Abstract:
A catheter and related methods for percutaneous treatment of an aneurysm, the catheter comprising: an outlet for deploying an occluding agent; and a deflector for deflecting said occluding agent. A second deflector may be provided to cooperate with the first deflector. One of both of the deflectors may comprise inflatable balloons. The occluding agent may comprise a length of wire.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to the percutaneous treatment of aneurysms, and in particular apparatus and methods for balloon assisted occlusion of cerebral aneurysms. 
         [0002]    Aneurysms of the cerebral arteries are areas of blood vessel which have been weakened through disease or injury and have subsequently expanded due to the pressure of blood flow. 
         [0003]    Cerebral aneurysms are particularly dangerous as thrombus (blood clot) formation can occur within the aneurismal sac, greatly increasing the risk of emboli formation and stroke. In addition, as the vessel is weakened at the aneurysm site, blood vessel rupture is more likely. This condition, if left untreated, quickly results in death. 
         [0004]    Traditional treatment of cerebral aneurysm at risk of rupture has been a craniotomy (drilling through the skull) and occlusion using a cerebral clip. This operation carries significant risk and complexity due to its invasive nature. It is also only indicated for a narrow selection of patients due to that risk and because some parts of the cerebral vasculature are simply not accessible through the skull without having to damage the brain. 
         [0005]    Cerebral aneurysms fall into two main anatomical variants, which are illustrated in  FIGS. 1   a  to  2   b:  1) “saccular aneurysms”  100  (see  FIGS. 1   a  and  1   b ), which as their name suggests are round sack-like distensions  100  with a narrow opening  102  into the native vessel  104 ; and 2) “fusiform aneurysms”  200  (see  FIGS. 2   a  and  2   b ), which are concentric distensions  200  of the blood vessel  104  with less well-defined edges than a saccular aneurysm  100 . 
         [0006]    In recent years, percutaneous techniques have arisen to treat cerebral aneurysms using wire coils to artificially embolise the distended tissue.  FIG. 3   a  illustrates application of this technique to a saccular aneurysm  100 . A catheter  300  is fed up to the aneurysm mouth  102  where a platinum wire  302  is pushed out of the catheter tip  304 , into the aneurismal sac  100 . This wire  302  then coils into the sac  100 , progressively occluding the aneurysm  100 . When enough wire  302  is implanted, the clinician can simply disconnect the wire  302 , which should stay in place. 
         [0007]    This method is well established and has been in use since 1991. However, it is generally only applicable for narrow necked, saccular aneurysms  100  as these shapes lend themselves well to the wire  302  coiling round into a ball. 
         [0008]    For wider necked aneurysms  320  (see  FIG. 3   b ), i.e. those which are less saccular and more fusiform, this process may not be possible, as the wire  302  will tend to exit the aneurysm mouth into the native vessel  104 . This scenario should be avoided as wire  302  coils in the blood stream may pose a thrombus risk. 
         [0009]      FIG. 3   b  illustrates one approach that clinicians have used to avoid this. A compliant balloon  312  is positioned at the site of interest via a second catheter  314  and used to force the wire  302  round and back into the aneurismal sac  320 . On inflation, the balloon  312  conforms to the local vessel anatomy forming a barrier to the coiling wire  302 . Such balloons  312  can only be inflated for a maximum of  2  minutes at a time because, when inflated, they occlude blood flow through the vessel  104 . 
         [0010]    This prior art procedure requires the coil delivery catheter  300  and at least one balloon delivery system to occlude the aneurysm. As separate units, these devices cause significant crowding in an already small vessel  104  and, due to the high compliance of the deployed balloon, there is little scope for manoeuvring to re-adjust the delivery catheter  300  if multiple balloons were to be used. 
         [0011]    An object of the present invention is to overcome at least some of the problems associated with the prior art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    According to an aspect of the invention, there is provided a catheter for percutaneous treatment of an aneurysm, comprising: an outlet for deploying an occluding agent; and a first deflector for deflecting said occluding agent. 
         [0013]    Having a single catheter with its own deflector enables an occluding agent to be delivered reliably into an aneurysm with a minimum of crowding in the region of treatment. In addition, all the equipment required for the procedure is contained on the one device. 
         [0014]    Optionally, the occluding agent comprises a length of wire to be coiled into a ball in the aneurysm. The wire may be formed from a suitably inert metal such as platinum. The first or second deflector may comprise an inflatable balloon and/or be configured to deflect the occluding agent after it has left the outlet. 
         [0015]    Optionally, the catheter may comprise a second deflector, which may also comprise an inflatable balloon. Either or both of the first and second deflectors may be configured to shift the position and/or orientation of the outlet. The two deflectors thus provide enhanced control of how the occluding agent is deployed, thus improving the reliability and safety of treatment. 
