Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-03-01
2002-04-16
Thissell, Jeremy (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S165020, C600S585000
Reexamination Certificate
active
06371940
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates broadly to surgical devices. More particularly, this invention relates to devices for an over-the-guidewire exchange of one catheter for another in the human body.
2. State of the Art
Catheterization procedures are well known for diagnosis and therapy of lesions in the cardiovascular system. One such procedure is angioplasty, for eliminating or ameliorating the vascular blockage or constriction in blood vessels associated with supplying blood to the heart or other organs. In an angioplasty procedure, an expandable balloon carried by an elongated catheter is introduced into the arterial system of a patient and advanced until it is positioned in the region of the blockage or constriction. Once so positioned, the balloon is expanded by filling it with a liquid. In successful procedures, the expandable balloon presses outwardly against the walls of the artery and expands the artery to a degree to which the artery is either partially or completely reopened to blood flow.
Prior to initiating the angioplasty procedure, a guiding catheter is placed, typically via the femoral artery, into the aorta and its tip is engaged into the coronary arteries which branch from the aorta. Once placed, the guiding catheter acts as a conduit to access the coronary arteries with a guidewire and balloon catheter. The guiding catheter is a portion of plastic tubing having a length of about 95 centimeters, an inside diameter of about 2 millimeters, and an outside diameter of about 2.5 millimeters. A hemovalve, i.e., a valve preventing blood loss through the guiding catheter when a tubular conduit such as a balloon catheter is passed therethrough, is provided at the proximal end of the guiding catheter.
Then, external of the patient, the physician threads a guidewire through a balloon catheter. The guidewire is a piece metal wire, e.g., titanium or nickel-titanium alloy wire, approximately 175 centimeters in length, and about 0.25 to 0.46 millimeters in diameter. The soft distal tip of the guidewire is often shaped to form a “J” configuration. This “J” shape allows the physician to steer the guidewire by twisting its proximal end while advancing or retracting the guidewire. The balloon catheter is an elongate flexible plastic tubular member defining two longitudinal passages and having a balloon located at or adjacent its distal end. One longitudinal passageway defines a conduit through which the guidewire can be passed. The other longitudinal passage defines a conduit in fluid communication with the interior of the balloon and through which inflation fluid can be injected to inflate the balloon.
Among the types of balloon catheters is one in which the two longitudinal passages are generally side by side and parallel. In another type of balloon catheter, the two longitudinal passages are coaxial. In this latter type, the guidewire is passed down the inner passage and the inflation fluid is injected into the balloon via the outer passage. Balloon catheters, as well as associated apparatus and their method for use in angioplasty, are generally described in U.S. Pat. No. 5,040,548 to Yock, which is hereby incorporated by reference herein in its entirety.
The physician passes the guidewire through the appropriate one of the longitudinal passages in the balloon catheter, leaving a portion of the guidewire extending from the distal and proximal ends of the balloon catheter. This assembly is then inserted through the hemovalve and into the proximal end of the guiding catheter, distal end first. The assembly is inserted until the balloon which is attached at or near the distal end of the balloon catheter is near the distal end of the guiding catheter. At this point, the physician, while maintaining the balloon catheter stationary, pushes on the guidewire to advance it outwardly from the distal end of the guiding catheter.
The physician steers the guidewire into the chosen one of the coronary arteries, and advances it until it reaches a location of constriction which the physician desires to open. Carefully, the physician eases the distal end of the guidewire through the region of constriction until the guidewire tip is on the opposite side of the constriction relative to the guiding catheter.
With the guidewire held stationary, the physician advances the balloon catheter over the guidewire until it is located in the region of constriction of the artery. Then, with the balloon held stationary, inflation fluid is injected into the conduit which communicates with the balloon, causing it to inflate. Inflation of the balloon expands the walls of the artery in the region of constriction and, in successful procedures, opens the artery to sufficient blood flow.
Arteries vary in size, and therefore balloon catheters having balloons of different sizes are provided for selection by the physician. These balloons, when inflated, range from about 1.5 millimeters to about 4 millimeters in diameter. Sometimes, it is necessary for the physician to use more than one balloon to open an artery, as in some instances, the chosen balloon may be too large to be advanced into the constricted area, or in other instances, the first chosen balloon size, even when inflated, is not large enough to open the constricted area to the degree desired. In such cases, it is necessary to exchange one balloon catheter for another during the same angioplasty procedure.
In order to accomplish this exchange, the guidewire is left in place, and the balloon catheter is withdrawn entirely from the guiding catheter until it is completely disengaged from the proximal end of the guidewire. A new balloon catheter, having a different sized balloon, is then reinserted over the guidewire and advanced back to the location of the constricted area, where it is used to effect the desired result.
It is highly desirable to leave the guidewire in position; i.e., once the guidewire is passed through the constricted area, preferably the guidewire remains extending through the constriction for the duration of the angioplasty procedure. This means that the guidewire must remain in place even during the exchange of balloon catheters. The reason for this is that when a foreign object, such as the guidewire, is introduced into an artery, the artery walls sometimes go into spasm, and constrict the artery generally along a substantial portion of its length. If the artery tends to contract in this way, removal of the guidewire while the artery is so contracted will sometimes render it virtually impossible to reinsert the guidewire through the contracted artery.
Withdrawal of the balloon catheter without dislocating the guidewire is a difficult and cumbersome procedure, requiring both a second individual, in addition to the physician, and the attachment of a removable extension to the proximal end of the guidewire. Attachment of the extension to the guidewire during withdrawal of the balloon catheter is necessary because, if the balloon catheter were withdrawn over the proximal end of the guidewire, there would be no way that the guidewire could be manually held stationary. The extension is required to provide a proximal end of the guidewire which will extend outwardly from the proximal end of the balloon catheter even when the balloon catheter is entirely withdrawn from the patient. Even with the extension, the physician must enlist the aid of an assistant to manually hold stationary the proximal end of the guidewire, preventing guidewire movement, while the physician withdraws one balloon catheter and inserts a replacement balloon catheter. This is a cumbersome and awkward procedure at best.
One solution to this difficult procedure is provided in U.S. Pat. No. 4,762,129 to Bonzel. Bonzel discloses a balloon catheter having a single lumen for inflation fluid and a balloon at the distal end of the catheter. The balloon has two passages: a first passage in fluid communication with the lumen of the balloon catheter to inflate the balloon and a second passage for receiving a guidewire therethrough. A guidewir
Acocella Giovanni
Frigerio Federico
Nasio Alejandro
Valencia Carlos A.
Gallagher Thomas A.
Gordon David P.
Jacobson David S.
Mark Two Engineering, Inc.
Thissell Jeremy
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