CURVED S-SHAPE FOR CATHETER SHAFT AND DISTAL TIP

A catheter for removing an object in a body lumen includes an outer tube, a drive shaft surrounded by the tube, a cutting member connected to a distal end of the shaft to be rotated by the shaft with respect to a rotation axis and by which the object is cut, a guide wire tube attached to a distal end of the outer tube and having a first lumen extending adjacent to the cutting member along the axis, and a distal tip attached to a distal end of the guide wire tube and having a second lumen extending parallel to the rotation axis and communicating with the first lumen. The drive shaft includes a curved portion near the distal end thereof to cause the tip to contact a first inner surface of the body lumen when the curved portion contacts an opposite second inner surface of the body lumen.

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to a catheter, a medical device, and a method for removing an object in a body lumen.

BACKGROUND

Medical devices that have a catheter including a rotatable drive shaft and a cutting member are widely used to remove an object from a body lumen such as a blood vessel. Such medical devices have a motor for generating torque and a hub for storing a mechanism which transmits the generated torque to the cutting member through the drive shaft.

A catheter has at its distal end a guide wire lumen into which a guide wire for guiding the catheter inside a body lumen is inserted. At the beginning of an operation, an introducer sheath is inserted into the body vessel, and then the guide wire is inserted through the sheath toward and beyond a target object to be removed. Subsequently, the guide wire outside the body is inserted into the guide wire lumen of the catheter, which is then inserted through the introducer sheath into the body lumen along the guide wire. Once the distal end of the catheter has reached the object, the motor is turned on causing the cutting member to rotate, and the catheter is further moved forward so that the cutting member contacts and cuts the object.

A conventional standardized catheter has a cutting diameter of up to 2 mm and thus can effectively cut an object that is present in a body lumen of up to 2 mm. However, using the conventional standardized catheter, it is difficult to effectively cut an object that is present in a body lumen of a larger diameter, e.g., 4 mm.

SUMMARY OF THE INVENTION

In an embodiment, a catheter for removing an object in a body lumen includes an outer tube, a rotatable drive shaft surrounded by the outer tube, a cutting member connected to a distal end of the drive shaft to be rotated by the drive shaft with respect to a rotation axis and by which the object is cut, a guide wire tube attached to a distal end of the outer tube and having a first guide wire lumen extending adjacent to the cutting member along the rotation axis, and a distal tip attached to a distal end of the guide wire tube and having a second guide wire lumen extending parallel to the rotation axis and communicating with the first guide wire lumen. The drive shaft includes a first curved portion near the distal end of the drive shaft to cause the distal tip to contact a first inner surface of the body lumen when the first curved portion contacts a second inner surface of the body lumen that is on an opposite side of the body lumen with respect to the first inner surface.

DESCRIPTION OF EMBODIMENTS

The following detailed description describes a catheter, a medical device, and a method for cutting an object inside a body lumen. In the present specification, a side of the medical device or the catheter which is inserted into a body lumen is defined as a distal side, and the other side of the medical device which is held by an operator during an operation is defined as a proximal side.

FIGS.1and2depict a medical device1in one embodiment. As shown in the figures, the medical device1includes a catheter10to be inserted into a body lumen for removing an object and a handle20held by an operator. The handle20includes a torque generating element such as a motor and an aspiration pump to aspirate the object that has been removed from the body lumen.FIG.1shows a state of the medical device1in which the catheter10is detached from the handle20, andFIG.2shows a state in which the catheter10is attached to the handle20.

The catheter10includes an elongated drive shaft30surrounded by an outer tube30A and rotatable therein, and further includes, at its distal end, a cutting member40that rotates together with the drive shaft30to cut an object. For example, the cutting member40is a directional cutter for removing an object located in a particular direction. At the proximal end of the catheter10, a hub50for housing rotating and aspiration mechanisms is attached. The hub50can be integrated into the catheter10or detachable from the catheter10.

The drive shaft30has the characteristics of being flexible and capable of transmitting rotational power applied from the proximal side to the distal side. Specifically, the drive shaft30transmits the rotational torque generated by the torque generating element to the cutting member40. The drive shaft30has an aspiration lumen through which the object that has been cut by the cutting member40is moved to the proximal side. The aspirated object is stored in a collection bag90. The drive shaft30penetrates the outer tube30A, and the cutting member40is fixed to the distal end of the drive shaft30. The proximal portion of the drive shaft30is positioned inside of the hub50.

The drive shaft30has a distal opening at which the aspiration lumen opens at the distal end thereof. The distal opening is an entrance into which the cut object enters. The proximal end of the drive shaft30is connected to an aspiration port through which the object that has entered the drive shaft30is discharged.

