Vein valve cutter apparatus

A cutter for the in-situ cutting of valves within a vein. The cutter comprises a catheter having cutter fingers extending from its open distal end in an annular pattern. A sheath is selectively extensible over the fingers to shield them from inadvertent contact with the vein being treated. A fiberoptic viewer extends through the catheter to view through its open distal end.

BACKGROUND OF THE INVENTION 
The present invention relates to a vein valve cutter for use in disrupting 
vein valves during vascular reconstructive surgery. In its more particular 
aspects, it is concerned with a method and apparatus for use in a 
procedure known as in-situ saphenous vein bypass. 
In the in-situ saphenous procedure, atherosclerotic occlusive disease in 
the femoropopliteal arterial system is bypassed with a segment of nearby 
saphenous vein left "in situ"; that is, undissected from its native bed. 
In order to use the saphenous vein as an arterial conduit, the valves of 
the vein must be disrupted. This allows arterial flow to proceed in a 
direction normally prevented by the intact valves. The saphenous vein 
segment, now devoid of valves, is anastamosed to the femoral artery and a 
distal artery, such as the tibial artery, to bypass the diseased section. 
Previous efforts to achieve the in-situ disruption of the valves within a 
vein have included the following techniques: 
1. Valve incision with a pair of tiny scissors performed through venotomies 
proximal the valve sites, or through side branches close to the valve 
sites. 
2. Valve incision performed from below the valve site by passage of a 
valvulotome through the valve followed by incision of the leaflets upon 
pulling of the device back through the valve. The valvulotome is a long 
thin instrument with a curved hook-like cutting tip. It may be introduced 
in the vein being treated through a side branch. 
3. Vein strippers which break the valves upon passage of the strippers in a 
direction against normal blood flow. Such strippers consist of one or two 
bullet-shaped members which are initially introduced in either antegrade 
or retrograde directions. One type of stripper, known as a "Cartier 
stripper" employs a cone-shaped stripper with a circular cutting edge 
around its divergent end. This type of stripper is passed through the 
valve apex end first in the normal direction of blood flow and then drawn 
back in the reverse direction to cut the valve with the circular cutting 
edge. 
4. A more recent type of stripper somewhat related to the latter type 
provides a double cylinder arrangement which is passsed through the vein. 
The initial cylinder is blunt and the second cylinder has two cutting 
blades. In use, the instrument is first passed through the vein and valve 
to be treated in the direction of normal blood flow and then drawn back in 
reverse direction to draw the cutting blades of the second cylinder 
through the valve. 
The above prior techniques involve either cutting of the valves through an 
open incision near the valve site, or the blind passage of a cutting or 
stripping device. The direct open incision method of valve cutting is 
tedious and time-consuming. Blind incision of valves, however, is 
hazardous to the vein being treated. Side branches may be caught and 
avulsed by the valve cutters. Endothelial damage may also result from the 
blind incision of valves. 
SUMMARY OF THE INVENTION 
The cutter of the present invention embodies a catheter having an open 
distal end with annularly arranged cutting fingers extending therefrom. 
The cutter is operable under direct visualization through a lighted 
fiberoptic viewer which extends through the catheter. A sheath surrounds 
the catheter for selective extension over the cutting fingers to shield 
them from undesired contact with the internal walls of a vein as the 
cutter is being directed to the situs of a valve to be cut. In the 
preferred embodiment, the cutter includes fluid infusion means to provide 
pulsatile flow to aid in the identity of valves through the fiberoptic 
scope, and close the valves during the cutting process. 
A principal object of the invention is to provide an improved in-situ vein 
valve cutter which provides for visual viewing to locate valves and assist 
in the control of the cutting operation. 
Another object of the invention is to provide such a cutter which employs a 
plurality of annularly arranged cutting fingers which assure that the 
valve will be effectively cut with a minimum of trauma to the vein. 
Still another object of the invention is to provide such a cutter with a 
sheath to selectively shield the cutting fingers from contact with the 
vein. 
Yet another object of the invention is to provide such a cutter with fluid 
infusion means to provide pulsatile flow during placement of the cutter to 
locate valves. 
A further object is to provide a cutter with such fluid infusion means 
which may be used to apply fluid pressure to a valve during the cutting 
operation to maintain the valve in a closed condition during the 
operation. 
