looking at fig1 a and 8a , the microcatheter 10 has a hub portion 11 joined to catheter portion 12 . in its preferred embodiment for use in interventional radiology , the catheter portion 12 is a 3 . 5 french or smaller diameter catheter with an internal lumen of 0 . 026 to 0 . 010 inches . as seen in fig1 a , 2b , 3a , and 8a , the catheter portion 12 can be viewed as having a proximal segment 13 near the hub 11 , followed by a middle segment 14 , and a distal segment 15 which terminates in a tip 16 . the over all length of the catheter portion 12 will typically measure 150 cm , but it can be made in varying sizes between 60 cm and 175 cm in length . the catheter portion 12 is made of any of a number of plastic materials , including polyethylene , polyurethane , may be coated internally or externally with a hydrophilic coating , and may contain metal braiding inherent to its walls . preferably , the distal segment 15 of the catheter will include a radio - opaque marker band 27 ( fig3 a ) near the tip 16 so that the radiologist can accurately track the movement and position of the catheter tip 16 . in accordance with one of the novel features of the microcatheter 10 , a parachute structure 20 is attached to the distal segment 15 of the catheter 12 by one or more distal control strings 21 and one or more proximal control strings 22 . the strings 21 , 22 can be strings , wires , or cables made of a flexible , high - tensile strength biocompatible material . they may be radioopaque . the parachute structure 20 will preferably have either a rectangular shape ( fig5 a - c ) or a triangular shape ( fig6 a - c ). the hub portion 11 of the microcatheter 10 remains outside the body when the microcatheter 10 is used . the hub 11 is also made of plastic and has an internal geometry in the shape of a funnel such that the input side of the hub 11 is easily connected to a standard 2 or 3 - way stopcock ( not shown ). the output side of the hub 11 ( the narrow end of the funnel ) connects to the small internal lumen of the catheter portion 12 . looking at fig2 a , the cylindrical wall 17 of the catheter 12 is manufactured so that four small diameter string channels 18 are formed within the wall 17 and traverse the length of the catheter 12 either in a straight ( fig2 b ) or spiral ( fig2 c ) configuration . the string channels 18 must be large enough to slidably accommodate the distal and proximal control strings 21 , 22 and small enough so that they do not significantly alter the strength , trackability , or stiffness of the inherent microcatheter . when the triangular form of the parachute 20 is used , only 3 straight or spiral channels 18 are necessary . within each of the four channels 18 are the proximal and distal control strings 21 , 22 . the control strings 21 , 22 enter their corresponding channels 18 through openings in the catheter wall 17 near or through the base of the hub 11 ( fig1 a and 1b .) the strings 21 , 22 then extend through their corresponding channels 18 the length of the catheter 12 to the distal segment 15 of the catheter . the distal control strings 21 exit their corresponding channels 18 through distal string apertures 23 through the catheter wall 17 , close to the tip 16 . as seen on fig3 b , the distal string apertures 23 are formed at opposed positions that are near but slightly separated from the transverse midline 25 of the catheter tip 16 . as best seen on fig3 c and 3d , the proximal control strings 22 exit from their channels 18 through proximal string apertures 24 that are positioned away from the distal string apertures 23 . the proximal string apertures 24 are located through the catheter wall 17 in positions opposite of the distal string apertures 23 , separated slightly away from the midline 25 . thus , the linear distance between the respective distal and proximal string apertures 23 , 24 is slightly less than the diameter of the catheter 12 . in the preferred embodiments of fig5 a - c , the distal and proximal control strings 21 , 22 are attached to the corners of a rectangular parachute 20 made of a radio - opaque , biocompatible material , such as silicon , that retains its shape when exposed to blood at 37 ° centigrade . alternatively , the parachute 20 may be triangular in shape ( fig6 a - c ) with the proximal corner 26 aligned with the long axis of the catheter 12 when the parachute 20 is in a parked or non - deployed position as shown on fig7 . the control strings 21 , 22 may be attached to the parachute 20 in any of a number of configurations , some of which are illustrated in fig5 a - c and 6a - c . for example , as seen in fig5 a , the four control strings 21 , 22 can be attached to the four corners