         [0016]    The first and second deflectors may be configured to be actuatable selectively and/or to a variable extent so as cooperatively to adjust the direction of deployment of the occluding agent and/or the position and/or orientation of the outlet. Sequential and independent balloon inflation allows accurate positioning of the coil catheter for precise coil placement. 
         [0017]    According to an alternative aspect of the invention, there is provided a method of treating an aneurysm, comprising: percutaneously inserting a catheter according to any one of the preceding claims so that a distal end thereof is brought into the region of the aneurysm; using said outlet to deploy an occluding agent; and using said first deflector to deflect said deployed occluding agent into said aneurysm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: 
           [0019]      FIG. 1   a  shows a saccular aneurysm in  3 - d;    
           [0020]      FIG. 1   b  shows a saccular aneurysm in cross section; 
           [0021]      FIG. 2   a  shows a fusiform aneurysm in  3 - d;    
           [0022]      FIG. 2   b  shows a fusiform aneurysm in cross section; 
           [0023]      FIG. 3   a  shows a saccular aneurysm being treated with a simple coil embolisation; 
           [0024]      FIG. 3   b  shows a wider necked aneurysm being treated with the same coil dispensing type catheter as in  FIG. 3   a , with an additional compliant balloon catheter; 
           [0025]      FIG. 4   a  shows a combination catheter according to an embodiment of the invention, in an un-actuated state; 
           [0026]      FIG. 4   b  shows the combination catheter of  FIG. 4   a  with a primary balloon inflated so as to deflect a coil outlet; 
           [0027]      FIG. 4   c  shows the combination catheter of  FIG. 4   b  after actuation of a secondary balloon; 
           [0028]      FIG. 4   d  illustrates the fully actuated device of  FIG. 4   c  in situ; 
           [0029]      FIG. 5  illustrates an alternative deployment of the arrangement of  FIG. 4   d ; and 
           [0030]      FIG. 6  shows a control system for assisting treatment of an aneurysm. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIGS. 4   a  to  4   c  depict a catheter  400  according to an embodiment of the invention in three different states of actuation. 
         [0032]    The catheter  400  comprises a primary stem  410 , a secondary stem  408  and a tertiary stem  402 . At a distal end of the catheter  400 , the primary stem  410  comprises a first controllably expandable balloon  406   a / 406   b,  the secondary stem  408  comprises an outlet  412  for an occluding agent, and the tertiary stem  402  comprises a second controllably expandable balloon  404   a / 404   b.    
         [0033]      FIG. 4   a  depicts the catheter  400  before actuation; the first and second balloons  406   a  and  406   b  are both deflated and the outlet  412  is directed parallel to a longitudinal axis of the catheter  400  at the distal end (i.e. the end that will be pushed inside the vessel  104  to the treatment site). 
         [0034]      FIG. 4   b  shows the catheter  400  after actuation of the first balloon to an inflated state  406   a.  At the distal end of the catheter  400 , the secondary stem  408  is rotated anticlockwise so that the outlet orientation and position is changed. Occluding agent will thus be output in a different direction and from a different starting location in the configuration of  FIG. 4   b  in comparison with the situation in  FIG. 4   a.    
         [0035]      FIG. 4   c  shows the catheter  400  after actuation of the second balloon to an inflated state  404   b.  Inflation of the second balloon can be used to adjust the position and/or orientation of the outlet  412  further by pressing against the vessel wall  104  (and thereby pushing the distal end of the catheter  400  further away from the region of contact between the inflated second balloon  404   b  and the vessel wall  104 ). An example of this function is shown in  FIG. 4   d.    
         [0036]      FIG. 4   d  shows the fully actuated catheter  400  in situ in the body to be treated. The first and second balloons have both been actuated to inflated states  406   b  and  404   b  so as to guide the outlet  412  into a position opposite to the neck  414  of the aneurysm  320  and oriented so that an occluding agent will enter the aneurysm reliably and with a minimal risk of leakage of the occluding agent into the portion of the vessels  104  outside of the aneurismal sac. 
         [0037]    In the examples shown, the first balloon expands substantially symmetrically in two directions either side of the longitudinal axis of the primary stem  410  (i.e. two lobes are present in an axial sectional view). Alternatively, the first balloon  406   a / 406   b  may expand coaxially so as to extend radially outwards in all directions (to the same or different relative extents). Further alternatively, the first balloon  406   a / 406   b  may expand radially so as to form a single sectional lobe or three or more sectional lobes. The first balloon may be compliant and conform to the shape of the portion of the vessel  104  within which it is located, for example so as to substantially block this portion of the vessel  104 . 
         [0038]    The catheter  400  may be arranged so that inflation of the first balloon  406   a / 406   b  simultaneously causes: 1) the catheter  400  to be pushed away from a part of the wall of the vessel  104  with which the inflated first balloon  406   b  comes into contact; and 2) the secondary stem  408  to deflect to as to adjust the orientation of the outlet  412 . 
