WO2003049794A1

WO2003049794A1 - An apparatus and method for determining the length and size of stents to be deployed in a stenotic blood vessel and for test of passage for direct stenting

Info

Publication number: WO2003049794A1
Application number: PCT/SG2002/000285
Authority: WO
Inventors: Siam Soon Philip Koh; Ye Ping; John E. Shulze; Douglas Robert Savage; Dan Wang; Kok Wui Guan
Original assignee: Biosensors International Pte Ltd
Priority date: 2001-12-12
Filing date: 2002-12-09
Publication date: 2003-06-19
Also published as: AU2002366628A1

Abstract

The present invention provides a novel gauging for accurately assisting in determining the length and size of a suitable stent to be deployed. The distal end of the catheter is furnished with a series of radio- opaque markings in a unique and novel arrangement which makes for ease of determination of length of stent to be used. The markings also aid in the determination of the size of the stent. The present invention also serves to function as a test of passage for direct senting. The distal end of the same gauging catheter is bulleted to simulate the profile of a stent and balloon assembly for this purpose.

Description

AN APPARATUS AND METHOD FOR DETERMINING THE LENGTH AND SIZE

OF STENTS TO BE DEPLOYED IN A STENOTIC BLOOD VESSEL AND FOR

TEST OF PASSAGE FOR DIRECT STENTING

FIELD OF THE INVENTION

The present invention relates in general to the field of catheters for use in non-surgical treatment of stenotic lesions in coronary artery. More particularly, the present invention relates to an apparatus and method for measuring and gauging the length and size of the intra-coronary stents to be used.

BACKGROUND OF THE INVENTION

Catheters are well known and commonly used in the medical treatment of disorders. Catheters allow for access into organs, both solid and hollow, luminal/ductal passages and vascular structures enabling the delivery of diagnostic or therapeutic agents besides the drainage of accumulated bodily fluids or debris. A wide range of catheters have been invented to access the arterial vasculature, in particular the coronary vessels, to treat stenotic artheromatous plaques.

Percutaneous Transluminal Coronary Angioplasty is now a widely used procedure. It involves the use of a catheter with a preformed "sausage- shaped" inflatable balloon at its distal end (commonly referred to as a balloon catheter) riding on a slender steerable guide wire to be delivered to the stenotic lesion site. The balloon is then inflated to re-open or dilate the artery so as to re-establish flow of blood. This procedure is sometimes referred to as "balloon angioplasty". The inflation of this balloon through a pressure gauge at the proximal end of the balloon catheter stretches and remodels the stenotic lesion site. In effect achieving a wider lumen in the artery that approximates its original luminal diameter. This method of balloon angioplasty has its attendant problems/complications dissection and restenosis.

The introduction of stents has seen dramatic improvements in the outcomes associated with balloon angioplasty. Stents are metallic scaffoldings of varied designs that are implanted at stenotic lesion sites in arteries to achieve a more predictable and controlled result following balloon angioplasty. Stents are commonly made of surgical stainless steel, "wire- meshed" like or netted in appearance that are commonly crimped onto the deflated balloon and delivered to the desired site for deployment. The balloon is then deflated and withdrawn from the artery. The stent remains in place, serving as a scaffolding for the newly opened or dilated artery. The alternative to balloon expandable stents are self-expanding stents, delivered via plain catheters but retained in position on it by a retaining outer sheath. Pulling back of such a sheath allows the deployment of a self expanding stent. The use of stents have eliminated many of the complications associated with balloon angioplasty, and the additional strength of the stent keeps the artery open whilst in the healing process.

