Abstract:
A delivery catheter having a shaft with a distal end and a proximal end for delivering an ablation probe to a body site. The delivery catheter comprises mounting members located at the distal end configured to receive an ablation probe; and attachment members configured to attach the distal end to a tissue surface. The delivery catheter preferably configured to allow an ablation probe mounted on the distal end to be manipulated so as to extend from the distal end in a direction selected from a range of directions. Even more preferably, the delivery catheter is configured to allow an ablation probe mounted on the distal end to be manipulated so as to move along a tissue surface and perform linear ablation. The invention also provides a system comprising the delivery catheter of the invention and an ablation device having an ablation probe, wherein the delivery catheter and the ablation probe are configured to allow the ablation probe to be mounted at the distal end of the delivery catheter.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention is generally in the field of medical devices. More specifically, the invention concerns delivery catheters for delivering an object to a body site.  
       BACKGROUND OF THE INVENTION  
       [0002]     Medical refractory cardiac arrhythmia can be treated using catheter ablation techniques. However, ablation of cardiac tissue along a continuous trace over a tissue surface (referred to herein as “linear ablation”) is difficult to achieve by this technique. Linear ablation in cardiac tissue is an accepted procedure for treating arrhythmias, such as atrial fibrillation, which is the most common cardiac arrhythmia. In this procedure, more than one line of tissue ablation is usually needed for successful treatment. However, generating continuous ablation lines in catheter ablation techniques is difficult to achieve. Thus, rather than utilizing the generally preferred per-cutaneous catheter ablation technique that makes use of an ablation catheter, ablation is carried out in an open-heart procedure in which the chest of the treated individual is opened to expose the heart tissue. While the open heart procedure is more traumatic and fully invasive, it is none the less become the standard ablation procedure. At times, ablation needs to be performed on heart portions that face the pulmonary veins. The lack of a direct view of these regions by the surgeon during an open heart procedure complicates the open heart ablation procedure.  
       SUMMARY OF THE INVENTION  
       [0003]     In its first aspect, the present invention provides a delivery catheter for delivering an ablation probe to a site within the body in order to perform ablation of tissue at the site. The delivery catheter is configured to carry an ablation probe near the distal end of the catheter. The delivery catheter comprises means for attaching the distal end of the delivery catheter to a tissue surface at the site. The delivery catheter is also configured to allow the ablation probe to extend from the delivery catheter and to be manipulated in a body cavity so as to contact a tissue surface at a selectable location the site and to ablate the tissue at that location. Manipulating the ablation probe also allows linear ablation along a selectable trace over the tissue surface at the site to be performed.  
         [0004]     The distal end of the delivery catheter carrying the ablation probe is delivered to the body site where ablation is to be carried out. The distal end of the catheter is then affixed to a tissue surface at the site. The ablation probe is then manipulated so as to extend out from the catheter and contact the tissue surface at a desired location at the site in order to carry out tissue ablation at that location. The probe may be manipulated so as to carry out linear ablation over a tissue surface at the site.  
         [0005]     The invention also provides a system comprising a delivery catheter of the invention and a tissue ablation device having an ablation probe. The delivery catheter and the ablation device are configured to allow the ablation probe to be carried by the delivery catheter at the distal end for the delivery catheter. The ablation device also preferably includes a utility for delivering ablative energy that may be heat or cold, to the probe. The ablation probe delivers the ablating energy to the tissue in contact therewith. The ablating energy delivered by the ablation probe can be in the form of Radio-Frequency (RF), microwave, laser, ultrasound, heat, cryo energy, etc. As will be appreciated, the invention is not limited to any specific ablation catheter. The probe may be essentially straight although it may also be curved or even define a closed loop.  
         [0006]     The system may also include a guide wire that is first delivered to a body site where ablation is to be performed. The delivery catheter carrying the ablation probe on its distal end is then mounted on the guide wire and delivered to the site along the guide wire. For example, the delivery catheter may be delivered into the left atrium through the intra-atrial septum.  
         [0007]     The utility for delivering ablative energy to the probe is either linked to the probe or is associated therewith in an induction association to permit the delivery of ablative energy to the probe.  
