Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
1999-12-30
2003-01-21
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C600S467000
Reexamination Certificate
active
06508781
ABSTRACT:
BACKGROUND
The invention relates generally to medical devices, and more particularly to an improved connector assembly for connecting an ultrasound transmission member to an ultrasound transducer for use in an ultrasonic angioplasty catheter.
In typical percutaneous transluminal coronary angioplasty (“PTCA”) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced therein until the distal tip is in the ostium of the desired coronary artery. A guide wire and a dilatation catheter having a balloon on the distal end are introduced through the guiding catheter with the guide wire slidably disposed within an inner lumen of the dilatation catheter. The guide wire is first advanced into the patient's coronary vasculature until its distal end crosses the lesion to be dilated and then the dilatation catheter is advanced over the previously introduced guide wire until the dilatation balloon is properly positioned across the lesion. The balloon may then be inflated to treat the lesion. Thereafter, a stent device may be located at the treated lesion, if deemed necessary.
In “ultrasonic” angioplasty, an ultrasonic angioplasty catheter is similarly advanced to an area of vascular blockage, and mechanical vibration at ultrasonic frequencies, generated typically by a piezoceramic transducer, is delivered along an elongated ultrasonic angioplasty transmission member or wire to a distal catheter tip. When the distal catheter tip is abutted against intravascular blockage, the vibration of the distal end of the ultrasonic angioplasty transmission member removes the obstruction by mechanical impact and cavitation.
Ultrasonic angioplasty transmission members are commonly connected to an extra-corporeal source of ultrasonic energy, so that it is generally necessary to deliver the ultrasonic energy over a relatively long distance, such as approximately 150 cm., to the intravascular blockage to be treated. Over such a distance, the ultrasonic energy attenuates as it passes along the length of the ultrasonic angioplasty transmission member, resulting in a loss of system efficiency, and requiring the delivery of a greater amount of acoustic energy to the ultrasonic angioplasty transmission member than actually reaches the treatment site, which can increase fatigue of the ultrasonic angioplasty transmission member and thereby increase the chances of fracturing and breakage during use, especially when the wires are bent. It is therefore desirable to provide an ultrasonic angioplasty transmission member mounting that has a lower loss of the ultrasonic energy so that lower levels of energy may be applied to the member.
Amplification of the ultrasonic vibrations typically occurs at areas of reduced cross-sectional diameter. Regions where the highest amplification occurs are generally located where the transition to a reduced diameter occurs, at the proximal end of a smaller diameter section where transverse vibration of ultrasonic energy transmitted from a larger section is amplified. These areas are prone to higher stresses due to increased longitudinal and transverse vibration as a result of amplification. One such area is a connection point of the ultrasound transmission member to the ultrasonic transducer. There typically exists a significant step down resulting in amplification. Firmly connecting the member to the transducer will result in fewer inefficiencies.
Accurate positioning of the ultrasonic angioplasty catheter and ultrasound transmission member in the vascular system to be treated is important for the successful application of ultrasonic energy to an intravascular blockage. It is therefore desirable that the ultrasound transmission wire and ultrasound transducer be firmly aligned with the catheter. It is important that as few losses as possible occur between the application of ultrasonic energy to the ultrasonic wire at its proximal end by the ultrasound transducer and the application of that ultrasonic energy at its distal end to the vascular blockage. The ultrasonic angioplasty transmission member should not rotate independently of the rest of the catheter due to transverse or longitudinal vibrations. Rotation of the wire inside the catheter dampens the transmission of ultrasonic energy through the wire resulting in a less efficient energy transfer. Firmly mounting the wire in place will increase the efficiency in that less energy is absorbed by the wire.
Since the connection point of an ultrasonic transducer to the ultrasound transmission wire is the region where the greatest amplification of ultrasonic energy occurs due to the large reduction in diameter, it is possible for the ultrasonic angioplasty transmission member to rotate independently of the rest of the catheter due to transverse or longitudinal vibrations during use. Such rotation can interfere with the accurate positioning of an ultrasonic angioplasty catheter and the included ultrasound transmission member in the vascular system. While conventional connector assemblies are known that firmly grip and hold the ultrasound transmission member in relation to the ultrasound transducer, they can permit rotation of the ultrasound transmission member and connector assembly relative to the ultrasonic angioplasty catheter during use.
An ultrasound catheter having an ultrasound transmission member or wire and a proximal end member connector assembly is known from U.S. Pat. No. 5,382,228 to Nita et al. The proximal end member connector assembly of U.S. Pat. No. 5,382,228 can include a compressible gripping ferrule, compressible plugs, or a combination of both, for securing the ultrasound transmission member or wire to an ultrasound transducer. The compressible gripping ferrule is received in a proximal connector member threadedly connected to a transducer horn, and has a small aperture through which the ultrasound transmission member passes. A frontal member compresses the gripping ferrule to cause the gripping ferrule to firmly grip and hold the ultrasound transmission member to the transducer. The proximal connector member can then be compressed or crimped inwardly to additionally hold the ultrasound transmission member. Although the '228 patent represents an advance in the art, such a connector assembly can permit rotation of the ultrasound transmission member and connector assembly relative to the ultrasonic angioplasty catheter, particularly under the stress of longitudinal and transverse vibrations during use.
Hence, those skilled in the art have recognized a need for an improved connector assembly to more efficiently transfer ultrasonic energy to an ultrasound transmission member to lessen inefficiencies. Further, those skilled in the art have recognized a need for a mounting system that keeps the connector assembly and the ultrasound transmission member from rotating independently relative to the ultrasonic angioplasty catheter. The present invention fulfills this need and others.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention is directed to an improved connector assembly for connecting an ultrasound transducer and an ultrasound transmission member of an ultrasonic angioplasty catheter. Further it is directed to an improved device to prevent the connector assembly and ultrasound transmission member from rotating independently relative to the ultrasonic angioplasty catheter.
In one aspect, there is provided an ultrasonic angioplasty device for connection to an ultrasound transducer, the ultrasonic angioplasty device comprising an elongated catheter body having a lumen extending longitudinally therethrough, the catheter body having a proximal end and a distal end, an ultrasound transmission member located in the lumen of the catheter body and having a distal end for applying ultrasonic energy to a biological subject, and having a proximal end, a connector assembly configured to connect the proximal end of the ultrasound transmission member to an ultrasound transduc
Brennan Lawrence
Cornish Wayne E.
Gesswein Douglas H.
Tran Martinos
Advanced Cardiovascular Systems Inc.
Casler Brian L.
Fulwider Patton Lee & Utecht LLP
Han Mark
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