Abstract:
A device for causing dilation of a tubular anatomy comprising; an active element comprising: a plurality of elongate flexible members, each having a first end and a second end; a first connector connected to the first ends of the strips; a second connector connected to the second ends of the strips; a compressor for causing one of the connectors to move towards the other connector thereby causing the elongate members to bow laterally.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a device for measuring pressure within a tubular anatomy, and particularly, but not exclusively, to a device for measuring pressure within the oesophagus of a human or animal.  
       DESCRIPTION OF THE RELATED ART  
       [0002]     The oesophagus is a tube that connects the mouth with the stomach. The walls of the oesophagus are very muscular, and contract rhythmically. This rhythmical movement is known as peristalsis and serves to transfer food from the mouth to the stomach for digestion within the stomach.  
         [0003]     The oesophagus is connected to the stomach by a valve known as the lower oesophageal sphincter. The sphincter prevents the backward flow of food from the stomach into the oesophagus.  
         [0004]     It can sometimes be necessary to measure how well the muscles of the oesophagus are working and to measure the strength of the lower oesophageal sphincter. Such measurements may assist diagnosis of a medical condition present in a patient.  
         [0005]     These measurements are known as oesophageal manometry or as an oesophageal function or oesophageal motility study.  
         [0006]     It is known to carry out such measurements by passing a soft tube through the nose or mouth of a patient. The tube has pressure sensors along its length and when in place can measure the pressure that is produced by the oesophageal muscles when relaxing or compressing during the peristaltic process, or the pressure within a stricture.  
         [0007]     It is known that strictures may develop in the oesophagus. The presence of one or more strictures in an oesophagus may lead to problems and clinical conditions such as dyspepsia, dysphasia and asthma. It is therefore desirable to be able to dilate the oesophagus in the region of the stricture in order to reduce or overcome these problems.  
         [0008]     It is known to use a device which is generally olive shaped and made of metal to dilate the oesophagus in the region of a stricture. These devices are available in a range of sizes, and are passed through the stricture in turn, starting with the largest device that can just pass through the stricture, and increasing the size of the device until the desired dilation of the stricture is achieved. It is also possible to use, in a similar way, soft, flexible rubber tubes in place of the metal olive shaped devices.  
         [0009]     Surgery of the oesophagus, particularly conventional or laparoscopicfundoplication used in the treatment of gastroesophageal reflux disease can result in severe post-operative dysphagia. This is because the wrap (i.e. the stomach wall wrapped around the oesophagus) is too tight. The ability to perform manometry in the oesophagus pre, intra and post operation would reduce the extent of dysphagia suffered since it would enable the wrap tension to be measured.  
         [0010]     In addition, a means for carrying out pre, intra and post operative manometry combined with a means for measuring the dilation of strictures would assist in the selection of the most appropriate technique to use to carry out the surgery.  
       SUMMARY OF THE INVENTION  
       [0011]     According to the invention there is provided a device for causing dilation of a tubular anatomy comprising: 
        an active element comprising:     a plurality of elongate flexible members, each having a first end and a second end;     a first connector connected to the first ends of the strips;     a second connector connected to the second ends of the strips;     a compressor for causing one of the connectors to move towards the other connector thereby causing the elongate members to bow laterally.        
 
         [0017]     The compressor is controlled to exert a predetermined pressure on the elongate members. This means that an appropriate degree of dilation may be achieved. The pressure applied by the compressor may be either constant or stepped to allow graduated expansion to predetermined dilation sizes.  
         [0018]     By means of the present invention, therefore, it is possible to achieve controlled dilation of a stricture in a tubular anatomy without having to use a plurality of devices each having a predetermined size. This in turn means that devices do not have to be taken in and out of the tubular anatomy, since once the device has been inserted, it can remain in place until the surgical operation or procedure is complete. This reduces the severity of dysphagia experienced after the operation or procedure.  
         [0019]     Advantageously, the device further comprises at least one stop for preventing over-compression of the active element. This ensures that over dilation does not occur. The expansion of the active element is restricted by the at least one stop, past which the moveable elements cannot move. In other words, maximum expansion is set.  
         [0020]     Preferably, the device comprises a plurality of stops positioned to ensure stepped dilation of the tubular anatomy. The stops may comprise a plurality of grooves positioned along the length of the active element and a moveable member in the form of a ring or disc. The grooves are adapted to retain the moveable ring and are each collated with a predetermined movement of the elongate members.  
