Abstract:
An apparatus and method for insertion of a catheter, such as an IAB catheter, into a blood vessel such that the cross-sectional area of the catheter will be minimized while the circumference of the catheter is maximized. The apparatus is formed as an oval tube of flexible plastic. When placed in a blood vessel, the catheter retains its oval configuration to minimize obstruction to blood flow. During inflation of the balloon bladder at the end of the catheter, the catheter retains its general oval shape. When the catheter is placed in the blood vessel by pre-loading the catheter over a guide wire and inserting the catheter and guide wire without an introducer sheath into the blood vessel both the catheter and its leading balloon bladder are approximately of the same perimeter thereby reducing the possibility of arterial bleeding.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to catheters inserted into the vascular system for extended periods of time, and more particularly, to an oval IAB catheter for insertion into a blood vessel, and the method for placing such catheter into the blood vessel. 
     2. Description of the Related Art 
     Insertion of catheters into the vascular system of humans is a commonly performed procedure. These catheters function as a conduit for inflation of IAB. When a catheter needs to be in place for an extended period of time, it is common to place the catheters from the lower half of the body. Such catheters may have single or multiple lumens, and are typically made from a relatively rigid plastic material with a standard, round cross-section, both to facilitate placement of the catheter into the vessel and to prevent the catheter lumens from collapsing within the vessel. Generally speaking theses catheters are constructed in such a way that the lumen or lumens extending therethrough retain their circular cross-sectional configuration unless an external mechanical force compresses the catheter. 
     A complication of placing such a catheter is formation of clots on the wall of the catheter located in the vascular system. Blood clots form for several reasons. The vessel causes turbulence and slowing of the blood flow through the vessel, and these factors induce the formation of clots. Generally, the greater the cross-sectional area of the catheter relative to the blood vessel, the greater the induced turbulence and slowing of the blood. In addition, the catheter is a foreign body, and the surface of the catheter in contact with blood is an ideal site for clot formation. Once again, the greater the amount of surface area of the catheter or other foreign body in contact with the blood, the more likely that clots will form. 
     Such clots can break away and flow in the blood stream to the heart and lungs, causing severe complications. Furthermore, the formation of clots can often cause such vessels to become irreversibly damaged and thrombose, preventing further blood flow through such vessels. This may ultimately cause debilitating swelling of the limb. 
     Accordingly, it is an object of the present invention to provide a catheter which reduces the likelihood of the formation of clots or reduction in blood flow within the blood vessel into which the catheter is placed while reducing the chances of arterial bleeding at the puncture site of the artery all due to its oval or non-circular shape which has approximately the same perimeter as the balloon attached to the oval catheter. 
     It is another object of the present invention to provide such a catheter which presents a minimal cross-section obstruction to the normal flow of blood within the blood vessel, yet has a maximum circumference to prevent blood leakage at the point of insertion. However, while it is desirable to have a catheter that has a low profile shape, when such a catheter is inserted behind the balloon bladder attached to the front of the catheter, which bladder is larger than the normally used circular catheter, the bleeding may occur at the site of introduction into the body. This is due to the fact the larger diameter of the wrapped balloon bladder which first enters the insertion site leaves behind a diameter opening larger than the smaller circular catheter following the balloon into the insertion site and thereby leaving a space for blood to flow from said opening. Such a problem is discussed, especially when sheathless insertion is performed, in U.S. Pat. No. 4,897,077. The solution to the blood leakage, in that Patent, was to use a hemostasis sheath, but that doesn&#39;t solve the problem of the catheters obstruction of blood flow in the blood vessel. 
     A still further object of the present invention is to provide a method for conveniently placing such a catheter within the desired blood vessel using commonly available vascular apparatus. 
     These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds. 
     SUMMARY OF THE INVENTION 
     Briefly described, and in accordance with the preferred embodiments thereof, the present invention is a catheter apparatus for inserting an IAB device into the body in a modified percutaneous insertion technique without the use of an insertion sheath. Additionally, there is described a device and method to control bleed back through the insertion site after insertion of the wrapped balloon bladder. 
     In accordance with the invention, an insertion technique is provided to enable insertion of an wrapped balloon bladder followed by an oval catheter device directly into a blood vessel over a guide wire, without the need first to inset and use an introducer sheath and with the catheter having a profile within the blood vessel such that it minimizes blood flow restriction. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to the following drawings, which are merely exemplary and are not meant to limit the scope of the invention in any respects. 
     FIGS. 1 a-d  show in succession (a) the puncture of the skin and artery, (b) insertion of the guide wire, (c) dilation of the insertion site and (d) insertion of an insertion sheath all employing a prior art (Seldinger) technique. 
