reference is made to fig1 - 6 which schematically illustrate perfusion dilatation catheter 10 embodying features of the invention . catheter 10 has an elongated shaft 11 with proximal and distal shaft sections 12 and 13 , an adapter 14 on the proximal end of the shaft and a dilatation balloon 15 on the distal shaft section spaced proximal to the distal end . an inflation lumen 16 extends between the proximal end of shaft 11 and a location spaced proximal to the distal end 16 and is in fluid communication with the interior of the dilatation balloon 15 . the catheter shaft 11 is provided with a first inner tubular member 18 and an outer tubular member or jacket 19 of suitable polymeric material . a guidewire receiving lumen 20 extends within both the proximal and distal shaft sections 12 and 13 . in the distal shaft section 12 , the lumen 20 is defined at least in part by the first inner tubular member 18 . the distal shaft section 13 is also provided with a second inner tubular member 21 which defines the inflation lumen 16 therein . the outer tubular member 19 secures the inner tubular members 18 and 21 and preferably is bonded to the exterior surface of first tubular member 17 by suitable means such as a suitable adhesive or heat or fusion bonding . additionally , the outer tubular member 19 may be heat shrunk onto the inner tubular members 18 and 21 . the balloon 15 has a proximal skirt 22 which is secured to distal end of the outer tubular member 19 and a distal skirt 23 which is secured to the distal end of the first inner tubular member 18 and which extends beyond the distal end of the inner tubular member forming the guidewire lumen 20 from the distal end of the first inner tubular member the distal port 24 in the distal end of the catheter . a distal perfusion portion 25 of the distal shaft section 13 is formed at least in part by the portion of the distal skirt 23 which extends beyond the distal end of the first inner tubular member 18 and it is preferably tapered as shown . four perfusion ports 26 are disposed circumferentially about the axis 27 of the catheter shaft 11 at the large diameter end of the distal perfusion section and three perfusion ports 28 are disposed circumferentially about the axis 27 of the catheter shaft at the small diameter end of the distal perfusion section . a radiopaque marker 29 is provided at the distal end of the first inner tubular member 18 to facilitate fluoroscopic observation thereof within the patient &# 39 ; s vasculature , particularly the patient &# 39 ; s coronary anatomy . a proximal perfusion portion 30 of the distal shaft section 13 is located proximal to the balloon 15 . typically , the proximal perfusion portion 30 has about 8 to about 12 perfusion ports 31 which extend through the secured or bonded walls of the first inner tubular member 18 and the outer tubular member 19 . while a plurality of ports 31 are depicted in the drawing , a single elongated perfusion port can be employed in the proximal perfusion portion 30 in lieu of a plurality of ports 31 . the outer tubular member or jacket 19 may be formed of suitable polymeric material such as polyethylene , a polyester such as hytrel ® ( trademark of dupont ), polyetheretherketone ( peek ) or a variety other polymeric materials . see , for example , the discussions of high modulus polymeric materials for catheter shafts found in u . s . application ser . no . 08 / 280 , 210 , filed on jul . 25 , 1994 , which is incorporated herein by reference in its entirety . the first inner tubular member 18 may be formed of the same material as the outer tubular member 19 or a lubricous material such a fluoropolymer or a hydrophilic material , e . g . the ethylene ethyl acrylate copolymer described in copending application ser . no . 08 / 279 , 239 , filed on jul . 22 , 1994 , which is incorporated herein by reference in entirety . the low friction surface of the guidewire receiving lumen 20 facilitates the advancement of a guidewire 31 within the guidewire receiving lumen defined by the first inner tubular member 18 . the first inner tubular member 18 typically has an outer diameter of about 0 . 036 inch ( 0 . 9 mm ) an inner diameter of about 0 . 033 inch ( 0 . 8 mm ). the second inner tubular member 21 typically has an outer diameter of about 0 . 044 inch ( 1 . 1 mm ) and an inner diameter of about 0 . 040 inch ( 1 mm ). fig7 and 8 schematically illustrate another embodiment of the invention wherein the perfusion dilatation catheter 50 is provided with rapid exchange characteristics such as described in u . s . pat . no . 5 , 040 , ( yock ), u . s . pat . no . 4 , 748 , 982 horzewski et al ), u . s . pat . no . 5 , 496 , 275 ( sirhan et al ) and u . s . application ser . no . 08 / 183 , 574 , filed on jan . 18 , 1994 which have been incorporated herein . the catheter 50 generally has an elongated catheter shaft 51 and an inflatable dilatation balloon 52 on the distal shaft section 53 . an inflation lumen 54 extends within the proximal shaft section 55 and the distal shaft section 53 to a location spaced proximal to the distal end of the catheter shaft 51 and is in fluid communication with the interior of the balloon 52 . a guidewire receiving lumen 56 extends from the distal port 57 in the distal end of the catheter shaft 51 to a proximal port 58 spaced proximal to the distal end of the catheter shaft . the distal shaft section 53 , as best shown in fig8 has a dual lumen construction and generally is formed by extruding into that form . alternatively , the distal shaft section may have a first inner tubular member , a second inner tubular member which defines the inflation lumen 54 within the distal shaft section and an outer tubular member or jacket which surrounds and secures together the first and second tubular members as in the prior embodiment . a slit 60 is preferably provided through the wall defining the guidewire lumen 56 which extends from the proximal port 58 to a location spaced proximal to the proximal perfusion portion 61 of the distal shaft section 53 . the distal perfusion portion 62 is shown as being essentially the same as in fig1 - 6 and is similarly numbered . fig9 illustrates a distal tip of a perfusion catheter wherein the ports 70 in a first row of circumferentially arranged perfusion ports are staggered with respect to the perfusion ports 71 in a second row of circumferentially arranged perfusion ports located adjacent to the first row . to the extent not described herein or in any of the u . s . patents or patent applications which have been incorporated herein by reference , the dimensions , structural details and materials of construction may follow conventional practice for intravascular catheters such as balloon dilatation catheters used in angioplasty procedures . various changes and modification may be made to the present invention without departing from the scope of the invention . moreover , although individual features of the several embodiments of the invention may be shown in some of the drawings and not in others , those skilled in the art will recognize that individual features of one embodiment of the invention can be combined with any or all the features of another embodiment . for example , the construction of the distal shaft section of the catheter shown in fig1 - 6 could be that shown in fig7 and 8 , i . e . the distal shaft section could be of a extruded dual lumen .
a perfusion catheter of the invention has an improved short , distal perfusion portion with a high flow rate . the distal perfusion portion has at least two rows of circumferentially disposed perfusion ports and is preferably tapered in the distal direction from larger cross - sectional dimensions to smaller cross sectional dimensions , with the number of perfusion ports in the most distal row of circumferentially disposed perfusion ports being less than the number of a perfusion ports in a row of perfusion ports proximal to the most distal row . the distal perfusion portion is most conveniently formed from a distal skirt of a dilatation balloon on the distal section of the catheter .