         [0021]     Alternatively, the device comprises a screw thread extending along the length of the active element, and a moveable member, moveable along the screw thread.  
         [0022]     Conveniently, the moveable member is internally threaded.  
         [0023]     The moveable member is moveable along the screw thread. This means that the movement of the elongate members is not limited to predetermined positions defined by the position of grooves, for example. This in turn means that dilation of the active element is not stepped.  
         [0024]     Conveniently the first and second connectors are substantially disc shaped. The device in its un-bowed state is therefore substantially cylindrical in shape. This ensures easy insertion into a tubular anatomy.  
         [0025]     The connectors may be formed integrally with the elongate members. In other words, the elongate members and the retaining means may be formed from a unitary sheet. Alternatively, the retaining means may be formed separately from the elongate members.  
         [0026]     Advantageously, the first connector comprises at least one pressure sensor. The at least one pressure sensor is able to measure pressure exerted on the active element. This means that when the device is in place in a tubular anatomy, the at least one pressure sensor is able to measure either the proximal or the distal pressure exerted on the active element by the walls of the tubular anatomy.  
         [0027]     The presence of the at least one pressure sensor means the device according to the invention is able to cause dilation of a stricture in a tubular anatomy and also carry out oesophageal manometry. This means that it is not necessary to insert a separate manometer into the tubular anatomy, further reducing the severity of any dysphagia experienced by the patient.  
         [0028]     Advantageously, the compressor comprises a first sleeve associated with the active element, which sleeve is mechanically driven. When activated, the sleeve pushes against one end of the active element causing compression of the active element.  
         [0029]     Alternatively, the compressor comprises means for pulling one connector towards the other. Conveniently, the compressor comprises a wire connected to the distal end of the active element. By pulling the wire it is possible to cause the distal end to move towards the other end of the active element.  
         [0030]     Conveniently, the compressor comprises a threaded elongate member associated with the active element.  
         [0031]     Advantageously, the device further comprises an outer sleeve extending over the active element. This allows smooth passage of the device through the tubular anatomy. The outer sleeve may be made from any suitable material, but preferably it is made from rubber.  
         [0032]     Alternatively, the outer sleeve may be made from polytetrafluoroethylene or a polyurethane elastomer.  
         [0033]     Other parts of the device, such as the flexible members may be made from any suitable material such as Nitinol (Nytinol).  
         [0034]     Preferably, the device further comprises a cone at the distal end of the active element. The cone facilitates initial passage though a stricture and reduces or prevents damage to the surrounding tissue and structure of the tubular anatomy.  
         [0035]     Conveniently, the cone is made from rubber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]     The invention will now be further described by way of example only with reference to the accompanying drawings in which:  
         [0037]      FIG. 1  is a schematic representation of a device according to the present invention;  
         [0038]      FIG. 2  is a cross-sectional representation of the device of  FIG. 1 ;  
         [0039]      FIG. 3  is a schematic representation of the device of  FIG. 1  with the outer sleeve in place;  
         [0040]      FIG. 4  is a schematic representation of the device of  FIG. 1  in a non bowed stated;  
         [0041]      FIG. 5  is a schematic representation of the device of  FIG. 1  in a bowed state;  
         [0042]      FIGS. 6 and 7  are schematic representations of a second embodiment of a device according to the present invention;  
         [0043]      FIGS. 8 and 9  are schematic representations of a third embodiment of a device according to the present invention; and  
         [0044]      FIG. 10  is an illustration of components forming a plurality of devices according to an embodiment of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0045]     Referring to the figures a device according to the present invention is designated generally by the reference numeral  10 . The device can be used in, for example, an oesophageal manometry and also for the measurement of dilation within a tubular anatomy such as the oesophagus. The device may also be used to dilate strictures within the oesophagus.  
         [0046]     The invention will be described in terms of use within oesophagus of a human or animal. However, it would also be a great benefit in a wide range of surgical procedures of tubular anatomy including the oesophagus; ureter, urethra, bronchus, or similar tubular structures; and vascular and cardiac structures.  
         [0047]     The invention may also be used in balloonangioplasty procedures.  