In one embodiment, a distal portion of the drive shaft30is curved to form an angle between the rotation axis of the cutting member40and the other portion of the drive shaft30as shown inFIGS.1and2. With this angle, when the distal end of the catheter10is guided to a particular area of a body lumen where an object is formed, the curved portion contacts the opposite area of the body lumen, and thereby pushing the cutting member40toward the particular area and helping the cutting member40in removing the object. The detail of the curved structure is described later.

The handle20is detachable from the catheter10to be reusable in multiple medical procedures. When a medical procedure is performed, the handle20is attached to the catheter10via the hub50so that the drive shaft30and the cutting member40can rotate according to the torque generated by the torque generating element housed in the handle20. Thereafter, the drive shaft30and the cutting member40are inserted into a body lumen, e.g., a vein, using a guide wire. In one embodiment, the hub50and the handle20may be integrated into a single component so as not to be detachable.

Further details of the aspiration and torque generating mechanisms are described in U.S. application Ser. No. 16/998,824, the entire contents of which are incorporated by reference herein.

FIGS.3and4each show a distal portion of the catheter10. The curved portion of the catheter10is not shown in these figures. As described above, the catheter10includes the cutting member40at the distal end thereof. The catheter10further includes a guide wire tube61having a guide wire lumen61L, a fixing tube62for fixing the guide wire tube61to the outer tube30A, and a distal tip63having a guide wire lumen63L. The distal end of the catheter10is inserted into a body lumen along a guide wire70in a state in which the guide wire70passes through the guide wire lumens61L and63L.FIG.4shows the guide wire lumens61L and63L that form a single path for the guide wire70to pass. The catheter10and the guide wire70are connected to each other in a body lumen only through the guide wire lumens61L and63L.

For example, the guide wire tube61is formed of polyimides, PEEK, and the like. The fixing tube62is a heat-shrinkable tube that shrinks at a temperature lower than the guide wire tube61so that the guide wire tube61is strongly fixed to the outer tube30A when heated. The distal tip35is a resin, preferably a thermoplastic resin, which is softer than the guide wire tube61so that the catheter10can proceed smoothly inside a body lumen.

The catheter10further includes a stopper64on the distal side of the cutting member40, which stops the cutting member40from proceeding further when the catheter10is unintentionally guided toward the body lumen. The stopper64is formed of a metal material and is fixed to the guide wire tube61. A distal portion of the stopper64is covered by the distal tip63.

FIG.5depicts a proximal portion of the catheter10and the hub50into which the drive shaft30is inserted. The hub50includes a rotatable knob81and a connector82connectable to the handle20. The knob81is connected to the outer tube30A and rotatable by an operator so as to adjust an orientation and/or location of the drive shaft30and the cutting member40inside a body lumen during an operation. The knob81allows the outer tube30A to rotate independently of the drive shaft30and the connector82.

The drive shaft30is, directly or indirectly via one or more other shafts, connected to a coupler83with a recess84that can engage with a drive shaft (not shown) connected to the torque generating element inside the handle20. Further, the aspiration lumen of the drive shaft30communicates with an aspiration port85via an opening84inside the connector82. When the catheter10is connected to the handle20via the connecter82, the generated torque is transmitted to the drive shaft30via the coupler83while the object that has entered the aspiration lumen of the drive shaft30is discharged from the aspiration port85via the opening84.

FIG.6depicts a curved portion of the catheter10in one embodiment, andFIGS.7A and7Bdepict the catheter10cutting an object inside a body lumen. The dimension of the elements shown in these figures is different from the actual dimension thereof. As described with reference toFIGS.1and2, the catheter10has at least one curved portion near the distal end of the catheter10.

As shown inFIG.6, the catheter10or the drive shaft30has one curved portion at a position Y near the distal end of the catheter10or the cutting member40(e.g., 3-100 mm from the distal end of the catheter10). The radius of curvature of the curved portion is, e.g., 5 mm to 60 mm. Additionally, the distal tip63of this embodiment has a relatively shorter length, e.g., 2 mm to 10 mm, than a length of a conventional distal tip to prevent the guide wire that is inserted in the guide wire lumen63L at the distal tip63from reducing the curved bend of the drive shaft30too much due to the guide wire's stiffness.

When the catheter10is guided along a guide wire70inside a body lumen, its curved portion contacts an inner surface of the body lumen (e.g., at position C1depicted inFIG.7A), and the cutting member40is positioned for cutting an object formed on the opposite side of the body lumen (e.g., at position C2depicted inFIG.7A). The distal tip63is made of a soft material and thus is deformed when pushed against the body lumen. If the catheter10is repositioned so that its curved portion contacts the other side of the body lumen (e.g., at position C3depicted inFIG.7B), the cutting member40is positioned for cutting an object formed on the opposite side of the body lumen (e.g., at position C4depicted inFIG.7B). As a result, the effective cutting diameter is D1, which is larger than the cutting diameter d1that the catheter10would be able to achieve without the curved portion.

