Magnetic Coupling to Prevent Guidewire Loss During Catheterization

Abstract

A guidewire comprising a magnetic element that would help to avoid accidental release of the guidewire. The magnetic element is located at a proximal one-fourth segment of the guidewire. The guidewire could be used in a variety of contexts, such as central venous catheterization, endovascular radiology procedures, or cardiac catheterization. Also disclosed are vascular instruments comprising a magnetic element or magnetically responsive element. Examples of such vascular instruments include finder needles, dilation cannulas, and various types of catheters. The vascular instrument could be used in combination with a magnetic guidewire to help to avoid accidental release of the guidewire.

Claims

1. A guidewire comprising: a proximal end; a distal end; a magnetic element located at a proximal one-fourth segment of the guidewire.

2. The guidewire of claim 1, wherein the magnetic element is located within 5 cm from the proximal end.

3. The guidewire of claim 1, wherein the guidewire has a length of 2.5 to 600 cm long.

4. The guidewire of claim 1, wherein the guidewire has a diameter of 0.6 to 3.3 mm wide.

5. The guidewire of claim 1, wherein the guidewire has a length shorter than 60 cm.

6. The guidewire of claim 5, wherein the guidewire has a length shorter than 45 cm.

7. The guidewire of claim 1, wherein the guidewire does not have a magnetic element at a distal one-fourth segment of the guidewire.

8. The guidewire of claim 1, wherein the distal end is more flexible than the proximal end.

9. A vascular catheterization kit comprising: (i) a guidewire comprising: a proximal end; a distal end; a magnetic element located at a proximal one-fourth segment of the guidewire. (ii) a vascular instrument comprising a magnetic element or magnetically responsive element.

10. The vascular catheterization kit of claim 9, wherein vascular instrument is a dilation cannula.

11. The vascular catheterization kit of claim 9, wherein the vascular instrument is a vascular catheter.

12. The vascular catheterization kit of claim 9, wherein the vascular instrument is a finder needle.

13. The vascular catheterization kit of claim 9, wherein the vascular instrument's magnetic element or magnetically responsive element is located at a proximal one-fourth section of the vascular instrument.

14. The vascular catheterization kit of claim 9, wherein the vascular instrument comprises a magnetic element.

15. The vascular catheterization kit of claim 9, wherein the vascular instrument comprises a magnetically responsive element.

16. The vascular catheterization kit of claim 11, wherein the vascular catheter comprises a hub and the hub comprises the magnetic element or magnetically responsive element.

17. The vascular catheterization kit of claim 14, wherein the polarity orientation of the magnetic element on the vascular instrument is opposite the polarity orientation of the magnetic element on the guidewire.

18. The vascular catheterization kit of claim 9, wherein the guidewire does not have a magnetic element at a distal one-fourth segment of the guidewire.

19. A method of retrieving a guidewire from a patient, wherein the guidewire comprises a magnetic element and is within the patient's body, the method comprising: inserting an endovascular retrieval instrument into the patient's body; guiding the endovascular retrieval instrument towards the guidewire; magnetically coupling the magnetic element on the guidewire with the endovascular retrieval instrument; withdrawing the endovascular retrieval instrument from the patient's body with the guidewire in tow.

20. The method of claim 19, further comprising ensnaring the guidewire with the endovascular retrieval instrument.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIGS. 1A-1F show an example of how a central venous catheterization procedure is conventionally performed.

[0026] FIG. 2 demonstrates the partitioning of a guidewire into four equal one-fourth segments.

[0027] FIG. 3 shows an example of a guidewire of my invention.

[0028] FIG. 4 shows an example of a dilation cannula of my invention used in combination with the guidewire shown in FIG. 3.

[0029] FIG. 5 shows an example central venous catheter of my invention.

[0030] FIGS. 6A and 6B (on the landscape oriented drawing sheet alongside FIG. 8 below) show how the polarity of the magnetic elements could be arranged for enhancing function.

[0031] FIGS. 7A-7C illustrate an example of a lost guidewire situation.

[0032] FIG. 8 illustrate an example of how two magnetic guidewires of my invention could be used in a lost guidewire situation.

DETAILED DESCRIPTION

[0033] To assist in understanding my invention, reference is made to the accompanying drawings to show by way of illustration specific embodiments in which the invention may be practiced.

1. GUIDEWIRE

[0034] In one aspect, my invention is a guidewire that comprises a magnetic element to allow magnetic coupling with the relevant device or instrument to help in retaining the guidewire and avoid accidental release of the guidewire out of the instrument. The magnetic element is located somewhere on the proximal one-fourth segment of the guidewire. This is demonstrated in FIG. 2, which depicts a guidewire 34 in a straightened configuration. To specify orientation, the distal end is indicated by the reference label D and the proximal end is indicated by the reference label P. There are a variety of possible ways to distinguish the proximal end of a guidewire from its distal end. That is, the guidewire could be longitudinally asymmetric by material composition, shape, markings, radiographic features, configuration, mechanical properties, etc. For example, it is common for guidewires to have a J-tip or pig tail shape at its distal end (but straight at its proximal end). Also, the distal segment of the guidewire may be relatively softer or more flexible than the proximal segment, or vice versa, the proximal segment may be relatively stiffer.

