustrates an additional embodiment of a delivery device according to the present invention, wherein the delivery device is provided with an electrode  708  located at the distal portion of the tube  710 , making up the catheter body. Catheter body  710  may otherwise correspond to catheter body  10  of the device illustrated in FIGS.  1 - 4 . As illustrated, the device is shown with its distal end extending through the wall  100  of a chamber of a patient&#39;s heart, for example, extending through the right atrial appendage. Elastic tube  712  may correspond to tube  30 , illustrated in FIG. 1, serving to anchor the device in the wall of the atrium in the same fashion as described in conjunction with FIGS.  1 - 4 , above. Extending into the pericardial space is an electrode lead  714 , in this case taking the form of a defibrillation lead with an elongated coil electrode  17 . In an embodiment as illustrated, electrode  708  may be employed to sense or pace the atrium or other chamber of a patient&#39;s heart, with electrode  17  employed in conjunction with cardioversion or defibrillation functions. Alternatively, a lead carrying pacing and/or electrogram sensing electrodes may be substituted for lead  714 , or lead  714  may be omitted, and the device simply employed to deliver drugs to the pericardial space in conjunction with pacing or monitoring the electrical activity of the patient&#39;s heart via electrode  708 .  
         [0063]    [0063]FIG. 27 illustrates an additional alternative embodiment to a device generally corresponding to that illustrated in FIG. 26. In this case, the device is provided with an electrode  724  located on a laterally extending arm  726  in addition to ring electrode  709  to contact the wall  100  of a chamber of a patient&#39;s heart. Catheter body  720  may correspond to the catheter body  10 , as illustrated in FIGS.  1 - 4  above, and is stabilized in the wall  100  of a chamber of the patients heart by elastic tube  722  which also may correspond to elastic tube  30  in FIGS.  1 - 4 . In this case, an electrode lead  228  which carries pacing/sensing electrodes  730  and  732  is shown extending into the pericardial space. As in conjunction with the device illustrated in FIG. 26, lead  728  may be replaced by a cardioversion/defibrillation lead, an ablation catheter, or may be omitted entirely.  
         [0064]    [0064]FIG. 28 illustrates an additional alternative embodiment of a delivery catheter or cannula  740 , which is provided with a helical fixation member  746  which might also function as an electrode. Helical fixation  746  may be coupled to a coiled conductor  742  within the body of the cannula  740  by means of a conductive sleeve  750  as illustrated. In alternative embodiments, the helix  746  may merely serve to anchor the catheter or cannula  740  adjacent the wall  100  of the heart chamber. The catheter or cannula  740  is provided with a molded polymer seal  748  through which a catheter, guidewire, or electrode lead  744  passes. Seal  748  serves to seal the distal end of the delivery catheter or cannula  740  from fluid intrusion.  
         [0065]    In cases in which the helix  746  is coupled to an internal conductor within the delivery catheter or cannula  740  and is intended to be used as an electrode, it may be used, for example, to stimulate the right atrium of the heart, with the electrode lead  744  extending therethrough passing into the pericardial space and around the heart into contact with another chamber of the heart, such as the left atrium or left ventricle of the heart.  
         [0066]    [0066]FIG. 29 illustrates an additional alternative embodiment of a delivery catheter or cannula according to the present invention. The delivery catheter or cannula comprises an outer tubular sheath  800  mounted concentrically around an inner tubular sheath  806 . The outer tubular sheath  800  is provided with a series of longitudinal slots  802  which separate the outer sheath into parallel ribs which, as illustrated in FIG. 30 below, may be deflected outward to provide a mechanism for anchoring a delivery catheter or cannula adjacent one surface of a wall of a heart chamber. Inner catheter or cannula  806  is provided with a rearward facing generally conical resilient flange  808 , corresponding generally to the flange  218  on the introducer catheter or cannula of FIG. 9. Inner tubular member  806  may be displaced longitudinally relative to outer tubular member  800  by means of associated handles  810  and  804 . Located within inner tubular sheath  806  is a fluid delivery catheter  812 , which extends out the distal end of inner tubular member  806  and is slidable longitudinally with regard to inner tubular member  806 . Fluid delivery catheter  812  also has a handle  814  on its proximal end and is provided with a luer fitting  816  allowing for connection to a fluid source.  
         [0067]    [0067]FIG. 30 illustrates the configuration of the delivery catheter or cannula of FIG. 29 as it passes through the wall  100  of a chamber of the heart. The catheter or cannula is anchored to the wall  100  of the heart by first passing the conical flange  804  of the inner tubular member  806  through the wall of the heart, thereafter advancing the outer tubular member distally until its distal end engages the wall of the heart, and then advancing the tubular member further distally, causing lateral expansion of the ribs  803  as illustrated to anchor the catheter. Tubular delivery catheter  812  may then be advanced distally the distal end of the inner tubular member  806 , exposing laterally oriented delivery ports  820 , which ports were previously located within and sealed by a distal portion of the inner tubular member  806 .  
         [0068]    While the present invention is directed primarily toward access to the pericardial space, it is believed that the devices illustrated and describe herein may also usefully be employed to access other portions of the body, particularly spaces within or between other body organs and more particularly to spaces which need to be accessed by penetrating a layer or wall of body tissue. As such, it should be understood that the devices which are the subject of the following claims are not necessarily limited in use to pericardial access.  
         [0069]    In conjunction with the above specification, we claim: