Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION: A CATHETER SYSTEM FOR INFUSION AND ASPIRATION

2. APPLICANT:
Meril Corporation (I) Private Limited, an Indian company of the address Survey No. 135/139, Muktanand Marg, Bilakhia House, Pardi, Vapi, Valsad-396191 Gujarat, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

 
FILED OF THE INVENTION
[001] The present disclosure relates to medical devices. More particularly, the present disclosure relates to a catheter system for infusion and aspiration.
BACKGROUND OF THE INVENTION
[002] Thrombosis is a condition in which thrombus is formed within one or more blood vessels of a patient. Thrombus (also referred to as a blood clot) is essentially a solid mass composed of fibrin, platelets, red blood cells, and white blood cells. Thrombosis can cause health related issues such as pulmonary embolism, strokes, heart attacks, serious breathing issues, necrosis, and the like etc.
[003] Catheter-directed Thrombolysis (CDT) is a popular, minimally invasive procedure to remove thrombi. Conventionally, a CDT procedure involves delivering thrombolytic medications to a target site via an infusion catheter. The thrombolytic medications break down or dissolve the thrombi. Further, an aspiration catheter is used to aspirate the dissolved thrombi from the blood vessel. Conventional catheter systems used for thrombus removal, have several disadvantages. Typically, separate catheters are used for infusing the thrombolytic medications and for aspirating the dissolved thrombi and a surgeon needs to switch between these catheters. Generally, a surgeon is required to first insert an infusion catheter inside the patient’s body to infuse the thrombolytic medications, remove the infusion catheter after that and insert an aspiration catheter inside the patient’s body to aspirate the dissolved thrombi. Such a switching between the infusion and aspiration catheters throughout the procedure increase the overall procedure time and associated costs for the patient. Moreover, these steps are repeated several times if the thrombus is present at multiple sites. This increases the risk of trauma and injury to the patient’s blood vessels, which may lead to serious consequences.
[004] Therefore, there arises a need for a catheter system for removing thrombus to overcome the aforesaid problems related to the conventional catheter systems.
SUMMARY OF THE INVENTION
[005] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are mere examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[006] The present disclosure relates to a catheter system capable of being used in an infusion procedure and an aspiration procedure. In an embodiment, the catheter system includes a shaft. The shaft has a tubular structure and includes a plurality of apertures provided circumferentially towards a distal end of the shaft. The catheter system further includes an inner tube is disposed with the shaft towards the distal end of the shaft. A plurality of apertures is provided circumferentially on the inner tube. The inner tube is movable between a first position and a second position. The apertures of the inner tube are aligned with the apertures of the shaft in the first position of the inner tube. The apertures of the inner tube are misaligned with the apertures of the shaft in the second position of the inner tube. The catheter system further includes an actuating assembly operatively coupled to the inner tube. The actuating assembly is configured to toggle the inner tube between the first position and the second position, thereby setting the catheter system in an infusion mode and an aspiration mode, respectively. The catheter system further includes a tip is provided at a distal end of the catheter system. The tip is coupled to the distal end of the shaft. A distal end of the tip includes an opening. The opening is configured to provide a passage for aspirated fluid or thrombus in the aspiration mode.
BRIEF DESCRIPTION OF DRAWINGS
[007] The summary above and the detailed description of descriptive embodiments, is better understood when read in conjunction with the apportioned drawings. For illustration of the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[008] Fig. 1 depicts an isometric view of a catheter system 100, according to an embodiment of the present disclosure.
[009] Fig. 1a depicts an exploded view of a distal portion of the catheter system 100, according to an embodiment of the disclosure.
[0010] Fig. 1b depicts a cross-sectional view of the distal portion of the catheter system 100, according to an embodiment of the present disclosure.
[0011] Fig. 2 depicts a perspective view of a shaft 110, according to an embodiment of the disclosure.
[0012] Fig. 3 depict a perspective view of an inner tube 150, according to an embodiment of the present disclosure.
[0013] Fig. 4 depicts a cross-sectional view of a tip 120, according to an embodiment of the present disclosure.
[0014] Fig. 5 depicts an isometric view of a proximal portion of the catheter system 100, according to an embodiment of the present disclosure.
[0015] Fig. 6a depicts a perspective view of the regulating knob 170, according to an embodiment of the present disclosure.
[0016] Fig. 6b depicts a coupling of the regulating knob 170 with a handle 160, according to an embodiment of the present disclosure.
[0017] Fig. 7 depicts a perspective view of a Y-hub 180, according to an embodiment of the present disclosure.
[0018] Fig. 8a depicts a perspective view of the proximal portion of the catheter system 100 in an aspiration mode, according to an embodiment of the present disclosure.
[0019] Fig. 8b depicts a cross-sectional view of the distal portion of the catheter system 100 in the aspiration mode, according to an embodiment of the present disclosure.
[0020] Fig. 8c depicts a perspective view of the proximal portion of the catheter system 100 in an infusion mode, according to an embodiment of the present disclosure.
[0021] Fig. 8d depicts a cross-sectional view of the distal portion of the catheter system 100 in the infusion mode, according to an embodiment of the present disclosure.
[0022] Fig. 9a depicts a side-view of a catheter system 200, according to an embodiment of the present disclosure.
[0023] Fig. 9b depicts an exploded view of a distal portion of the system 200, according to an embodiment of the present disclosure.
[0024] Fig. 10 depicts an isometric view of an assembly 230, according to an embodiment of the present disclosure.
[0025] Fig. 11a depicts a cross-sectional view of a distal portion of the catheter system 200 in an infusion mode, according to an embodiment of the present disclosure.
[0026] Fig. 11b depicts a proximal portion of the catheter system 200 in the infusion mode, according to an embodiment of the present disclosure.
[0027] Fig. 11c depicts a cross-sectional view of the proximal portion of the catheter system 200 in an aspiration mode, according to an embodiment of the present disclosure.
[0028] Fig. 11d depicts a cross-sectional view of the distal portion of the catheter system 200 in the aspiration mode, according to an embodiment of the present disclosure.
DETAILED DESCRIPTION OF DRAWINGS
[0029] Prior to describing the disclosure in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like. Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[0030] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[0031] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[0032] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[0033] The present disclosure relates to a catheter system for infusion and aspiration of fluids. According to the teachings of the present disclosure, the proposed catheter system includes a single catheter (or a shaft) that can be used for both infusion and aspiration. The catheter system includes an inner tube disposed within the shaft towards the distal end of the shaft. Both the shaft and the inner tube are provided with apertures. The inner tube is movable so as to align or misalign the apertures on the inner tube with the plurality of apertures on the shaft. When the apertures of the inner tube and the shaft are aligned a passage is formed for infusing a fluid at a target site within a patient’s vasculature, thereby facilitating the infusion of fluid. When the apertures of the inner tube are misaligned with the apertures of the shaft, a flow of fluid from the shaft to the patient’s vasculature is restricted while allowing a passage for a fluid or thrombus from a distal end of the catheter system into the shaft, thereby facilitating the aspiration of fluid or thrombus. A surgeon can easily switch between the infusion and the aspiration modes by moving the inner tube with the help of a control element (e.g., a regulating knob or a sliding button). By using the same catheter system for both the infusion and aspiration, a need for inserting/removing separate catheters is eliminated. Consequently, the disclosed catheter system reduces time for the infusion and aspiration procedures.
[0034] Though the present disclosure has been explained in the context of a thrombolytic procedure, the teachings of the present disclosure may be extended to any application requiring both infusion and aspiration at a target site during a medical procedure without deviating from the scope of the present disclosure.
[0035] Now referring to the figures, Fig. 1 illustrates a catheter system 100 (hereinafter, system 100), according to an embodiment. The catheter system 100 is capable for being used in bother an infusion procedure and an aspiration procedure without a need to change the catheter system 100. The catheter system 100 is used for both – infusing thrombolytic medications at a target site and aspirating thrombus from the target site. According to an embodiment, the catheter system 100 is operable in a first mode (also, interchangeably referred to as an infusion mode) and a second mode (also, interchangeably referred to as an aspiration mode). In the first mode, the catheter system 100 functions as an infusion catheter used for infusing an infusion fluid at a target site within a patient’s vasculature. The infusion fluid may, for example, be a thrombolytic medication for dissolving and/or breaking down a thrombus. In the second mode, the catheter system 100 functions as an aspiration catheter used for aspirating the thrombus from the target site. By switching the catheter system 100 between the first mode and the second mode, the catheter system 100 enables a surgeon to perform a thrombolytic procedure using a single catheter. The system 100 has a proximal end 100a and a distal end 100b. Fig. 1a illustrates an exploded view of a distal portion of the catheter system 100 and Fig. 1b illustrates a cross-sectional view of the distal portion of the catheter system 100. In an embodiment, the system 100 includes a tip 120, a shaft 110, an inner tube 150, a handle 160, and a Y-hub 180.
[0036] Referring to Fig. 2, the shaft 110 has a proximal end 110a and a distal end 110b. The shaft 110 is coupled to the tip 120 at the distal end 110b of the shaft 110 and is coupled to the handle 160 at the proximal end 110a of the shaft 110. The shaft 110 has an elongated, tubular structure. The shaft 110 may be made of a biocompatible material, such as, without limitation, polyether block amide (PEBAX), polyether ether ketone (PEEK), polyamide, nylon, etc. In an embodiment, the shaft 110 is made of polyether block amide (PEBAX). The shaft 110 may have a length ranging between 150 mm and 1350 mm. The shaft 110 may have an outer diameter ranging between 1 mm and 4 mm. In an example implementation, the length and the outer diameter of the shaft 110 are 900 mm and 1.67 mm, respectively. The shaft 110 includes at least one lumen. In an embodiment, the shaft 110 includes a first lumen (not shown) configured to provide a passage for the infusion fluid in the first mode and for the aspirated thrombus in the second mode. The shaft 110 may further include a second lumen (not shown) configured to provide a passage to a guidewire (not shown). The guidewire helps in navigating the shaft 110 through the patient’s vasculature to and from a target site.
[0037] In an embodiment, the shaft 110 includes a plurality of apertures 112 (hereinafter, apertures 112) provided circumferentially on an outer surface of the shaft 110. The apertures 112 are disposed towards the distal end 110b of the shaft 110. The apertures 112 provide a passage for the infusion fluid to flow into the vasculature in the first mode. The apertures 112 may have a pre-defined shape, such as, without limitation, triangular, oval, square, hexagonal, rectangular, heart, rhombus, crescent, etc. In an example implementation, the apertures 112 are circular. The length of the shaft 110 on which the apertures 112 are provided and the dimensions of the apertures 112 may be chosen based upon requirements. The apertures 112 may be uniformly or non-uniformly. In the depicted embodiment, the apertures 112 are distributed uniformly.
[0038] In an embodiment, the shaft 110 includes a projection 111 provided at the distal end 110b of the shaft 110. The projection 111 has a smaller diameter compared to the diameter of the shaft 110 such that the projection 111 forms a step-profile. The projection 111 helps in coupling the shaft 110 with the tip 120.
[0039] Fig. 3 illustrates the inner tube 150, according to an embodiment. The inner tube 150 is disposed within the shaft 110 towards the distal end 110b of the shaft 110. The inner tube 150 has a proximal end 150a and a distal end 150b. The inner tube 150 has a tubular shape defining a lumen. The inner tube 150 is disposed within a portion of the first lumen of the shaft 110 such that the lumen of the inner tube 150 aligns with and is continuous with a remaining portion of the first lumen of the shaft 110. The lumen of the inner tube 150 provides a passage to the infusion fluid in the first mode and to the aspirated thrombus in the second mode. The inner tube 150 may be made of a biocompatible material, such as, without limitation, nylon, polyether block amide (PEBAX), polyether ether ketone (PEEK), polyamide, etc. In an example implementation, the inner tube 150 is made of nylon. The inner tube 150 may have a length ranging between 20mm mm and 600 mm. The inner tube 150 may have an outer diameter ranging between 0.65 mm and 3.4 mm. In an example implementation, the length and the outer diameter of the inner tube 150 are 150 mm and 1.47 mm, respectively.