A further object of the invention is to provide a cutter which may be drawn 
through a vein by pushing or pulling forces, or a combination of such 
forces. 
The foregoing and other objects will become more apparent when viewed in 
light of the following detailed description and accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The vein shown in FIG. 1 is designated by the numeral 10 and is shown as 
having a first valve v.sub.1 which has been cut by the instrument of the 
present invention and a second valve V.sub.2 which is intact and in the 
process of being approached by the cutter. The vein shown in FIG. 5 is 
also designated by the numeral 10. As there shown, a third valve v.sub.3 
is shown in the process of having the cutter drawn thereto by the pulling 
instrument of the invention. 
The cutter assembly of the invention is designated in its entirety by the 
numeral 12 and comprises: a catheter 14 having a distal end 16 and a 
through lumen 18 opening through the distal end; four cutting fingers 20 
secured to and extending from the distal end of the catheter; an 
illuminated fiberoptic scope 22 extending slidably through the lumen 18 
for viewing through the open distal end thereof; and, a sheath 24 
telescopically received on the catheter 14 for movement relative thereto 
between the retracted and extended conditions shown in solid and phantom 
lines, respectively, in FIG. 2. A first seal block 26 is secured in sealed 
and concentric relationship to the sheath 24, said seal block housing an 
O-ring 28 in sealed slidable engagement with the catheter 14 and having an 
infusion port 30 in fluid communication with the annular space between the 
catheter 14 and the sheath 24. A second seal block 32 is sealingly secured 
to the proximal end of the catheter 14, said block housing an O-ring 34 in 
sealed slidable engagement with the fiberoptic scope 22. The assembly 
shown in FIG. 1 is completed by a syringe 36 connected in fluid 
communication with the infusion port 30 through a flexible tube 38. The 
syringe provides means whereby fluid pressure may be provided to the 
interior of a vessel within which the cutter assembly is placed. 
The fiberoptic scope 22 may be of the lighted type manufactured by Edwards 
Laboratories of Santa Ana, Calif. In the preferred embodiment of the 
present invention, a scope having an outside diameter of approximately 1 
mm is used. Such scopes have a central monolithic viewing strand 
surrounded by a plurality of peripheral illuminating strands. Although not 
illustrated, it should be understood that the proximal end of the scope 
would be secured to a suitable viewer, such as a magnifying eyepiece or 
video viewer. 
In the illustrated embodiment, the cutting fingers 20 are secured to the 
distal end of the catheter 14 by adhesive and suture winding 40. 
Alternatively, the fingers may be molded into the catheter or attached by 
other means, such as brazing onto a metal insert which is attached to the 
catheter tip. The fingers have rounded smooth distal ends to avoid digging 
into the vein walls. In the embodiment of FIGS. 1, 2, 4 and 5, the fingers 
20 are of cylindrical cross-section, with divergent proximal portions and 
convergent distal portions. This divergent convergent configuration also 
assures that the fingers will not dig into the vein walls. FIG. 3 shows an 
alternative configuration of the cutting fingers, designated 28, wherein 
the fingers have a cross-section with the inner side thereof in the form 
of a knife edge. This embodiment has the same divergent convergent 
configuration and rounded distal ends of the embodiment of FIGS. 1, 2, 4 
and 5. 
The divergent convergent configuration of the cutting fingers 20 and 28 
conforms to the natural configuration of a vein valve leaflet, allowing 
the cutting fingers to slide to the apex of the valve and achieve complete 
valve incision. In the preferred embodiment, four fingers are used to help 
distend the vein for adequate fiberoptic scope visualization during 
cutting, and to assure that at least one of the cutting arms advances to 
the apex of each valve leaflet. Normally, there are two valve leaflets per 
valve. 
The catheter 14 and sheath 24 may be fabricated of any suitable polymer 
material capable of bending to conform to the shape of a vein through 
which the cutter assembly is directed. Ideally, the catheter 14 should 
have sufficient column strength to enable it to be used in a "push mode" 
as shown in FIG. 1. However, in the preparation of extended lengths of 
vein, it may become necessary to pull the cutting assembly to cut the 
valves if the force necessary exceeds the column strength of the catheter 
14. Such a "pulling mode" is seen in FIG. 5. 
Regardless of whether the assembly is placed through a "pushing mode" or a 
"pulling mode", normally the cutting fingers are enclosed by the sheath 14 
until immediately prior to valve cutting. This enclosed condition is shown 
in phantom lines in FIG. 2 and in solid lines in FIG. 4. It assures that 
the cutting fingers will not dig into the walls of the vein through which 
the cutting assembly is passed. 
