A minimally invasive medical device

Abstract: A minimally invasive intravascular medical device (10) for providing a radiation treatment in a body passageway such as a coronary vessel of the vascular system. The device (10) includes a flexible elongated member (11) having distal (14) and proximal (13) portions. The distal portion (14) is percutaneously insertable into a vessel and includes a distal end (15) that is directable through the vessel to the treatment site. A radiation source (12) is attached about the distal portion (14) for delivering a radiation treatment to the walls a vessel having a stent positioned thereagainst. The distal portion of the elongated member includes a wire coil (16) positioned about the tapered distal end (22) of a mandril wire (21). The combination of the wire coil (16) and the tapered distal end (22) of the mandril wire (21) provides variable flexibility to the distal portion (14) of the device. The distal portion (14) also has a predetermined curvature for directing the distal end (15) of the device (10) through the vessel. A safety wire is also extendable through the passageway of the wire coil to provide further flexibility to the distal portion. The radiation source is fixedly positioned about either the tapered distal end of the mandril wire or the safety wire in the passageway of the wire coil. An annular recess is included about the tapered distal end of the mandril wire to fixedly position a source of radioactive material therein.

Description: This invention relates to minimally invasive medical devices such as wire guides or catheters. In addition to balloon, angioplasty or laser ablation a coronary stent can be positioned in a treated vessel to maintain the patency of the vessel. However, one problem is that smooth muscle proliferates or intimal hyperplasia occurs in response to the presence of the stent in the vessel. As a result, restenosis of the vessel typically occurs within a period of six months. Another problem is that abrasion or dissection of the vessel wall may occur during a therapeutic procedure to reopen or enlarge the lumen of the vessel. As a result, thrombi formation and occlusion of the vessel lumen may also occur. These problems apply to parts of the vascular system other than coronary vessels, such as the occlusion of the femoral or iliac vessels. FR-A-2348715 describes a medical device as described in the preamble of claim 1. According to the invention there is provided a device as claimed in claim 1. Preferred features of the invention are set out in the dependent claims. The device can provide localized radiation treatment in a body passageway such as a coronary vessel in the vascular system. That decreases reproduction of intimal and smooth muscle cells to prevent or curtail intimal hyperplasia and smooth muscle proliferation. Advantageously, restenosis of the treated vessel is significantly minimized. The distal portion preferably has a distal end that is directable through the tortuous segments of coronary vessels. Brief Description of the Drawing FIG. 1 depicts the minimally invasive medical device of the present invention; FIG. 2 depicts an enlarged view of the distal portion of the medical device of FIG. 1; FIG. 3 depicts an alternative enhancement to the minimally invasive medical device of FIG. 1; FIG. 4 depicts a second alternative enhancement to the minimally invasive medical device of FIG. 1; and FIG. 5 depicts an enhancement to the distal portion of the medical device of FIG.1. Detailed description Depicted in Fig.1 is preferred embodiment of an illustrative minimally invasive medical device 10, such as a wire guide, for providing a radiation treatment in part of a body such as a passageway thereof. This minimally invasive medical device has particular application as a percutaneously inserted intravascular device for providing a radiation treatment to the area of a coronary vessel having, for example, a stent positioned therein. Device 10 comprises flexible elongated member 11 and radiation source 12. Flexible elongated member 11 includes proximal portion 13 and distal portion 14. The distal portion is insertable in a body passageway such as a coronary artery of the vascular system and has a distal end 15 that is directable through the vascular system to the treatment site. Radiation source 12 comprises commercially available iridium radioactive material attached about or within distal portion 14 as shown. Distal portion 14 includes wire coil 16 of commercially available 0.01cm (0.004") diameter stainless steel wire that is wound into a coil having an outside diameter of approximately 0.046cm (0.0183") to 0.048cm (0.019") and a length of approximately 6 to 9cm. Distal portion 14 has a predetermined longitudinal curvature such as approximately 90° longitudinal curvature 17 that extends for about 15mm from distal end 15. As a result, distal end 15 is directable through the body