Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-01-11
2001-09-04
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S467000
Reexamination Certificate
active
06283921
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to ultrasonic visualisation and catheters therefor.
The present invention relates generally to the field of ultrasonic imaging intravascular ultrasound imaging or IVUS in transluminal coronary angioplasty known as PCTA.
In a previously proposed 5 French IVUS device having an annular array of piezo-electronic transducers at its distal end, the array which could comprise sixty-four transducer elements is about 1.6 mm in diameter. In this arrangement the transducer elements were excited in pairs thus necessitating thirty two interconnections and given the size of the catheter outer body, it was possible to route four eight-way ribbon cables within it.
When designing such a catheter with dimensions less than 5 French problems relating to the greatly reduced diameter and thus available space for interconnections are encountered. Excitation signals from an external separate apparatus are routed through a small number of interconnections (for example ten) to individual transducer elements through the use of flip-chip-bonded multiplexers positioned at the distal end of the catheter and proximally to the transducer array. A method of manufacturing the transducer array and associated multiplexers is disclosed in our copending published UK Patent Application No. 2.287,375 in which the assembly is first formed in the flat and then wrapped into a substantially cylindrical configuration. More particularly, the flat assembly comprises the transducer array, the multiplexer chips, electrically conducting multiplexer chips, electrically conducting leads and a suitable matching layer. The use of the multiplexer chips which act as electronic switches permits the use of fewer interconnections which can thus fit into a smaller lumen. In conventional PCTA an incision is made in the femoral region of the patient's leg to introduce a mid-length sheath having a diameter of typically 8 French or 2.66 mm into the femoral artery. A much thinner guide wire (typically 0.014 inches or 0.356 mm diameter) is then introduced via the resulting opening and is manually guided right up to the exact location of the affected region. The affected regions of the coronary arteries follow a tortuous route and the cardiologist relies upon the rigidity of this wire to guide it into place.
Once the end of the guide wire arrives at the required location it is kept firmly in place and in current PCTA/IVUS applications the cardiologist next has to go through an involved procedure of inserting further guide catheters, or sheath catheters prior to finally introducing the IVUS or other treatment catheter.
Keeping the guide wire firmly fixed, a guide catheter of similar dimensions to the mid-length sheath is then inserted over the guide wire, the mid-length sheath still being in place and manually guided through the opening of the aorta stopping a short distance into the coronary artery. There are various versions of guide catheters which usually have the distal ends gently curved or looped depending upon their ultimate destination within the artery system. Contrast opaque dye is then pumped through the guide catheter to flush through the aortic system rendering the cardiac vessels visible on the fluoroscope monitor to enable the cardiologist to visualise the situation.
The device catheter has a central lumen whose diameter is slightly larger (typically 0.017 inches or 0.43 mm) than that of the guide wire. This time, keeping the guide-wire/guide-catheter assembly firmly in place, the device catheter is fed over the guide wire and is simply pushed up the guide wire through the guide catheter.
The progress is monitored by noting the location of an X-ray opaque marker on the moving device catheter relative to the X-ray opaque marker on the fixed guide catheter. When the two markers are coincident the cardiologist knows that the calcified region of interest has been reached. If a balloon catheter is being used saline solution may now be pumped into the balloon to inflate it thereby dilating the affected artery. The results of the procedure are then examined using the imaging device.
The disadvantage of this known system is the inconvenience of having to withdraw one catheter and insert another in order to swap between the PCTA or other treatment procedure and the imaging procedure.
SUMMARY OF THE INVENTION
The flexible transducer design permits the possibility of mounting radially thin ultrasound arrays onto catheter configurations that can be used to simplify the swapping between procedures, and the present invention is concerned with these catheter configurations.
Published International Patent Application No. WO94/17734 (PCT/US94/00474) incidentally discloses a catheter arrangement in which a balloon is mounted distal of an ultrasonic transducer array. However, this patent application is actually concerned with overcoming the problem of the mutually incompatible performance requirements for the backing layer of the transducer array on the one hand and for the carrier of the associated electronic components on the other hand, particularly when the material of the transducer array comprises lead zirconate titanate (PZT). It is not concerned with the same problem addressed by the present invention.
Published lnternational Patent Appln. No. WO 89/04143 (PCT/US/88/04036) also discloses a catheter arrangement having a balloon and ultrasonic transducer array mounted at or near the distal end of the catheter.
A first aspect of the present invention relates to the design and manufacture of a catheter which has both a wrapped acoustic tip according to our UK Patent Application 2,287,375 and an angioplasty balloon, the acoustic tip being located distal to the balloon.
A second aspect of the present invention relates to the manufacture of a 5-6French or a 8-9French sheath catheter having a wrapped acoustic tip (according to our UK Patent Application No 2,287,375) within its body. The resultant combined sheath and transducer array catheter may be used in conjunction with current commercially available 2.9French or 5.0French balloon catheters respectively for angioplasty and stent delivery purposes or with atherectomy devices such as a Rotoblator (Registered Trade Mark) which could be inserted into the sheath catheter of the present invention.
A third aspect of the present invention relates to the combination of a wrapped acoustic fixed array transducer mounted on a guide wire which could be 0.0 14 inches in diameter to provide a 1 French catheter to produce what may be referred to as a guide-wire catheter. One key feature of this third aspect of the present invention is the manner in which the 0.014 inch dimension is maintained throughout the entire length of the catheter thus permitting device interchange during PCTA procedures with minimal disruption. The invention also reduces the number of electrical interconnections which in the specific embodiment are four.
How the invention may be carried out will now be described by way of example only and with reference to the accompanying drawings in which:
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Nix Elvin Leonard
Pacey Andrew Robert
Rothman Martin Terry
Som Amit Kumar
Goldberg Richard M.
Intravascular Research Limited
Lateef Marvin M.
Patel Martin
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