         [0008]     By a further aspect of the invention, there is provided a medical procedure that comprises: (a) mounting an ablation probe onto the distal end of a delivery catheter according to the invention; (b) delivering the distal end of the delivery catheter to a body site where tissue ablation is to be performed; (c) extending the ablation probe from the distal end of the delivery catheter and manipulating the ablation probe so as to contact at a desired location on a tissue surface at the site where ablation is to be performed; and (d) applying ablative energy to the tissue at the desired location at an intensity and for time to yield effective tissue ablation.  
         [0009]     A person versed in the art should be able to determine both the intensity of the ablative energy and the length of time for its application. This may be determined, for example, on the basis of either the scientific literature relating to tissue ablation techniques, on his own experience, or by resorting to some limited set of experiments that may be carried out in a variety of animal models (e.g., in pigs) as well as on humans, within the framework of appropriate clinical trials, for determining both the intensity and the time needed to yield an effective tissue ablation.  
         [0010]     The ablation energy that is delivered may be any form of energy, for example in the form of Radio-Frequency (RF), microwave, laser, ultrasound heat, cryo, etc. The probe is preferably made of a heat conducting material such as metal. The energy may, in accordance with one embodiment may be delivered from a source directly to the probe, as known per se. For example, the probe may have a lumen that is fed with an energy-delivering fluid, e.g. a cooled gas, from a source of such fluid, fed to the probe through the length of the delivery catheter via an appropriate ducting arrangement. The probe may also be provided with an internal electric heating device connected by wire leads running along the length of the delivery catheter to a power source. Additionally, heating of the probe may be achieved through an induction heating process. As is clear to the artisan, the invention is not limited to the type of ablative energy nor to any manner in which it is delivered to the probe. On the contrary, any energy-delivering technique used or otherwise known in the art may be employed in the system and catheter of the invention. As may also be appreciated, the above described ablation energy delivering means is not a conclusive list but is rather an example thereof.  
         [0011]     According to one embodiment of the invention, the attachment arrangement includes an attachment body that defines a trough with an open side that faces the tissue to be ablated and accommodating said probe. Said probe may be firmly associated with the attachment body or alternatively, the attachment body may be designed so as to permit the probe to be manipulated from outside the body to move linearly within said trough. As an example of the latter probe design, the attachment body may be fitted at the distal end of the catheter and the probe guided in this way along the catheter into the trough of the attachment body.  
         [0012]     The attachment body may comprise attachment members disposed on both sides of said probe for holding said body and the probe against said tissue. By one example, said attachment members are small hooks or micropods.  
         [0013]     By another embodiment, said attachment members are a plurality of suction ducts or cups that attach to a tissue surface by negative pressure or vacuum. The attachment in this case is through the vacuum that forms within the cups. The cups may be passive vacuum cups with the vacuum being formed during the attachment process. Alternatively, and preferably, the vacuum may be an active one with each vacuum cup being linked via a conduit running through the delivery catheter to a vacuum source located outside the body.  
         [0014]     A preferred but not exclusive implementation of the invention is in ablation of cardiac tissue. In this procedure a guide wire is inserted through an incision in the skin into a vein, typically a femoral vein and is guided first to the right atrium and from there to the left atrium through the inter-atrial septum. The delivery catheter of the invention carrying an ablation probe on its distal end is then mounted on the guide wire and delivered to the left or right atrium. Then the distal end fo the delivery catheter is attached to an internal surface of the atrium, and the tissue is ablated. The ablation design is typically based on the surgical Maze procedure and includes, encircling of the pulmonary veins and various ablation lines and points throughout both the right and the left atria. The same system can serve for ablation in the ventricles for ventricular arrhythmias. Other types of cardiac arrhythmias that can be treated by ablation include, but are not limited to, Ventricular Tachycardia (VT), Supra Ventricular Tachycardia (SVT), Atrial Flutter and Wolf Parkinson White (WPW). For the right ventricle the distal end of the delivery catheter may be inserted into the femoral vein and delivered to the right atrium then through the tricuspid valve to the right ventricle. For ablation in the left ventricle the distal end of the delivery catheter may be delivered to the left atrium as described above and then through the mitral valve to the left ventricle. In some cases the distal end of the catheter can be delivered to the left ventricle via the Aortic valve. Ablation can also be performed in the right atrium for certain arrhythmias originating in the right atrium.  