[0035] As shown here, for definition purposes, the guidewire 34 could be considered divided into four equal segments. There is a distal segment 39, which is the distal one-fourth section of the guidewire 34; there is a proximal segment 36, which is the proximal one-fourth section of the guidewire 34; and there is a middle segment in between, which are the two middle one-fourth sections 37 and 38 of the guidewire 34. This type of segmentation pattern could also be applied to the other devices or instruments of my invention.

[0036] Thus, according to my invention, the magnetic element is located somewhere on segment 36 of the guidewire 34. In some embodiments, the magnetic element is located within a distance of 5 cm from the proximal end of the guidewire 34. In some embodiments, none of the other segments (distal 39 and middle 37, 38) comprise a magnetic element.

[0037] FIG. 3 shows an example of a guidewire 50 of my invention. To specify orientation, the distal end is indicated by the reference label D and the proximal end is indicated by the reference label P. The main body 52 of the guidewire 50 is made of stainless steel. However, the proximal tip section 54 of the guidewire 50 is magnetic.

[0038] The guidewire of my invention could be used in any suitable vascular catheterization procedure. But in some embodiments, the guidewire is not a guidewire that is used in coronary angioplasty procedures, endovascular interventional radiology procedures, or other procedures in which the catheter is visualized under x-ray fluoroscopy in real-time. Because of the real-time x-ray visualization, there is less need for safeguarding against guidewire loss. Longer guidewires are typically used in such interventional procedures, whereas shorter guidewires are used in central venous catheterization procedures. As such, the guidewire of my invention could be shorter than those used in such interventional procedures. In some cases, the guidewire of my invention has a length shorter than 60 cm; and in some cases, shorter than 45 cm.

2. VASCULAR INSTRUMENT

[0039] FIG. 4 shows an example of a dilation cannula of my invention used in combination with the guidewire 50 shown in FIG. 3. The dilator 60 comprises a hollow shaft 62 with a tapered tip 64 to facilitate penetration into the skin and tunnel passageway. There is a distal opening on the tapered tip 64 for receiving the guidewire 50. The guidewire 50 is inserted into the dilator 60 at its tip 64, threaded through the shaft 62, and then exits out of flange port 61. The operator firmly grasps the guidewire 50 at its proximal end and pushes the dilator 60 through the skin and subcutaneous tunnel as it tracks along the guidewire 50. The dilator 60 has a magnetic element 65 embedded in the flange port 61. If the operator loses grip on the guidewire 50 and lets it slide too far back down the dilator shaft 62 (and further into the blood vessel), then the magnetic tip 54 would magnetically couple to magnetic element 65 on the flange port 61. This magnetic coupling is sufficiently strong to impede further backsliding of the guidewire 50 down the shaft 62 and into the blood vessel. The dilator 60 also has a stainless steel cuff 67 on the shaft 62. This may be useful as backup in magnetic guidewires to prevent the guidewire 50 from backsliding even further down the dilator shaft 62.

[0040] FIG. 5 shows an example central venous catheter 70 of my invention. To specify orientation, the distal end is indicated by the reference label D and the proximal end is indicated by the reference label P. This triple-lumen catheter 70 has a main tubular shaft 72 with three separate lumens therein. One of the lumens (main lumen) opens out to opening at the distal tip 74 of the main shaft 72. The other two accessory lumens open out to side openings on the main shaft 72 (not shown here). The main lumen extends through connecting line 84, which terminates at a main port 87. During the insertion procedure, the opening at the distal tip 74 would receive a guidewire, which is already inserted inside the target vein. This could be any conventional guidewire or a magnetic guidewire of my invention. The guidewire is threaded backwards through the main shaft 72, and through main connecting line 84 until the proximal end of the guidewire exits out from main port 87. Securely grasping the proximal end of the guidewire, the catheter 70 is then advanced over the guidewire and into the target vein. Once the catheter 70 is securely in place, the entire guidewire is withdrawn out of the main port 87 and removed.

[0041] The two accessory lumens extend through connecting lines 83 and 85, which terminate at accessory ports 86 and 88, respectively. The connecting lines (83, 84, 85) are bundled together by hub 76, which assembles the separate lines together with their respective lumens in main shaft 72. The hub 76 has a magnetic strip 80 embedded therein. There is also a magnetic cuff 82 on the main connecting line 84. The magnetic strip 80 and magnetic cuff 82 would help to retain the guidewire in case of accidental release of the guidewire or inadvertent failure to withdraw the guidewire after the procedure is completed.