One major concern in intracoronary stenting involves the accurate sizing and gauging of vessel diameter and length of stent to be used. Previously and still practiced, the operator "eye-balls" i.e. visually estimates the vessel diameter and lesion length based on the angiographic images obtained. The operator's estimate is aided by the use of the guiding catheter's guage. Hence, a 6F guiding catheter will provide a 2mm measurement guide. Still field distortions on angiography can add to inaccuracies. The use of computerized digital softwares can improve on the accuracies but are also subject to the inaccuracies posed by the field distortions inherent in the angiographic images acquisition. To better the referencing for improved accuracy of gauging both size and length by whichever method/s available, a catheter with precisely marked and designed markers at its distal end is mentioned later. Currently available "marker" catheters have proved inadequate. Reading the detailed markings of the "rulers" on the fluoroscope is not easy. The flexibility of the catheters were also compromised when too many markings were provided. This is because markings were often made of metal rings. This is to ensure that the markings were radio-opaque allowing the images to be viewed on a fluoroscope. Current markings provided are typically in 5 or 10 millimeter intervals and are inadequate and merely assist and improve on the estimation process.

To further increase the accuracy of such estimations and measurements during fluoroscopy, the use of sophisticated computers and imaging software may be used. However, the disadvantage here is mainly with regard to high costs of such equipment.

Previously, intra-coronary artery stenting was always carried out following balloon angioplasty. The stent deployed was indicated when there was suboptimal luminal result, a threatening tear/dissection has occurred or when predictably better longer term result can be achieved. The newer idea of performing direct stenting i.e. without pre-balloon dilatation of the lesion can obviate all the above concerns. Latest trial results have all been highly supportive of doing de novo stenting (i.e. first time treatment) of coronary lesions to achieve better immediate(primary)and long term outcomes. And with direct stenting not only cost but technical and procedural benefits all can be achieved with similar or improved outcomes for patients.

There is increasing interest and use of the direct stenting technique.

Two key issues encountered by all operators are the confidence of deliverability of the stent delivery system and the accurate gauging of both the size and length of stent selected to match the vessel size at site of lesion and the length of lesion to be covered. The latter issue of gauging of size and length and having an improved catheter to address this has been mentioned previously. The gauging catheter mentioned here has an added feature that specifically addresses the issue of predicting the deliverability of higher profile stent delivery system, besides facilitating in the same gauging maneuver the subsequent passage of the stent delivery system.

OBJECTIVE OF THE PRESENT INVENTION

It is therefore an object of the present invention to provide a series of markings on an apparatus for ease of determining a suitable length and size of stent to be deployed in a diseased blood vessel. It is also an object of the invention to provide an apparatus for testing of passage in a diseased blood vessel for direct stenting.

SUMMARY OF THE INVENTION

The present invention provides a novel intracoronary lesion gauging catheter for accurately assisting in determining the length and size of a suitable stent to be deployed. The distal end of the catheter is furnished with at least 4 radio-opaque markings or markers in a unique and novel arrangement which makes for ease of determination of length of the suitable stent to be used. The markers also aid in the determination of the size or diameter of the stent. The markings are arranged in the following manner: a first marker at distal end of catheter; a second marker positioned 5 m m proximally from first marker; a third marker positioned 3 mm proximally from second marker, and a fourth marker positioned 10 mm proximally from third marker. The present invention also serves to function as a test of passage for direct stenting. The same distal end of the gauging catheter is bulleted to simulate the profile of a stent and balloon assembly for this purpose.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partial cut-away plan view of a gauging catheter according to one form of the present invention.

Fig. 2 shows an enlarged view of the distal end of the gauging catheter according to the present invention. Fig. 3 shows a generic illustration of a typical marker according to one form of the present invention.

Fig. 4 shows a partial cut-away plan view of an Intracoronray Lesion Gauging Catheter according to the preferred form of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Fig. 1, a gauging catheter 100 according to one form of the present invention comprises of a hub 102 at the proximal end, a flexible catheter tube 104, and a tip 106 at the distal end. At the distal end of the flexible catheter tube 104 are disposed a series of markers 110a to 11 Oe. A bulleted structure 108 is provided at the distal end to simulate the profile of a stent and balloon assembly.

Referring to Fig. 2 and Fig 3, the markers 110a to 110e, generally referred to as markers 110 are radio-opaque to allow viewing of the markers through fluoroscopy or similar technology. The markers have been positioned in a unique and novel arrangement to allow for ease of matching of a suitable stent length to a lesion of a stenotic blood vessel. Presently, the most popular and readily available stents are in the lengths of : 8mm, 13mm, 15mm, 18mm, 23mm, 25mm, 28mm, 33mm and 38mm. As such when a surgeon is examining the lesion, he does not require an exact measurement of length. Instead, he needs to match a stent of standard length to best match the lesion length. The present invention allows the surgeon to easily match the markings on the gauging catheter to the lesion in the blood vessel.