         [0015]     Thus, in its first aspect, the invention provides a delivery catheter having a shaft with a distal end and a proximal end for delivering an ablation probe to a body site, comprising: 
        (a) mounting members located at the distal end configured to receive an ablation probe; and     (b) attachment members configured to attach the distal end to a tissue surface.        
 
         [0018]     In its second aspect the invention provides a medical system comprising: 
        a delivery catheter of the invention; and     a tissue ablation device having an ablation probe;     wherein the delivery catheter and the ablation probe are configured to allow the ablation probe to be mounted at the distal end of the delivery catheter.        
 
         [0022]     In its third aspect, the invention provides a method for ablating a body tissue, comprising: 
        (a) mounting an ablation probe onto the distal end of a delivery catheter of the invention;     (b) delivering the distal end of the delivery catheter to a body site where tissue ablation is to be performed;     (c) extending the ablation probe from the distal end of the delivery catheter and manipulating the ablation probe so as to contact one or more desired locations on a tissue surface at the site where ablation is to be performed; and     (d) applying ablative energy to the tissue at each of the one or more desired locations at an intensity and for time to yield effective tissue ablation.       
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     For a better understanding the invention will now be described with reference to some non-limiting specific embodiments shown in the annexed drawings. In the drawings:  
         [0028]      FIG. 1A  shows a bottom perspective view of the distal end of a delivery catheter in accordance with an embodiment of the invention having a vacuum attachment to a tissue surface;  
         [0029]      FIG. 1B  is a longitudinal cross-section through the delivery catheter of  FIG. 1A , accommodating an ablation probe;  
         [0030]      FIG. 2  shows a delivery catheter in accordance with another embodiment of the invention having a vacuum attachment mechanism, illustrated in a state in which it is attached to a tissue surface with the ablation probe in contact with tissue;  
         [0031]      FIG. 3A  shows a delivery catheter accommodating an ablation probe with a helical attachment member for a screw-type engagement to tissue;  
         [0032]      FIG. 3B  shows the delivery catheter of  FIG. 3A  with the helical attachment member engaged into the tissue and with an ablation probe in contact with tissue;  
         [0033]      FIG. 4A  shows a delivery catheter with an attachment mechanism in accordance with another embodiment of the invention that comprises hooks that are strained within the catheter that once released can be inserted into a tissue for attachment of the distal end of the catheter to the tissue;  
         [0034]      FIG. 4B  shows the hooks after being released and inserted into a tissue with the probe resting against the tissue.  
         [0035]      FIG. 5A  shows a delivery catheter in accordance with the invention with an attachment mechanism that includes a vacuum attachment arrangement combined with deployable trough-like member that can accommodate and firmly hold an ablation probe to a tissue;  
         [0036]      FIG. 5B  shows the delivery catheter of  FIG. 5A  attached to a tissue with the trough-like member deployed and firmly holding an ablation catheter to a tissue;  
         [0037]      FIG. 6A  shows a delivery catheter in accordance with another embodiment of the invention with an attachment mechanism that includes a vacuum-type attachment arrangement involving a vacuum cup held in a folded and strained state in the distal end of the catheter that can be released from the distal end;  
         [0038]      FIG. 6B  shows the catheter of  FIG. 5A  attached to a tissue with the vacuum cup fully opened firmly attached to a tissue;  
         [0039]      FIG. 7  shows a delivery catheter for an ablation device in accordance with one embodiment of the invention; and  
         [0040]      FIG. 8  shows a delivery catheter for an ablation device in accordance with another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0041]     Referring first to  FIG. 7 ,  FIGS. 7   a  through  7   f  show a delivery catheter for delivering a tissue ablation probe to a body site, in accordance with one embodiment of the invention. As seen in  FIG. 7   a , the delivery catheter  700  has a slender flexible shaft  702  having a proximal end  704  and a distal end  706 . The distal end  706  is tapered and terminates in a terminal opening  708 . A side opening  710  is located in the wall of the shaft  702  near its distal end  706 . The proximal end  704  of the catheter  702  has a handle  712  and a controller  714  described in detail below.  