[0040] The inner tube 150 includes a plurality of apertures 151 provided circumferentially on an outer surface of the inner tube 150 along at least a partial length of the inner tube 150. In an embodiment, the apertures 151 are provided along the entire length of the inner tube 150. The apertures 151 provide a passage for the infusion fluid to flow into the vasculature in the first mode. The apertures 151 may be distributed uniformly or non-uniformly. In the depicted embodiment, the apertures 151 are distributed non-uniformly. The apertures 151 may have a pre-defined shape, such as, circular, triangular, oval, square, hexagonal, rectangular, heart, rhombus, crescent, oblong, etc. In an example implementation, the apertures 151 are oblong. According to an embodiment, the apertures 151 have a larger longitudinal length than the apertures 112 of the shaft 110.
[0041] The inner tube 150 is movable within the shaft 110 between a first position and a second position. In the first position, the apertures 112 of the shaft 110 and the apertures 151 of the inner tube 150 are aligned to form a channel for the infusion fluid, thereby facilitating the delivery of the infusion fluid at the target site into the patient’s vasculature. In the second position, the apertures 112 of the shaft 110 are misaligned with the apertures 151 of the inner tube 150 such that the inner tube 150 blocks the apertures 112 of the shaft 110 and the shaft 110 blocks the apertures 151 of the inner tube 150. This prevents any solids and/or fluids from passing through the apertures 112 and the apertures 151. According to an embodiment, the second position of the inner tube 150 is proximal to the first position of the inner tube 150.
[0042] The inner tube 150 is moved between the first position and the second position by an actuating assembly. The inner tube 150 is operatively coupled to the actuating assembly. In an embodiment, the inner tube 150 is coupled to the actuating assembly with the help of a pull wire 153. The pull wire 153 has a proximal end 153a and a distal end 153b. The distal end 153b of the pull wire 153 is coupled to the inner tube 150 towards the proximal end 150a of the inner tube 150. The pull wire 153 may be coupled to the inner tube 150 using any coupling mechanism, such as, without limitation, riveting, knotting, crimping, male-female locking, clamping, hooking, welding, brazing, etc. In an embodiment, the distal end 153b of the pull wire 153 is coupled to the inner tube 150 using welding. The pull wire 153 may be made of a biocompatible material, such as, without limitation, stainless steel, nitinol, polymer, etc. In an embodiment, the pull wire 153 is made of stainless steel. The pull wire 153 helps to pull the inner tube 150 in proximal direction to align or misalign the apertures 151 of the inner tube 150 and the apertures 112 of the shaft 110 to trigger the infusion mode or the aspiration mode, respectively. In the depicted embodiment, the pull wire 153 helps in pulling the inner tube 150 to the second position to trigger the aspiration mode. In an embodiment, the shaft 110 includes a first opening (not shown) provided inside the shaft 110 proximal to the proximal end 150a of the inner tube 150, a second opening 114 (shown in Fig. 2) provided towards the proximal end 110a of the shaft 110 and a third lumen (not shown) extending between the first opening and the second opening 114. The third lumen is configured to receive a portion of the pull wire 153. The pull wire 153 enters the shaft 110 from the first opening and exits the shaft 110 from the second opening 114. The pull wire 153 includes a coupling element 154 is coupled to the proximal end 153a of the pull wire 153. The pull wire 153 is coupled to the actuating assembly with the help of the coupling element 154. In an embodiment, the coupling element 154 is a hook.
[0043] Referring back to Figs. 1a – 1b, in an embodiment, the catheter system 100 includes a resilient element 140 coupled to the inner tube 150 at the distal end 150b of the inner tube 150 using any coupling technique, such as, without limitation, bonding, knotting, crimping, male-female locking, clamping, hooking, welding, brazing, etc. In an example implementation, a proximal end of the resilient element 140 is coupled to the distal end 150b of the inner tube 150 using welding. The resilient element 140 resides within the shaft 110. The resilient element 140 helps to retract the inner tube 150 from the second position to the first position as explained later. According to an embodiment, when the inner tube 150 is in the first position, the resilient element 140 is in a rest state and when the inner tube 150 is in the second position, the resilient element 140 is in an expanded state. A distal end of the resilient element 140 is also coupled to the proximal end of the tip 120. The resilient element 140 may be a helical tension spring, helical extension spring, barrel spring, magazine spring, etc. In an example implementation, the resilient element 140 is a helical tension spring. The resilient element 140 may be made of a biocompatible material, such as, without limitation, stainless steel, nitinol, polymer, etc. In an example implementation, the resilient element 140 is made of stainless steel.