FIG.8depicts a catheter10A in another embodiment. The catheter10A has a structure similar to the catheter10as shown inFIG.6, but the positions of the cutting member40, the guide wire tube61, and the distal tip63are different. As shown inFIG.8, the cutting member40is located on an outer surface side of a convex part that the curved portion forms, and the guide wire tube61and the distal tip63are located on an inner surface side of the convex part. This arrangement can mitigate damage to a body lumen even when a force to move the cutting member40toward a surface of the body lumen is applied (seeFIG.9), because the curved portion contacts that surface first and thus the cutting member40contacts the body lumen from its side surface.

FIG.10depicts a catheter110in another embodiment with a second curved portion on a distal tip163at a position Z (e.g., 0-40 mm from the proximal end of the distal tip163) in addition to the curved portion on the drive shaft30shown inFIG.6. The second curved portion is curved in the opposite direction of the curvature of the drive shaft30with respect to the rotation axis of the cutting member40. The radius of curvature of the second curved portion is, for example, 1 mm to 20 mm. The distal tip163of this embodiment also has a relatively short length, e.g., 25 mm. The second curved portion of the distal tip163allows for more stable positioning of the cutting member40with respect to the inner surfaces of the body lumen.

In yet another embodiment, as shown inFIG.11, a catheter110A includes a distal tip163A with a straight portion on the distal side of the second curved portion. The length W1of the straight portion is shorter than the length W2of the second curved portion to enhance to enhance the guidewire trackability.

FIG.12schematically depicts the catheter110(or110A) guided along the guide wire70inside a body lumen. The dimension of the elements shown in the figure is different from the actual dimension thereof. As shown in the figure, the catheter110with two curved portions has been guided along the guide wire70and has reached an object formed on a surface of the body lumen. Here, the outer tube30A of the drive shaft30contacts the body lumen at point P1, the distal tip163contacts the body lumen at point P2, and the guide wire70contacts the body lumen at point P3. In this state, the cutting member40is supported by at least points P1and P2and pushed toward direction F against the object, resulting in deeper removal of the object and forming of a larger lumen inside the body lumen.

FIGS.13A and13Bdepict that catheter110(or110A) cutting an object inside a body lumen. The dimension of the elements shown in these figures is different from the actual dimension thereof. As described with reference toFIG.12, when the catheter110is guided along the guide wire70inside a body lumen, each curved portion contacts an inner surface of the body lumen (e.g., at positions E1and E2depicted inFIG.13A), and the cutting member40is positioned for cutting an object formed on the inner surface (e.g., at position E2). The guide wire contacts the body lumen at position E3. If the catheter110is repositioned so that each curved portion contacts the other side of the body lumen (e.g., at positions E4and E5depicted inFIG.13B), the cutting member40is positioned for cutting an object formed on the opposite side of the body lumen (e.g., at position E5). The guide wire contacts the body lumen at position E6. As a result, the effective cutting diameter is D2, which is larger than the cutting diameter d2that the catheter10would be able to achieve without the curved portion.

FIG.14depicts a flowchart of a method for removing an object in a body lumen using the medical device1or the catheter10described above. At the beginning of a medical operation, the operator connects the catheter10to the handle20via the hub50and inserts the guide wire70into the body lumen from its distal end using an introducer sheath so that the guide wire70passes near a target location where the object is formed. After those steps, the operator passes the proximal end of the guide wire70through the guide wire lumens61L and63L of the catheter10, and then inserts the catheter10into the body lumen along the guide wire70(Step101).

Once the distal end of the catheter10has reached the target location, the operator rotates the knob81to adjust the orientation and/or location of the catheter10inside the body lumen so that the cutting member40is directed toward the object by the curvature (Step102). The operator then turns on the aspiration and torque generating mechanisms of the handle20to start cutting and aspirating the object (Step103), and moves the catheter10forward along the guide wire70until the target object is removed and aspirated (Step104).

Once the target object has been removed, the operator turns off the aspiration and torque generating mechanisms (Step105), and removes the catheter10from the body lumen (Step106). The guide wire and introducer sheath are removed thereafter.

The order of one or more of the steps shown inFIG.14can be modified. For example, the aspiration and torque generating mechanisms can be turned on at any time after the catheter10has been inserted into the body lumen. Additionally, one or more of the steps can be repeated if necessary. For example, the orientation of the catheter10can be adjusted at any time during the operation to remove the object.