         [0042]      FIG. 7   b  shows the delivery catheter  700  in longitudinal section. The shaft  702  of the catheter  700  comprises an outer sheath  716 . Within the outer sheath  716  is an inner sleeve  718 . The inner sleeve  718  extends from an opening  726  in the handle  712  through the handle  712  and controller  714  through the outer sheath  716 , and terminates in a distal end  715  just proximally to the side opening  710 . A helical spring  720  located in the space between the outer sheath  716  and the inner sleeve  718  surrounds the inner sleeve  718 .  
         [0043]     The inner sleeve  718  is configured to receive in its lumen the shaft of an ablation catheter.  FIG. 7   c  shows the delivery catheter  700  after an ablation catheter  724  has been inserted into the inner sleeve  718 . The ablation catheter is inserted through the opening  726  at the end of the handle  712  and slides through the inner sleeve  718  until the distal end of the ablation catheter  724  is located at the distal end of the inner sleeve  718 , which, as explained above, is adjacent and proximal to the opening  710 . The ablation catheter  724  may be any type of ablation catheter known in the art and may use any type of ablative energy, such as radio frequency (RF) energy or cryo energy. The ablation catheter is connected at a proximal end (not shown) to a source of ablative energy (also not shown). The distal end of the ablative catheter includes a probe  728  for delivering ablative energy to a body tissue, as explained below.  
         [0044]     With the delivery catheter  700  and the ablative catheter  724  in the configuration shown in  FIG. 7   c , the distal end  706  of the delivery catheter is inserted into the body and delivered to a body site where ablation of tissue is to be carried out. For example, a guide wire (not shown) may be inserted into the body through an incision in the skin and then delivered via the vasculature to a body site such as a heart, where ablation is to be carried out. The delivery catheter  700  may then be mounted on the guide wire and the distal end  706  delivered to the site where the ablation is to be carried out on the guide wire. Alternatively, the distal end  706  of the delivery catheter  700  may be delivered to an epicardial site in a beating heart surgical procedure.  
         [0045]      FIG. 7   d  shows the delivery catheter  700  after having been delivered to a body site where ablation is to be carried out. The site may be, for example, a body cavity  730  such as a heart ventricle. With the delivery catheter  700  in the arrangement shown in  FIG. 7   d , the control  714  is rotated. The control has a cylindrical extension  732  having a helical screw thread  734  on it outer surface that mates with a helical screw thread  736  on the inner surface of the outer sheath  716 . Rotation of the control  714  in a clockwise direction when viewed from the proximal end  704  causes the extension  732  to progress towards the distal end  706  of the shaft  702 . Graduation marks  713  on the controller  714  indicate the amount the controller  714  has been rotated from its original position. As the extension  732  progresses distally inside the shaft  702  it presses upon the spring  720 . Pressing upon the spring  720  in this way causes the spring  720  to rotate inside the shaft  702  and to move distally through the shaft  720 , so that the distal end of the spring  720  passes through the opening  708  and extends beyond the distal end  706  of the shaft  720 .  
         [0046]     The spring  720  terminates at its distal end in a sharp point  715 . Thus, as the spring  720  continues to be rotated, the portion of the spring  720  extending beyond the opening  708  screws into the body tissue  738  in the wall of the cavity  730 , as shown in  FIG. 7   e  so as to attach the distal end  706  of the delivery catheter  700  to the wall of the cavity  730 . The controller  714  is provided with a locking mechanism (not shown) that prevents unwanted rotation of the controller.  
