Surgery – Instruments – Blood vessel – duct or teat cutter – scrapper or abrader
Reexamination Certificate
1999-10-01
2001-04-24
Recla, Henry J. (Department: 3731)
Surgery
Instruments
Blood vessel, duct or teat cutter, scrapper or abrader
C606S180000
Reexamination Certificate
active
06221087
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus for ablating unwanted material from a patient's vasculature.
BACKGROUND OF THE INVENTION
Vascular diseases, such as atherosclerosis and the like, have become quite prevalent in the modern day. These diseases may manifest themselves in a number of ways, often requiring different forms or methods of treatment for curing the adverse effects of the diseases. For example, vascular diseases may take the form of deposits or growths in a patient's vasculature which may restrict, in the case of a partial occlusion, or, stop, in the case of a total occlusion, blood flow to a certain portion of the patient's body. This can be particularly serious if, for example, such an occlusion occurs in a portion of the vasculature that supplies vital organs with blood or other necessary fluids.
To treat these diseases, a number of different therapies have been developed. For example, treatment devices have been developed that remove the material occluding a vascular lumen. Such treatment devices, sometimes referred to as atherectomy devices or ablation devices, use a variety of material removal means, such as rotating cutters or ablaters for example, to remove the occluding material. (The term “atherectomy device” as used in the specification refers to ablation devices for use in any portion of a patient's vasculature. Thus, while the atherectomy devices provided in accordance with preferred embodiments of the present invention are well suited for use in the coronary arteries, their use is not limited to the coronary arteries.) The material removal device, such as a rotatable burr, is typically rotated via a driveshaft that extends out of the vasculature of the patient and to an electric motor.
In operation, an ablation device is typically advanced over a guide wire placed in vivo until the material removal device is positioned just proximal to the occluded site. The motor is used to rotate the driveshaft and the material removal device, and the material removal device is moved through the occluded vessel. The material removal device removes the material from the vessel, rather than merely displacing or reforming the material as in a balloon angioplasty procedure.
Although such types of ablation devices provide desirable results, it is sometimes difficult to operate them strictly within preferred operating parameters. For example, it is desirable to only operate the material removal device while it is in contact with the lesion to be ablated. However, with conventional systems, once the ablation device works through a distal end of the lesion, the sudden lack of resistance causes the ablation device to dart forward. Such darting may result in unwanted ablation of a vessel wall, and is typically accompanied by an undesirably large rpm drop. More particularly, when in use, a material removal device, such as a rotatable burr, is spun at approximately 180,000 rpm. When the burr engages the lesion or unwanted deposits, the ablation process causes a drop of approximately 5,000 rpm. It is desirable to maintain a consistent rpm drop of approximately 5,000 during ablation of the lesion. If an excessive rpm drop occurs, it is typically accompanied by increased torque and an undesirable increase in heat, as well as an increase in quantity and size of particles generated by the ablation. Furthermore, if the ablation device darts forward far enough, it may engage a spring tip located at a distal end of a guide wire. The friction caused by the rotating ablation device may generate sufficient heat to weld the burr to the spring tip of the guide wire.
Given the considerations discussed above, it would be desirable to provide an ablation device that is easier to operate within selected parameters. The present invention fulfills this need, and provides further related advantages.
SUMMARY OF THE INVENTION
Briefly, the present invention provides an improved ablation assembly that is easier to operate within desirable operating parameters than conventional systems. In a preferred embodiment, the ablation assembly includes an advancer mechanism coupled to an ablation device, such as a rotatable burr. The advancer mechanism is moveable along a longitudinal path of motion to advance the ablation device from a first position adjacent a proximal end of a lesion to be ablated forward through the lesion.
In a preferred embodiment, the ablation assembly includes a rotatable burr coupled to a distal end of a driveshaft. A proximal end of the driveshaft is coupled to a drive assembly positioned within an advancer housing. The drive assembly is moveable from a first, retracted position, forward along a longitudinal path of motion. The coupling of the drive assembly to the driveshaft causes the burr to advance through a vessel lumen of a patient as the drive assembly is moved forward along its path of motion. A stop device is coupled to the housing, and is moveable from a first position to a second selected position along a path of motion that is parallel to the longitudinal path of motion of the drive assembly. The stop is securable to the housing at the second selected position. Furthermore, the stop has a flange that extends into the longitudinal path of motion of the drive assembly to a sufficient degree, such that as the drive assembly is moved forward, it contacts the flange, thereby stopping the forward motion of the drive assembly and associated burr.
Prior to performing an ablation procedure, the length of the lesion to be ablated is measured, for example, through the use of fluoroscopy, or any other procedure known in the art. A stop that extends into the longitudinal path of motion of the drive assembly or other advancer mechanism is secured at a location that is spaced forward from the starting position of the advancer mechanism by a length equal to the length of the lesion. As such, as the advancer mechanism is moved forward along the longitudinal path of motion, thereby advancing the burr through the lesion, the advancer mechanism moves a distance equal to the length of the lesion and hits the stop, which prevents further forward motion of the advancer mechanism. The burr coupled to the advancer mechanism moves a corresponding distance equal to the length of the lesion, which allows the cardiologist or other operator to cease operation of the device as soon as the burr clears the distal end of the lesion.
Alternatively, in a preferred embodiment, the stop is secured forward of the starting point of the advancer mechanism by a distance that is less than the length of the lesion by a small amount, such that when the advancer mechanism hits the stop, the operator knows that the burr is approaching the end of the lesion. It is then possible to release the stop, and slowly move the burr forward through the remainder of the lesion. By advancing through the end of the lesion at a slower rate than that used to proceed through the initial part of the lesion, the size of the rpm drop is reduced, and the unwanted effects associated with darting of the burr are minimized.
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Anderson David M.
Barry Robert L.
Christensen O'Connor Johnson & Kindness PLLC
Ngo Lien
Recla Henry J.
Sci-Med Life Systems, Inc.
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