Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
1999-05-27
2001-06-05
Jaworski, Francis J. (Department: 3737)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C606S169000
Reexamination Certificate
active
06241703
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to medical devices and, more particularly, to an improved ultrasound probe and a method of using the improved ultrasound probe for treating conditions to such as stenotic or occlusive vascular disorders.
Stenotic or occluded arteries are commonly treated by using one or several methods, which include, balloon or laser angioplasty, atherectomy and bypass surgery. While these types of treatments have had some success, they each have undesirable side effects. For example, following a balloon angioplasty procedure, the stenosis often rebounds to again obstruct the s vessel; laser angioplasty and atherectomy procedures carry the risk of damaging the arterial structure; and bypass surgery is traumatic and requires a prolonged recovery period.
In recent years, a number of devices that use ultrasonic energy to ablate obstructive material from blood vessels have been described in U.S. patents, such as U.S. Pat. No. 4,870,953 (Don Michael), U.S. Pat. No. 4,920,954 (Alliger et al.), and U.S. Pat. No. 5,269,287 (Weng et al.), the contents of which are incorporated herein by reference. In general, ultrasound transmitting devices have been reasonably successful when used to ablate obstructions located in peripheral blood vessels, such as the femoral artery. However, conventional ultrasound devices have been shown not to be fully satisfactory. For example, in applications within smaller blood vessels, such as the distal sections of coronary arteries, successful applications have been harder to achieve in practice due in part to the more tortuous paths and smaller vessel diameters involved.
While a number of devices that use ultrasonic energy to ablate obstructive material from blood vessels have been described in recent years, very little has been written about methods of using such devices. One method of ablating material from blood vessels by using heat is disclosed in U.S. Pat. No. 4,773,413 (Hussein et al.), which is hereby incorporated by reference. A second U.S. patent, U.S. Pat. No. 5,324,255 (Passafaro et al.), describes a method of using ultrasound to treat vasospasm, the content of which is incorporated herein by reference. However, little has been written on a method of using ultrasound devices, apparently due to a general lack of success in providing a safe, effective ultrasonic device capable of ablating clots.
Accordingly, it is desirable to provide an improved device and method for the treatment of stenotic or occluded arteries and the like which overcomes shortcomings of the prior art.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, an ultrasonic treatment system and method for utilizing ultrasound to treat stenotic and occluded regions of blood vessels and artificial vessels, such as grafts or shunts used by dialysis patients, are provided. The ultrasonic treatment system includes an ultrasonic probe, having a proximal and distal end, and an ultrasonic energy source. The distal end vibrates at ultrasonic frequencies at the treatment site when the energy source is applied to the proximal end. The amplitude of vibration is herein also referred to as displacement. A guide catheter may be provided, and the probe may be slidably disposed within the guide catheter. A guidewire may be provided and the probe may be slidably disposed over the guidewire. The probe may include a horn at the proximal end, a transmission member with a proximal and a distal end connected to the horn at the transmission member's proximal end, and a distal tip at the transmission member's distal end. The transmission member may include one or more co-axial transmission wires, having proximal and distal ends, connected serially.
One section of the transmission member may be formed with multiple transmission wires arranged in parallel. The diameter or cross-sectional area of the proximal end of each successive transmission wire, moving toward the distal end of the probe, whether the transmission wires are in series or in parallel, may be less than the cross-sectional area of the distal end of the preceding transmission wire.
The diameter or cross-sectional area of the proximal end of the initial transmission wire may be less than the diameter or cross-sectional area of the distal end of the horn. In accordance with the foregoing elements, a step-down in cross-sectional area can occur at the transition between the horn and the first transmission wire, successive transmission wires and elsewhere in the probe. Some or all of the step transitions should be located at or near displacement nodes (minima) in order to effect maximum displacement amplification and maximize the delivery of ultrasound energy to the distal working end of the device. Each step transition that is located at or near a displacement node is consequently located at or near a stress maximum. Therefore, this invention reaps the benefit gained from high displacement amplification at each step transition located at or near a displacement node because the design withstands the high stresses at these transitions.
It will be understood by those experienced in the art that both the frequency and wavelengths of resonance (or anti-resonance) of the probe and the associated standing wave developed along the probe may shift depending upon the tortuosity of the blood vessels to be treated. Thus, the various nodal and anti-nodal portions of the standing wave may shift as a probe is advanced, retracted, and manipulated in a blood vessel. It will be understood that the probe is designed in accordance with an average frequency and an average standing wave. More particularly, the placement of the standing wave nodes and anti-nodes relative to the structural elements of the probe are referenced herein to the average geometric conditions or tortuosity of the treatment application.
It is an advantage of this invention that the placement of one or more step transitions at or near displacement nodes will tend to reduce the probe's sensitivity to tortuosity, especially when the step transitions are located proximal of the most tortuous sections. Therefore, in accordance with another aspect of this invention, those step transitions which are placed at or near displacement nodes can be used to effectively reduce the probe's sensitivity to tortuosity.
It will be understood that the techniques for assembling the sections of this invention are equally applicable to systems that promote or focus ultrasound energy to enhance the absorption of drugs, induce apoptosis in cells, and/or treat tissue, tumors, obstructions, and the like, within and without the body, and in systems to be utilized for laproscopic surgery, for ultrasonic scalpels, and to induce tissue hyperthermia for cancer radiation therapy, for example.
Furthermore, it will be understood that while several examples given herein refer to intravascular applications of the invention employing guide catheters, introducer sheaths, guidewires, and the like, the invention is equally applicable to topical or superficial treatments, therapies administered in cavities of the body, intramuscular and intra-tissue treatments, including the application of ultrasound to fatty deposits to assist in their removal, the use of ultrasound to enhance healing, or to stimulate or suppress the functioning of bodily organs.
In accordance with another aspect of this invention, some or all of the step transitions are fashioned as joints wherein the same or different materials, selected for their particular advantageous properties, are joined to form the step transition. For example, an aluminum wire of a thick diameter may be joined to a higher strength titanium wire of a smaller diameter.
In accordance with another aspect of this invention, each step transition, which is fashioned as a joint, is designed as a high strength coupling. For example, a crimp joint may be used with enhanced strength by roughening the surface of one or all of the joining members.
In accordance with another aspect of this invention, there is provided a
Levin Philip S.
Nguyen Loi
Saltonstall Jon
Taylor Warren
Angiosonics Inc.
Cowan Liebowitz & Latman P.C.
Dippert William H.
Jaworski Francis J.
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