Method and device for sheathless arterial catheterization

1. A kit for gaining access to a vessel of a patient, comprising:

a first dilator having an elongated body with proximal and distal ends, a distal portion with a maximal outer diameter having a cylindrical configuration that extends from the distal end to a guidewire exit port, a proximal portion with a reduced profile having a semi-cylindrical configuration that extends from the guidewire exit port to the proximal end and a lumen defined by an inner wall that extends between the distal end and the guidewire exit port, wherein a portion of the inner wall continues to extend through the proximal portion; and

a second dilator having an elongated body with proximal and distal ends, a distal portion with a maximal outer diameter having a cylindrical configuration that extends from the distal end to a guidewire exit port, a proximal portion with a reduced profile having a semi-cylindrical configuration that extends from the guidewire exit port to the proximal end and a lumen defined by an inner wall that extends between the distal end and the guidewire exit port, wherein a portion of the inner wall continues to extend through the proximal portion;

wherein the first dilator is configured to be inserted into a radial artery, and the second dilator is configured to be inserted into the radial artery upon removal of the first dilator;

wherein the lumen of the first dilator has a smaller inner diameter than the lumen of the second dilator; and

wherein the maximal outer diameter distal portion of the first dilator has an outer diameter the same as the maximal outer diameter distal portion of the second dilator.

2. The kit of claim 1 , wherein the maximal outer diameter of the first dilator is about 1.80 mm.

3. The kit of claim 1 , further comprising a marker positioned on the proximal portion of the first dilator.

4. The kit of claim 1 , wherein the lumen of the first dilator has a diameter of about 0.58 mm and the lumen of the second dilator has a diameter of about 0.88 mm.

5. The kit of claim 1 , wherein the reduced profile proximal portion of the first dilator has a cross sectional area at least 40% smaller than a cross sectional area of the maximal outer diameter distal portion of the first dilator.

6. The kit of claim 5 , wherein the reduced profile proximal portion of the first dilator has a cross sectional area at least 50% smaller than a cross sectional area of the maximal outer diameter distal portion of the first dilator.

7. The kit of claim 1 , wherein the semi-cylindrical configuration of the proximal portion of the first dilator is configured to receive a guidewire therein and the cylindrical configuration of the distal portion of the first dilator is configured to receive the guidewire in the lumen therein.

8. The kit of claim 1 , wherein the maximal outer diameter of the second dilator is about 1.80 mm.

9. The kit of claim 1 , wherein the distal end of the first dilator is tapered.

10. The kit of claim 9 , wherein the tapered distal end of the first dilator has a hydrophilic coating.

11. The kit of claim 1 , wherein the distal end of the second dilator is tapered.

12. The kit of claim 11 , wherein the tapered distal end of the second dilator has a hydrophilic coating.

13. The kit of claim 1 , wherein the first and second dilators are formed from a polymeric material.

14. A method for gaining access to a radial artery of a patient, comprising:

providing a first dilator having an elongated body with proximal and distal ends, a distal portion with a maximal outer diameter having a cylindrical configuration that extends from the distal end to a guidewire exit port, a proximal portion with a reduced profile having a semi-cylindrical configuration that extends from the guidewire exit port to the proximal end and a lumen that extends between the distal end and the guidewire exit port;

positioning a first guidewire within the radial artery of the patient;

advancing the first dilator over the first guidewire into the radial artery without being inserted through a sheath;

advancing a first guide catheter over the first dilator;

removing the first dilator;

providing a second dilator having an elongated body with proximal and distal ends, a distal portion with a maximal outer diameter having a cylindrical configuration that extends from the distal end to a guidewire exit port, a proximal portion with a reduced profile having a semi-cylindrical configuration that extends from the guidewire exit port to the proximal end and a lumen that extends between the distal end and the guidewire exit port; and

introducing the second dilator through the first guide catheter and positioning a distal end of the second dilator at a desired region of the radial artery, wherein the lumen of first dilator has a smaller inner diameter than a lumen of the second dilator;

wherein the maximal outer diameter distal portion of the first dilator has an outer diameter the same as the maximal outer diameter distal portion of the second dilator.

15. The method of claim 14 , further comprising preloading the first dilator into the first guide catheter before advancing the first dilator.

16. The method of claim 14 , further comprising introducing a second guidewire through the first guide catheter and positioning a distal end of the second guidewire at a desired region of the radial artery, wherein the second guidewire has a larger diameter than the first guidewire.

17. The method of claim 16 , further comprising performing at least a portion of a procedure with the first guide catheter.

18. The method of claim 17 , further comprising:

withdrawing the first guide catheter;

advancing the second dilator over the second guidewire into the vessel without being inserted through a sheath;

advancing a second guide catheter over the second dilator; and

removing the second dilator.

19. The method of claim 18 , further comprising preloading the second dilator into the second guide catheter before advancing the first dilator.

20. The method of claim 19 , further comprising performing at least a portion of the procedure with the second guide catheter.