Diagnostic imaging catheter

1. A diagnostic imaging catheter comprising:

a sheath;

a drive shaft provided with a signal transmitting and receiving unit at a distal portion thereof, which is configured to be inserted into the sheath, and which is rotatable and movable forward and backward relative to the sheath;

a relay connector coupled to a proximal end of the sheath;

a support tube provided at an outer circumference of the drive shaft along an axial direction and which moves forward and backward in conjunction with the drive shaft;

a seal member provided inside the relay connector and which seals a space between the relay connector and the support tube; and

an injection opening which is located in a region closer to a distal side of the catheter than the seal member and closer to a proximal side of the catheter than a distal end of the support tube when the support tube is in a backward movement limit position and via which a liquid is able to be injected into the sheath.

2. The diagnostic imaging catheter according to claim 1 , wherein the injection opening is provided in the relay connector.

3. The diagnostic imaging catheter according to claim 2 , wherein the injection opening is located closer to the proximal side than a center of the relay connector in the axial direction.

4. The diagnostic imaging catheter according to claim 1 , further comprising a sealing member which is provided inside a hub located on a proximal side of the relay connector and operable to rotate and move the drive shaft forward and backward and which restrains the liquid from moving toward the proximal side of the catheter.

5. The diagnostic imaging catheter according to claim 1 , further comprising a port which communicates with the injection opening,

wherein the port is configured to be inclined from a direction perpendicular to the axial direction toward the proximal side of the catheter.

6. The diagnostic imaging catheter according to claim 5 , further comprising a tube which communicates with the injection opening via the port and which extends along the axial direction.

7. The diagnostic imaging catheter according to claim 5 , wherein the port is integrally formed with the relay connector.

8. The diagnostic imaging catheter according to claim 1 , further comprising an outer tube provided at a proximal side of the sheath, the relay connector interconnecting the sheath and the outer tube.

9. The diagnostic imaging catheter according to claim 8 , wherein the relay connector includes an outer tube holding portion provided on a proximal side of the relay connector and an anti-kink protector provided on a distal side of the relay connector.

10. The diagnostic imaging catheter according to claim 9 , wherein the seal member seals a space between the outer tube holding portion and the support tube.

11. A diagnostic imaging catheter comprising:

a sheath including a lumen;

a drive shaft including a signal transmitting and receiving unit at a distal portion thereof, the drive shaft configured to be inserted in the lumen of the sheath and be rotatable and movable forward and backward relative to the sheath;

a relay connector coupled to a proximal end of the sheath;

a support tube provided around an outer circumference of the drive shaft along an axial direction, the support tube being movable forward and backward in conjunction with the drive shaft from a forward movement limit position to a backward movement limit position;

a seal member provided inside the relay connector, the seal member configured to seal a space between the relay connector and the support tube; and

an injection opening configured for fluid to be injected therethrough and into the sheath,

wherein, when the support tube is in the backward movement limit position, the injection opening is located closer to a distal side of the catheter than the seal member and closer to a proximal side of the catheter than a distal end of the support tube, whereby fluid injected through the injection opening contacts the support tube provided around the outer circumference of the drive shaft rather than directly contacting the drive shaft.

12. The diagnostic imaging catheter according to claim 11 , wherein the seal member comprises an X-ring.

13. The diagnostic imaging catheter according to claim 11 , further comprising a hub located on a proximal side of the relay connector and operable to rotate and move the drive shaft forward and backward.

14. The diagnostic imaging catheter according to claim 11 , wherein the sheath includes a discharge hole formed at a distal portion thereof such that fluid injected into the sheath through the injection opening can be discharged from the sheath via the discharge hole.

15. The diagnostic imaging catheter according to claim 11 , further comprising a port configured to communicate with the injection opening, the port being inclined from a direction perpendicular to the axial direction toward the proximal side of the catheter.

16. The diagnostic imaging catheter according to claim 15 , wherein the port is integrally formed with the relay connector.

17. A method of using a diagnostic imaging catheter comprising the steps of:

providing a diagnostic imaging catheter including a sheath including a lumen; a drive shaft including a transducer unit at a distal portion thereof, the drive shaft configured to be inserted in the lumen of the sheath and be rotatable and movable forward and backward relative to the sheath; a relay connector coupled to a proximal end of the sheath; a support tube provided around an outer circumference of the drive shaft along an axial direction, the support tube being movable forward and backward in conjunction with the drive shaft from a forward movement limit position to a backward movement limit position; an injection opening configured for fluid to be injected therethrough and into the sheath; a port which communicates with the injection opening; and a hub located on a proximal side of the relay connector and operable to rotate and move the drive shaft forward and backward;

pulling the hub toward a proximal side of the catheter to a maximum extent;

connecting a syringe filled with a fluid to the port;

pushing a plunger of the syringe such that the fluid is injected into the relay connector via the injection opening;

discharging the fluid outside of the sheath via a discharge hole in the sheath; connecting a connector portion of the diagnostic imaging catheter to an external apparatus;

pushing the hub toward a distal side of the catheter to a maximum extent and moving the transducer unit toward a distal side of the sheath;

inserting the sheath to a target position inside a body cavity;

acquiring a tomographic image at the target position by moving the transducer unit toward the proximal side of the catheter in a pullback operation while being rotated together with the drive shaft;

wherein the drive shaft is covered by the support tube at the injection opening during the pullback operation, thereby preventing the drive shaft from entering the injection opening;

wherein the diagnostic imaging catheter further comprises a seal member provided inside the relay connector, the seal member configured to seal a space between the relay connector and the support tube; and

wherein, when the support tube is in the backward movement limit position, the injection opening is located closer to a distal side of the catheter than the seal member and closer to a proximal side of the catheter than a distal end of the support tube, wherein the fluid injected through the injection opening contacts the support tube provided around the outer circumference of the drive shaft rather than directly contacting the drive shaft.

18. The method of using a diagnostic imaging catheter according to claim 17 , wherein the external apparatus utilizes intravascular ultrasound.

19. The method of using a diagnostic imaging catheter according to claim 17 , further comprising providing the port at an incline toward the proximal side of the catheter from a direction perpendicular to the axial direction.