US 20060111660 A1
Disclosed is a conduit that provides a bypass around a stenosis or occlusion in a coronary artery. The conduit is adapted to be positioned in the myocardium to provide a passage for blood to flow from a heart chamber to a coronary artery, at a site distal to the blockage or stenosis in the coronary artery. The conduit has a one-way valve positioned therein to prevent the backflow of blood from the coronary artery into the heart chamber.
36. A device for treating a heart, the device comprising:
a hollow implant having an interior wall surface defining a lumen, the hollow implant being configured to be positioned in a heart wall between a heart chamber and a coronary vessel so as to support a, blood flow passage between the heart chamber and the coronary vessel,
wherein portions of the interior wall surface are moveable relative to each other such that, during diastole, the portions reduce the cross-sectional area of the lumen so as to at least partially obstruct blood flow through the implant.
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This is a continuation of U.S. patent application Ser. No. 10/463,798, filed Jun. 18, 2003, now pending, which is a continuation application of U.S. patent application Ser. No. 09/368,393, filed on Aug. 4, 1999, now U.S. Pat. No. 6,641,610, and claims the benefit of U.S. Provisional Patent Application Ser. No. 60/099,777, filed Sep. 10, 1998, all of which are incorporated herein by reference.
This invention relates to apparatus and method for implanting a conduit to allow communication of fluids from one portion of a patient's body to another; and, more particularly, to a blood flow conduit to allow communication from a heart chamber to a vessel or vice versa, and/or vessel to vessel. Even more particularly, the invention relates to a left ventricular conduit and related conduit configurations for controlling the flow of blood through the conduit to achieve bypass of a stenosed or occluded coronary artery.
Coronary artery disease is a major problem in the U.S. and throughout the world. Coronary arteries as well as other blood vessels frequently become clogged with plaque, which at the very least impairs the efficiency of the heart's pumping action, and can lead to heart attack, arrhythmias, and death. In some cases, these arteries can be unblocked through noninvasive techniques such as balloon angioplasty. In more difficult cases, a bypass of the blocked vessel is necessary.
In a bypass operation, one or more venous segments are inserted between the aorta and the coronary artery. The inserted venous segments or transplants act as a bypass of the blocked portion of the coronary artery and thus provide for a free or unobstructed flow of blood to the heart. More than 500,000 bypass procedures are performed in the U.S. every year.
Such coronary artery bypass surgery, however, is a very intrusive procedure that is expensive, time-consuming and traumatic to the patient. The operation requires an incision through the patient's sternum (stemotomy), and that the patient be placed on a bypass pump so that the heart can be operated on while not beating. A vein graft is harvested from the patient's leg, and a delicate surgical procedure is required to piece the bypass graft to the coronary artery (anastomosis). Hospital stays subsequent to the surgery and convalescence are prolonged. Furthermore, many patients are poor surgical candidates due to other concomitant illnesses.
As mentioned above, another conventional treatment is percutaneous transluminal coronary angioplasty (PTCA) or other types of angioplasty. However, such vascular treatments are not always indicated due to the type of location of the blockage or stenosis, or due to the risk of emboli.
Thus, there is a need for an improved bypass system that is less traumatic to the patient.
The preferred embodiments of the present invention address the need in the previous technology by providing a bypass system that avoids the stemotomy and other intrusive procedures normally associated with coronary bypass surgery. These embodiments also free the surgeon from the need to perform multiple anastomoses as is necessary in the current process.
The preferred device provides a conduit or shunt for diverting blood directly from the left ventricle of the heart to a coronary artery, at a point distal to the blockage or stenosis, thereby bypassing the blocked portion of the vessel. The conduit preferably comprises a tube adapted to be positioned in the myocardium and having a one way valve therein. The valve prevents the backflow of blood from the coronary artery into the left ventricle.
The conduit device is delivered through the coronary artery to a position distal the blockage or stenosis. At that position, the coronary artery, the myocardium and the wall of the left ventricle are pierced to provide an opening or channel completely through from the coronary artery to the left ventricle of the heart. The conduit is then positioned in the opening to provide a permanent passage for blood to flow between the left ventricle of the heart and the coronary artery, distal to the blockage or stenosis. The conduit is sized so that one open end is positioned within the coronary artery, while the other open end is positioned in the left ventricle. The hollow lumen of the conduit provides a passage for the flow of blood.
To prevent the backflow of blood from the coronary artery to the left ventricle of the heart, the conduit is provided with a one-way valve. The valve is preferably a windsock type valve, a flapper valve, a bi- or tricuspid valve, a ball valve, a valve formed from the myocardium itself, or a valve that opens and closes in response to the contraction and relaxation of the heart muscle, or in response to the electrical signals in the heart.