[0044] Fig. 4 depicts the tip 120, according to an embodiment. The tip 120 is provided at the distal end 100b of the catheter system 100. The tip 120 is coupled to the shaft 110 at the distal end 110b of the shaft 110. The tip 120 has a tubular structure. The tip 120 may be made of a biocompatible material, such as, without limitation, polyether block amide (PEBAX), silicone, nylon, polyether block amide (PEBA), polyethene terephthalate (PET), polyamide, polyurethanes, polyvinyl chloride (PVC), polyethylene (PE), etc. In an embodiment, the tip 120 is made of polyether block amide (PEBAX). The tip 120 may have a length ranging between 5 mm and 20 mm. The tip 120 may have an outer diameter ranging between 1 mm and 4 mm. In an example implementation, the length and the outer diameter of the tip 120 are 10 mm and 1.67 mm, respectively. The tip 120 includes an opening 121, a first slot 122 and a second slot 123. In an embodiment, the first slot 122 of the tip 120 is configured to receive the projection 111 of the shaft 110, thereby coupling the tip 120 and the shaft 110 by a slot-fit mechanism. The tip 120 may have a step-profile complementary to the step-profile of the shaft 110 so that when the tip 120 and the shaft 110 are coupled together, outer surfaces of the tip 120 and the shaft 110 form a continuous surface. It should be understood that the tip 120 and the shaft 110 may be coupled via any other coupling technique known in the art. The opening 121 is provided at a distal end of the tip 120 and provides a passage for the aspirated thrombus (or aspirated fluid) to enter the inner tube 150 and the shaft 110 in the aspiration mode. The tip 120 further includes a helical hole (not shown) provided towards a proximal end of the tip 120. The helical hole is configured to receive a proximal portion of the resilient element 140, thereby coupling the resilient element 140 with the tip 120. The second slot 123 of the tip 120 is used to couple with a flow regulator such as a valve.
[0045] In an embodiment, the catheter system 100 may further include a duck valve 130 coupled to the tip 120. The second slot 123 of the tip 120 is configured to receive a distal portion of the duck valve 130, thereby coupling the tip 120 and the duck valve 130. In an embodiment, the second slot 123 includes a circular cavity to slot-fit the distal portion of the duck valve 130. The duck valve 130 is disposed such that two flaps (not shown) of the duck valve 130 are extending towards the proximal end 100a of the catheter system 100. In the presence of the infusion fluid, the flaps of the duck valve 130 remain closed wherein when the aspirated thrombus enters from the opening 121 of the tip 120, the flaps of the duck valve 130 are opened. Thus, the duck valve 130 restricts the passage of the infusion fluid from the distal end 100b of the catheter system 100 via the opening 121 of the tip 120 during the infusion mode of operation and allows the flow of the aspirated thrombus from the opening 121 into the inner tube 150 and the shaft 110 during the aspiration mode of operation. The duck valve 130 may be used to insert and/or removal of a guidewire during and after the procedure.
[0046] Now referring to Fig. 5, the handle 160 includes a proximal end 160a and a distal end 160b. The handle 160 is disposed towards the proximal end 100a of the catheter system 100 and enables a user to manipulate the catheter system 100. The handle 160 may be made from a material, such as, without limitation, polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), etc. In an embodiment, the handle 160 is made from polycarbonate (PC). The handle 160 includes a first portion 161 and a second portion 162. The first portion 161 and the second portion 162 of the handle 160 may be coupled using any known coupling mechanism, such as, without limitation, slot fit, press-fit, clamp fit, etc. In an embodiment, the first portion 161 and the second portion 162 of the handle 160 are coupled using slot-fit. The handle 160 may have an ergonomic design, enabling a surgeon to hold the handle 160 easily. In an embodiment, a top surface of the handle 160 may have a plurality of serrations providing a better grip to the surgeon. Each of the first portion 161 and the second portion 162 may have a semi-circular cut-out extending for the respective length such that when the first portion 161 and the second portion 162 are coupled together, the semi-circular cut-outs form a circular channel configured to receive a portion of the shaft 110.
[0047] The handle 160 houses one or more components the actuating assembly operatively coupled to the inner tube 150 and configured to toggle the inner tube 150 between the first position and the second position, thereby, switching the catheter system 100 between the first mode (i.e., the infusion mode) and the second mode (i.e., the aspiration mode). In an embodiment, the handle 160 includes a tension mechanism for actuation. In an embodiment, the actuating assembly includes a control element, the resilient element 140 and the pull wire 153. The control element enables the surgeon to control the movement of the inner tube 150 between the first position and the second position. The control element is operatively coupled to the coupling element 154 of the pull wire 153. The control element is configured to pull and push the pull wire 153 in a proximal and a distal direction, respectively by a pre-defined distance, causing the inner tube 150 to move from the first position to the second position and from the second position to the first position, respectively. The pre-defined distance depends upon the positions of and the distance between the apertures 112 and the apertures 151. The control element is disposed with the handle 160. In an embodiment, the control element includes a regulating knob 170 as depicted in Fig. 5. The regulating knob 170 is rotatable. The regulating knob 170 is coupled to the handle 160. The regulating knob 170 may be coupled to either the first portion 161 or the second portion 162 of the handle 160. In the depicted embodiment, the regulating knob 170 is coupled to the first portion 161 of the handle 160.
[0048] Figs. 6a – 6b illustrate the regulating knob 170, according to an embodiment. The rotating knob 170 may be made from a material, such as, without limitation, polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), etc. In an embodiment, the regulating knob 170 is made from polycarbonate (PC). The regulating knob 170 includes a first disc 171, a second disc 172 and a groove 173. The first disc 171 and the second disc 172 are circular, though the first disc 171 and the second disc 172 may have any other shape. The second disc 172 allows the surgeon to grip the regulating knob 170 and rotate the regulating knob 170 in a desired direction. In an embodiment, the second disc 172 is rotatable in a first pre-defined direction and a second pre-defined direction. The first disc 171 is disposed within the handle 160 and is rotatably coupled to the second disc 172. The groove 173 is configured to receive a portion of the handle 160. The first disc 171 includes a pin 174 coupled to the coupling element 154 of the pull wire 153. The pin 174 is movable between a distal-most position (depicted in Fig. 6b) and a proximal-most position. The proximal-most position is diametrically opposite to the distal-most position. The distance between the proximal-most position and the distal-most position is indicated by ‘D’ in Fig. 6b. In an embodiment, when the pin 174 moves from the distal-most position to the proximal-most position, the pull wire 153 is pulled, causing the inner tube 150 to move in a proximal direction. Similarly, when the pin 174 moves from the proximal-most position to the distal-most position, the tension on the pull wire 153 is released and the resilient element 140 applies a restoring force on the inner tube 150, causing the inner tube 150 to move in a distal direction. In other words, when the inner tube 150 is in the second position, the resilient element 140 is configured to apply a restoring force on the inner tube 150, facilitating the movement of the inner tube 150 from the second position to the first position. The position of the pin 174 (which determines the distance ‘D’) is designed such that when the pin 174 is in the distal-most position, the apertures 112 and 151 are aligned (thereby, setting the catheter system 100 in the infusion mode) and when the pin 174 is in the proximal-most position, the apertures 112 and 151 are misaligned (thereby, setting the catheter system 100 in the aspiration mode).