     FIG. 2 is a side elevation view of an IAB device showing the IAB bladder being directly inserted into the femoral common artery without an insertion sheath according to the inventive method; 
     FIG. 3 is a side elevation view of an IAB device showing an oval catheter directly inserted into the femoral common artery without an insertion sheath according to the inventive method; 
     FIG. 4 is a sampling of oval or non-circular cross-sectional area catheters that may be used in the present invention as compared to the present prior art profiles of catheters; 
     FIG. 5 is a side elevation view of an IAB device showing the oval catheter of approximately the same cross-sectional area as the puncture site accordance with the present invention directly inserted into the femoral common artery without an insertion sheath; 
     FIG. 6 is a side elevation view of an IAB device showing the IAB bladder connected to an oval catheter of approximately the same cross-sectional area in accordance with the present invention directly inserted into the femoral common artery without an insertion sheath; 
     FIG. 7 is an alternative to the oval or non-circular cross-sectional area catheters of FIG. 4, wherein the cross-sectional area is shaped in general the same configuration of the insertion site; and 
     FIG. 8 is a side view of an IAB catheter with circular and non-circular cross-sections. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 a-d.  shows various steps employed in the prior art (Seldinger) technique for inserting an IAB device percutaneously. There is show needle  1 , guide wire  5 , dilator  29 , insertion sheath  30 , skin  20  and femoral artery  10 . FIG. a shows puncture of the skin and the femoral artery using a hypodermic needle  1 . FIG. 1 b  shows placement of a guide wire  5  into the artery through the hollow bore of the needle. FIG. 1 c  shows removal of the hypodermic needle  1  from the artery leaving the guide wire  5  in place and the dilation of the opening with dilator  29  (e.g., Grunzig type). Finally, FIG. 1 d  shows placement of any insertion sheath  30 , normally used to control arterial bleeding at the puncture site, into the artery over the guide wire following dilation of the insertion site. This sheath  30 , however, is not needed in the present invention due to the oval cross-section area of catheter  50  as shown in FIG.  4 . 
     With reference to FIGS. 1,  2  and  6  the insertion of an IAB device into the body via a nonsurgical insertion into the femoral common artery through the skin using a percutaneous insertion technique according to the invention will be described. A physician (not shown) would be positioned in the left-hand margin in relation to the various elements being described. In FIGS. 1 a-d.,    2  and  3 , the location of the physician is designated by the symbol “P,”. The terms “proximal” and “distal” as used herein shall refer to position relative to that of the physician. 
     Referring to FIGS. 1 and 2, the IAB device generally comprises IAB bladder  40  which is attached to balloon catheter  42 . The IAB is a double lumen device with a central hollow inner lumen  44  and preferably of the type described in U.S. Pat. No. 4,362,150, which patent is incorporated herein by reference. The hollow inner lumen  44  preferably is a hypodermic tubing with a flexible segment within the balloon. 
     Prior to insertion, the bladder  40  is usually pre-wrapped about itself to reduce its diameter by the manufacturer. The balloon catheter  42  may, for example, as is known in the art is usually connected in a known manner to an intra aortic balloon pumping/monitoring system (also not shown). 
     The insertion technique according to the invention will now be described. 
     With reference to FIGS. 1 a-d  and  3 , a small hypodermic needle is inserted through the skin  20  of a patient to perforate or puncture the femoral artery,  10 . When blood spurts from the open external end of the needle, placement of the hypodermic needle within the artery  10  is confirmed. A guide wire  5  sufficient in length to reach the central aorta is fed into the artery  10  by passing the guide wire through the center of the hollow hypodermic needle. 
     Next, the hypodermic needle is removed leaving the guide wire  5  in place. One or more progressively larger dilators is then placed over the guide wire and advanced through the perforated skin  20  and into the artery  10  in order to expand the holds in order to achieve an opening large enough to permit the passage of the wrapped IAB bladder  40 . For example, when using a 10.5 French IAB the hole should be dilated to approximately 10 French in diameter. Once the skin  20  and artery  10  have been fully dilated, the dilator is removed and the IAB device is inserted directly into the patient without passing it through the insertion sheath. 
     Referring to FIGS. 1 and 3, the JAB bladder  40  of the prior art even in its wrapped condition has a larger outside diameter than the circular IAB catheter  42 . As a result the IAB bladder  40  will dilate the insertion site to a large diameter than that of the catheter  42 . 