         [0048]     The device  10  comprises a plurality of elongate members  12  in the form of flexible strips. The elongate members  12  may be made from any convenient material for example metal. The flexible strips are held by connectors  14 ,  16  which, in the non active state hold the elongate members  12  in a substantially cylindrical shape. The connectors  14 , 16  together with the strips  12  comprise the active element  100  of the device  10 .  
         [0049]     Although in this example the connectors  14 ,  16  are shown as being formed separately from the elongate members  12 , in other embodiments, the connectors  14 , 16  may be formed integrally with the elongate members  12 .  
         [0050]     The device further comprises a first sleeve  18  which is mechanically driven.  
         [0051]     By driving the sleeve  18  towards connector  14 , the elongate members  12  are caused to bow out laterally as shown in  FIG. 1 . The sleeve  18  may be controlled by any suitable means for example it may be computer controlled.  
         [0052]     By means of the expansion of the elongate members  12 , predetermined stages of dilation of the oesophagus, particularly a stricture in the oesophagus may be achieved.  
         [0053]     By means of the present invention therefore it is not necessary to have a range of devices of graduated size and to repeatedly insert appropriately sized devices into a patient&#39;s oesophagus. It is merely necessary to insert the device according to the invention once, and to cause dilation of the stricture in a controlled manner.  
         [0054]     The expansion of the elongate members  12  may take place either continuously with a gradual increase in expansion, or may take place in stepped increases, depending on the conditions prevailing.  
         [0055]     The connector  16  further comprises pressure sensors (not shown). The pressure sensors are able to measure pressure against the expanded active element. The pressure sensors are variably calibrated and are mounted proximal to a distal tip of the connector  16 . The pressure sensors are able to measure proximal or distal pressure against the elongate members.  
         [0056]     The sleeve  18  may be moved by the tensioning or pulling of an integral wire  30  connected to the distal end of the connector  14 . Alternatively, a wire may be connected to the connector  16  ( FIG. 3 ).  
         [0057]     The active element  100  is covered with an outer sleeve  22  ( FIG. 3 ) which allows smooth passage of the device  10  through an oesophagus or similar tubular anatomy.  
         [0058]     The device further comprises a cone  24  fitted to the distal end of the device which facilitates initial passage through a stricture and prevents or reduces damage to surrounding tissue and structure. The cone may be made of soft rubber, or any other suitable material.  
         [0059]     The device  10  is designed so that it can either form a component of an existing device, such as a flexible fibre optic endoscope, an endoscope insertion tube, a non-viewing endoscope tube; or it may be a stand alone device.  
         [0060]     Referring to  FIGS. 4 and 5 , the device  10  is shown to comprise a compressor  40  in a form of a mechanical compression screw. The connector  14  is attached to the screw  40 , and by tightening the screw  40 , the connector  14  is moved towards the connector  16 . This causes the elongate members  12  to bow and to take the position shown in  FIG. 5 .  
         [0061]     Referring now to  FIGS. 6 and 7  a second embodiment of the present invention is shown. Parts of the device  60  which correspond to parts of the device shown in FIGS.  1  to  5  have been given corresponding reference numerals for ease of reference.  
         [0062]     The device is designated generally by the reference numeral  60 . The device comprises a strain sensor  62 , for example a mechanical strain gauge or a peizo effect measurement-based strain sensor. The latter may be a PVDF strain sensor, essentially a silver screen printed onto clear PVDF film available from Measurement Specialities Inc (www. measurementspecialities.com). The strain gauge  62  serves to connect together the connectors  14  and  16 . The gauge  62  thus replaces the mechanical compression screw  40  shown in  FIGS. 4 and 5  and serves to cause bowing and unbowing of the device  60 .  
         [0063]     Referring to  FIGS. 8 and 9 , a further embodiment of a device  10  according to the present invention is shown. Parts of the device  10  which correspond to parts of the device  10  as illustrated in  FIG. 1  to  5  have been given corresponding reference numerals for ease of reference.  
         [0064]      FIG. 8  shows the device  10  in an active, or dilated state, and  FIG. 9  shows the device in a non-active state.  
         [0065]     Referring to  FIG. 10 , components which may be used to form a plurality of the devices shown in  FIGS. 8 and 9  are illustrated. The illustrated components comprise a plurality of flexible members  12 , sleeves  14 ,  16  and sleeves  18 .