The sheath 24 provides an annular conduit around the catheter 14 through 
which fluid may be injected into the vein. In use, pulsatile flow is 
applied through this passage to flutter the valves as the cutting assembly 
is passed through a vein so that the valves may be easily visually 
identified through the fiberoptic scope 22. Also, in the preferred use, 
pressure is so applied on a continuous basis to close a valve as it is 
being cut by the fingers 20. Such closing will automatically occur by 
applying reverse pressure to the valves. 
The pulling mode, as seen in FIG. 5, is facilitated by a pulling loop 42 
incorporated into the distal tip of the catheter 14. This loop is normally 
tucked away in a recessed section of the catheter and held in place with a 
circumferential band of shrinkable plastic tubing. When needed, the loop 
is taken out and extended forwardly of the cutting fingers 20. A pulling 
instrument, designated in its entirety by the numeral 44, is provided to 
apply tension to the catheter through the loop 42. This instrument, as 
will be described in more detail subsequently, is threaded through the 
vein in the direction of normal blood flow. 
The pulling instrument 44, comprises a flexible catheter or sleeve 46 
having a wire 48 extending therethrough. A third seal block 50 is 
sealingly secured to the sleeve 46 and contains an O-ring 52 disposed in 
sealed sliding engagement with the wire 48. A side branch conduit 54 is 
incorporated into the block 50 to provide an infusion port 56 in fluid 
communication with the annular passage defined between the sleeve 46 and 
the wire 48. This port provides means whereby fluid pressure may be 
applied to a vein through the pulling instrument. 
The proximal end of the wire 48 has a control knob 58 secured thereto. The 
distal end of the wire is folded over at 60 to provide a hook which may be 
extended over the pulling loop 42. In use, the folded-over distal end 60 
is extended out of the sleeve 46 so that it may be hooked over the loop 
and then drawn back into the sleeve, as shown in FIG. 5. Thus, the loop is 
secured in place and the distal end of the wire is shielded from contact 
with a vein within which the instrument 44 is used. 
In the "pulling mode" the pulling instrument is placed within the vein to 
be treated in advance of securing the cutter assembly to the instrument. 
This is achieved by directing the catheter 46 fully through the vein in 
the normal direction of blood flow and then exiting the distal end of the 
catheter from a proximal venotomy. During such placement, the folded end 
of the wire 48 is retracted within the catheter. Upon exiting from the 
proximal venotomy, the wire is advanced forward by means of the knob 58 
and the folded-over end is hooked around the loop 42. The folded-over end 
is then drawn into the catheter and the pulling instrument is then 
retracted to draw the cutter assembly into the vein, as seen in FIG. 5. 
The cutting operation is then carried out by the same process used in the 
"pushing mode"; the only difference being that the cutter assembly is 
drawn through the vein by a pulling force exerted through the pulling 
instrument, or a combination of pulling force exerted through the 
instrument and pushing force exerted through the cutter assembly. 
As an alternative to the embodiments illustrated and described above, the 
cutting fingers 28 may be bonded directly to the outside cover of the 
fiberoptic scope 22, instead of requiring a separate catheter 14. The 
fiberoptic scope would then not be movable relative to the cutting fingers 
28, and the second seal block 32 would not be required. The sheath 24 and 
first O-ring seal 26 would remain as before, as would the operation, 
except for movement of the scope relative to the catheter 14. This 
embodiment reduces the overall diameter of the cutter. 
Conclusion 
From the foregoing description, it is believed apparent that the present 
invention enables the attainment of the objects initially set forth 
herein. In particular, it provides an in-situ vein valve cutting apparatus 
and method wherein the cutting operation may be visually observed and 
avulsion of side branches and endothelial damage may be avoided. It should 
be understood, however, that the invention is not intended to be limited 
to the specifics of the preferred embodiments, but rather is defined by 
the accompanying claims.