         [0047]     At this point, the distal end of the ablation catheter  724  is made to pass through the side opening  710 . This is carried out by grasping the exposed part  725  of the ablation catheter  724  extending from the opening  726  in the handle  712  and sliding the ablation catheter  724  distally. The spacing between adjacent turns of the helical spring  720  is less than the diameter of the ablation catheter, so that the ablation catheter is prevented from passing between adjacent turns of the spring  720 . However, one turn of the spring  720 , indicated by the arrow  740  in  FIGS. 7   d  and  7   e  is wider than the other turns of the helical spring  720 . The spacing of the turn  740  is greater that the diameter of the ablation catheter  724  and in the configuration of the delivery catheter  700  shown in  FIG. 7   e , with the helical spring  720  screwed into the tissue  738 , the turn  740  is positioned at the opening  710 . In this configuration, distal sliding of the ablation catheter  724  causes the distal end of the ablation catheter to pass through the opening  710 , as shown in  FIG. 7   f.    
         [0048]     In the configuration of  FIG. 7   f , the distal end of the ablation catheter  724  extends through the opening  710  and contacts body tissue at a location  742 . Ablation energy may then be delivered to the ablation catheter so as to cause ablation of the tissue at the location  742 .  
         [0049]     The opening  710  occupies an arc in the wall of the inner sleeve  718  that preferably occupies about 180° of the circumference of the shaft  702 . In this case, the ablation catheter may be rotated in the inner sleeve about the longitudinal axis of the shaft  702  by grasping the exposed portion of the ablation catheter extending from the handle  712  and rotating the exposed portion of the ablation catheter. In this way, the exposed portion of the ablation catheter extending from the opening  710  will sweep out an arc of up to about 180° as the ablation catheter is rotated in the inner sleeve  718 . The direction from which the ablation catheter extends from the opening  710  may thus be selected. Also, the position of the distal end of the ablation catheter in the body cavity  730  may be changed by longitudinal displacement of the shaft  702  of the delivery catheter. Moreover, applying ablation energy to the ablation catheter  714  as the distal end of the ablation catcher is moved in the body cavity  730  allows linear ablation to be carried out on the wall of the body cavity  730 .  
         [0050]     When tissue ablation has been completed, the ablation catheter  724  is pulled proximally so as to retract the distal end of the ablation catheter  724  in the inner sleeve  718  so as to regain the configuration shown in  FIG. 7   e . The distal end of the helical spring is then unscrewed from the tissue  738  by rotating the controller counter clockwise when viewed from the proximal end back to its original position, as determined by the graduations  713  on the controller, so as to bring he deliver catheter back to the configuration shown in  FIG. 7   d . The delivery catheter  700  is then removed form the body.  
         [0051]      FIG. 7   g  shows an alternative arrangement  750  of the delivery catheter  700  having a distal end  706 ′. In the arrangement  750 , the distal end  706 ′ is not tapered and there is no side opening  710  as in the arrangement of the distal end  706  shown in  FIGS. 7   a  to  7   f.    
         [0052]      FIG. 7   h  shows the delivery catheter  750  with the distal end  706 ′ after having been delivered to a body site where ablation is to be carried out. The site may be, for example, a body cavity  730  such as a heart ventricle. With the delivery catheter  750  in the arrangement shown in  FIG. 7   h , the control  714  is rotated so as to press upon the spring  720  as explained above with reference to  FIGS. 7   a  to  7   f . Pressing upon the spring  720  in this way causes the spring  720  to rotate inside the shaft  702  and to move distally through the shaft  720 , so that the distal end of the spring  720  passes through the distal opening  758  and extends beyond the distal end  706 ′ of the shaft  720 . The distal end  706 ′ is maintained a certain distance away from the wall of the cavity  730  as shown in  FIG. 7   h  so as to allow the ablation catheter  724  to exit through the opening  758 , as explained below.  
         [0053]     Thus, as the spring  720  continues to be rotated, the portion of the spring  720  extending beyond the opening  758  screws into the body tissue  738  in the wall of the cavity  730 , with the distal end  706 ′ separated from the wall of the cavity  730 , as shown in  FIG. 7   i.    
