Surgery – Instruments – Cutting – puncturing or piercing
Reexamination Certificate
2000-03-01
2001-05-29
Truong, Kevin (Department: 3731)
Surgery
Instruments
Cutting, puncturing or piercing
Reexamination Certificate
active
06238406
ABSTRACT:
FIELD OF THE INVENTION
The present application is related to devices and methods for promoting blood circulation to the heart muscle. Specifically, the present invention is related to percutaneous myocardial revascularization (PMR) devices and methods.
BACKGROUND OF THE INVENTION
A number of techniques are available for treating cardiovascular disease such as cardiovascular by-pass surgery, coronary angioplasty, laser angioplasty and atherectomy. These techniques are generally applied to by-pass or open lesions in coronary vessels to restore and increase blood flow to the heart muscle. In some patients, the number of lesions are 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 by-passing 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 hearts muscle is supplied primarily by blood perfusing directly from within heart chambers to the heart muscle. This contrast 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 remains to be provided are improved methods and devices for increasing blood perfusion to the myocardial tissue. What remains to be provided are methods and devices for increasing blood flow beyond what has hitherto been possible with PMR.
SUMMARY OF THE INVENTION
The present invention includes devices and methods for increasing blood circulation to the myocardium. Circulation can be increased through patent holes into the myocardium from a heart chamber and from new blood vessel growth. New blood vessels can provide blood supplied from within a heart chamber, such as the left ventricle, and from pre-existing vessels in nearby healthy heart tissue. New vessel growth can be promoted by the healing response to wounds created in accordance with the present invention. New vessel growth can also be promoted by angiogenic substances supplied to the myocardium in accordance with the present invention.
One set of methods according to the present invention utilizes shafts such as tubes or spikes driven into the myocardium, preferably from within the heart, delivered by a catheter. The tubes preferably contain, or are coated with, an angiogenic substance capable of being released over time. These tubes can be biodegradable, being absorbed by the body, some embodiment tubes leaving a patent hole in the myocardium surrounded by the absorbed angiogenic material. Other PMR tubes are not biodegradable, but have lumens therethrough with side holes along the tube length, providing access to the myocardium from with the lumen. The non-biodegradable tube can be formed from a metal, polymeric or other bio-stable material. The non-biodegradable tubes are preferably coated with and contain releasable angiogenic material, promoting new vessel growth along the length of the tube, where the new vessels can be supplied with blood through the tube side holes. One method utilizes PMR spikes driven into the myocardium from outside the heart and can be performed during open heart surgery or during a minimally invasive procedure.
Another set of methods according to the present invention involves injecting angiogenic material into the myocardium. A preferred method includes creating small bore holes or direct needle injection into the myocardium utilizing a catheter within the heart. After hole creation, a fluid, gel or adhesive carrying an angiogenic material is injected into the hole. As the angiogenic substance is absorbed into the myocardium, in one method, a patent hole remains surrounded by myocardial tissue treated with angiogenic material. In another method, the injection hole closes, leaving no patent hole. New vessel growth is promoted by both the healing response to the wound and by the angiogenic substance. Blood circulation to myocardial tissue is increased by both the presence of the patent hole and the presence of new blood vessels supplied by existing coronary vessels and the heart interior. An alternative method utilizes angiogenic material injected into the myocardium from the exterior of the heart, in conjunction with open heart surgery or during a minimally invasive procedure.
Yet another set of methods includes externally wounding the heart and applying an external patch containing angiogenic substance to the wound. The wound preferably penetrates into the myocardium. The healing response, enhanced by the angiogenic material, promotes new vessel growth near the wound. While the wound does not normally penetrate through to the heart chamber interior, new vessel formation can reach the chamber interior and also connect with pre-existing vessels in healthy heart muscle. A wound or series of wounds extending from healthy into hibernating tissue can create a network of vessels from healthy into hibernating tissue, supplying the hibernating tissue with blood. In another method, an external patch containing angiogenic material is applied to the heart without significant injury to the heart.
Angiogenic materials believed suitable for use with present invention include Vascular Endothelial Growth Factor (VEGF) and Fibroblast Growth Factors (FGFs). Carriers for the growth factors of the present invention include hydrogels. Adhesives suitable for binding the present invention include fibrin glues and cyanoacrylates.
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Ellis Louis
Harrison Kent D.
Hendrickson Gary L.
Mickley Timothy J.
Wang Lixiao
Crompton Seager & Tufte LLC
Sci-Med Life Systems, Inc.
Truong Kevin
LandOfFree
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