Micromachined composite guidewire structure with anisotropic bending properties

1. A medical device, comprising:

an elongate core member having a proximal portion and a distal portion;

wherein the distal portion includes a distal end and a flattened region disposed proximally of the distal end, the flattened region having a height and a width, the width being twice or more as large as the height;

a tubular member disposed over the distal portion, the tubular member having a plurality of slots formed therein; and

wherein the flattened region of the core member individually has anisotropic bending properties and includes at least one preferred bending direction, wherein the tubular member individually has anisotropic bending properties and includes at least one preferred bending direction, and wherein the tubular member is disposed over the distal portion such that the preferred bending direction of the flattened region of the core member is aligned with the preferred bending direction of the tubular member.

2. The medical device of claim 1 , wherein the medical device is more flexible in a direction extending through the height of the core wire than in another direction extending through the width of the core wire.

3. The medical device of claim 1 , wherein the tubular member is isotropic in bending.

4. The medical device of claim 1 , wherein the proximal portion of the core member has a substantially round cross-sectional shape.

5. The medical device of claim 1 , wherein the flattened region is disposed at least one centimeter proximally of the distal end of the core member.

6. The medical device of claim 1 , wherein the flattened region is disposed more than one centimeter proximally of the distal end of the core member.

7. A guidewire, comprising:

an elongate shaft having a preferred bending direction, the shaft including a core member and a tubular member having a plurality of slots formed therein;

wherein the core member includes a hinge region disposed proximally from a distal end of the core member and a distal region extending between the hinge region and the distal end of the core member, the hinge region having a height and a width, the width being larger than the height;

wherein the distal region of the core member has a substantially circular cross-sectional shape;

a tip member attached to the distal end of the core member; and

wherein the preferred bending direction extends through the height of the hinge region.

8. The guidewire of claim 7 , wherein the width is two or more times larger than the height.

9. The guidewire of claim 7 , wherein the width is three or more times larger than the height.

10. The guidewire of claim 7 , wherein the width is four or more times larger than the height.

11. The guidewire of claim 7 , wherein the width is five or more times larger than the height.

12. The guidewire of claim 7 , wherein the hinge region is disposed at least one centimeter proximally of the distal end of the core member.

13. The guidewire of claim 7 , wherein the hinge region is disposed more than one centimeter proximally of the distal end of the core member.

14. A method for manufacturing a medical device, the method comprising:

providing an elongate core member having a proximal portion and a distal portion;

flattening a region of the distal portion to define a flattened region, the flattened region having a height and a width, the width being twice or more as large as the height;

wherein the distal portion of the core member has a distal end and wherein the flattened region is disposed proximally of the distal end and between the flattened region and the distal end the core member has a substantially circular cross-sectional shape;

disposing a tubular member over the distal portion, the tubular member having a plurality of slots formed therein; and

attaching a tip member to the distal end of the distal portion of the core member.