[0042] FIGS. 6A and 6B (on the landscape oriented drawing sheet alongside FIG. 8 below) show how the polarity of the magnetic elements could be arranged for enhancing function. FIG. 6A shows a catheter 110 having a magnetic segment 112, which is oriented with the magnetic north pole 114 () towards the proximal end and the magnetic south pole 116 (+) towards the distal end. There is a guidewire 120 having a magnetic tip 122, which is oriented with the magnetic south pole 124 (+) towards the proximal end and the magnetic north pole 126 () towards the distal end. As the catheter 110 is being inserted and advanced over the guidewire 120 (see-through view), the magnetic south pole 124 (+) approaches the magnetic north pole 116 (+) of the magnetic segment 112 on the catheter 110. The guidewire 120 travels in the direction of arrow 118 relative to the catheter 110. This creates some magnetic repulsion that impedes further advancement of the catheter 110 over the guidewire 120. But this resistance is easily overcome by the operator's manual manipulation to force the opposing magnetic elements to traverse each other.

[0043] FIG. 6B shows the catheter 110 and the guidewire 120 after the two magnetic elements (112, 122) have traversed each other. In this alignment, loss of grip on the guidewire 120 would be less problematic because there would be magnetic resistance to the guidewire 120 traveling backwards (in the direction of arrow 128) relative to catheter 110. The magnetic repulsion between the guidewire's magnetic north pole 126 () and the catheter's magnetic north pole 114 () would resist inadvertent traveling of the guidewire 120 in the backwards direction. Moreover, if the guidewire 120 does continue to travel in a backwards direction such that magnetic element 112 overlaps with magnetic element 122, then opposite pole attraction would cause magnetic coupling between the guidewire 120 and the catheter 110. This magnetic coupling would impede further travel of the guidewire 120 in a backwards direction.

3. GUIDEWIRE RETRIEVAL

[0044] The magnetic guidewire of my invention could also be useful for facilitating retrieval in the situation where the guidewire is trapped in the catheter or lost into the blood vessel. In this situation, a retrieval device could be used to retrieve the lost guidewire. The retrieval device could be another guidewire, which could be a conventional metal guidewire or a second magnetic guidewire of my invention. Also, there are various types of endovascular retrieval devices that are commonly used in interventional radiology, such as snare catheters, wire graspers, intravascular baskets, cable forceps, etc. Examples of magnetic snare catheters are described in U.S. Pat. No. 6,554,842 (Heuser et al); U.S. Pat. No. 7,144,408 (Keegan et al); and U.S. Pat. No. 5,706,827 (Ehr et al).

[0045] FIGS. 7A-7C illustrate an example of a lost guidewire situation. As shown in FIG. 7A, during a catheter insertion procedure, a guidewire 94 was inserted into the subclavian vein, but inadvertently lost. A chest x-ray showed that the lost guidewire 94 is lodged within the right ventricle 96 of the patient's heart. To retrieve the lost guidewire 94, a snare catheter 90 has been inserted through the subclavian vein and visualized under x-ray fluoroscopy. The snare catheter 90 has a set of snare hoops 92 at its distal end for snaring intravascular foreign objects.

[0046] As shown in FIG. 7B (close-up view), the snare catheter 90 has a magnetic band 100 at its distal end. Extending out from the distal end are three flexible hoops 102 that are tied together by an end cap 104. The guidewire 94 has a magnetic segment 106 at its proximal end. Magnetic attraction between the magnetic segment 106 on guidewire 94 and the magnetic band 100 on the snare catheter 90 draws in guidewire 94 close so that it becomes nestled within the hoops 102. As shown in FIG. 7C, the hoops 102 are retracted into the snare catheter 90 to cause the hoops 102 to constrict and ensnare the guidewire 94. The snare catheter 90 is then withdrawn backwards out the vein with the ensnared guidewire 94 in tow to retrieve the lost guidewire 94.

[0047] FIG. 8 illustrate an example of how two magnetic guidewires of my invention could be used in a lost guidewire situation. In this example, magnetic guidewire 142 (having a magnetic tip 144) has accidentally slid too far down the catheter 130 (see-through view). To retrieve this wayward guidewire 142, a second magnetic guidewire 132 is inserted in a backwards orientation down through catheter 130. The second guidewire 132 is advanced towards guidewire 142 until magnetic tip 134 (at the proximal end of guidewire 132) draws near magnetic tip 144 (at the proximal end of guidewire 142) so that they are magnetically coupled. The second guidewire 132 is withdrawn from catheter 130 with wayward guidewire 142 in tow behind.

4. CONCLUSION

[0048] The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Each of the disclosed aspects and embodiments of the invention may be considered individually or in combination with other aspects, embodiments, and variations of the invention. In addition, unless otherwise specified, the steps of the methods of the invention are not confined to any particular order of performance. Modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, and such modifications are within the scope of the invention.

[0049] Any use of the word or herein is intended to be inclusive and is equivalent to the expression and/or, unless the context clearly dictates otherwise. As such, for example, the expression A or B means A, or B, or both A and B. Similarly, for example, the expression A, B, or C means A, or B, or C, or any combination thereof.