[0049] The actuating assembly may include a locking mechanism configured to lock the pin 174 at the proximal-most and the distal-most positions when set. In an embodiment, a projection 175 is provided on a periphery of the first disc 171. The projection 175 is aligned with the placement of the pin 174 on the first disc 171. Further, proximal stoppers 164 and distal stoppers 165 are provided within the handle 160 adjacent to a proximal end and a distal end of the first disc 171, respectively. When the pin 174 is in the proximal-most position, the projection 175 is configured to reside within a spacing between the proximal stoppers 164, preventing further movement of the pin 174 in the absence of an actuating force. Similarly, when the pin 174 is at the distal-most position, the projection 175 is configured to reside within a spacing between the distal stoppers 165, preventing further movement of the pin 174 in the absence of an actuating force. In an embodiment, in response to the second disc 172 being rotated in a first pre-defined direction (e.g., clockwise in the depicted embodiment) by a half rotation, the pin 174 is configured to move from the distal-most position to the proximal-most position, pulling the pull wire 153 in the proximal direction by the pre-defined distance (denoted by ‘D’ in Fig. 6b). Similarly, in response to the second disc 172 being rotated in a second pre-defined direction (e.g., anticlockwise in the depicted embodiment) by a half rotation, the pin 174 is configured to move from the proximal-most position to the distal-most position, pushing the pull wire 153 in the distal direction by the pre-defined distance. The second disc 172 of the regulating knob 170 includes an indicator 176. The indicator 176 indicates a position of the pin 174. For example, when the indicator 176 points towards the distal end 100b, the pin 174 is in the distal-most position (and the catheter system 100 is in the infusion mode of operation) and when the indicator 176 points towards the proximal end 100a, the pin 174 is in the proximal-most position (and the catheter system 100 is in the aspiration mode of operation). Thus, the position of the indicator 176 helps the user to verify the current mode of operation of the catheter system 100 and change the mode of the operation of the catheter system 100.
[0050] According to another embodiment, the control element may include a sliding button (not shown) instead of the regulating knob 170. The sliding button may be provided on the handle 160. The sliding button is movable between a proximal-most position and a distal-most position. The coupling element 154 is operatively coupled to the sliding button such that in response to moving the sliding button from the distal-most position to the proximal-most position, the sliding button is configured to pull the pull wire 153 in the proximal direction by the pre-defined distance (and as a result, the catheter system 100 is set to the aspiration mode). Similarly, in response to moving the sliding button from the proximal-most position to the distal-most position, the sliding button is configured to push the pull wire 153 in the distal direction by the pre-defined distance (and as a result, the catheter system 100 is set to the infusion mode in a similar manner as described earlier. Thus, by moving the sliding button from the distal-most position to the proximal-most position and vice versa, the surgeon may set the operating mode of the catheter system 100.
[0051] Now referring to Fig. 7, the Y-hub 180 is provided at the proximal end 100a of the catheter system 100. In an embodiment, a distal end of the Y-hub 180 is coupled with the proximal end 110a of the shaft 110 via UV bonding. It should be understood though that the Y-hub 180 and the shaft 110 may be coupled using any other coupling technique known in the art. The Y-hub 180 may be made from a material, such as, without limitation, polycarbonate (PC), polypropylene, methylmethacrylate acrylonitrile butadiene styrene (MABS), polyvinylchloride (PVC), nylon, etc. In an embodiment, the Y-hub 180 is made from polycarbonate (PC). The Y-hub 180 includes a first port 181 and a second port 182. The first port 181 may be coupled to one of an infusion apparatus and an aspiration apparatus as needed during a thrombolysis procedure. The first port 181 is fluidically coupled to the first lumen of the shaft 110 and provides a passage for the infusion fluid to enter the shaft 110 and/or for the aspirated thrombi out of the shaft 110. A guidewire (not shown) may be inserted and/or removed from the second port 182. Thus, the second port 182 provides a passage to the guidewire. The guidewire facilitates navigating the shaft 110 to the target site through the patient’s vasculature.
[0052] The use of the system 100 during a thrombolytic procedure is now explained, according to an embodiment. A guidewire is inserted into the shaft 110 from the distal end 100b through the duck valve 130 and passed until the guidewire exits the second port 182 of the Y-hub 180. The distal end 100b of the system 100 is inserted into a patient’s body via an access site (e.g., internal jugular vein, common femoral vein, radial artery, subclavian artery, etc.). The shaft 110 is then navigated through the patient’s vasculature to a target site with the help of the guidewire. The target site pertains to a location in a vessel where thrombus is present. The system 100 is set to the infusion mode at this stage.
[0053] To aspirate the thrombus during the thrombolytic procedure, the system 100 is set to the aspiration mode (or the second mode) by rotating the second disc 172 of the regulating knob 170 towards the proximal end 100a of the system 100 such that the indicator 176 points towards the proximal end 100a (depicted in Fig. 8a). Due to the rotation of the regulating knob 170, the projection 175 of the regulating knob 170 decouples from the distal stoppers 165, moves to the proximal-most position and couples to the proximal stoppers 164. As a result, the pull wire 153 is pulled in the proximal direction by the distance D, causing the inner tube 150 to move in the proximal direction inside the shaft 110 by the same distance to the second position. This movement of the inner tube 150 misaligns the apertures 151 of the inner tube 150 and the apertures 112 of the shaft 110. Consequently, the apertures 112 of the shaft 110 are blocked, preventing any unwanted passage of the thrombus (or any other fluid) through the apertures 112. The first port 181 of the Y-hub 180 is coupled to an aspiration apparatus (not shown). The aspiration apparatus may be any known apparatus used for aspiration. The aspiration apparatus creates a suction force required to aspirate the thrombus from target site. Due to the pressure of the inflow of the thrombus from the distal end 100b of the system 100, the duck valve 130 opens, providing a passage to the aspirated thrombus as depicted in Fig. 8b. Further, as shown in Fig. 8b, the movement of the inner tube 150 in the proximal direction stretches the resilient element 140 to the expanded state.