     Reference is now made to FIG. 2 b  which shows from left to right, the circular IAB catheter  42  of FIG. 3 with the IAB bladder  40  now inserted into the aorta (not shown). 
     As can be seen in FIG. 3, the insertion site  8  after passage of the IAB, may have an opening which due to some inelasticity in the skin was not completely closed around the circular catheter  42 , this condition may result in uncontrollable bleeding from the insertion site  8 . 
     As a means to diminish this bleeding when it occurs, the present invention utilizes an oval catheter  50  which is coupled to the IAB bladder  40 . 
     The oval catheter  50  has one of the oval configuration of the type shown in FIG.  4 . Oval catheter  50 , in the preferred embodiment is only slightly larger than the outside diameter of the normal circular catheter  42  for such an IAB. Preferably, oval catheter  50  has an outside diameter which is about at least as large or slightly larger than the outside diameter of the IAB bladder  40  in its wrapped condition. 
     FIG. 6 shows the oval IAB catheter  50  now positioned in the insertion site  8  with the insertion site almost completely closed about oval catheter  50 . 
     With reference to FIG. 3, the oval catheter  50  has now been inserted partially into the opening  14  in the wall of the artery  10  with its distal end  52  extending inside the artery  10 . The oval catheter  50  is inserted into the artery  10  such that the oval catheter  50 , fills the opening  14 . As shown in FIG. 6, the oval catheter  50  is thereby able to stops the bleeding which might have resulted after insertion of the normal IAB device. Additionally, the oval catheter  50  dimensioned to pass through the skin  20  and into the artery  10 , and is able with its oval configuration to control bleeding without restricting good blood flow through the artery  10  to any great degree. 
     In accordance with the inventive method, the oval catheter  50  is advanced along the balloon catheter  42  through the skin and into the artery by a sufficient distance to control bleeding from the insertion site  8 . In particular, the oval catheter  50  is advanced to a point where its outside oval diameter sufficiently fills the opening made by the passage of the IAB bladder through the skin and artery to provide an elastic contact between the skin opening and the outside diameter of the oval catheter  50 . In this previously described insertion two seemingly conflicting requirements are met, namely the cross-sectional area of the catheter  50  is minimized, to allow free flow of blood through the vessel  10  while the perimeter of the catheter  50  is maximized to prevent flow of blood from the insertion site  14 . The minimizing of bleeding from the insertion site  14  is the result of the perimeter of the catheter  50  being the same or slightly less than the perimeter of the opening created by the wrapped balloon  40  and therefore chances of bleeding at the insertion site  14  are substantially reduced. Geometrically, this means that the shape of the catheter  50  should not be round. For a given cross-sectional area, a circular body has the minimum cross-sectional area. A non-circular catheter  50  of the same cross-sectional area will have a larger perimeter and will allow for a larger diameter of a wrapped balloon  40 . All non-circular designs, shown in FIG. 4 assume the principle of matching the outside cross-sectional area of a 8.5 Fr design catheter  50  while at the same time having an outside perimeter of a 9.0 Fr. catheter. The non-circular designs of FIG. 4 provide a design which allows for adequate inflation/deflation speeds and also accommodate the a regular size of guide wire  5 . 
     As an alternative to the oval or non-circular catheters of FIG. 4, the catheter may have the shape of FIG.  7 . With the catheter having the shape of FIG. 7, it is closer in shape to the insertion site  8  due to the slightly pointed ends  100  of this catheter. These pointed ends  100  match closely the pointed ends  101  of the insertion site  8  and therefore when insertion site  8  has inserted into it the catheter of FIG. 7, insertion site  8  almost completely mates with the catheter of FIG. 7 to form a complete or almost complete seal and therefore substantially prevents blood from leaking from any space that may be between the outer perimeter of catheter of FIG.  7  and the inner perimeter of insertion site  8 . 
     A further alternative to the catheter  50  is the compound catheter of FIG. 8 in which section A—A is non-circular and section B—B is circular with both section having the same perimeter. In this manner when balloon  40  is tightly wrapped the step down between section B—B and balloon  40  and therefore the size of the insertaion site  8 , which is non-circular can also be minimized. But, since section A—A is the section that ultimately contacts the inner perimeter of insertion site  8  when balloon reaches it final location, the non-circular perimeter of section A—A and the non-circular inner perimeter of insertion site  8  substantially match and therefore there is little or no space between the two for blood to leak. 
     The various features and advantages of the invention are though to be clear form the foregoing description. Various other features and advantages not specifically enumerated will undoubtedly occur to those versed in the are as likewise will many variations and modifications of the invention as defined by the following claims.