Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1998-08-10
2001-09-04
Buiz, Michael (Department: 3731)
Surgery
Instruments
Internal pressure applicator
C606S108000, C623S001130
Reexamination Certificate
active
06283983
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to myocardial revascularization cardiac surgery, and more particularly to an improved method and apparatus for performing coronary lesion bypass to restore patency to blocked coronary or stenotic arteries.
II. Discussion of the Prior Art
Coronary artery disease is a major cause of death in the United States. The disease results in the build-up of calcified, fibrous and fatty deposits on the walls of the coronary arteries supplying blood to the myocardium. The narrowing of one or more cardiac arteries often results in ischemia, leading to angina pain. Moreover, clots may result in blockage of the flow of blood through a blood vessel that has been narrowed by the stenotic lesion, resulting in myocardial infarction or unstable angina.
One approach for restoring patency to a narrowed coronary artery is commonly referred to as “balloon angioplasty”. Here, a catheter having an inflatable expanding member on its distal end is routed through the vascular system until the yet uninflated member is juxtaposed with the lesion to be treated. Saline and/or contrast is then introduced through a lumen in the catheter to the interior of the expander member with sufficient pressure to inflate the expander member and fracture or compress the lesion into the wall of the blood vessel. When the expander member is deflated and the catheter removed from the patient, patency is restored to the affected coronary artery.
Not all patients suffering from coronary artery disease are candidates for balloon angioplasty. A significantly more invasive procedure, commonly referred to as coronary bypass surgery, may then be called for. In this procedure, the sternum is divided and retractors are used to expose the chest cavity. The pericardial sack is opened and the patient is placed on a heart/lung machine, allowing the patient's own heart to be stopped. A vascular segment, which may be harvested from the patient's saphenous vein or the internal mammary or radial artery, is then anastomosed to the blocked artery beyond the point of obstruction to thereby provide a shunt blood path along that lesion. Once the necessary bypass segment(s) have been sutured in place, the heart is then restarted, the chest wall is reanastomosed together and the surgical incision closed.
Such coronary bypass surgery is not only quite expensive in terms of medical costs, but also in terms of the relatively lengthy time required for recuperation.
A need exists for a less traumatic coronary bypass procedure. Some medical centers have recently reported on minimally invasive surgery wherein the bypass procedure is conducted through a relatively small wound in the chest and rib cage, with drugs being given to slow the heart rate. At this point, however, such a procedure is not widely practiced and can only be performed in selective cases where reasonable access can be had to the coronary artery containing the stenotic lesion.
A real need exists for a catheter based procedure for performing coronary bypass in those cases where balloon angioplasty is determined to be ineffective. It is the principal purpose or object of the present invention to provide such a new technique as well as instruments and devices for carrying out the procedure.
SUMMARY OF THE INVENTION
We have developed a procedure which we call “percutaneous in-situ bypass surgery” which will be referred by the acronym, PIBS. Referring to
FIGS. 1 and 2
, which respectively show the anterior and posterior view of a human heart, it can be noted that the major coronary arteries and branches thereof are physically located in close and generally parallel proximity to corresponding venous structures. Thus, with reference to
FIG. 1
, the left anterior descending coronary artery runs generally parallel with the anterior descending vein of the heart across the left ventricle and, similarly, in
FIG. 2
, the right coronary artery is closely juxtaposed to the small veins of the heart. The posterior interventricular branch of the right coronary artery extends generally parallel to the middle vein of the heart on the posterior side of the right ventricle. The circumflex branch of the left coronary artery generally underlies the great vein of the heart.
The fundamental principle involved in the PIBS procedure of the present invention is to utilize a coronary vein as a conduit, either to convey arterial blood directly around an arterial stenosis or occlusion or to use the vein as a chamber in which to place an arterial conduit, such as a tubular stent, and where the procedure can be performed entirely percutaneously.
In accordance with one aspect of the invention, the coronary artery is connected to the neighboring vein proximal to a stenosis or occlusion and the vein is then reconnected to the affected artery distal to the occlusion. In carrying out the method, an elongated instrument, much like a conventional guide wire, is routed through the vascular system and through the ostium of the stenosed artery until the tip thereof is proximal to the lesion to be bypassed. Either the guide wire itself or an instrument carried by the guide wire may be used to pierce through the artery wall and through a wall of the neighboring vein. A stent delivery catheter is then routed over the guide wire until the tubular stent bridges the surgically created openings in the artery and vein and the stent is deployed at this point to create a blood impervious channel. The guide wire may then be advanced down the vein to a location distal of the arterial blockage and, again, the guide wire or another instrument is deployed over the guide wire to puncture through the vein wall and the neighboring arterial wall. Again, a second stent is then inserted to anastomose the opening in the vein and the opening in the artery. As a result, a blood flow path is created from the artery through the vein segment bypassing the lesion in the artery and then back into the artery distal of the blockage. A blocking stent may be placed in the coronary vein proximal to the anastomosis to prevent arterial blood flow back to the right ventricle via the coronary sinus.
In accordance with a closely related procedure, a vein segment is again used as a conduit but, in this case, the vein merely serves as a conduit for an arterial graft. In accordance with this second procedure, the artery is entered, a hole is again made through the artery wall and through the neighboring vein wall using a percutaneous approach with the piercing instrument also being used to puncture through the vein wall and the neighboring arterial wall at a location distal of the blockage. An elongated stent having its proximal end in the artery and extending through the first puncture wounds and through the lumen of the neighboring vein and its distal end extending through the puncture in the vein and into the neighboring artery, provides a bypass path for arterial blood flow.
The stent(s) may be either of the self-expanding type or a stent delivery catheter preferably having two balloon expanders thereon for expanding the proximal and distal stents may be utilized. To enhance the compatibility of the stent or stents employed with the adjacent natural tissue and with blood, they may first be covered with a blood impervious layer. Then, by using novel materials technology, endothelialization of both surfaces of the stent conduit can occur and will develop and maintain both a neointimal lining and an external endothelium as well.
Another special instrument to be used in carrying out the method of the present invention resides in a catheter to be used in placing the puncturing instrument at the desired locations proximal to and distal to the lesion being bypassed. The guiding catheter may have two lumens, a central lumen capable of accepting a standard guide wire and a second carrying the wire for piercing through the blood vessel walls. The piercing instrument may include a mechanical cutting device on its distal end or, alternatively, may comprise an electrosurgical electrod
Holmes David R.
Makower Joshua
Schwartz Robert S.
Van Tassel Robert A.
Buiz Michael
Buyan Robert D.
Lewis William W.
Stout, Uxa Buyan & Mullins, LLP
TransVascular, Inc.
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