[0054] During the thrombolytic procedure, a thrombolytic medication (or any other desired fluid) may need to be infused at the target site, for example, to dissolve the thrombus. In such a situation, the system 100 is set to the infusion mode (or the first mode) by rotating the regulating knob 170 in the distal direction such that the indicator 176 points towards the distal end 100b as shown in Fig. 8c. The rotation of the regulating knob 170 moves the projection 175 from the proximal-most position to the distal-most position and engages with the distal stoppers 165. As a result, the tension on the pull wire 153 and the resilient element 140 is released. The resilient element 140 applies the restoring force on the inner tube 150, causing the inner tube 150 to move in the distal direction to the first position and the resilient element 140 returns to the normal state. As explained earlier, in the first position of the inner tube 150, the apertures 112 of the shaft 110 and the apertures 151 of the inner tube 150 are aligned as depicted in Fig. 8d. Further, the first port 181 of the Y-hub 180 is coupled to an infusion apparatus. The infusion apparatus may be any known infusion apparatus capable of infusing the infusion fluid into the shaft 110. The alignment of the apertures 151 and the apertures 112 provides a passage for infusing the infusion fluid at the target site. The first mode of the system 100 allows infusion of the infusion fluid from the first port 181 of the Y-hub 180. At this stage the duck valve 130 remains in a closed position due to the pressure of the infusion fluid on the flaps of the duck valve 130, restricting the flow of the infusion fluid out of the shaft 110 from the distal end 100b of the system 100.
[0055] Fig. 9a illustrates a catheter system 200 (hereinafter, system 200) for infusion and aspiration of fluids at a target site, according to another embodiment of the present disclosure. Fig. 9b illustrates an exploded view of a distal portion of the system 200. The system 200 has a proximal end 200a and a distal end 200b. The system 200 includes a shaft 210, a tip 220, a resilient element 240, an inner tube 250, a handle 260, and a Y-hub 280. Further, the system 200 includes an actuating assembly including a pull wire 253 and a regulating knob 270. Structure and functioning of the shaft 210, the tip 220, the resilient element 240, the inner tube 250, the handle 260, the pull wire 253, the regulating knob 270 and the Y-hub 280 can be referred from the shaft 110, the tip 120, the resilient element 140, the inner tube 150, the handle 160, the pull wire 153, the regulating knob 170 and the Y-hub 180, respectively, of the system 100 and is not repeated for the sake of brevity. The system 200 is operable in the infusion mode (or the first mode) and the aspiration mode (or the second mode) as needed like the system 100. Further, the shaft 210 includes a plurality of apertures 212 and the inner tube 250 includes a plurality of apertures 251. The plurality of apertures 212 of the shaft 210 and the plurality of apertures 251 of the inner tube 250 are similar to the plurality of apertures 112 of the shaft 110 and the plurality of apertures 151 of the inner tube 150, respectively.
[0056] According to an embodiment, instead of the duck valve 130 of the system 100, the system 200 includes an assembly 230. Similar to the duck valve 130, the assembly 230 configured to prevent the flow of the infusion fluid from the distal end 200b of the system 200 during the infusion mode and allow the flow of the aspirated thrombus from the distal end 200b of the system 200 during the aspiration mode. Fig. 10 illustrates the assembly 230 according to an embodiment of the present disclosure. The assembly 230 has a proximal end 230a and a distal end 230b. In an embodiment, the assembly 230 includes a blocking member 231, a rod 233 and a gripper assembly 236 (hereinafter, referred to as gripper 236).
[0057] The blocking member 231 is provided towards the distal end 230b of the assembly 230. In an embodiment, the blocking member 231 has a conical shape. The conical shape of the blocking member 231 prevent trauma to the patient’s vessels and other tissues during navigation of the shaft 210 through the patient’s vasculature. It should be understood that the blocking member 231 may have any other shape based upon requirements. The blocking member 231 is configured to block the passage of fluids (e.g., the infusion fluid) from the distal end 200b of the system 200 in the first mode or the infusion mode of the system 200 and allow the passage of fluids (e.g., the aspirated thrombus) via the distal end 200b of the system 200 in the second mode or the aspiration mode of the system 200. The blocking member 231 may include a seal (not shown), for example, a gasket, to ensure no leakage and block the distal end 200b of the system 200 during the first mode or infusion mode of operation of the system 200. The blocking member 231 is movable between a proximal position and a distal position. The blocking member 231 is set to the proximal position in the infusion mode and to the distal position in the aspiration mode. In the proximal position, the blocking member 231 is coupled to the tip 220 such that a proximal face of the blocking member 231 mates with a distal face of the tip 220 and the blocking member 231 seals an opening of the tip 220, thereby preventing the passage of the infusion fluid from the distal end 200b during the infusion mode. In the distal position, the blocking member 231 is disposed from the tip 220 at a pre-defined distance, such that the proximal face of the blocking member 231 and the distal face of the tip 220 have a gap therebetween. This unblocks the opening of the tip 220, facilitating the aspirated thrombus to enter the shaft 210 from the opening of the tip 220 in the aspiration mode. A proximal end of the blocking member 231 is coupled to a distal end of the rod 233. In an embodiment, a portion of the rod 233 is disposed within a first lumen of the shaft 210. The rod 233 extends towards the proximal end 230a of the assembly 230. The rod 233 may be, for example, cylindrical, cuboidal, hexagonal, pentagonal, heptagonal, octagonal, etc. In an embodiment, the rod 233 is cylindrical. The rod 233 may have a diameter ranging between 0.2 mm and 2 mm. In an example implementation, the diameter of the rod 233 is 0.4 mm. In an embodiment, the rod 233 has a tubular structure defining a lumen 237. The lumen of the rod 233 provides a passage for a guidewire (not shown) for navigation. In an embodiment, the rod 233 may be solid. In this case, a