         [0039]    In the examples shown, the second balloon  404   a / 404   b  expands predominantly in a single sectional lobe (to the left in  FIG. 4   d ), so as to push the catheter  400  away from a region of contact between the inflated second balloon  404   b  and the vessel  104  (i.e. to the right in  FIG. 4   d ). However, other arrangements are possible. For example, the multiple lobe arrangements discussed above in respect of the inflated first balloon  406   b  could also be used for the inflated second balloon  404   b.    
         [0040]    In the example shown, the primary, secondary and tertiary stems are parallel, but other arrangements are possible. Arrangements having fewer than three stems can also be envisaged. For example, the functionality associated with the three stems may be incorporated into a single stem or two stems. 
         [0041]    In the examples shown, the second balloon  404   a / 404   b  is positioned near a distal end of the catheter  400 , in close proximity to the first balloon  406   a / 406   b.  However, the function of controllably displacing the catheter  400  by inflating the second balloon  404   a / 404   b  could be achieved via a balloon located further away from the distal end of the catheter  400  (i.e. further downwards in  FIGS. 4   a  to  4   d ). 
         [0042]    Deflection mechanisms other than balloons may also be provided, for deflecting the position of the distal end of the catheter  400 , for deflecting the orientation of the outlet  412  relative to the main longitudinal axis of the catheter  400  (near the distal end, for example relative to the stem  410  near the distal end), and/or for deflecting a direction of deployment of the occluding agent after it has left the outlet  412  (or of a portion of the occluding agent that has left the outlet  412 ). 
         [0043]    In the particular example shown in the  FIGS. 4   a  to  4   d , two balloons are used to deflect (control) the position and/or orientation of the occluding agent outlet  412 . Neither of the two balloons in this example are arranged to influence the direction of deployment of the occluding agent after it has left the outlet  412  (or of a portion of the occluding agent that has left the outlet—for example, a length of deployed wire). However, one or both of the balloons may be arranged to do this. For example, the first balloon may be configured to provide this functionality in addition to influencing the position and/or orientation of the outlet  412 . 
         [0044]      FIG. 5  shows an adaptation of the arrangement of  FIG. 4   d  (i.e. the same apparatus deployed differently or a differently configured apparatus) in which the inflated first balloon  406   b  is used to deflect a deployment direction of occluding agent at a point in time after it has been output from the outlet  412 . In this example, the inflated first balloon  406   b  is used to deflect occluding agent back into the aneurismal sac after it has been deflected by the inside of the aneurismal sac in a direction which, in the absence of the inflated first balloon  406   b,  might lead to escape of the occluding agent from the aneurismal sac. This arrangement reduces the risk of leakage of occluding agent into regions of the vessel  104  other than the aneurismal sac and helps to ensure efficient occlusion of the aneurismal sac. 
         [0045]    The arrangement of  FIG. 5  shows how deflection of the occluding agent can usefully be effected by the catheter of an embodiment after it has first been deflected by the inside of the aneurismal sac (or other interface within the body to be treated). However, alternatively or additionally, means may be provided to deflect the direction of deployment of the occluding agent immediately after it has left the outlet (before any deflection with other interfaces such as the interior of the aneurismal sac). 
         [0046]      FIG. 6  is a schematic illustration of a control system for assisting treatment of aneurysms using a catheter  400  according to embodiments of the invention. A scanner  602  is provided for determining the position and/or orientation of an outlet  412  of a catheter  400  relative to an aneurysm to be treated and/or the direction of deployment of occluding agent entering the aneurismal sac. This information is fed as input to a controller  600 , which may be implemented by a suitably programmed computer, for example. The controller  600  may process data input from the scanner  602  and present an image to a user via a display  606 . Using the display  606  as reference, the user may then input directions via input means  608  (comprising a joystick or similar, for example) to direct the controller  600  to adjust the degree of actuation (e.g. degree of inflation) of first and/or second balloons  406   a / 406   b / 404   a / 404   b  in the catheter  400  in order to adjust the position and/or orientation of the outlet  412  relative to the aneurysm to be treated and/or the direction of deployment of occluding agent entering the aneurismal sac. This user input is processed by the controller  600  and suitable commands are issued to a balloon controller  604  configured to carry out the necessary adjustments to the degree of actuation of the balloons (e.g., by inflating or deflating the first and/or second balloons  406   a / 406   b / 404   a / 404   b  to the appropriate extent). The balloon controller  604  may comprise means for measuring a pressure within the first and/or second balloons  406   a / 406   b / 404   a / 404   b,  for example, or other means for determining a degree of actuation of the first and/or second balloons  406   a / 406   b / 404   a / 404   b.