This invention generally relates to a catheter system which is suitable for intravascular procedures such as percutaneous transluminal coronary angioplasty (PTCA) and which allows for the exchange of guidewires and catheters during such procedures.
In classic PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient. The guiding catheter is advanced until its preshaped distal tip is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter, so it can be guided into the coronary ostium.
A dilatation catheter having a balloon on its distal end and a guidewire slidably disposed within an inner lumen of the dilatation catheter are introduced into and advanced through the guiding catheter to its distal tip. The distal tip of the guidewire is usually manually shaped (i.e. curved) by the physician or one of the attendants before the guidewire is introduced into the guiding catheter along with the dilatation catheter.
The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, into the patient's coronary artery. A torque is applied to the proximal end of the guidewire, which extends out of the patient, to guide the curved or otherwise shaped distal end of the guidewire as the guidewire is advanced within the coronary anatomy until the shaped distal end of the guidewire enters the desired artery. The advancement of the guidewire within the selected artery continues until it crosses the lesion to be dilated.
The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the flexible, relatively inelastic balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., 4–12 atmospheres) to dilate the stenosed region of the diseased artery. The balloon is then deflated, so the dilatation catheter can be removed from the dilated stenosis and blood flow can then be resumed.
Further details of guiding catheters, dilatation catheters, guidewires, and the like for angioplasty procedures can be found in 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. 4,438,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,582,185 (Samson); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,898,577 (Badger et al.); and U.S. Pat. No. 4,748,982 (Horzewski et al.) which are incorporated by reference.
Recently, Advanced Cardiovascular Systems, Inc., introduced into the marketplace an improved dilatation catheter which is described and claimed in copending application Ser. No. 07/550,801 (Yock), filed Jul. 9, 1990 and U.S. Pat. No. 4,748,982 (Horzewski et al.). This dilatation catheter has a short guidewire-receiving sleeve or inner lumen extending through just the distal portion of the catheter. The sleeve extends proximally at least 10 cm, typically about 25 cm, from a guidewire port in the distal end of the catheter to another guidewire port in the wall of the catheter. A slit is provided in the catheter wall. The slit extends distally from the second guidewire port to a location proximal to the proximal end of the inflatable balloon. The structure of the catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire.
The catheter design embodying the Yock and Horzewski et al. improvements has been widely praised by members of the medical profession and has met with much commercial success in the market place. Nonetheless, there are some inconveniences in its use because the catheter does not allow for the exchange or replacement of the guidewire. For example, the shaped distal tip of the guidewire may become deformed in use or the shape of the distal tip or the size of the guidewire may be found to be no longer suitable for the particular procedure within the patient's vasculature. In this instance the physician might want to remove the guidewire and reshape the distal tip or replace the first guidewire with another having the desired size, stiffness or shape.
When the guidewire in a dilatation catheter system embodying the Yock and Horzewski et al. improvements is removed, however, access to the desired arterial location through the distal guidewire lumen of the catheter is lost. Unfortunately, there is no way to clinically determine before the guidewire is inserted into the patient in an angioplasty procedure whether a guidewire or a catheter will have to be exchanged during the procedure.