of the parachute 20 . in fig5 b , two control strings are actually one string , with a proximal string 22 attached along the proximal marginal edge of the parachute 20 , and the distal control string 21 attached along the more distal marginal edge of the parachute 20 . or , as illustrated in fig5 c , the distal and proximal control strings 21 , 22 can be oriented in a criss - cross configuration , with the distal string 21 extending from a distal corner of the parachute 20 and , embedded into the parachute 20 , connected to the diagonally opposite proximate corner of the parachute 20 . the proximal string 22 is then attached in an opposite diagonal configuration . when employing a triangular shaped parachute 20 as in fig6 a - c , the two distal strings 21 are attached to the distal corners of the parachute 20 ( fig6 b ). alternatively , a single distal string 21 can be attached along the distal margin of the parachute , as seen in fig6 c . the control strings 21 , 22 must be attached to the parachute 20 in a conventional manner such that there would be no possibility of tearing at the junction point . as seen on fig3 d and fig8 b , the proximal width of the deployed parachute 20 should be slightly less than the width of the catheter 12 . the length of the parachute 20 is approximately 3 mm . when beginning use of the parachute microcatheter 10 , the non - deployed parachute 20 will be &# 34 ; parked &# 34 ; near the exterior surface of wall 17 at the distal segment 15 so that the catheter 10 and parachute 20 combination will have a low profile . this is done by having the radiologist manipulate the hub end of the control strings 21 , 22 ( fig1 a - b ). the catheter 12 and parachute 20 will then be advanced through a &# 34 ; y &# 34 ; connector connected to a guiding catheter ( not shown ), exiting the vessel in which the tip of the guiding catheter resides . once the catheter 12 is recognized to have exited the guiding catheter and is identified by the radio - opaque marker band 27 in the tip of the microcatheter , the control strings 21 , 22 are then advanced distally by the radiologist so that the parachute 20 is deployed , as shown on fig8 . the parachute 20 is opened by the flowing blood and / or injection of saline or contrast through the tip 16 of the catheter 12 . once the parachute 20 is opened , this will pull the catheter 12 into the cerebral vasculature . movement of the catheter can be directed to the appropriate vasculature by manipulation of the control strings 21 , 22 just as a target skydiver will control his or her parachute . alternatively , if a high - flow situation is not present , the parachute 20 can be used to access the largest intracranial vessels then can be withdrawn to resume its parked position flush with the tip 16 . then a guide wire can be employed through the lumen of the catheter 12 . because of the location of the control string apertures 23 , 24 the strings will not obstruct the tip 16 and will assume a position along the outer wall 17 . when the procedure is complete , the radiologist will then manipulate the control strings 21 , 22 in a proximal direction , causing the parachute to once again assume the parked position . the catheter 12 can then be withdrawn . the embodiments of the microcatheter described herein are shown with three or four control strings . however , more control strings could be used without departing from the scope of the invention . thus , although there have been described particular embodiments of the present invention of a new and useful &# 34 ; microcatheter with auxiliary parachute guide structure &# 34 ;, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims . further , although there have been described certain dimensions used in the preferred embodiment , it is not intended that such dimensions be construed as limitations upon the scope of this invention except as set forth in the following claims .
a microcatheter with a deployable parachute attached to its distal tip is disclosed . the parachute in its retracted position lies flush against the exterior wall of the distal segment of the catheter . control strings , cables or wires traverse the length of the microcatheter through channels within its wall and exit through strategically placed apertures at the tip of the microcatheter to attach to the parachute . when the parachute is deployed , the microcatheter is guided by blood flow or jets of liquid that are injected through the microcatheter . when the parachute is retracted , the microcatheter may be used with a guidewire to superselect vasculature . the microcatheter device has multiple uses permitting diagnostic and therapeutic superselective angiography .