FIGS. 5A-D are cross-sectional views of a valve formed from the myocardium for use in conjunction with a heart conduit in accordance with a preferred arrangement;
FIGS. 6A-B are cross-sectional views of a valve that is activated by the contractions of the heart muscle for use in conjunction with a heart conduit in accordance with a preferred arrangement;
As is well known, the coronary artery branches off the aorta and is positioned along the external surface of the heart wall. Oxygenated blood that has returned from the lungs to the heart then flows from the heart to the aorta. Some blood in the aorta flows into the coronary arteries, and the remainder of blood in the aorta flows on to the remainder of the body. The coronary arteries are the primary blood supply to the heart muscle and are thus critical to life. In some individuals, atherosclerotic plaque, aggregated platelets, and/or thrombi build up within the coronary artery, blocking the free flow of blood and causing complications ranging from mild angina to heart attack and death. The presence of coronary vasospasm, also known as “variant angina” or “Prinzmetal's angina,” compounds this problem in many patients.
As used herein, the term “heart chamber” primarily refers to the interior, or lumenal, aspect of the left or right ventricle or the left or right atrium. The term “conduit,” “stent,” and “tube” herein refer to physical structures, preferably primarily artificial, that can be positioned between two or more chambers or vessels, to allow blood flow from one chamber or vessel to another. A “shunt” is any natural or artificial passage between natural channels, such as heart chambers or blood vessels. The conduit in the preferred arrangement can be made of a variety of materials, including various metals, such as nitinol, or plastics.
As used herein, the term “heart wall” comprises any one or more of the following portions or layers of the mammalian heart: the epicardium, myocardium, endocardium, pericardium, interatrial septum, and interventricular septum
The principles of the present invention are not limited to left ventricular conduits, and include conduits for communicating bodily fluids from any space within a patient to another space within a patient, including any mammal. Furthermore, such fluid communication through the conduits is not limited to any particular direction of flow and can be antegrade or retrograde with respect to the normal flow of fluid. Moreover, the conduits may communicate between a bodily space and a vessel or from one vessel to another vessel (such as an artery to a vein or vice versa). Moreover, the conduits can reside in a single bodily space so as to communicate fluids from one portion of the space to another. For example, the conduits can be used to achieve a bypass within a single vessel, such as communicating blood from a proximal portion of an occluded coronary artery to a more distal portion of that same coronary artery.
In addition, the conduits and related methods can preferably traverse various intermediate destinations and are not limited to any particular flow sequence. For example, in one preferred embodiment of the present invention, the conduit communicates from the left ventricle, through the myocardium, into the pericardial space, and then into the coronary artery. However, other preferred embodiments are disclosed, including direct transmyocardial communication from a left ventricle, through the myocardium and into the coronary artery. Thus, as emphasized above, the term “transmyocardial” should not be narrowly construed in connection with the preferred fluid communication conduits, and other nonmyocardial and even noncardiac fluid communication are preferred as well. With respect to the walls of the heart (and more specifically the term “heart wall”), the preferred conduits and related methods are capable of fluid communication through all such walls including, without limitation, the. pericardium, epicardium, myocardium, endocardium, septum, etc.
The bypass which is achieved with certain preferred embodiments and related methods is not limited to a complete bypass of bodily fluid flow, but can also include a partial bypass which advantageously supplements the normal bodily blood flow. Moreover, the obstructions that are bypassed may be of a partial or complete nature, and therefore the terminology “bypass” or “occlusion” should not be construed to be limited to a complete bypass or a complete occlusion but can include partial bypass and partial occlusion as described.
The preferred conduits and related methods disclosed herein can also provide complete passages or partial passages through bodily tissues. In this regard, the conduits can comprise stents, shunts, or the like, and therefore provide a passageway or opening for bodily fluid such as blood. Moreover, the conduits are not necessarily stented or lined with a device but can comprise mere tunnels or openings formed in the tissues of the patient.
The conduits of the present invention preferably comprise both integral or one-piece conduits as well as plural sections joined together to form a continuous conduit. The present conduits can be deployed in a variety of methods consistent with sound medical practice including vascular or surgical deliveries, including minimally invasive techniques. For example, various preferred embodiments of delivery rods and associated methods are disclosed. In one-embodiment, the delivery rod is solid and trocar-like. It may be rigid or semi-rigid and capable of penetrating the tissues of the patient and thereby form the conduit, in whole or in part, for purposes of fluid communication. In other preferred embodiments, the delivery rods may be hollow so as to form the conduits themselves (e.g., the conduits are preferably self-implanting or self-inserting) or have a conduit mounted thereon (e.g., the delivery rod is preferably withdrawn leaving the conduit installed). Thus, the preferred conduit device and method for installation is preferably determined by appropriate patient indications in accordance with sound medical practices.
