Percutaneous femoral bypass system

A percutaneous dilator system comprising: PA0 (i) a first dilator tube having a tapered leading end and inwardly directed shoulder means spaced from the trailing end defining a gripping section between the shoulder and the trailing end; PA0 (ii) a bore through the tube dimensioned to receive a guide wire; and PA0 (iii) a second dilator tube having a bore corresponding to the outside diameter of the first tube, a tapered leading end, and an inwardly directed flange at the trailing end dimensioned to note with the shoulder means to limit relative axial mating movement of the first and second tubes while exposing the gripping section; whereby a puncture through tissue containing a guide wire of predetermined guage may be enlarged without substantial tissue damage by placing the first tube over the guide wire through the puncture, then sliding the second dilator tube over the wire and first dilator tube until its flange means engages the shoulder means to enlarge the puncture further, the dilator tubes being subsequently removable as a unit by pulling on the gripping section.

This invention relates to a kit for cannula placement consisting of a 
system of guide wire dilators, sheath, cannulae, obturators and couplers 
for human tissue, and in particular for use in percutaneous 
femoral-femoral bypass systems. 
There are many surgical procedures in which it is necessary to perforate 
tissue and insert a cannula into an internal organ, body cavity or blood 
vessel. Such systems have particular utility in cardiac support prior to 
which it is necessary to bypass the heart to maintain circulation of blood 
through an external circuit. It is common practice to insert a cannula in 
a vein or artery by making an incision through the tissue above a vein or 
artery and in the vessel wall, following which a cannula is sewn in place. 
There is a considerable amount of time necessary, the attendant loss of 
blood, and a risk of damaging of the vessel wall. 
What is required, therefore, is a cannula introducer system with which a 
tube may be placed in a body cavity, organ or vessel in the least invasive 
manner while minimizing the loss of fluids, and which can be inserted with 
relative ease by a skilled technician or physician without the need for 
the presence of a surgeon. 
The present invention, in one aspect, accordingly provides such a system 
comprising of a series of dilator sleeves of gradually increasing internal 
and external diameters, which can be progressively inserted over a wire 
that has been placed into the body within a needle by which an initial, 
small perforation is made. The dilator sleeves have smoothly tapered tips 
such that the perforation can be gradually enlarged without risk of 
tearing of the tissue. The sleeves are flexible and once a perforation of 
the desired size has been made a sheath can be placed over them; 
alternatively the sheath can be mounted around the outer sleeve prior to 
insertion. The innermost sleeve is provided with a shoulder remote from 
its tip and each progressively larger sleeve has an inwardly directed 
flange engageable with the shoulder so that removal of the innermost 
sleeve naturally results in removal of the whole series of sleeves in one 
movement. Subsequently a cannula having an external diameter corresponding 
to the internal diameter of the sheath and having its own obturator may be 
threaded through the sheath over the wire and the cannula eventually 
coupled to whatever equipment is appropriate to the support process, for 
example a heart lung machine. 
According to another aspect of the invention there is provided a cannula 
assembly comprising a conventional cannula adapted for threading over a 
wire, in which there is placed with an interference fit an obturator 
containing a through bore dimensioned to receive a wire. The obturator may 
be provided with an air release valve. 
According to a third aspect of the invention, there is provided a sleeve 
normally placed in position with the outer dilator and including a section 
radially inwardly compressible to act as an obturator. 
According to a fourth aspect of the invention, there is provided a kit 
comprising the components described above packaged for use, for example in 
an emergency room, in cases where a heart perhaps weakened by a heart 
attack can be relieved of a portion of its job by use of the kit and an 
associated pump. 
It should be understood that each of the components, especially the dilator 
kit, is capable of use in other surgical procedures and while the 
invention is described in the environment of giving access to an artery or 
vein, it can be used elsewhere, for example in procedures where 
percutaneous access to the kidney is required or to other internal organs.

