Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1995-06-07
2001-11-27
Thaler, Michael H. (Department: 3309)
Surgery
Instruments
Internal pressure applicator
C604S096010
Reexamination Certificate
active
06322577
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to a dilatation catheter for angioplasty procedures such as percutaneous transluminal coronary angioplasty (PTCA).
In PTCA procedures, a dilatation catheter having an inflatable, relatively inelastic balloon on the distal end thereof is advanced through a patient's arterial system until the balloon crosses the atherosclerotic lesion to be dilated. The balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., 8 atmospheres) to dilate the stenotic region and then the balloon is deflated so that the catheter can be removed and blood flow resumed.
Usually a guiding catheter having a preformed distal end is first percutaneously introduced into the patient's arterial system and advanced therein until the distal tip of the guiding catheter is disposed in the appropriate ostium of the patient's coronary artery. A guidewire is preloaded within a dilatation catheter and both are advanced through the previously positioned guiding catheter to the distal end thereof. The guidewire is first advanced out of the guiding catheter into the patient's coronary anatomy until the distal end of the guidewire crosses the stenotic region to be dilated. The dilatation catheter is then advanced over the guidewire, with the guidewire slidably disposed within an inner lumen of the catheter until the inflatable balloon is positioned within the stenosis. The balloon is inflated to a relatively high pressure to dilate the stenosis and then deflated and removed over the guidewire. For a detailed description of procedures, reference is made to U.S. Pat. No. 4,332,254 (Lundquist), U.S. Pat. No. 4,323,071 (Simpson-Robert), U.S. Pat. No. 4,439,185 (Lundquist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat No. 4,516,972 (Samson), U.S. Pat. No. 4,538,622 (Samson et al.), U.S. Pat. No. 4,554,929 (Samson et al.), U.S. Pat. No. 4,569,347 (Frisbie), U.S. Pat. No. 4,571,240 (Samson et al.), U.S. Pat. No. 4,638,805 (Powell), U.S. Pat. No. 4,748,982 (Horzewski et al.), all of which are hereby incorporated herein in their entirety by reference thereto.
Efforts have been made to develop dilatation catheters which perfuse blood through an inner lumen of the catheter which traverses the interior of the balloon when the balloon is inflated during angioplasty procedures in order to avoid ischemic conditions distal to the inflated balloon. For example, dilatation catheters providing perfusion capabilities are described in U.S. Pat. No. 4,423,725 (Baran et al.) and U.S. Pat. No. 4,790,315 (Mueller, Jr. et al.) which are incorporated herein by reference thereto. See also, U.S. Pat. No. 4,581,017 (Sahota). However, these perfusion dilatation catheters generally have relatively large deflated profiles and as a result they frequently are not employed in those situations where the stenoses to be treated are deep within the patient's coronary anatomy.
Additionally, in instances where there is an acute or sudden blockage of the arterial passageway after dilatation of a stenotic region, conventional dilatation non-perfusion type catheters must first be removed from the patient before a perfusion-type dilatation catheter can be advanced over the guidewire in place within the patient. Usually, such catheter exchanges require the use of an exchange wire or extension wire such as described in U.S. Pat. No. 4,827,941 (Taylor et al.), which can add considerable time and complexity to a procedure frequently performed under emergency conditions.
What has been needed and heretofore unavailable is a perfusion-type dilatation catheter which can quickly and easily be introduced into a patient's arterial system and which has sufficient pushability to be advanced deep within the patient's vasculature. The present invention satisfies this need.
SUMMARY OF THE INVENTION
The present invention is directed to a dilatation catheter which can be readily exchanged without the need for extension wires or for the replacement of the guidewire with an exchange wire and which can also perfuse blood distal to the catheter when a vascular procedure is being performed within the blood vessel which otherwise blocks the flow of blood through.
A catheter in accordance with the invention generally has an elongated catheter body with an inflatable, relatively inelastic balloon near the distal end thereof. The catheter body has a first elongated inner lumen extending from the proximal end of the catheter body to the interior of the inflated balloon near the distal end thereof to deliver inflation fluid to the interior of the balloon. A second, much shorter inner lumen extends within the distal portion of the catheter body between a proximal guidewire port and a distal guidewire port provided in the distal end of the catheter body. The distal guidewire port is in the very distal tip of the catheter body and the proximal guidewire port is at least 10 cm but not more than about 50 cm from the distal guidewire port. The second, much shorter lumen within the catheter body is adapted to slidably receive a guidewire to facilitate the advancement of the catheter over the guidewire into the patient's coronary anatomy.
At least one proximal perfusion port is provided in the catheter body between the proximal guidewire port and the proximal end of the balloon and at least one distal perfusion port is provided in the catheter body between the distal end of the balloon and the distal end of the catheter body. Both the proximal and distal perfusion ports are in fluid communication with the second, shorter lumen disposed within the catheter body so that blood flows distal to the catheter when the balloon is inflated during the vascular procedure. The number, size and location of the perfusion ports can be varied depending upon the blood flow required, the size of the catheter and the size of the inner lumen. Typically, there may be 6 to 20 perfusion ports proximal to the balloon and about 4 to 12 perfusion ports distal to the balloon. In a preferred embodiment 10 ports are provided proximal to the balloon and 4 are provided distal to the balloon.
The cross-sectional area of the last or most distal part of the inflation lumen, which is less than 30 cm, preferrably in the last 10 cm the inflation lumen proximal to the balloon, is at least about 3 to about 20×10
−5
inch
2
and should not be greater than about one-third of the cross-sectional area of the perfusion lumen. This reduces considerably the catheter profile, allowing the catheter to be advanced much deeper into a patient's coronary vasculature, yet maintains adequate inflation and deflation times (e.g. less that about 30 seconds preferably less than about 20 seconds). The proximal end of the catheter body is provided with an adapter with at least one arm for the delivery of inflation fluid from a high pressure source thereof such as a syringe to the proximal end of the inflation lumen leading to the interior of the balloon for inflation purposes.
Preferably, the catheter wall which defines at least in part the second, shorter, guidewire-receiving lumen disposed within the catheter body is provided with a slit which extends from the proximal guidewire port to a location proximal to the section containing the proximal perfusion ports. The purpose of this slit, as described in U.S. Pat. No. 4,748,982 (Horzewski et al.) which has been previously incorporated herein, allows the guidewire to be pulled out of a significant portion of the second lumen to increase the ease in which catheters can be exchanged.
The portion of the elongated catheter body proximal to the proximal guidewire port is provided with a stiffening member such as a rod or wire which increases the pushability of the catheter and thereby allows for more distal advancement of the catheter into the patient's coronary anatomy than previous perfusion-type catheters.
In the performance of an angioplasty procedure utilizing the catheter assembly of the invention, it is preferred to preload the guidewire w
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