         [0054]     At this point, the distal end of the ablation catheter  724  is made to pass through the opening  758 . This is carried out by grasping the exposed part  725  of the ablation catheter  724  extending from the opening  726  in the handle  712  and sliding the ablation catheter  724  distally. The spacing between adjacent turns of the helical spring  720  is less than the diameter of the ablation catheter, so that the ablation catheter is prevented from passing between adjacent turns of the spring  720 . However, one turn of the spring  720 , indicated by the arrow  740  in  FIGS. 7   g  and  7   h  is wider than the other turns of the helical spring  720 . The spacing of the turn  740  is greater that the diameter of the ablation catheter  724  and in the configuration of the delivery catheter  700  shown in  FIG. 7   g , with the helical spring  720  screwed into the tissue  738 , the turn  740  is positioned beyond the opening  758  so as to be exposed in the cavity  730 . In this configuration, distal sliding of the ablation catheter  724  causes the distal end of the ablation catheter to pass through the opening  758  and between the turn  740 , as shown in  FIG. 7   i.    
         [0055]     In the configuration of  FIG. 7   i , the distal end of the ablation catheter  724  extends through the opening  758  and contacts body tissue at a location  752 . Ablation energy may then be delivered to the ablation probe so as to cause ablation of the tissue at the location  742 .  
         [0056]     The ablation catheter may be rotated in the inner sleeve about the longitudinal axis of the shaft  702  by grasping the exposed portion of the ablation catheter extending from the handle  712  and rotating the exposed portion of the ablation catheter. In this way, the exposed portion of the ablation catheter extending from the opening  710  will sweep out an arc of up to almost 360° as the ablation catheter is rotated in the inner sleeve  718 . The direction from which the ablation probe extends from the opening  758  may thus be selected. Also, the position of the distal end of the ablation catheter in the body cavity  730  may be changed by longitudinal displacement of the shaft  702  of the delivery catheter. Moreover, applying ablation energy to the ablation catheter  714  as the distal end of the ablation catcher is moved in the body cavity  730  allows linear ablation to be carried out on the wall of the body cavity  730 .  
         [0057]     Referring now to  FIG. 8 ,  FIGS. 8   a  to  8   f  shows a delivery catheter  800  for delivering a tissue ablation probe to a body site, in accordance with another embodiment of the invention. As seen in  FIG. 8   a , the delivery catheter  800  has a flexible shaft  802  having a proximal end  804  and a distal end  806 . The shaft  802  contains two lumens  803  and  805 . The lumen  803  has an opening  807  at its proximal end, and an opening  808  at its distal end. The lumen  803  is configured to receive an ablation catheter, as explained below. The lumen  805  has an opening  809  at its distal end and an opening  815  at its proximal end. The lumen  805  contains an attaching member that is retracted into the lumen  805  during delivery of the distal end  806  of the catheter  800  to a body site, and is then made to extend through the opening  809  to attach to a tissue surface, as explained below. Movement of the attaching member in the lumen  805  is controlled by a controller  814  located at the proximal end  804  of the lumen  805 , as explained below.  
         [0058]      FIG. 8   b  shows the delivery catheter  800  in longitudinal section. The attaching mechanism includes a helical element  810  that terminates in a sharp point  812 . The helical element  810  is attached to the controller  814  by a flexible rod  816  that extends along the length of the lumen  805  from the helical element  810  to the controller  814 . Rotation of the controller  814  relative to a fixed ring  820  drives rotation of the rod  816  which in turn drives rotation of the helical element  810 . Longitudinal movement of the controller  814  drives longitudinal movement of the rod  816  which in turn drives longitudinal movement of the helical element  810 . Thus, longitudinal movement of the controller  810  from its position shown in  FIG. 8   b  in which a gap  818  between the controller  814  and the distal end of the lumen  805  towards the distal end  806  of the lumen  805  causes the helical member  810  to move through the opening  809  so as to extend beyond the distal end of the lumen  809 , as shown below.  
         [0059]     The lumen  808  is configured to receive in its lumen the shaft of an ablation catheter.  FIG. 8   c  shows the delivery catheter  800  after an ablation catheter  824  has been inserted into the lumen  808 . The ablation catheter is inserted through the opening  807  at the distal end of the lumen  808  and is slid through the lumen  808  until the distal end of the ablation catheter  824  is located at the distal end of the lumen  808 . The ablation catheter  824  may be any type of ablation catheter known in the art and may use any type of ablative energy, such as radio frequency (RF) energy or cryo energy. The ablation catheter is connected at a proximal end (not shown) to a source of ablative energy (also not shown). The distal end of the ablative catheter includes a probe  828  for delivering ablative energy to a body tissue, as explained below.  
