Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-02-14
2003-04-08
Mancene, Gene (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S249000, C251S129060
Reexamination Certificate
active
06544220
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related generally to medical devices. More specifically, the present invention includes devices for performing myovascular revascularization including percutaneous myocardial revascularization (PMR).
BACKGROUND OF THE INVENTION
A number of techniques are available for treating cardiovascular disease, such as cardiovascular bypass surgery, coronary angioplasty, laser angioplasty and atherectomy. These techniques are generally applied to bypass or open lesions in coronary vessels to restore and increase blood flow to the heart muscle. In some patients, the number of lesions is so great, or the location so remote in the patient vasculature, that restoring blood flow to the heart muscle is difficult. Percutaneous myocardial revascularization (PMR) has been developed as an alternative to these techniques which are directed at bypassing or removing lesions. PMR is performed by boring holes directly into the myocardium of the heart.
PMR was inspired in part by observations that reptilian heart muscle is supplied primarily by blood perfusing directly from within heart chambers to the heart muscle. This contrasts with the human heart which is supplied by coronary vessels receiving blood from the aorta. Positive results have been demonstrated in some human patients receiving PMR treatments. These results are believed to be caused in part by blood flowing from within a heart chamber through patent holes formed by PMR to the myocardial tissue. Suitable PMR holes have been proposed to be burned by laser, cut by mechanical means, and burned by radio frequency devices. Increased blood flow to the myocardium is also believed to be caused in part by the healing response to wound formation, specifically, the formation of new blood vessels in response to the newly created wound.
What would be desirable are improved methods and devices for performing myocardial revascularization. In particular, methods allowing simultaneous hole formation in the myocardium and injection of contrast media would be advantageous. Improved methods for stabilizing myocardial revascularization catheters during use would also be desirable.
SUMMARY OF THE INVENTION
The present invention includes catheters for forming holes in the myocardium of a heart chamber wall. One catheter has a distal region, a proximal region, and an elongate tubular shaft having a lumen therethrough. A distal nozzle in fluid communication with the lumen can be disposed at the distal-most region of the catheter shaft. A fluid control valve can be disposed somewhere along the catheter shaft length for controlling fluid flow through the fluid lumen. The fluid flow through the valve can be controlled using varying devices in the various catheters.
One device includes electrical means for actuating the fluid control valve. In another device, the valve includes a biasing spring to bias the valve in a closed position, with the opening force being provided by an electrically actuated member acting to oppose the biasing spring. In one device, the electronic actuating member is a Nitinol member heated by current passing from one end to the other end through the member. In this embodiment, heating a Nitinol wire shortens the wire, which opens the valve to fluid flow. In another embodiment, a flow or control pressure lumen is provided through the catheter, with the control pressure used to open and shut the valve, thereby allowing the high pressured jet fluid to flow through the valve. In one embodiment, a needle valve is used which includes a valve stem seated within a valve seat, where the valve stem can be retracted proximally to allow flow through the valve seat. In yet another embodiment, a mechanical actuating wire is used to open the control valve. In one embodiment, an elongate control wire is operably coupled to a distal valve stem. The valve stem can have a first position for occluding flow through a valve seat, and a second position for allowing flow through the valve seat. In one device, the actuation wire is proximally retracted to allow flow, and distally extended to preclude flow. In another embodiment, a biasing spring is included within the distal region, acting to shut the valve in the absence of any applied mechanical force. In this embodiment, the actuation wire can be retracted to open the valve to fluid flow. In one embodiment, the retractable activation wire may be sufficiently strong under tension, but not compression, to open the valve.
The control valve can be located at any position along the catheter shaft length, with a preferred embodiment having a distally disposed control valve. The distally disposed control valve can allow for a relatively large inside diameter distal accumulator and orifice, while having a substantially smaller cross-section supply lumen extending the length of the catheter. This allows for a slow pressure buildup in the distal region of the catheter, followed by rapid injection of high pressure fluid into the heart wall.
One catheter includes preferentially expandable regions which expand more readily than other regions under pressure. In one example, a far distal region of a catheter device is formed of a more pliant, more easily expandable tube wall material. The more readily expanded material may inflate and expand radially under pressure. In one device, the distal-most region of the catheter is formed of a readily inflatable material. In use, the catheter formed of the more readily inflated material may be inflated to significantly increase the distal cross-sectional area of the catheter, whereupon the increased cross-sectional distal tip is forced against the heart chamber wall, for improving the seal against the heart wall. One catheter according to the present invention includes an intermediate region which is also more readily expandable than the immediate more proximal and distal regions. The expandable intermediate region can serve to anchor the fluid jet catheter within an enclosing guide catheter. The anchored catheter can more easily withstand pressures or forces which could otherwise act to shift the position of the fluid jet catheter.
Fluids which are used in the present invention can include relatively inert fluids such as saline, suitable therapeutic substances, angiogenic enhancing substances, as well as radiopaque contrast media. Adhesive agents can also be included for enhancing the retention of therapeutic substances within the heart wall. The inclusion of radiopaque contrast media allows holes to be formed and contrast media to be injected in a single step. The contrast media allows the already treated regions to be visualized under fluoroscopy by the treating physician.
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Guo Zihong
Johnson Tim
Pearce Joseph
Shuman Brandon J.
Buechner Patrick
Christensen O'Connor Johnson & Kindness PLLC
Mancene Gene
Scimed Life Systems Inc.
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