rapid exchange port (not shown) may be provided at a distal portion of the shaft 210. The rapid exchange port provides a passage to the guidewire for navigation. A proximal end of the rod 233 extends proximally from the Y-hub 280 and is coupled to the gripper 236. The gripper 236 is provided towards the proximal end 230a of the assembly 230 and situated proximal to the Y-hub 280. The gripper 236 is removably coupled to the Y-hub 280 (explained later). The gripper 236 is configured to move the blocking member 231 from the proximal position to the distal position and vice versa as needed. The gripper 236 includes a clamping mechanism. In an embodiment, the gripper 236 includes a first clamp 234 and a second clamp 235. The first clamp 234 and the second clamp 235 are configured to move between a clamped position and an unclamped position. The gripper 236 may include a torsion spring (not shown) to facilitate the first clamp 234 and the second clamp 235 to move between the clamped position and the unclamped position. The first clamp 234 includes a first coupling portion 234a and a first gripping portion 234b. Similarly, the second clamp 235 includes a second coupling portion 235a and a second gripping portion 235b. The first coupling portion 234a and the second coupling portion 235a are removably coupled to a second port 282 of the Y-hub 280. The first gripping portion 234b and the second gripping portion 235b enable a surgeon to operate the gripper 236. The first clamp 234 and the second clamp 235 are configured to be in the clamped position or the unclamped position.
[0058] The system 200 may be operated in a similar manner as the system 100 except for a few additional steps as explained below. For example, to configure the system 200 to the first mode or the infusion mode, the blocking member 231 is moved to the proximal position by setting the first clamp 234 and the second clamp 235 in the unclamped position. To do this, the first gripping portion 234b of the first clamp 234 and the second gripping portion 235b of the second clamp 235 are pressed towards each other and pulled in a proximal direction until the first coupling portion 234a of the first clamp 234 and the second coupling portion 235a of the second clamp 235 are disengaged from the second port 282 of the Y-hub 280 and disposed proximal to the second port 282 of the Y-hub 280 (as shown in Fig. 11b). As a result, the rod 233 moves in the proximal direction. Thus, the disengagement of the first coupling portion 234a and the second coupling portion 235a from the second port 282 of the Y-hub 280, causes the blocking member 231 to move to the proximal position and block the opening of the tip 220 (as shown in Fig. 11a), preventing the infusion fluid from flowing out from the opening of the tip 220 in the infusion mode. The first gripping portions 234b and the second gripping portion 235b are then released.
[0059] To configure the system 200 to second mode or the aspiration mode, the blocking member 231 is moved to the distal position. To do this, the first gripping portion 234b of the first clamp 234 and the second gripping portion 235b of the second clamp 235 are by pressed towards each other, this widens the gap between the first coupling portion 234a of the first clamp 234 and the second gripping portion 235b of the second clamp 235. The first coupling portion 234a of the first clamp 234 and the second coupling portion 235a of the second clamp 235 are pushed in the distal direction to engage with the second port 282 of the Y-hub 280, for example, with a respective slot provided on the second port 282 of the Y-hub 280 (as shown in Fig. 11d) and the first clamp 234 and the second clamp 235 are in the clamped position. This causes movement of the rod 233 in the distal direction. As a result, the blocking member 231 moves to the distal position, thereby creating a gap between the blocking member 231 and the tip 220 and permitting the aspiration of thrombus through the opening of the tip 220 (as shown in Fig. 11c). The first gripping portion 234b and the second gripping portion 235b are then released.
[0060] The present disclosure presents several advantages over conventional catheter systems, which use separate infusion and aspiration catheters. The proposed catheter system uses a single shaft and is easily toggled between the infusion and aspiration modes as needed during a medical procedure. Consequently, the proposed catheter system reduces the trauma caused to the patient’s during removal and navigation of two separate catheters. Further, the proposed catheter system drastically reduces time for the infusion and aspiration procedures by eliminating the time needed for inserting and removing the two separate catheters. Thus, the proposed catheter system enhances the effectiveness of the medical procedure, reduces procedural cost, and improves the overall outcome for the patient.
[0061] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. , Claims:WE CLAIM:
1. A catheter system (100, 200) capable of being used in an infusion procedure and an aspiration procedure, the catheter system (100, 200) comprising:
a. a shaft (110, 210) having a tubular structure, the shaft (110, 210) comprising a plurality of apertures (112, 212) provided circumferentially towards a distal end (110b) of the shaft (110, 210);
b. an inner tube (150, 250) disposed within the shaft (110, 210) towards the distal end (110b) of the shaft (110, 210) and comprising a plurality of apertures (151, 251) provided circumferentially, the inner tube (150, 250) is movable between a first position and a second position, wherein in the first position, the plurality of apertures (151, 251) of the inner tube (150, 250) are aligned with the plurality of apertures (112, 212) of the shaft (110, 210) and in the second position, the plurality of apertures (151, 251) of the inner tube (150, 250) are misaligned with the plurality of apertures (112, 212) of the shaft (110, 210);
c. an actuating assembly operatively coupled to the inner tube (150, 250) and configured to toggle the inner tube (150, 250) between the first position and the second position, thereby setting the catheter system (100, 200) in an infusion mode and an aspiration mode, respectively; and
d. a tip (120, 220) provided at a distal end (100b, 200b) of the catheter system (100, 200) and coupled to the shaft (110, 210) at the distal end (110b) of the shaft (110, 210), the tip (120, 220) comprising an opening (121) provided at a distal end of the tip (120, 220), the opening (121) configured to provide a passage for aspirated fluid or thrombus in the aspiration mode.