Referring to Fig.2 and Fig. 3, the markers 110 are each 1mm in width with a distal edge 112 and a proximal edge 114. The distance from the proximal edge 114 of the first marker 110a to the proximal edge 114 of the second marker 110b is 5 mm. The distance from the proximal edge 114 of the second marker 110b to the proximal edge 114 of the third marker 110c is 3mm. The distance from the proximal edge 114 of the third marker 110c to the proximal edge of the fourth marker 110d is 10mm, likewise between the fourth marker 110d to the fifth marker 110e. The markers 110 are all 1mm in width and can be made of any radio-opaque materials. As such, the same lengths of 5mm, 3mm and 10 mm are achieved when measuring from the distal edge 112 of one marker to the distal edge 112 of the next marker 110.

Using such a "5-3-10-10" arrangement, a great number of combinations of different lengths can be achieved as seen in Fig. 2. Some of the possible combinations are : 8mm, 13mm, 14mm, 18mm, 23mm, 24mm and 28mm. Comparing these possible combinations to the standard lengths of stents available, it can be observed that almost all the stent lengths have been matched by the markers 110. The 15mm and 25mm stents could easily be approximated using the marker combination for 14mm and 24mm.

Surgeons can easily use this arrangement of markers for determining the suitable length of stent they require. The gauging catheter 100 is inserted into the diseased blood vessel and the distal end is introduced into the location of the lesion. The surgeon can then match the markers 110 on the gauging catheter to the length of the lesion and determine the most suitable length of stent to be used. The surgeon is in effect not so much taking a measurement of the lesion as to matching the best fit length of stent to be used. Under the fluoroscope, the distortions of the image does not severely impair the surgeon's ability to match and compare the markers 110 to the lesion. This method is advantageously more intuitive and simpler to put into practice then taking an actual measurement of the lesion. The markers 110 are all 1mm in length and provides a more accurate reference when estimating the size or diameter of stent required as compared to using the catheter diameter.

The invention also serves to simulate the profile of a crimped stent and balloon assembly and to function as a test of passage for direct stenting. Referring to Fig. 2, the bulleted structure 108 has a diameter of 0.049 inch or about 1.24 mm and a length of 18 mm. These dimensions are slightly larger than the typical crimped stent and balloon assembly. These dimensions have been deemed to produce the best results in terms of tractability and maneuverability of the bulleted structure in the blood vessel. The length of the bulleted structure 108 also encompasses the first marker 110a to the fourth marker 110d.

In use, the surgeon would introduce the gauging catheter 100 into the diseased blood vessel and attempt to push the bulleted structure 108 at the distal end of the catheter into the artery across the lesion. If successful, this would indicate to the surgeon that direct stenting is possible. Whereas inability to push the bulleted structure in would mean that a first balloon angioplasty is required before deployment of the stent. The present invention thus advantageously allows the test of passage of a stent and balloon assembly for direct stenting.

The bulleted structure 108 could be made of a variety of materials and would not only provide the physical aspects in terms of dimensions, but also the flexibility and feel of the simulated stent and balloon assembly. Thus far, the present bulleted structure 108 is made of a combination of different grades of stiffness of a thermoplastic polyether which is commonly known as PEBAX. PEBAX is also commonly used in the manufacture of catheters. As such, the gauging catheter 100 uses readily available materials for its construction and is typically simple and easily manufactured at a low cost. However, the bulleted structure 108 should not be mistaken to be simply a slightly larger deflated balloon or a slightly inflated balloon of a balloon catheter.

The materials and dimensions mentioned above are however not meant to restrict the scope of the invention. It would be obvious to one skilled in the art to modify and adjust the dimensions or type of materials of the bulleted structure to suit the necessary application.