         [0060]     With the delivery catheter  800  and the ablative catheter  824  in the configuration shown in  FIG. 8   c , the distal end  806  of the delivery catheter is inserted into the body and delivered to a body site where ablation of tissue is to be carried out. For example, a guide wire (not shown) may be inserted into the body through an incision in the skin and then delivered via the vasculature to a body site such as a heart, where ablation is to be carried out. The delivery catheter  800  may then be mounted on the guide wire and the distal end  806  delivered to the site where the ablation is to be carried out on the guide wire. Alternatively, the distal end  806  of the delivery catheter  800  may be delivered to an epicardial site in a surgical procedure.  
         [0061]      FIG. 8   d  shows the delivery catheter  800  after having been delivered to a body site where ablation is to be carried out. The site may be, for example, a body cavity  830  such as a heart ventricle. With the delivery catheter  800  in the arrangement shown in  FIG. 8   d , with a gap  831  between the distal end  906  and the tissue surface  833 , the control  814  is moved longitudinally towards the distal end  806 , so as to cause the helical member  810  to pass through the opening  809  and to extend beyond the distal end of the lumen  805 , as shown in  FIG. 8   e.    
         [0062]     At this point, controller  814  is rotated in a clockwise direction when viewed from the proximal end  804 . As explained above, rotation of the controller  814  drives rotation of the helical element  810 . The helical element  810  terminates at its distal end in a sharp point  812 . Thus, as the controller  814  continues to be rotated, the helical element  810  screws into the body tissue  838  in the wall of the cavity  830 , as shown in  FIG. 8   f  so as to attach the distal end  806  of the delivery catheter  800  to the wall of the cavity  830 . As the helical member  810  screws into the wall of the cavity  830 , the controller  814  is drawn further towards the proximal end of the lumen  805 . Graduation marks  813  on the controller  814  (see  FIG. 8   a ) indicate the amount the controller  814  has been rotated from its original position. The controller  814  is provided with a locking mechanism (not shown) that prevents unwanted rotation of the controller.  
         [0063]     Now the distal end of the ablation catheter  824  is made to pass through the opening  808  at the distal end of the lumen  803 . This is carried out by grasping the exposed part  825  of the ablation catheter  824  extending from opening  807  at the proximal end of the lumen  803  sliding the ablation catheter  824  distally as shown in  FIG. 8   g.    
         [0064]     In the configuration of  FIG. 8   g , the distal end of the ablation catheter  824  extends through the opening  808  and contacts body tissue at a location  842 . Ablation energy may then be delivered to the ablation catheter so as to cause ablation of the tissue at the location  842 .  
         [0065]     The ablation catheter  824  may be rotated in the lumen  803  about the longitudinal axis of the lumen  803  by grasping the exposed portion  825  of the ablation catheter extending from the lumen  803  and rotating the exposed portion  825  of the ablation catheter. In this way, the exposed portion of the ablation catheter extending from the opening  808  can be made to sweep out an arc of up to 360° as the ablation catheter is rotated in the lumen  803 . The direction from which the ablation probe extends from the opening  808  may thus be selected. Applying ablation energy to the ablation probe  828  as the distal end of the ablation catcher is moved in the body cavity  830  allows linear ablation to be carried out on the wall of the body cavity  830 .  
         [0066]     When tissue ablation has been completed, the ablation catheter  824  is pulled proximally so as to retract the distal end of the ablation catheter  824  into the lumen  803  so as to regain the configuration shown in  FIG. 8   f . The helical element  810  is then unscrewed from the tissue  838  by rotating the controller counter clockwise when viewed from the proximal end back to its original position, as determined by the graduations  813  on the, so as to bring he deliver catheter back to the configuration shown in  FIG. 8   d . The delivery catheter  800  is then removed form the body.  