THE DILATOR ASSEMBLY 
FIG. 1 illustrates a series of four dilator sleeves 16, 17, 18 and 19, each 
of which has a tip 14, 14', 14"0 and 14"' that is tapered gently to 
facilitate dilation as will be described below. Of particular note is the 
shoulder 15 and the reduced end portion or tail 20 on dilator 16. 
Referring to FIG. 2a, the dilators are shown interlocked with dilator 16 
threaded through dilator 17, dilator 17 through dilator 18 and dilator 18 
through dilator 19. At the end opposite the tips of the dilators, 
shoulders are provided that are engageable with the shoulder 15 (FIG. 2c) 
on dilator 16 so that shoulder 21 on dilator 17 engages the shoulder 15 on 
dilator 16 and so on. Thus, as will be described below once all of the 
dilators are in place, pulling on the removal tail 20 of dilator 16 will 
effect immediate removal of all of the dilator tubes as will be described 
below. 
It should be noted that the internal diameter of the dilator 16 closely 
corresponds to the external diameter of a guide wire 13 (see e.g. FIG. 3) 
so that leakage of blood between the wire and the dilator does not occur, 
at least to any appreciable extent. Similarly, each of the dilators is 
freely but not loosely slidable in relation to its adjacent dilator. The 
dilator sleeves are formed from a suitable polymeric material. 
THE SHEATH AND OBTURATOR 
In FIG. 3, as noted above the wire and dilator sleeves are in place in a 
vein or artery 12. Additionally, there is shown a sheath 24 having an 
obturator 25 with a portion 26 that is readily compressible. The sheath 24 
may be installed after emplacement of the dilator sleeve 16, or may be 
inserted with it for which purpose the assembly of dilator sleeves prior 
to emplacement will have the sheath 24 mounted thereon. The compressible 
portion 26 is shown in FIG. 4 in its compressed state and after removal of 
the dilator sleeves where, to prevent the loss of blood through the sheath 
24 the compressible portion 26 is tightly squeezed over the wire 13 to 
prevent the loss of blood. 
THE CANNULAE 
In FIGS. 5a through 5d, cannulae suitable for use with the dilator system 
described above are illustrated. In FIG. 5a, a cannula 30 having a smooth, 
rounded leading end 43 and a proximal connecting end 44 is shown threaded 
over the wire 13. Within the cannula 30 there is an obturator of tubular 
form 34, with a central bore dimensioned to receive the wire 13. Secured 
to the proximal end 44 of the cannula 30 is a connector 40 of a type known 
to those skilled in the art, and likewise an air release valve 42 having a 
knob 35 is illustrated as secured to the sleeve. A handle element 36 is 
secured to the proximal end of the obturator 34. It will be noted that 
distal end 37 of the obturator is smoothly tapered so that when the 
cannula is passed into a vein or artery or other organ, damage will not 
occur. 
FIG. 5c illustrated a standard tubular arterial cannula tip, and FIG. 5d 
illustrated a venous drainage cannula tip having perforations 33 extending 
over a substantial portion of the leading end of the cannula so that if 
negative pressure is applied at the proximal end of the cannula, there 
will be less of a tendency for the vein in which displaced to collapse. In 
FIG. 5a, a sleeve will be noted, slidable along the exterior of the 
cannula 30, with a slight interference fit. The purpose for the sleeve 
will be described below. 
Referring now to FIGS. 6 through 23, an application for the system 
described is illustrated. Here, a femoral-femoral by-pass is being 
installed, for example for cardiac support. 
In FIG. 6, syringe 10a is illustrated having mounted to it a needle 10. The 
needle is being pushed through the skin into the inferior vena cava 44. As 
is standard in the art, the syringe and needle are operated to withdraw a 
small amount of blood so that the doctor can ensure that the needle is in 
the vein 44. 
Next, as shown in FIG. 7b, wire 13 is threaded through needle 10 and up 
into the inferior vena cava toward the heart. The wire acts as a guide for 
installation of the remaining equipment as described below. 
FIG. 7a illustrated the removal of the needle 10 over the wire 13 after the 
wire is in place. 
In FIG. 8, a scalpel 5 is used adjacent the wire 13 to make a small 
incision in the skin so that the latter will not impede the movement of 
the dilator sleeves. 
In FIG. 9, the inner dilator sleeve 16 is threaded over the wire 13 and 
upwardly into the vein. The tail 20 will be noted at the bottom of the 
Figure. 
In FIG. 10, there is illustrated the progressive threading of the dilator 
sleeves 17, 18 and 19 over the dilator sleeve 16 and wire 13. The opening 
in the skin, subcutaneous tissue and the wall of the vein is thus 
progressively increased to the diameter of the dilator sleeve 19. In FIG. 
11a, the outermost dilator sleeve 19 is shown with the sheath 24 and 
obturator portion 25, following the outside of the sleeve 19. The sheath 
24 may be inserted with the sleeve 19, or may be inoortod separately--it 
is more convenient for it to be inserted with the sleeve 19 as a unit. 
FIG. 11b illustrates the grasping of the tail by the Doctor, and the 
obturation by squeezing of the portion 25 of the sleeve 24. It will 
readily be appreciated that manipulation of the portion 25 of the sleeve 
24 is quite easy, in such a manner that blood cannot escape around the 
wire 13 as the dilator assembly is removed. 
Next, in FIG. 12 prior to installation of the cannula, in this case a 
cannula 30 of the type having a venous drainage tip 32, the cannula is 
being measured for its appropriate penetration into the inferior vena 
cava. The Doctor has laid out the cannula over the abdomen of the patient, 
from a point approximately 2 inches below the nipple line to the point at 
which the perforation has been made in the patient's groin. The sleeve 38 
shown in FIG. 5a is then moved along the cannula until the appropriate 
distance has been established. The cannula, with its obturator as shown in 
FIG. 5a, is then as illustrated in FIG. 13 inserted through the sheath 24 
until the sleeve 38 reaches the sleeve. The Doctor then knows that the tip 
of the cannula is in its correct place, subjacent the heart. After this, 
as shown in FIGS. 13-21, the same series of steps is followed for 
insertion of an arterial cannula of the type shown in part in FIG. 5c. 
Again, the steps of perforating the skin and gaining access to the artery, 
threading of the wire, incision and insertion of dilators (FIG. 17) is 
followed, however, since in this case arterial pressure is met only two 
dilator sleeves are required to provide an opening of the appropriate 
diameter. Otherwise, the steps followed are the same as shown in sequence 
in FIGS. 18, 19a, and 20. In FIG. 20, it can be seen that the Doctor is 
measuring the location of the sheath by laying the cannula over the 
abdomen of the patient from approximately the level of his naval to the 
incision. The arterial cannula does not have to penetrate the artery to as 
great an extent as the venous cannula. 
In FIG. 22, both cannulae are in place and the sleeves 38 have been slipped 
down the cannulae to lock into place, using conventional connectors, on 
tubing conveying blood from the venous system of the patient through e.g. 
a pump back into the arterial system for arterial support. Often, this 
will be preparatory to open heart surgery and it can be seem from FIG. 24 
that in the event that of the patient's chest being opened for open heart 
surgery, an additional venous catheter is installed into the superior vena 
cava connected to the pump through a Y so that the blood will flow in the 
same direction as from the first installed cannula.