In order to restore the flow of oxygenated blood through the coronary artery, the preferred arrangement provides for the shunting of blood directly from the heart to a site in the coronary artery which is distal the blockage or stenosis.
Although the specification herein will describe the conduit primarily with reference to the left ventricle, the preferred arrangement can be used with any of the four heart chambers, and with any coronary artery, including the left main coronary artery, the right coronary artery, the left anterior descending artery, the left circumflex artery, the posterior descending artery, the obtuse marginal branch or a diagonal branch.
A tunnel or opening is formed through the wall of the coronary artery and the heart wall and into the left ventricle of the heart which lies beneath, or deep to, the coronary artery. A conduit is positioned in the opening to keep it open, and a one-way valve is positioned within the conduit to prevent blood from flowing back into the left ventricle of the heart from the coronary artery.
The conduit may be introduced into the heart wall in a variety of ways, including by a catheter threaded through the femoral artery into the aorta and thence into the left ventricle and, if necessary, the left atrium; or by a catheter threaded through the femoral vein into the inferior vena cava and thence into the night atrium and right ventricle. Alternatively, the conduit may be introduced through a surgical incision in chest wall (thoracotomy) or sternum (sternotomy).
Further details regarding conduits and conduit delivery systems are described in U.S. patent applications entitled DELIVERY METHODS FOR LEFT VENTRICULAR CONDUIT U.S. application Ser. No. 09/368,868, now U.S. Pat. No. 6,261,304; DESIGNS FOR LEFT VENTRICULAR CONDUIT U.S. application Ser. No. 09/369,048, now U.S. Pat. No. 6,290,728; LEFT VENTRICULAR CONDUIT WITH BLOOD VESSEL GRAFT U.S. application Ser. No. 09/369,061, now U.S. Pat. No. 6,254,564; LEFT VENTRICULAR CONDUITS TO CORONARY ARTERIES AND METHODS FOR CORONARY BYPASS U.S. application Ser. No. 09/369,039, now abandoned, and BLOOD FLOW CONDUIT DELIVERY SYSTEM AND METHOD OF USE U.S. application Ser. No. 09/368,644, now U.S. Pat. No. 6,302,892, filed on the same day as the present application, and U.S. Pat. Nos. 5,429,144, and 5,662,124, the disclosures of which are all hereby incorporated by reference in their entirety.
The opening through the heart wall (including endocardium, myocardium, and epicardium) and coronary artery can be formed in a variety of ways, including by knife or scalpel, electrocautery, cryoablation, radiofrequency ablation, ultrasonic ablation, and the like. Other methods will be apparent to those of ordinary skill in the art.
Referring now to
One embodiment of the preferred arrangement is illustrated in
The valve 10 is preferably constructed from a biocompatible and very compliant fabric or other material that is pushed aside by the high forward blood pressure created from the contraction of the heart muscle, but opens to “catch” the back-flow of blood passing back through the conduit 12. The valve 10 is preferably constructed by incorporating the fabric or other material into the conduit 12 directly during its manufacture. This allows the valve 10 and conduit 12 to be introduced as a single unit.
Another embodiment of the preferred arrangement is illustrated in
The third embodiment of the valve 16 is illustrated in
A further embodiment of the conduit is illustrated in FIGS. 5A-D. Here, the heart wall, which includes the myocardium MYO, lying between the coronary artery CA and the left ventricle of the heart LV, is cut using known techniques to form a passage through the myocardium MYO.
As illustrated in
In another embodiment, the valve in the conduit may be controlled in response to the contractions of the heart. As illustrated in
The valve 24 may also be controlled by a hydrodynamic or electric pump or motor, which is responsive to the contractions of the heart, causing the valve 24 to open and close in response to various parts of the cardiac cycle.
A further embodiment of the preferred arrangement is illustrated in
Another embodiment is illustrated in
Another embodiment is illustrated in
Instead of a spring mechanism 50, the walls of the conduit 12 can have other mechanisms therein to allow differential flow during various parts of the cardiac cycle. For example, the valve 48 can have a gas- or liquid-filled balloon 52 in its wall, as shown in
Another embodiment of the valve mechanism is illustrated in
The present vascular conduit and valve system provides significant improvements in the present treatment of blockages and significant stenoses in the coronary artery. Although the invention has been described in its preferred embodiments in connection with the particular figures, it is not intended that this description should be limited in any way.