Referring to Fig. 4, a preferred example of the invention would be a Intracoronary Lesion Gauging Catheter. The Intracoronary Lesion Gauging Catheter will specifically be used for treatment of a stenotic coronary artery. Its design would be one based on the rapid exchange system. The design comprises of a distal tubing 213 (usually made of nylon or PEBAX material) with a soft and flexible distal tip 206. Mounted on the distal tubing are the markers 210a to 21 Oe. According to the invention the markers 210 are arranged in a "5-3-10-10" arrangement as described. The distal tubing 213 is about 20 cm in length from the distal tip 206 and ends proximally in a guide wire hole 216. The guide wire hole 216 and opening at distal tip 206 forms a channel for guide wire passage.

The distal tubing 213 is reinforced by a stylet 214 for a distance of 16 cm from the distal end of the hypotube. The stylet 214 is typically a stainless steel wire. It maintains the shape and rigidity of the distal tubing 213 when inserting into the stenotic coronary artery.

A bulleted structure 208 encompasses the distal tubing 213 from the first marker 210a to the fourth marker 21 Od. The bulleted structure 208 is about 1.24 mm in diameter and about 18 mm in length. The bulleted structure 208 is hollow and has a perfusion hole 207 at its distal end. A sleeve 212 continues from the bulleted structure 208 over the distal tubing 213 and is bonded to the catheter shaft 204. The stylet 214 is also welded to the catheter shaft 204.

The catheter shaft 204 is made of a stainless steel hypotube. It is designed for optimum tractability during catheter insertion. The hypotube is coated with a thin layer of PTFE materal. The catheter shaft 204 is provided with a first marker 205a at distance of 90 cm from the distal tip 206. A second marker 205b at a distance of 100 cm from the distal tip 206. The proximal end of the catheter shaft 204 is bonded to a hub 202. The hub 202 is provided with a female luer fitting for engaging with other instrument or medical devices.

The hub 202, catheter shaft 204, sleeve 212 and perfusion hole 207 at the distal end of the bulleted structure 208 form a channel for infusion of a contrast medium.

The above description, dimensions and example do not in any way limit the scope of the invention. Catheters are generally well known in the art, and the invention can be used in the many forms and types of catheters available. Some of the more common catheters are : over the wire systems, rapid exchange system or fixed wire systems. They may not necessarily be made up of only one flexible catheter tube, and may consist of a plurality of flexible tubes or lumens each serving a separate function. It would be apparent to one skilled in the art that the present invention may be modified or used in or with other types of catheter systems without departing from the scope of the invention.

Claims

1. A catheter for determining size and length of a suitable stent for deploying across a lesion of a stenotic blood vessel and for performing test of passage for direct stenting in said blood vessel, said catheter comprising : a distal end and a proximal end; a bulleted structure located at said distal end for simulating a crimped stent and deflated balloon assembly, and a predetermined arrangement of at least 4 markers located at said distal end.

2. A catheter according to claim 1 wherein said predetermined arrangement of at least 4 markers comprises : a first marker at said distal end; a second marker positioned 5 mm proximally from first marker; a third marker positioned 3 mm proximally from second marker; and a fourth marker positioned 10 mm proximally from third marker.

3. A method according to claim 2 wherein a fifth marker is positioned 10 mm proximally from fourth marker.

4. A catheter according to claim 1 wherein said markers are made of a radio-opaque material.

5. A catheter according to claim 1 wherein said markers are 1 mm in width.

6. A catheter according to claim 3 wherein said predetermined arrangement of markers correlates in combination suitable stent length to a lesion in the following lengths : 8 mm, 13 mm, 14 mm, 18 mm, 23 mm, 24 mm and 28 mm.

7. A catheter according to claim 2 wherein the position of said markers are measured from proximal end of one marker to proximal end of next marker or from distal end of one marker to distal end of next marker.