passageway. Wire coil 16 includes distal end 18, proximal end 19, and passageway 20 extending longitudinally therebetween. Flexible elongated member 11 comprises a stainless steel mandril wire 21 having a uniform diameter of 0.046cm (0.018") about the proximal portion 13. This uniform diameter is within a tolerance of -0.0038cm (-0.0015") of the wire coil diameter. Mandril wire 21 is approximately 40cm in length and has a longitudinally tapered distal end 22 for a length of approximately 15cm. Tapered distal end 22 of the mandril wire is inserted through passageway 20 and attached to distal coil end 18 in a well-known manner by, for example, weld 24. Proximal coil end 19 is attached to tapered distal end 22 in a well-known manner using, for example, soft solder 25. Flexible elongated member 11, known as a "Cope Mandril" (Registered Trade Mark) wire guide, is commercially available from Cook Incorporated, Bloomington, Indiana. Tapered distal end 22 also includes an annular recess 23 circumferentially positioned thereabout approximately 10mm from directable distal end 15. Radiation source 12 comprising a ring of commercially available iridium radioactive material is fixedly positioned in annular recess 23 for providing the radiation treatment. FIG.2 depicts an enlarged view of annular recess 23 and radiation source 12 fixedly positioned therein. Depicted in FIG.5 is distal portion 66 of a minimally invasive medical device which includes an enhancement to the device of FIG.1. Distal portion 66 includes proximal wire coil 68 and distal wire coil 69 having respective longitudinally extending passageways 70 and 71. The elongated flexible member of the device includes a mandril wire having tapered distal end 72. The tapered distal end of the mandril wire extends longitudinally through the wire coil passageways. The distal ends of the mandril wire and distal wire coil 69 are attached together using, for example, weld 76. This forms directable end 67 of distal portion 66 of the minimally Invasive medical device. The medical device also includes radiation source 73 which is a tubular sleeve of commercially available iridium radioactive material positioned about tapered distal end 72 of a mandril wire and between proximal wire coil 68 and distal wire coil 69. Wire coils 68 and 69 are wound from commercially available 0.01cm (0.004") stainless steel wire into coils having an outside diameter of approximately 0.046cm (0.0183") to 0.048cm (0.019"). The tubular sleeve has an outside diameter approximating that of the wire coils. Proximal wire coil 68 is positioned over the tapered distal end of the mandril wire with the proximal end of the coil being affixed thereto with, for example, soft solder. Tubular sleeve radiation source 73 is positioned about the tapered distal end of the mandril wire next to the distal end of proximal wire coil 68. The abutting ends of the proximal wire coil and tubular sleeve are affixed to tapered distal end 72 of the mandril wire using, for example, soft solder 74. Distal wire coil 69 is positioned about the tapered distal end of the mandril wire abutting the proximal end of the tubular sleeve radiation source. The abutting ends of the distal wire coil and tubular sleeve are affixed to tapered distal end 72 of the mandril wire using, for example, soft solder 75. Depicted in FIG.3 is minimally invasive medical device 26 which includes an alternative enhancement to the minimally invasive device of FIG.1. Medical device 26 includes flexible elongated member 27 and radiation source 28. The flexible elongated member includes proximal portion 29 and distal portion 30. Distal portion 30 has longitudinal curvature 43 and directable distal end 44. With this enhancement, mandril wire 31 has distal end 32 that is tapered a shorter distance of, for example, 7cms and extends only partially through wire coil passageway 33 of wire coil 34. Wire coil 34 has proximal end 40, distal end 41, and passageway 33 extending longitudinally therebetween. The proximal end of the coil is attached to tapered distal end 32 in a well-known manner using, for example, soft solder 42. A safety second wire 35 of, for example, 0.0076cm (0.003") by 0.02cm (0.008") rectangular stainless steel having proximal end 36 and distal end 37 is inserted into passageway 33 of wire coil 34. The distal ends of the safety wire and wire coil are attached in a well-known manner using, for example, weld 38. Proximal end 36 of the safety wire extends through passageway 33 to tapered distal end 32 of mandril wire 31. Tapered distal end 32 and proximal safety wire end 36 are attached to wire coil 34 in a well-known manner using, for example, soft solder 39, as shown. Radiation source 28 comprising, for example, a sleeve of iridium radioactive material, is fixedly positioned about tapered distal end 32 in wire coil passageway 33 proximal to solder joint 39. Depicted in FIG.4 is minimally invasive