2. The catheter system (100, 200) as claimed in claim 1, wherein the actuating assembly comprises:
a. a pull wire (153, 253) having a distal end (153b) coupled to the inner tube (150, 250) and a proximal end (153a), the pull wire (153, 253) comprising a coupling element (154) provided at the proximal end (153a) of the pull wire (153, 253); and
b. a control element coupled to the coupling element (154), the control element configured to pull the pull wire (153, 253) in a proximal direction by a pre-defined distance, causing the inner tube (150, 250) to move from the first position to the second position and configured to push the pull wire (153, 253) in a distal direction by the pre-defined distance, causing the inner tube (150, 250) to move from the second position to the first position; and
c. a resilient element (140, 240) having a proximal end coupled to a distal end (150b) of the inner tube (150, 250) and a distal end coupled to a proximal end of the tip (120, 220), the resilient element (140, 240) is configured to apply a restoring force on the inner tube (150, 250) when the inner tube (150, 250) is in the second position, facilitating the movement of the inner tube (150, 250) from the second position to the first position.
3. The catheter system (100, 200) as claimed in claim 2, wherein the control element comprises a regulating knob (170, 270) coupled to a handle (160, 260), the regulating knob (170, 270) comprising:
a. a second disc (172) rotatable in a first pre-defined direction and a second pre-defined direction; and
b. a first disc (171) disposed within the handle (160, 260) and rotatably coupled to the second disc (172), the first disc (171) comprising a pin (174) coupled to the coupling element (154) of the pull wire (153, 253) and movable between a distal-most position and a proximal-most position;
c. wherein in response to rotating the second disc (172) in the first pre-defined direction by a half rotation, the pin (174) is configured to move from the distal-most position to the proximal-most position, pulling the pull wire (153, 253) in the proximal direction by the pre-defined distance;
d. wherein in response to rotating the second disc (172) in the second pre-defined direction by a half rotation, the pin (174) is configured to move from the proximal-most position to the distal-most position, pushing the pull wire (153, 253) in the distal direction by the pre-defined distance.
4. The catheter system (100, 200) as claimed in claim 3, wherein the second disc (172) comprises an indicator (176) indicating a position of the pin (174).
5. The catheter system (100, 200) as claimed in claim 3, wherein the first disc (171) comprises a projection (175) provided on a periphery of the first disc (171) and configured to reside within a spacing between distal stoppers (165) provided on the handle (160, 260) when the pin (174) is at the distal-most position and configured to reside within a spacing between proximal stoppers (164) provided on the handle (160, 260) when the pin (174) is at the proximal-most position.
6. The catheter system (100, 200) as claimed in claim 2, wherein the control element comprises a sliding button operatively coupled to the coupling element (154) of the pull wire (153, 253) and movable between a proximal-most position and a distal-most position, wherein in response to moving the sliding button from the distal-most position to the proximal-most position, the sliding button is configured to pull the pull wire (153, 253) in the proximal direction by the pre-defined distance and in response to moving the sliding button from the proximal-most position to the distal-most position, the sliding button is configured to push the pull wire (153, 253) in the distal direction by the pre-defined distance.
7. The catheter system (100, 200) as claimed in claim 2, wherein the shaft (110, 210) comprises a third lumen configured to receive a portion of the pull wire (153, 253).
8. The catheter system (100, 200) as claimed in claim 1, wherein the plurality of apertures (151, 251) of the inner tube (150, 250) has a larger longitudinal length than the plurality of apertures (112, 212) of the shaft (110, 210).
9. The catheter system (100, 200) as claimed in claim 1, wherein the catheter system (100) comprises a duck valve (130) coupled to the tip (120) and having two flaps extending towards the proximal end (100a) of the catheter system (100).
10. The catheter system (100, 200) as claimed in claim 1, wherein the catheter system (100, 200) comprises a Y-hub (180, 280) coupled to the shaft (110, 210) and comprising a first port (181) removably coupled to one of an infusion apparatus and an aspiration apparatus.
11. The catheter system (100, 200) as claimed in claim 1, wherein the catheter system (200) comprises an assembly (230) having a proximal end (230a) and a distal end (230b), the assembly (230) comprising:
a. a blocking member (231) provided towards the distal end (230b) of the assembly (230) and movable between a proximal position and a distal position, wherein in the proximal position, a proximal face of the blocking member (231) mates with a distal face of the tip (220) and in the distal position, the proximal face of the blocking member (231) and the distal face of the tip (220) have a gap therebetween;
b. a rod (233) coupled to a proximal end of the blocking member (231) and extending towards the proximal end (230a) of the assembly (230); and
c. a gripper assembly (236) provided towards the proximal end (230a) of the assembly (230) and coupled to the rod (233), the gripper assembly (236) configured to move the blocking member (231) from the proximal position to the distal position and vice versa.
12. The catheter system (100, 200) as claimed in claim 11, wherein the gripper assembly (236) comprises:
a. a first clamp (234) comprising a first coupling portion (234a) and a first gripping portion (234b); and
b. a second clamp (235) comprising a second coupling portion (235a) and a second gripping portion (235b);
c. wherein the first coupling portion (234a) and the second coupling portion (235a) are removably coupled to a second port (282) of a Y-hub (280) and the first clamp (234) and the second clamp (235) are configured to be in a clamped position and an unclamped position;
d. wherein in the unclamped position, the first coupling portion (234a) and the second coupling portion (235a) are disengaged from the second port (282) of the Y-hub (280) and disposed proximal to the second port (282) of the Y-hub (280), causing the blocking member (231) to be in the proximal position and in the clamped position, the first coupling portion (234a) and the second coupling portion (235a) are engaged with the second port (282) of the Y-hub (280), causing the blocking member (231) to be in the distal position.