Shape memory medical device and methods of use
A shaped guidewire for use in medical applications is disclosed. The guidewire is shaped so as to prevent inadvertent advancement of the guidewire into the corpus of a patient during use. In one embodiment, the guidewire includes an elongate body that defines proximal and distal ends. The guidewire body further defines a shaped portion that is positioned intermediate the proximal and distal ends. The shaped portion of the guidewire is at least partially composed of a shape memory material, such as nitinol, and is deflected from a longitudinal axis defined by an undeflected portion of the guidewire body. The shaped portion is disposed in one embodiment at the proximal end of the guidewire. In another embodiment, a proximal portion of the nitinol guidewire can be treated to impart malleability and enable deflection by a clinician. Methods for forming the shaped or malleable guidewire to include a deflected portion are disclosed.
1. A guidewire system, comprising:
a shapeable guidewire having an elongate body defining proximal and distal ends aligned along a longitudinal axis of the elongate body, the body including:
a shapeable portion, wherein the shapeable portion:
is at least partially composed of a shape memory material,
is deflectable from the longitudinal axis of the body, and
is malleable so as to be shaped by a user before, during, or after use of the guidewire; and
an apparatus that can be positioned at an incision site on a corpus of a patient to interact in contact with the shapeable portion of the elongate body to prevent further advancement of the guidewire into a vasculature of the patient.
2. The guidewire system as defined in claim 1 , wherein the shape memory material is a shape memory alloy.
3. The guidewire system as defined in claim 2 , wherein the shape memory alloy includes nickel and titanium.
4. The guidewire system as defined in claim 3 , wherein the shapeable memory alloy includes nitinol.
5. The guidewire system as defined in claim 1 , wherein the shapeable portion includes a segment that is deflected an angle greater than zero with respect to the longitudinal axis.
6. The guidewire system as defined in claim 1 , wherein the shapeable portion is disposed at the proximal end of the guidewire body.
7. The guidewire system as defined in claim 6 , wherein the shapeable portion defines a semi-circular shape.
8. A method for forming a guidewire, the method comprising:
defining an elongate body of the guidewire including a proximal end and a distal end aligned along a longitudinal axis of the elongate body, a proximal portion of the body located proximate the proximal end including a shape memory material having superelastic characteristics;
heat-treating the proximal portion such that the proximal portion loses the superelastic characteristics and becomes malleable and bendable into multiple shapes by a user of the guidewire and remains malleable and bendable after cooling; and
cooling the proximal portion.
9. The method for forming as defined in claim 8 , wherein heat-treating the proximal portion is done without deflecting the proximal portion from the longitudinal axis.
10. The method for forming as defined in claim 8 , wherein heat treating the proximal portion further comprises:
heat treating the proximal portion for a time in a range of from about 30 seconds to about 15 minutes.
11. The method for forming as defined in claim 8 , wherein heat treating the proximal portion further comprises:
heat treating the proximal portion at a temperature in a range of from about 200 to about 395 degrees Celsius.
12. The method for forming as defined in claim 8 , wherein cooling the proximal portion further comprises:
cooling the proximal portion in a water bath.
13. The method for forming as defined in claim 8 , wherein the entire guidewire body includes nitinol, and wherein a distal portion of the guidewire body is not heat treated.
14. A shaped guidewire, comprising:
an elongate body, including:
a distal segment including nitinol; and
a proximal segment including stainless steel, the proximal segment including a shaped portion that is deflected from a longitudinal axis defined by an undeflected portion of the proximal segment, the shaped portion configured to prevent unintended advancement of the guidewire into a vasculature of a patient past the shaped portion when the shaped portion is in contact with tissue of a patient or an apparatus at an incision site.
15. The shaped guidewire as defined in claim 14 , wherein the shaped portion is semi-circularly shaped.
16. The shaped guidewire as defined in claim 14 , wherein the proximal and distal segments are joined to one another via welding.
17. The shaped guidewire as defined in claim 14 , wherein the distal segment is relatively more resistant to kinks than the proximal segment.
18. A shaped guidewire, comprising:
an elongate body defining proximal and distal ends aligned along a longitudinal axis of the elongate body, the body including:
a shaped portion at least partially composed of a shape memory material positioned intermediate the proximal and distal ends and deflected from the longitudinal axis of the body, the shaped portion configured to interact with tissue of a patient proximate an incision site on a corpus of the patient to prevent advancement of the guidewire into a vasculature of the patient past the shaped portion.
19. The shaped guidewire as defined in claim 18 , wherein the shaped portion is substantially deformable when a load is applied thereon, and wherein the shaped portion returns to its undeformed shape when the load is removed.
20. The shaped guidewire as defined in claim 18 , wherein the shaped portion is also configured to interact with an apparatus positioned at the incision site to prevent advancement of the guidewire into a vasculature of the patient past the shaped potion.