medical device 45 which is a second alternative enhancement to the device of FIG.1. Similar to the enhancement depicted in FIG.3, mandril wire 46 having distal end 47 is tapered a distance of, for example, 7cm, and extends only partially into passageway 48 of wire coil 49. However, safety second wire 50 having proximal end 51 and distal end 52 extends approximately the entire length of wire coil passageway 48. Distal safety wire end 52 is attached to distal coil end 53 in a well-known manner using, for example, weld 54. Proximal safety wire end 51 and tapered distal wire end 47 are attached to proximal wire coil end 55 in a well-known manner using, for example, soft solder 56. Radiation source 57 comprising, for example, a sleeve of iridium radioactive material, is fixedly positioned about safety second wire 50 in wire coil passageway 48 a predetermined distance, for example, 5mm from distal wire end 52 to permit controlled radiation of the affected area. This advantageously provides the distal portion with variable flexibility for atraumatic insertion of the device. The proximal portion of the cylindrical first wire has a uniform diameter. The outer diameter of the distal portion wire coil and the proximal portion of the first wire are within a close tolerance of each other to minimize trauma and abrasion to the vessel wall during insertion to the affected vessel site. It is to be understood that the above-described minimally invasive intravascular medical device for providing a radiation treatment in a body passageway is merely an illustrative embodiment of this invention and that alternative medical devices may be devised by those skilled in the art. In particular, it is contemplated that many commercially available wire guides and catheters may be modified to a medical device according to the invention for providing a radiation treatment to a body passageway and, in particular, preventing intimal hyperplasia and smooth muscle proliferation which causes stenosis or restenosis of the passageway. Although described as being particularly applicable to the vascular system using well-known percutaneous insertion techniques, it is contemplated that the minimally invasive medical device is applicable for providing treatment to the pulmonary system as well as the gastrointestinal tract. Treatment of the biliary and urinary system are also contemplated with medical devices according to the invention for treating the particular anatomical system.

Claims: A medical device (10,26,45) for insertion in a minimally invasive manner into a patient's body, said device comprising a flexible elongated member (11,27) having a proximal portion (13,29), and a distal portion (14,30) including a wire coil (16,34,49) having a distal end (18,41,53), a proximal end (19,40,55) and a passageway (20,33,48) extending longitudinally therebetween; at least one radiation source (12,28,57) supported by the said distal portion; characterised in that the elongated member further has a mandril wire (21,31,46) having a tapered distal end (22,32,47) which extends longitudinally in the passageway and is attached to the wire coil (16,34,49). A device according to claim 1, wherein the tapered distal end (22) extends along the passageway (20) between the proximal and distal ends (19,18) of the wire coil (16), and wherein the radiation source (12) is attached to the tapered distal end (22). A device according to claim 2, wherein the said tapered distal end (22) includes an annular recess (23) within which the radiation source (12) is fixed. A device according to claim 1, wherein the said tapered distal end (32,47) extends from the proximal end (40,55) of the wire coil (34,49) into the passageway (33,48) and terminates therein without contacting the distal end (41,53) of the coil, and wherein a second wire (35,50) extends either between the termination of the said tapered distal end (32,47) and the distal end (41) of the coil (34) or between the proximal end (55) of the coil (49) and the distal end (53) thereof. A device according to claim 4, wherein the second wire (35) is attached at both ends (36,37) to the wire coil (34). A device according to claim 4 or 5, wherein the radiation source (57) is attached to the second wire (50). A device according to any of claims 1 to 6, wherein the radiation source (12,57) is located adjacent to the distal end (18,53) of the coil (16,49). A device according to claim 1 or 2, wherein the wire coil (16,34,49) has a first predetermined outer diameter and wherein the proximal portion of said mandril wire (21,31,46) has a second predetermined outer diameter within a predetermined tolerance of said first outer diameter.

Inventors: FEARNOT NEAL EDWARD, ROUBIN GARETH SIDNEY SAMUEL, FEARNOT, NEAL EDWARD, ROUBIN, GARETH SIDNEY SAMUEL
Applicants: MED INST INC, MED INSTITUTE, INC.
Application year: 1992
Main classification: A61N5
IPC codes: A61M36, A61B17, A61M25, A61N5