Catheter having an improved distal tip

1. A medical device comprising:

a guidewire having a first diameter and a distal stop having a second diameter greater than the first diameter;

an elongate tubular member having a proximal end and a distal end with a guide wire receiving lumen extending therethrough, a distal portion of the guidewire lumen having an inner diameter of substantially the same magnitude as the first diameter; and

a tip disposed at the distal end of the elongate tubular member and having a distal end, a proximal end and a tip lumen therethrough, the tip having an elastic portion and a radially inextensible distal portion distal of the elastic portion;

wherein the elongate tubular member is slidably disposed on the guidewire such that the distal end of the tip engages against the distal stop when the elongate tubular member is advanced distally relative to the guidewire;

wherein the tip comprises an amorphous polymer and the radially inextensible distal portion comprises a locally crystalline section thereof;

wherein the radially inextensible distal portion is a distalmost extremity;

wherein when the tip directly contacts the distal stop and the elongate tubular member is forced distally relative to the guidewire, the elastic portion of the tip inverts inwardly and the radially inextensible distal portion enters an internal cavity within the tip.

2. The medical device of claim 1 , wherein the radially inextensible distal portion comprises a ring having a lumen therethrough.

3. The medical device of claim 1 , wherein the radially inextensible distal portion is machined.

4. The medical device of claim 1 , wherein the radially inextensible distal portion is formed by deposition.

5. The medical device of claim 1 , wherein the radially inextensible distal portion comprises a non-compliant plastic band.

6. The medical device of claim 1 , wherein the elastic portion tapers from a first outer diameter at a first location along the tip to a second outer diameter less than the first outer diameter at a second location along the tip distal of the first location.

7. The medical device of claim 6 , wherein at the first location along the tip, the tip has a first thickness and a first inner diameter, and wherein at the second location along the tip distal of the first location, the tip has a second thickness less than the first thickness and a second inner diameter greater than the first inner diameter.

8. The medical device of claim 7 , wherein the elastic portion comprises an inner surface concave in a first plane normal to a longitudinal axis and a second plane normal to the first plane.

9. The medical device of claim 1 , wherein the tip lumen further comprises a cavity within the tip, wherein the cavity forms a concave hollow that is larger in diameter than the inner diameter of the guidewire lumen.

10. A medical device comprising:

a guidewire having a first diameter and a distal stop having a second diameter greater than the first diameter;

an elongate amorphous polymeric tubular member having a proximal end, a distal end, and a guidewire lumen extending therethrough, wherein a distal portion of the guidewire lumen has an inner diameter of substantially the same magnitude as the first diameter; and

an integrally formed tip disposed at the distal end of the elongate tubular member and having a distal end, a proximal end, a tip lumen extending therethrough in fluid communication with the guidewire lumen, and an enlarged cavity formed within the tip lumen between the proximal end and the distal end of the tip;

wherein the tip includes an elastic portion disposed immediately proximal a radially inextensible distalmost extremity comprising a locally crystalline section thereof;

wherein the elongate amorphous polymeric tubular member is slidably disposed on the guidewire such that the distal end of the tip engages against the distal stop when the elongate tubular member is advanced distally along the guidewire;

wherein when the tip directly contacts the distal stop and the elongate tubular member is forced distally relative to the guidewire, the elastic portion of the tip inverts inwardly and the radially inextensible distalmost extremity enters the enlarged cavity within the tip.

11. The medical device of claim 10 , wherein the inverted tip stores energy that is released when the tip returns to an everted state, and the stored energy assists in peeling the tip off of the distal stop.

12. The medical device of claim 11 , wherein releasing the stored energy provides tactile feedback to an operator of the medical device.