Surgery – Instruments – Heat application
Reexamination Certificate
1998-07-14
2001-02-20
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Heat application
C606S041000, C607S101000, C604S113000
Reexamination Certificate
active
06190379
ABSTRACT:
BACKGROUND
This invention relates generally to the catheterized treatment of a stenosis or blockage in a bodily passageway such as an artery or the like, and more particularly the invention concerns an apparatus and method for determining the optimal placement of the catheter in the bodily passageway for treating the stenosis. The invention also relates generally to an apparatus and method for creating holes or channels in a hyproperfused area of a heart with a catheter tip energized by radio-frequency waves.
A stenosis is a narrowing or constriction in a bodily passageway such as an artery. One such type of stenosis is known as atherosclerosis and occurs in blood-conveying arteries in humans. Heretofore there have been a variety of apparatuses and methods for treating such stenoses, such as mechanical, ultrasound and laser apparatuses and methods. All of these apparatuses and methods have in mind the ultimate goal of treating a stenosis so that it does not reoccur. The ultimate goal of these treatments is to unblock the stenosis so that it does not return so that a patient who suffers from such condition may go on to lead a normal life.
The apparatuses and methods in the prior art have largely failed to achieve this goal because up until now, discovering the optimal placement of a catheter in a bodily passageway to achieve the most efficient heating of a stenosis has not been available. While the prior art apparatuses and methods have failed to determine the optimal placement of a catheter in an occluded passageway, the present invention has succeeded in providing an improved device and method which reduces the chances of restenosis or a reoccurrence of the stenosis.
A problem related to the stenoses in coronary arteries manifests as a hypoperfusion, or below normal blood flow, in one or more areas of the heart muscle, which are detectable by thallium scintigraphy. Lasers have been used to treat such hyproperfused areas of the heart by lasing the endocardial surface of the heart, for example in the left ventricle, to create small holes or channels part-way through the heart muscle, roughly perpendicular to the surface. The subsequent healing of the heart in the area of the channels is believed to involve the angiogenesis of small blood vessels, resulting in an increase in perfusion of the area. However, lasers designed for this technique are expensive, and the associated catheters are stiff and have an outer diameter that creates a risk of unwanted damage to the heart and blood vessels. Additionally, the catheters include a fiberoptic laser delivery device and are expensive, and can usually be used only one time.
With the above problems in mind, it is an object of the present invention to provide an apparatus and method for the treatment of a stenosis which reduces the chances of a reoccurrence.
It is another object of the present invention to provide an apparatus and method for locating the optimal position in a bodily passageway for the treatment of a stenosis.
It is yet another object of the invention to provide a catheter for use in treating a stenosis which uses radio frequency energy to capacitatively heat the same.
It is a further object of the invention to provide a catheter and a controller for delivering radio frequency energy to the catheter, in which the controller includes a system for determining the optimal placement of the catheter in the bodily passageway.
SUMMARY OF THE INVENTION
The invented system and method achieves the above results in the form of a catheter for the treatment of a stenosis in a bodily fluid passageway which includes a controller for generating radio frequency energy along a pair of output lines, monitoring the phase of the radio frequency energy along the output lines, and adjusting the output impedance so that it equals that of a load, e.g., the patient. The catheter includes a catheter body which is insertable into the bodily passageway and operatively connected to the controller. A lumen in the catheter body defines an opening and a mandril is disposed within the lumen so that a terminal end extends through the opening and into the bodily passageway. An internal electrode is joined to the terminal end of the mandril, with the other end of the mandril operatively connected to one of the output lines for receiving the radio frequency energy produced by the generator and delivering such energy to the terminal end and the internal electrode. An external electrode is located externally of the catheter so that when the radio frequency energy is delivered via the mandril to the internal electrode, the same causes or enables the capacitative heating of a stenosis.
The method of the present invention relates to finding the most optimal position for placement of the catheter so that optimal power may be delivered to the stenosis. The method involves the steps of providing a controller, which includes a radio frequency waveform generator, an impedance matching circuit, and a phase monitoring circuit, the controller being operatively connected to the catheter and a grounding pad; inserting the catheter into a bodily passageway so that it is positioned adjacent a stenosis; tuning the impedance matching circuit so that the impedance of the generator matches the output load impedance; delivering a produced waveform to the catheter; and, adjusting the phase of the waveform so that it is substantially 180-degrees out of phase relative to the grounding pad.
The present invention also provides an improved device and method for percutaneous myocardial revascularization of hypoperfused areas of the heart muscle that are less expensive and safer than the laser-based devices and methods. The channel-creating portion of the device is a radio-frequency wire, for example, the mandril and internal electrode described above, which is insertable through a balloon catheter or a simple end hole catheter such as a Tracker. The balloon catheter or Tracker is in turn insertable in a right Judkins catheter of 6-french size which can easily be inserted through a major blood vessel, for example, through the femoral artery, the abdominal aorta, and the aorta, into a chamber of the heart, for example, the left ventricle. The external diameter of the 6-french catheter is a third smaller than the 9-french catheter required for the laser-based catheters, reducing the danger of unwanted damage to the heart and blood vessels.
To create the channels in the heart wall, the radio-frequency wire is inserted into the heart chamber and its tip is brought into contact with the inner heart wall at a desired location. The controller with the radio frequency waveform generator is then adjusted for optimum energy delivery and a burst of energy is applied for about one second to bore a channel about 0.014-inches in diameter and about 3- to 4-mm deep. The tip position is then adjusted by longitudinal and rotational movement of the right Judkins catheter and the process is repeated to create a map or network of from about eight to about thirty channels, typically spaced apart by about one centimeter. The RF energy is safer because it is less likely than the laser to perforate all the way through the heart wall. Additionally, the controller and radio-frequency wire are considerably less expensive than the fiber-optic laser delivery device and laser.
These and additional objects and advantages of the present invention will be more readily understood after a consideration of the drawings and the detailed description of the preferred embodiment.
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Hara Shinji
Heuser Richard R.
Dvorak Linda C. M.
Gibson Roy
Kolisch Hartwell Dickinson & McCormack & Heuser
Sun Star Technology, Inc.
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