Dilatation catheter with side aperture

#"Rapid Exchange"-type balloon dilatation catheters are catheters which are capable of advancement into the vascular system of a patient along a pre-emplaced guidewire for balloon angioplasty or the like, in which the guidewire occupies a lumen of the catheter in only a distal portion thereof. With respect to the catheter proximal portion, the guidewire exits from the internal catheter lumen and extends along the side of the catheter, being typically retained in that position by a guiding catheter in which both the catheter and the guidewire are contained. Examples of catheters of this general type include those disclosed in Horzewski et al. U.S. Pat. No. 4,748,982; Bonzel U.S. Pat. No. 4,762,129; Yock U.S. Pat. No. 5,040,548; and Johnson U.S. Pat. No. 5,334,147.

#In the catheters of the above-cited patents, the distal guidewire lumens of the catheters shown have an aperture through which the guidewire can extend, so that in portions of the catheter proximal thereto the guidewire is outside of the catheter, running essentially parallel to it. By this means, the use of a guidewire extension can be avoided when exchanging catheters, providing a more rapid exchange.

#A disadvantage of some of the prior "rapid exchange" type catheter systems having a lateral aperture is that the reduced length of engagement between the guidewire and catheter can compromise the handling characteristics of the catheter.

#In the drawings, FIG. 1 is a longitudinal, partially sectional view of a catheter in accordance with this invention, positioned in a guiding catheter;

#FIG. 2 is an enlarged, sectional view taken along line 2--2 of FIG. 1;

#FIG. 3 is an enlarged sectional view taken along line 3--3 of FIG. 1; and

#Referring to the drawings, the proximal and distal portions of catheter 10 are shown in accordance with this invention. Catheter 10 is designed for balloon angioplasty, having a typical length of about 140 centimeters and a conventional diameter to permit entry into a small branch 11 of the coronary arteries, for angioplasty by inflation of balloon 12 by pressurizing inflation lumen 14.

#Lumen 14 extends from balloon 12 to a conventional hub 16. Hub 16 has a conduit connection 18 with the inflation lumen, and a second conduit connection 20 with a separate guidewire lumen 22, which extends the entire length of the catheter, as is conventional, to provide access to both lumens.

#Removable mandrin 28 is positioned in a proximal lumen 23, which is separated from guidewire lumen 22 by wall 35. Mandrin 28 can be advanced and retracted by grasping of proximal gripping ring 29. Mandrin 28 is provided for stiffening a proximal portion of the catheter during its insertion in the "rapid exchange" mode. Mandrin 28 may be removed or replaced with another, different mandrin in order to vary the stiffness and other properties of the catheter proximal portion as desired. This can be done at any time, even in the middle of a medical procedure. The mandrin may typically have a diameter of about 0.016 to 0.018 inch, specifically 0.017 inch. Also, mandrin 28 may be releasably locked in place by conventional, interrupted thread twist lock 31 or the like.