Metal working – Method of mechanical manufacture – Utilizing transitory attached element or associated separate...
Reexamination Certificate
2000-06-20
2001-10-02
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Utilizing transitory attached element or associated separate...
C140S092100, C156S155000, C156S175000, C156S189000
Reexamination Certificate
active
06295712
ABSTRACT:
TECHNICAL FIELD
The invention relates to devices and methods for removing tissue from body passageways, such as removal of atherosclerotic plaque from arteries, utilizing a rotational atherectomy device.
BACKGROUND OF THE INVENTION
A variety of techniques and instruments have been developed for use in the removal or repair of tissue in arteries and similar body passageways. A frequent objective of such techniques and instruments is the removal of atherosclerotic plaques in a patient's arteries. Atherosclerosis is characterized by the buildup of fatty deposits (atheromas) in the intimal layer (under the endothelium) of a patient's blood vessels. Very often over time, what initially is deposited as relatively soft, cholesterol-rich atheromatous material hardens into a calcified atherosclerotic plaque. Such atheromas restrict the flow of blood, and therefore often are referred to as stenotic lesions or stenoses, the blocking material being referred to as stenotic material. If left untreated, such stenoses can cause angina, hypertension, myocardial infarction, strokes and the like.
Several kinds of atherectomy devices have been developed for attempting to remove some or all of such stenotic material. In one type of device, such as that shown in U.S. Pat. No. 4,990,134 (Auth), a rotating burr covered with an abrasive cutting material such as diamond grit (diamond particles or dust) is carried at the distal end of a flexible drive shaft. The rotating burr is rigid and inflexible, however, making navigation around tight bends or curves in an artery more difficult, and making the removal of stenotic lesions in such bends or curves equally difficult.
U.S. Pat. No. 5,314,438 (Shturman) shows another atherectomy device having a drive shaft with a section of the drive shaft having an enlarged diameter, at least a segment of this enlarged diameter section being covered with an abrasive material to define an abrasive segment of the drive shaft. When rotated at high speeds, the abrasive segment is capable of removing stenotic tissue from an artery. In some of the embodiments depicted in the Shturman patent, wire turns of the enlarged diameter segment of the drive shaft are supported by a bushing. Even though this bushing may be made of a flexible material, nevertheless it decreases somewhat the flexibility of the enlarged diameter abrasive segment of the drive shaft.
Unless a bushing within the enlarged diameter section is utilized, Applicants have found that adjacent wire strands of this section can fall out of alignment with one another when the enlarged diameter portion of the drive shaft is bent around a curve of a relatively small radius.
SUMMARY OF THE INVENTION
The invention provides an atherectomy device comprised of a flexible, elongated drive shaft having an enlarged diameter tissue removal section which retains substantial flexibility while reducing the tendency of the wire turns to fall out of alignment with one another. The tissue removal section of the drive shaft of this atherectomy device includes proximal and distal portions comprised of helically wound wire, wire turns of the proximal portion of the tissue removal section having diameters that progressively increase distally at a generally constant rate thereby forming generally the shape of a cone. Wire turns of the distal portion of the enlarged diameter tissue removal section have diameters that gradually decrease distally thereby forming a generally convex distal portion.
The conical shape of the proximal portion of the tissue removal section substantially reduces the tendency of the wire turns to fall out of alignment with one another, without the need to utilize a bushing, thereby preserving substantial flexibility in the enlarged diameter section.
At least part of the tissue removal section includes an external coating of an abrasive material, secured to the wire turns of the drive shaft by a suitable binder, to define an abrasive segment of the drive shaft. Preferably the binder also secures some of the adjacent wire turns of the tissue removal section to one another, most preferably throughout a distal portion of the tissue removal section.
In a preferred embodiment, the drive shaft of the atherectomy device includes a reduced diameter segment, such segment being located near the tissue removal section of the drive shaft to function as a bearing for rotation of the drive shaft about a guide wire. The reduced clearance between the guide wire and the inner surface of the reduced diameter segment is less than in other portions of the drive shaft and is intended to reduce vibrations of the tissue removal section and facilitate smooth rotation of the drive shaft and its tissue removal section about the guide wire when the atherectomy device is rotated at high speeds. Two or more of such reduced diameter segments may be included, preferably at least one being located distally of the tissue removal section of the drive shaft, and at least one being located proximally of the tissue removal section of the drive shaft. Preferably such reduced diameter segments are located within about one inch from the enlarged diameter tissue removal section, and most preferably within about a quarter inch from such tissue removal section.
The maximum outer diameter and length of the abrasive segment of the enlarged diameter tissue removal section may be selected so that, at operational rotational speeds and under load, at least some of the wire turns of the proximal portion of the enlarged diameter tissue removal section unwind from their at-rest diameter to an effective outer diameter which is the same as or larger than the maximum outer diameter of the abrasive segment.
The drive shaft of the atherectomy device may include a distal end segment having an outer diameter which decreases distally to define a generally convex outer surface. At least a portion of this distal end segment may be provided with an external coating of an abrasive material to define a second abrasive segment at the very distal end of the drive shaft. Such an abrasive coated distal end segment facilitates passage of the rotating drive shaft of the atherectomy device across even very tight stenoses.
REFERENCES:
patent: 96020 (1869-10-01), Lyons
patent: 829801 (1906-08-01), Pratt et al.
patent: 1976522 (1934-10-01), Rose, Jr.
patent: 3110098 (1963-11-01), Sobrierajski
patent: 3146576 (1964-09-01), Wezel
patent: 3389872 (1968-06-01), Medney
patent: 3706624 (1972-12-01), Rinker
patent: 3793706 (1974-02-01), Dohlen et al.
patent: 4990134 (1991-02-01), Auth
patent: 5158564 (1992-10-01), Schnepp-Pesch et al.
patent: 5172568 (1992-12-01), Senanayake
patent: 5192291 (1993-03-01), Pannek, Jr.
patent: 5217474 (1993-06-01), Zacca et al.
patent: 5308354 (1994-05-01), Zacca et al.
patent: 5314438 (1994-05-01), Shturman et al.
patent: 5358485 (1994-10-01), Vance et al.
patent: 5395311 (1995-03-01), Andrews
patent: 5490859 (1996-02-01), Mische et al.
patent: 5681336 (1997-10-01), Clement et al.
patent: 5766192 (1998-06-01), Zacca
patent: 5772864 (1998-06-01), Moller et al.
patent: 6132444 (2000-10-01), Shturman et al.
patent: 2055991 (1996-03-01), None
Nevzorov Andrei
Shturman Leonid
Bryant David P.
Compton Eric
Perman & Green LLP
Shturman Cardiology Systems, Inc.
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