         [0067]     Reference is now being made to  FIG. 2  which is a longitudinal section through an end portion of a catheter  50 . Formed at the end of the catheter  50  is a space  52  defined between septum  54  and rim  56 . Space  52  opens to vacuum duct  58  that leads to a vacuum source (not shown). The formation of the vacuum within space  52  allows for the firm attachment of catheter  50  to a tissue portion  60 , such as a heart muscle tissue. The side wall of catheter  50  has an opening  62  permitting extraction of the probe  64  of catheter  66  (through pushing the catheter longitudinally in the direction of arrow  68  so as to bring it into contact with the tissue portion  60 .  
         [0068]     Reference is now being made to  FIGS. 1A and 1B  showing the end portion of a guiding catheter  20  having an attachment body  22  for attachment of an ablation probe  24  of an ablation catheter  26  to tissue. The attachment body  22  is oriented essentially in a right angle to the longitudinal axis of catheter  20  (as will be appreciated this right angle orientation is but an example and the angle may also be other than right angle) and has a trough-like recess  28  that accommodates the ablation probe  24 . Formed in its bottom face are a plurality of openings  30  that are linked through an internal cavity  32  to a vacuum duct  34  that leads to a vacuum source  36 . It is through this vacuum arrangement that the attachment body can firmly attach to a tissue whereby the ablation probe  24  of the ablation catheter  26  rests against a tissue portion to be ablated. The ablation catheter is linked to a unit  40  for delivering of the ablation energy to the ablation probe. The ablation energy may be, for example, a cold fluid for cryo type ablation, etc.  
         [0069]     In the description of other embodiments, like elements to those in the embodiment of  FIG. 2  will be given like reference numerals shifted by 100 for  FIGS. 3A and 3B , 200 for  FIGS. 4A and 4B , 300 for  FIGS. 5A and 5B  and 400 for  FIGS. 6A and 6B  (for example elements  150  and  164  in  FIGS. 3A and 3B  and elements  250  and  264  in  FIGS. 4A and 4B  are functionally the same as elements  50  and  64  in  FIG. 2 , respectively; etc.). The reader is referred to the description of  FIG. 2  for explanation of their function.  
         [0070]      FIG. 3  shows another embodiment of the distal end of a delivery catheter of the invention of the distal end of a delivery catheter of the invention. The attachment mechanism in the embodiment of the distal end of a delivery catheter of  FIG. 3  comprises a helical attachment member  170  that screws into a tissue when rotated as indicated by arrow  172  thereby attaching the catheter  150  to tissue  160  as shown in  FIG. 3B . Ablation probe  164  then attaches to tissue  160  in a manner similar to that of  FIG. 2 .  
         [0071]      FIG. 4  shows another embodiment of the distal end of a delivery catheter of the invention. The delivery catheter of the embodiment of  FIG. 4  includes an attachment mechanism comprising hooks  274  that are held in a strained state within the distal end and once released, by pushing distally on members  276  can become inserted into a tissue, to hold the catheter firmly against the tissue  260  as seen in  FIG. 4B .  
         [0072]      FIG. 5  shows another embodiment of the distal end of a delivery catheter of the invention. The delivery catheter of the embodiment of  FIG. 5  includes an attachment mechanism comprising, in addition to a vacuum type attachment similar to that of the embodiment of  FIG. 2 , a releasable sleeve member  380  that can rotate about a pivot  382  by pulling on wire  384 . Once the wire  384  is pulled, member  380  rotates and can accommodate probe  364  of ablation catheter  366  within its trough-like recess  386  to hold probe  364  firmly against tissue  360 .  
         [0073]      FIG. 6  shows another embodiment of the distal end of a delivery catheter of the invention. The distal end of the delivery catheter comprises an attachment mechanism including a vacuum cup  490  that is made of a flexible material such as silicone rubber and that in a configuration seen in  FIG. 6A  for delivery of the distal end to a body site where tissue ablation is to be carried out, maintained in a strained state with the end of the catheter. After delivery of the distal end to the body site, the vacuum cup is pushed distally and thus opens to a deployed position seen in  FIG. 6B  to yield a fully operational vacuum cup. The vacuum cup is linked to a vacuum duct  458  linked to a vacuum source (not shown).