8. A catheter according to claim 1 wherein said bulleted structure is about 1.24 mm in diameter.

9. A catheter according to claim 1 wherein said bulleted structure is about 18mm in length.

10. A method for determining size and length of a suitable stent for deploying across a lesion of a stenotic blood vessel and for performing test of passage for direct stenting in said blood vessel, steps comprising : a. inserting a gauging catheter into diseased blood vessel; b. pushing distal end of said gauging catheter into location of stenotic lesion for testing of passage for direct stenting; c. determining length of stent required using a predetermined arrangement of at least 4 markers on gauging catheter;

11 A method according to claim 10 wherein said gauging catheter comprises : a distal end and a proximal end; a bulleted structure located at said distal end for simulating a crimped stent and deflated balloon assembly, and a predetermined arrangement of at least 4 markers located at said distal end.

12. A method according to claim 10 wherein said predetermined arrangement of at least 4 markers comprises : a first marker at said distal end; a second marker positioned 5 mm proximally from first marker; a third marker positioned 3 mm proximally from second marker; and a fourth marker positioned 10 mm proximally from third marker.

13. A method according to claim 12 wherein a fifth marker is positioned 10 mm proximally from fourth marker.

14. A method according to claim 10 wherein said markers are made of a radio-opaque material.

15. A method according to claim 12 wherein said markers are 1 mm in width.

16. A method according to claim 12 wherein position of said markers are measured from proximal end of one marker to proximal end of next marker or from distal end of one marker to distal end of next marker.

17. A method according to claim 13 wherein said predetermined arrangement of markers correlates in combination suitable stent length to a lesion in the following lengths: 8 mm, 13 mm, 14 mm, 18 mm, 23 mm, 24 mm and 28 mm.

18. A method according to claim 11 wherein said bulleted structure is 1.24 mm in diameter.

19. A method according to claim 11 wherein said bulleted structure is about 18mm in length.

20. An intracoronary gauging catheter of rapid exchange design for determining size and length of a suitable stent for deploying across a lesion of a stenotic coronary artery and for performing test of passage for direct stenting in said stenotic coronary artery, said catheter comprising : a distal end and a proximal end; a bulleted structure located at said distal end for simulating a crimped stent and deflated balloon assembly, and a predetermined arrangement of at least 4 markers located at said distal end; said predetermined arrangement further comprising a first marker at said distal end, a second marker positioned 5 mm proximally from first marker, a third marker positioned 3 mm proximally from second marker, and a fourth marker positioned 10 mm proximally from third marker.

21. An intracoronary gauging catheter according to claim 20 wherein a fifth marker is positioned 10 mm proximally from the fourth marker.

22. An intracoronary gauging catheter according to claim 20 wherein said markers are made of a radio-opaque material.

23. An intracoronary gauging catheter according to claim 20 wherein said markers are 1 mm in width.

24. An intracoronary gauging catheter according to claim 20 wherein the position of said markers are measured from proximal end of one marker to proximal end of next marker or from distal end of one marker to distal end of next marker.

25. An intracoronary gauging catheter according to claim 21 wherein said predetermined arrangement of markers correlates in combination suitable stent length to a lesion in the following lengths : 8 mm, 13 mm, 14 mm, 18 mm, 23 mm, 24 mm and 28 mm.

26. An intracoronary gauging catheter according to claim 20 wherein said bulleted structure has a perfusion hole at the distal end, said perfusion hole for infusing of contrast medium.

27. An intracoronary gauging catheter according to claim 20 wherein said bulleted structure is 1.24 mm in diameter.

28. An intracoronary gauging catheter according to claim 20 wherein said bulleted structure is about 18mm in length.

29. An arrangement of at least 4 markers for easily determining the length and size of stents to be deployed in a stenotic blood vessel, said arrangement comprises : a first marker; a second marker positioned 5 mm proximally from first marker; a third marker positioned 3 mm proximally from second marker; and a fourth marker positioned 10 mm proximally from third marker.

30. An arrangement according to claim 29 wherein said markers are 1 mm in width.

31. An arrangement according to claim 29 wherein a fifth marker is positioned 10 mm from fourth marker.

32. An arrangement according to claim 29 wherein position of said markers are measured from proximal end of one marker to proximal end of next marker or from distal end of one marker to distal end of next marker.

33. An arrangement according to claim 31 wherein said arrangement of markers correlates in combination suitable stent length to a lesion in the the following lengths : 8 mm, 13 mm, 14 mm, 18 mm, 23 mm, 24 mm and 28 mm.